Release 0.18.0: email + webhook hygiene (roadmap items #18 + #20)

VERSION + frontend/package.json -> 0.18.0. CHANGELOG entry with
the binding Upgrade-steps block per SPEC.md §20.4.

This release lands all five slices of the v0.18.0 proposal at
~/git/ohm-infra/RFC-APP-EMAIL-HYGIENE-PROPOSAL.md:

  Slice 1: build_envelope helper + unit tests.
  Slice 2: migrate send paths; add POST /api/email/unsubscribe
           for RFC 8058 one-click.
  Slice 3: mandatory GITEA_WEBHOOK_SECRET (+ dev-bypass) +
           unknown-repo logging.
  Slice 4: outbound_emails audit table + admin endpoint.
  Slice 5: bounce correlation via Message-ID.

Full suite: 295 passed (was 252 pre-release).

Upgrade-steps (RFC 2119) block in CHANGELOG covers:
  * MUST: GITEA_WEBHOOK_SECRET non-empty at startup.
  * MAY: RFC_APP_INSECURE_WEBHOOKS=1 for local dev only.
  * MAY: EMAIL_UNSUBSCRIBE_MAILTO to route opt-out courtesy mail
         to a different mailbox than EMAIL_FROM.
  * MUST: apply migration 020_outbound_emails.sql (auto-applied
          on next start; no operator action).
  * MUST: rebuild frontend + restart backend.
  * SHOULD: run mail-tester.com probe post-upgrade.

CHANGELOG.md

@@ -23,6 +23,388 @@ skip versions are the composition of each intervening adjacent
 release's steps in order — no A-to-B path is pre-computed beyond
 that.
 
+## 0.18.0 — 2026-05-28
+
+**Minor — schema migration required; one env var now mandatory; no
+new secrets.** This release lands the framework-side half of OHM
+roadmap items #18 (Secure the SMTP relay + Gitea webhook) and #20
+(Email deliverability). It is the framework counterpart to the
+operator-side SMTP / DNS hardening covered in the
+`EMAIL-AND-WEBHOOK-HARDENING-RUNBOOK.md` companion doc.
+
+The release is shipped in five atomic slices per the v0.18.0 proposal:
+
+1. **`build_envelope` shared helper.** A single place where every
+   outbound `EmailMessage` is constructed. Lands the
+   deliverability-critical headers (`Date`, `Message-ID`,
+   `Auto-Submitted`) uniformly across OTC, invite, watcher
+   notification, bundle, and digest paths; exposes per-kind
+   unsubscribe semantics (none for OTC, mailto: for invites, full
+   one-click for bulk-adjacent paths) as explicit kwargs.
+2. **Migrated send paths.** `email_otc.py`, `email_invite.py`,
+   `email._deliver`, `email._send_bundle`, and `digest.py` now
+   build their envelopes through the helper. Per-RFC invite
+   (v0.16.0) rides through `email_invite.py`'s helper and picks
+   up the change for free. The shared `_SENT` test buffer also
+   carries the constructed `EmailMessage` under `envelope["message"]`
+   so tests can assert on the header surface directly.
+3. **Webhook handler tightening.** `GITEA_WEBHOOK_SECRET` is now
+   mandatory at startup — the framework refuses to load_config()
+   if it's empty, unless the operator explicitly opts into the
+   dev-bypass with `RFC_APP_INSECURE_WEBHOOKS=1`. The
+   `/api/webhooks/gitea` receiver carries defense-in-depth checks
+   that surface the misconfiguration loudly at the request layer
+   too. Mis-targeted webhooks (a hook on a fork or a stale Gitea
+   binding) now log at INFO instead of silently 200-OK'ing.
+4. **`outbound_emails` audit table + admin endpoint.** Every send
+   helper writes one row to `outbound_emails` before returning,
+   capturing the send attempt regardless of outcome
+   (status='sent' / 'failed' / 'deferred'). The new admin endpoint
+   `GET /api/admin/outbound-emails` (filterable by kind / status /
+   to_address) lets the operator answer "did this person ever get
+   their invite?" without grepping VM logs. No admin UI ships
+   with v0.18.0; operator queries via curl + jq for now.
+5. **Bounce correlation.** The `POST /api/webhooks/email-bounce`
+   body accepts a new optional `message_id` field; when supplied,
+   the handler stamps status='bounced' on the matching
+   `outbound_emails` row and returns the row id as
+   `correlated_id`. The pre-existing hard-bounce ->
+   `email_opt_out_all = 1` flow still fires.
+
+The `POST /api/email/unsubscribe` endpoint also lands in Slice 2
+as the matching receiver for the new `List-Unsubscribe-Post:
+List-Unsubscribe=One-Click` header (Gmail and Yahoo POST that
+payload on the user's one-click action per RFC 8058 — the GET
+endpoint alone is no longer sufficient for senders at OHM's tier).
+
+### Added
+
+- **`backend/app/email_envelope.py`** — the `build_envelope` helper.
+  Single source of truth for every outbound `EmailMessage`'s
+  headers + body shape. Standalone module so tests can exercise it
+  without booting the FastAPI app.
+- **`backend/migrations/020_outbound_emails.sql`** — the audit
+  table. Single new table with three indexes (to_address, sent_at,
+  message_id); no changes to existing tables.
+- **`email.record_outbound(...)`** — best-effort write helper every
+  send path calls. Catches `RuntimeError` (so pure-helper unit
+  tests where `db.init()` was never called don't break) and any
+  other exception (so the audit write never breaks a send).
+- **`GET /api/admin/outbound-emails`** in `api_admin.py` —
+  admin-only listing of `outbound_emails`. Newest-first, filterable
+  by kind, status, and to_address (case-insensitive). Returns
+  `{items: [...], has_more}` per the rest of the admin endpoints'
+  shape.
+- **`POST /api/email/unsubscribe`** in `api_notifications.py` —
+  RFC 8058 one-click receiver. Accepts the same `?t=` token as the
+  GET handler; idempotent; returns 200 + `{ok, category}` on
+  success.
+- **`all` synthetic category** for unsubscribe URLs. Used by the
+  bundle + digest paths (which can't honor per-category opt-outs
+  because they span multiple categories); flips
+  `email_opt_out_all = 1` rather than a per-category column.
+
+### Changed
+
+- **`backend/app/email.py`** — `EmailConfig` gains
+  `unsubscribe_mailto` (env: `EMAIL_UNSUBSCRIBE_MAILTO`, default
+  falls back to `EMAIL_FROM`). `_deliver` and `_send_bundle`
+  build envelopes through `build_envelope` and thread `kind` +
+  `notification_id` into the audit write.
+- **`backend/app/email_otc.py`** + **`email_invite.py`** — both
+  call `build_envelope` and `record_outbound`. OTC carries no
+  `List-Unsubscribe` (recipient explicitly requested the code);
+  invite carries `List-Unsubscribe: <mailto:…>` only (no signed
+  URL — the invitee isn't a user yet, no per-user opt-out row
+  exists).
+- **`backend/app/digest.py`** — calls `_deliver` with `kind='digest'`
+  + the new `all`-category one-click unsubscribe.
+- **`backend/app/webhooks.py`** — refuses 500 at request time if
+  the secret is empty + bypass isn't set; logs a loud warning
+  per-request when running under the bypass; logs INFO when a
+  hook targets a repo not in `cached_rfcs`.
+- **`backend/app/config.py`** — `load_config()` raises
+  RuntimeError if `GITEA_WEBHOOK_SECRET` is empty unless
+  `RFC_APP_INSECURE_WEBHOOKS=1`.
+- **`backend/app/api_notifications.py`** — GET unsubscribe handler
+  accepts the `all` category (sets `email_opt_out_all = 1`).
+  Bounce webhook body adds optional `message_id` field; response
+  shape adds `correlated_id` field. (Tests that read the exact
+  response shape — currently just
+  `test_bounce_webhook_refuses_unsigned_when_secret_configured`
+  in test_e2e_smoke.py — updated to assert on the new shape.)
+- **`backend/tests/test_propose_vertical.py`** — the shared
+  `tmp_env` fixture binds a fake `GITEA_WEBHOOK_SECRET` so all
+  252 pre-v0.18.0 tests boot cleanly under the new mandatory
+  secret. Tests that want to exercise the dev-bypass path
+  monkeypatch `RFC_APP_INSECURE_WEBHOOKS=1` explicitly.
+
+### Tests
+
+- 15 new unit tests in `test_email_envelope.py` for the helper.
+- 10 new integration tests across `test_otc_vertical`,
+  `test_admin_create_user_invite_vertical`, and
+  `test_notifications_vertical` covering: OTC has no
+  List-Unsubscribe; invite has mailto: only; notification has
+  full one-click; POST one-click flips per-category; `all` flips
+  global; respects `EMAIL_UNSUBSCRIBE_MAILTO` override.
+- 7 new integration tests in `test_webhooks_vertical.py` covering
+  the startup-time mandatory-secret check, the dev-bypass, and
+  the request-time signature verification including the unknown-
+  repo log line.
+- 11 new integration tests in `test_outbound_emails_vertical.py`
+  covering the audit table write path (OTC / invite / notification),
+  the admin endpoint (list, filter by kind, filter by to_address,
+  non-admin refusal), and the bounce correlation (matched
+  message_id stamps status='bounced'; unknown message_id is
+  logged; absent message_id falls back to legacy behavior; bounced
+  rows surface in admin endpoint with `?status=bounced`).
+- One test updated for intentional response-shape change:
+  `test_e2e_smoke.test_bounce_webhook_refuses_unsigned_when_secret_configured`.
+
+Full suite: 295 passed (was 252 pre-v0.18.0).
+
+### Migration
+
+- **`backend/migrations/020_outbound_emails.sql`** — auto-applied
+  on next backend start. Single new table with three indexes; no
+  changes to existing tables.
+
+### Upgrade steps (from 0.17.0)
+
+- Operators **MUST** ensure `GITEA_WEBHOOK_SECRET` is set in the
+  deployment's env. The framework now refuses to start if it's
+  empty. (For OHM-flotilla deployments,
+  `flotilla secret list <deployment>` confirms the binding; OHM
+  has carried this binding since v0.14.0, so the upgrade is
+  gesture-free for OHM specifically.)
+- Operators **MAY** set `RFC_APP_INSECURE_WEBHOOKS=1` to bypass
+  the requirement in local-dev environments. Production
+  deployments **MUST NOT** set this; if they do, every webhook
+  POST logs a loud warning line per request.
+- Operators **MAY** set `EMAIL_UNSUBSCRIBE_MAILTO` to route
+  `List-Unsubscribe: <mailto:…>` opt-out courtesy mail to a
+  humans-monitored mailbox distinct from the no-reply
+  `EMAIL_FROM` sender. Default falls back to `EMAIL_FROM`.
+- You **MUST** apply schema migration
+  `020_outbound_emails.sql`. The migration creates a single new
+  table with three indexes; the framework runs migrations
+  automatically at process start, so no manual step is required
+  beyond restarting the backend so the migration runner picks
+  the file up. Existing deployments pick it up on first start
+  after upgrade with no operator action required.
+- You **MUST** rebuild the frontend and restart the backend
+  after upgrading. `frontend/package.json#version` and `VERSION`
+  both move to `0.18.0`. No new secrets (the `outbound_emails`
+  table writes synchronously to the same SQLite file as every
+  other write).
+- Operators **SHOULD** run a `mail-tester.com` probe against the
+  upgraded deployment to confirm the new envelope headers
+  (`Date`, `Message-ID`, `Auto-Submitted`, `List-Unsubscribe`,
+  `List-Unsubscribe-Post`) land cleanly with the upstream SMTP
+  relay's DKIM signing. The expected delta from pre-v0.18.0 is
+  +2-3 points on the spam-score axis (typical 5-6/10 baseline
+  → 9+/10 post-upgrade).
+
+
+## 0.17.0 — 2026-05-28
+
+**Minor — schema migration required; no new env vars; no new secrets.**
+This release lands admin-create user with role assignment + invite
+email (roadmap item #16, §6.1). From the v0.9.0 `/admin/users` surface,
+an admin can now type first name, last name, email, role, and an
+optional custom message; the framework provisions the `users` row with
+the chosen role and `permission_state='granted'` (the admin's hand is
+the grant) and sends an invite email carrying a single-use claim link.
+The invitee clicks through to `/invites/claim?token=…`, the token is
+verified and consumed, the session is established, and the user is
+routed to the passcode-set screen (per v0.10.0) on first sign-in.
+
+Distinct from #12 (which ships in parallel in this wave): #12 is
+per-RFC contribution/discussion membership and uses
+`rfc_invitations` (slot 018). v0.17.0 is platform-level access
+provisioning by an admin and uses `user_invite_tokens` (slot 019).
+Both can coexist; both surface in the same SMTP relay but with
+distinct email templates.
+
+Design decisions documented inline (see `backend/app/invites.py`'s
+module docstring + the migration's header comment):
+
+  * **Token shape: opaque DB token, not JWT.** 256 bits of CSPRNG
+    entropy (`secrets.token_urlsafe(32)`), bcrypt-hashed at rest.
+    Opaque chosen over JWT because revocation is then a single SQL
+    UPDATE — admin-issued invites are exactly the kind of thing an
+    admin should be able to yank back without rotating a signing
+    key. The raw token only ever lives in the outbound email link
+    and the inbound claim body.
+  * **TTL: 7 days, hard-coded constant** (`INVITE_TOKEN_TTL_DAYS`
+    in `backend/app/invites.py`). Env-var configurability is a
+    §19.2 candidate; the constant is exposed as a single point of
+    edit if a deployment wants to override.
+  * **Immediate send, no admin-review-then-send queue.** Matches
+    how the v0.9.0 beta-request admin notification works (single
+    SMTP path). Admin-preview-before-send is a future enhancement.
+  * **Bulk-invite (CSV paste) deferred.** v0.17.0 is one-at-a-time;
+    a follow-up release can layer bulk on top of the same
+    `POST /api/admin/users` body shape with minimal disruption.
+  * **OTC skipped on first sign-in.** Per the roadmap: clicking the
+    unique token in the email is itself proof of email control, so
+    the claim flow signs the invitee in directly. Subsequent
+    sign-ins go through the standard OTC / passcode paths.
+  * **No `users` table changes.** The brief floated
+    `first_sign_in_at` / `last_seen_at IS NULL` as the
+    "(pending invite)" discriminator, but the existing
+    `users.last_seen_at` column is NOT NULL with a `datetime('now')`
+    default (migrations/001) and no `first_sign_in_at` column
+    exists. Rather than land a schema migration to introduce one,
+    the discriminator is the existence of an active (not-claimed,
+    not-expired) row in `user_invite_tokens` joined on
+    `invited_user_id`. The admin user-listing carries a
+    `pending_invite` field populated via that join; on claim, the
+    badge clears naturally as the invite row's `claimed_at`
+    populates.
+  * **Admin-create vs. self-flip refusals.** Self-invite is refused
+    422 (use the role-change channel for self-edits). Duplicate
+    email is refused 409 (use the existing role / grant gestures on
+    the existing user). Owner-grant by a non-owner admin is refused
+    422 (§6.1's owner-zero is the only owner bootstrap path; the
+    sitting owner must issue the invite).
+
+### Added
+
+- **`POST /api/admin/users`** (`backend/app/api_admin.py`) — admin-only.
+  Body: `{ email, first_name?, last_name?, role, custom_message? }`.
+  Provisions the `users` row with the chosen role and writes the
+  `user_invite_tokens` row + dispatches the invite email + writes a
+  `permission_events` row with `event_kind='user_invited'`. Returns
+  `{ ok, invite_id, invited_user_id, email, role }` on success;
+  surfaces the four refusals (403/422/409/422) per their distinct
+  paths.
+- **`GET  /api/admin/users/invites`** — admin-only. Lists active
+  (not claimed, not expired) invites with the admin who created them
+  joined through for display. Powers the "I sent these but they
+  haven't been claimed yet" admin view.
+- **`POST /api/invites/claim`** (`backend/app/main.py` — alongside
+  `/auth/otc/verify` and `/auth/device-trust/start` since it shares
+  the device-trust cookie helpers). Anonymous-reachable. Body:
+  `{ token, trust_device? }`. Validates the token, consumes the
+  invite row, signs the user in, optionally mints a device-trust
+  cookie, and returns `{ ok, user, needs_passcode }`. The
+  `needs_passcode` hint drives the frontend's route-to-passcode-set
+  vs. route-to-home decision. Maps token-failure modes to distinct
+  HTTP statuses: expired/claimed → 410, unknown/invalid → 400.
+- **`backend/app/invites.py`** — the create + claim + list module.
+  Mirrors the `device_trust.py` shape: opaque-token issuance with
+  bcrypt-at-rest, candidate-set walk on lookup, dataclass-bracketed
+  outcomes (`CreateOutcome` / `ClaimOutcome` / `PendingInviteRow`).
+  Carries the `INVITE_TOKEN_TTL_DAYS = 7` constant and the
+  `CUSTOM_MESSAGE_MAX_LENGTH = 500` mirror of the API-side bound.
+- **`backend/app/email_invite.py`** — sibling of `email_otc.py`. Reuses
+  `EmailConfig.from_env()` for the SMTP plumbing + From identity;
+  composes a separate template (subject "You're invited to <app> by
+  <admin>"; body names the inviter, embeds the optional custom
+  message in a clearly-delimited indented block if present, and
+  carries the claim URL). Dev / no-SMTP path logs the envelope to
+  the shared `_SENT` buffer so backend tests can assert on the
+  outbound shape.
+- **Schema migration `019_user_invite_tokens.sql`** — new
+  `user_invite_tokens` table (id, email, role, first_name, last_name,
+  custom_message, token_hash, expires_at, created_at,
+  created_by_admin_id, claimed_at, claimed_by_user_id,
+  invited_user_id). Three indexes: unique on `token_hash`
+  (documents the no-collision invariant); `(email, claimed_at)` for
+  the "is this email already invited?" pre-check; and
+  `(created_by_admin_id, created_at DESC)` for the per-admin
+  invites listing. Slot 018 is reserved for the parallel #12
+  release shipping in the same wave; slot 016 stays
+  reserved-and-skipped per Session K's v0.9.0 integration.
+- **`frontend/src/components/InviteClaim.jsx`** — the
+  `/invites/claim?token=…` landing page. Reads the token from the
+  URL, renders a "Claim my account" CTA with an optional
+  "trust this device for 30 days" checkbox, calls
+  `POST /api/invites/claim` on submit, and routes onward
+  (`/settings/notifications#sign-in` if `needs_passcode`, else `/`)
+  on success. Anonymous-reachable.
+- **"Create user + invite" affordance** on `/admin/users`
+  (`frontend/src/components/Admin.jsx`). A header button opens a
+  modal with email / first / last / role / custom-message inputs
+  (the textarea shows a "chars left" counter against the 500-char
+  ceiling). On submit, the modal calls
+  `POST /api/admin/users` and refreshes the user listing.
+- **Amplitude wiring** (per `ohm-rfc/ROADMAP.md` #21 Part C, shipped
+  inline with v0.17.0): `USER_INVITED` event fires from
+  `CreateUserInviteModal` on successful invite-send with
+  `{ target_user_id, initial_role, custom_message_chars }` — the
+  OHM `invited_user_id` returned by `POST /api/admin/users`
+  becomes the dashboard's binding for the future Amplitude user
+  record; `custom_message_chars` is a coarse signal of admin
+  effort (0 = template-only, 1+ = personalized) and carries no
+  PII. `INVITE_CLAIMED` event fires from `InviteClaim.jsx` on
+  successful claim with `{ invited_by_admin_id, initial_role,
+  needs_passcode, trust_device }` — BUT the claim handler first
+  calls `identify({ user_id, properties: { claim_method:
+  'admin-invite', invited_at (setOnce), invited_by_admin_id
+  (setOnce), initial_role (setOnce) } })` so the Amplitude user
+  record is created with the OHM user_id from the very first
+  event the invitee fires, never as an anonymous device that
+  retroactively links. setOnce semantics preserve the original
+  invite context even if the invitee later changes roles.
+- **"(pending invite)" badge** inline on the user-listing's
+  per-row handle (rendered when the row's `pending_invite` field
+  is populated by the backend's join through `user_invite_tokens`).
+  Clears automatically on claim as the invite row's `claimed_at`
+  populates.
+
+### Changed
+
+- **`backend/app/api_admin.py`** — imports `invites` + `email_invite`
+  + `EmailConfig`; adds the two new endpoints alongside the existing
+  `set_role` / `set_permission` neighbors; extends `list_users` to
+  join through `user_invite_tokens` and emit the `pending_invite`
+  field on each row. The new `CreateUserInviteBody` pydantic model
+  carries the body bounds (320-char email, 120-char first/last,
+  regex-pinned role, 500-char custom_message) so malformed input
+  fails at the body bound (422) instead of at the SQL layer.
+- **`backend/app/main.py`** — imports `invites as invites_mod`;
+  adds the `InviteClaimBody` pydantic model alongside
+  `PasscodeVerifyBody`; mounts the `POST /api/invites/claim`
+  endpoint in the OAuth router so it can reuse the
+  `_set_device_trust_cookie` helper.
+- **`frontend/src/api.js`** — exports `createUserInvite()`,
+  `listUserInvites()`, `claimInvite()`. Same fetch shape as the
+  rest of the v0.9.0 / v0.10.0 admin neighborhood.
+- **`frontend/src/App.jsx`** — imports `InviteClaim`; registers the
+  `/invites/claim` route alongside `/beta-pending` (both are
+  anonymous-reachable auth-shape landings).
+
+### Migration
+
+- **`backend/migrations/019_user_invite_tokens.sql`** — auto-applied
+  on next backend start. Single new table with three indexes; no
+  changes to existing tables.
+
+### Upgrade steps (from 0.14.0)
+
+- You **MUST** apply schema migration `019_user_invite_tokens.sql`.
+  The migration creates a single new table with three indexes; the
+  framework runs migrations automatically at process start, so no
+  manual step is required beyond restarting the backend so the
+  migration runner picks the file up.
+- You **MUST** rebuild the frontend and restart the backend after
+  upgrading. `frontend/package.json#version` and `VERSION` both
+  move to `0.17.0`. No new env vars; no new secrets (the invite
+  email rides the existing SMTP relay configured for v0.7.0's OTC
+  mail).
+- You **MAY** announce the new admin-create gesture to existing
+  admins. Existing user rows are unaffected — the
+  `user_invite_tokens` table is empty post-migration, and the
+  user-listing's new `pending_invite` field is null on every
+  existing row. The bootstrap shape for the very first admin
+  account stays the v0.9.0 path (DB-level role flip on an OTC-
+  provisioned row); the v0.17.0 admin-create gesture works
+  end-to-end once at least one admin exists.
+
+
 ## 0.16.0 — 2026-05-28
 
 **Minor — schema migration auto-applied; no operator action.** This

VERSION

@@ -1 +1 @@
-0.16.0
+0.18.0

backend/app/api_admin.py

@@ -11,6 +11,8 @@ The endpoints in this module:
   - `GET  /api/admin/users`                       — list users with role + mute
   - `POST /api/admin/users/<id>/role`             — set role per §6.1
   - `POST /api/admin/users/<id>/mute`             — set the §6.2 write-mute
+  - `POST /api/admin/users`                       — v0.17.0: create user + invite
+  - `GET  /api/admin/users/invites`               — v0.17.0: pending invites
   - `GET  /api/admin/audit`                       — paged `actions` log
   - `GET  /api/admin/permission-events`           — paged `permission_events` log
   - `GET  /api/admin/graduation-queue`            — super-drafts ready to graduate
@@ -33,8 +35,9 @@ from typing import Any
 from fastapi import APIRouter, HTTPException, Query, Request
 from pydantic import BaseModel, Field
 
-from . import auth, db
+from . import auth, db, email_invite, invites
 from .config import Config
+from .email import EmailConfig
 
 
 # ---------------------------------------------------------------------------
@@ -65,6 +68,32 @@ class AllowlistAddBody(BaseModel):
     note: str | None = Field(default=None, max_length=200)
 
 
+class CreateUserInviteBody(BaseModel):
+    """v0.17.0 / roadmap item #16 — admin-create user + invite email.
+
+    The admin types these fields on the "Create user + invite" modal on
+    `/admin/users`. The email + role are required; first/last name and
+    the optional custom message round out the body.
+
+    Bounds mirror the rest of the codebase:
+      * `email`: 320 chars — RFC 5321 envelope limit, same as
+        `OtcRequestBody` / `BetaRequestBody` / `AllowlistAddBody`.
+      * `first_name` / `last_name`: 120 chars — same as the v0.8.0
+        `BetaRequestBody` capture form.
+      * `role`: pydantic regex pinned to the §6.1 set so an unknown
+        role fails at the body bound (422) instead of landing as a
+        CHECK constraint violation in the migration.
+      * `custom_message`: 500 chars — the brief calls this out as
+        the max. The frontend modal shows a "remaining chars"
+        counter to match.
+    """
+    email: str = Field(min_length=3, max_length=320)
+    first_name: str = Field(default="", max_length=120)
+    last_name: str = Field(default="", max_length=120)
+    role: str = Field(pattern="^(owner|admin|contributor)$")
+    custom_message: str = Field(default="", max_length=500)
+
+
 # ---------------------------------------------------------------------------
 # Router
 # ---------------------------------------------------------------------------
@@ -156,6 +185,32 @@ def make_router(config: Config) -> APIRouter:
                 "inviter_login": ir["inviter_login"],
                 "inviter_display": ir["inviter_display"],
             })
+        # v0.17.0 / roadmap item #16: a user row whose `last_seen_at`
+        # is NULL is one of two things — a brand-new row that was just
+        # provisioned (rare, and the v0.7.0 OTC verify path stamps
+        # last_seen_at on the same call that creates the row), or an
+        # admin-created invite-pending row (v0.17.0 — created by
+        # `POST /api/admin/users`). We surface a `pending_invite_id`
+        # field by joining through `user_invite_tokens` so the
+        # Users tab can render a "(pending invite)" badge alongside
+        # the role/state controls. Filters to invites that are
+        # neither expired nor claimed — once the invitee clicks
+        # through, the badge clears (and `last_seen_at` populates).
+        pending_invite_rows = db.conn().execute(
+            """
+            SELECT invited_user_id, id AS invite_id, expires_at
+              FROM user_invite_tokens
+             WHERE claimed_at IS NULL
+               AND datetime(expires_at) > datetime('now')
+            """
+        ).fetchall()
+        pending_invites = {
+            r["invited_user_id"]: {
+                "invite_id": r["invite_id"],
+                "expires_at": r["expires_at"],
+            }
+            for r in pending_invite_rows
+        }
         return {
             "items": [
                 {
@@ -176,6 +231,215 @@ def make_router(config: Config) -> APIRouter:
                     "permission_decided_by_display": r["decided_by_display"],
                     # v0.16.0 additive — never null, always an array.
                     "rfc_invitations": per_user_invites.get(r["id"], []),
+                    # v0.17.0: present iff the row is invited-but-not-
+                    # claimed-yet. The frontend renders a "(pending
+                    # invite)" badge when this is non-null.
+                    "pending_invite": pending_invites.get(r["id"]),
+                }
+                for r in rows
+            ]
+        }
+
+    # ----- Create user + invite (v0.17.0 / roadmap item #16) -----
+
+    @router.post("/api/admin/users")
+    async def create_user_with_invite(
+        body: CreateUserInviteBody, request: Request,
+    ) -> dict[str, Any]:
+        """Provision a fresh `users` row with a pre-assigned role + send
+        an invite email carrying a claim link.
+
+        Refusals:
+          * `422` — the admin tries to invite their own email (no
+            self-invite; symmetric to `set_permission`'s self-flip
+            refusal and `set_role`'s self-downgrade refusal). Use
+            the existing role-change channel for self-edits.
+          * `422` — the admin tries to grant `owner` without being
+            owner themselves. §6.1: owner-zero is the only owner
+            bootstrap path; new owners come from a sitting owner's
+            hand. A 422 here matches the message shape; a 403 would
+            also be defensible, but staying with 422 keeps the
+            "your input is bad" framing.
+          * `409` — the email already maps to a `users` row. The
+            admin should use the existing role / grant gestures on
+            the existing user, not create a duplicate.
+          * `422` — pydantic-level: malformed email, role outside
+            the §6.1 set, custom_message over 500 chars.
+
+        On success:
+          1. The invitee `users` row lands with the chosen role and
+             `permission_state='granted'` (admin's hand is the grant)
+             and `last_seen_at IS NULL` (the "(pending invite)"
+             discriminator the listing surface joins through).
+          2. The `user_invite_tokens` row lands with the bcrypt-
+             hashed opaque token; the raw token rides only in the
+             email link.
+          3. The invite email dispatches with subject "You're
+             invited to <app> by <admin>" and the custom message
+             embedded in a clearly-delimited block if present.
+          4. A `permission_events` row records the admin-create
+             gesture so the §6.5 / `permissions` admin tab carries
+             the audit trail alongside the existing grant/revoke
+             flips.
+        """
+        viewer = auth.require_admin(request)
+        email_clean = body.email.strip().lower()
+        if "@" not in email_clean or len(email_clean.split("@")[-1]) < 2:
+            raise HTTPException(422, "Email looks malformed")
+
+        # Self-invite refusal. Compare the admin's own email
+        # case-insensitively against the invite target.
+        viewer_row = db.conn().execute(
+            "SELECT email FROM users WHERE id = ?", (viewer.user_id,)
+        ).fetchone()
+        viewer_email = (viewer_row["email"] or "").strip().lower() if viewer_row else ""
+        if viewer_email and viewer_email == email_clean:
+            raise HTTPException(
+                422,
+                "You cannot invite yourself — use the role-change channel "
+                "if you need to edit your own row",
+            )
+
+        # Owner-grant refusal: §6.1 says only a sitting owner can mint
+        # a new owner. An admin trying to invite-as-owner is refused
+        # at 422; the admin should ask the owner to issue the invite,
+        # or invite as `admin` and let the owner promote later.
+        if body.role == "owner" and viewer.role != "owner":
+            raise HTTPException(
+                422,
+                "Only an owner can invite a new owner — invite as admin and "
+                "ask the owner to promote, or have the owner issue this invite",
+            )
+
+        # Duplicate-email refusal. A pre-existing row (regardless of
+        # permission_state) means the admin should use the existing
+        # role / grant gestures, not create a parallel user.
+        existing = db.conn().execute(
+            "SELECT id FROM users WHERE email = ? COLLATE NOCASE LIMIT 1",
+            (email_clean,),
+        ).fetchone()
+        if existing is not None:
+            raise HTTPException(409, "A user with this email already exists")
+
+        # Create the invitee row + token row + send the email.
+        outcome = invites.create_invite(
+            email=email_clean,
+            first_name=body.first_name,
+            last_name=body.last_name,
+            role=body.role,
+            custom_message=body.custom_message,
+            created_by_admin_id=viewer.user_id,
+        )
+
+        # Audit row in permission_events so the admin Permissions tab
+        # carries the gesture. The before-state is "n/a" (the row
+        # did not exist); the after-state is the granted role. We
+        # use a new `event_kind='user_invited'` so the existing
+        # grant/revoke kinds stay scoped to their flip surface.
+        db.conn().execute(
+            """
+            INSERT INTO permission_events
+                (actor_user_id, subject_user_id, event_kind, details)
+            VALUES (?, ?, 'user_invited', ?)
+            """,
+            (
+                viewer.user_id,
+                outcome.invited_user_id,
+                json.dumps({
+                    "email": email_clean,
+                    "role": body.role,
+                    "invite_id": outcome.invite_id,
+                    "custom_message_chars": len(body.custom_message or ""),
+                }),
+            ),
+        )
+
+        # Build the claim URL using the same APP_URL the email module
+        # reads. The token rides as a query-string param to the
+        # frontend route `/invites/claim?token=…`; the frontend POSTs
+        # it back to `/api/invites/claim` which consumes the row.
+        cfg = EmailConfig.from_env()
+        from urllib.parse import urlencode
+        claim_url = f"{cfg.app_url}/invites/claim?{urlencode({'token': outcome.raw_token})}"
+
+        # Fetch the inviter display so the email body can render
+        # "Ben Stull (ben@example.com) has invited you to …". We
+        # read off the row fresh rather than trusting the session
+        # cookie's cached display_name.
+        inviter_row = db.conn().execute(
+            "SELECT display_name, email FROM users WHERE id = ?",
+            (viewer.user_id,),
+        ).fetchone()
+        inviter_display = (
+            (inviter_row["display_name"] if inviter_row else "") or viewer.display_name or "An admin"
+        )
+        inviter_email_for_body = (inviter_row["email"] if inviter_row else "") or viewer.email or ""
+
+        email_invite.send_invite_email(
+            to_address=email_clean,
+            claim_url=claim_url,
+            inviter_display=inviter_display,
+            inviter_email=inviter_email_for_body,
+            custom_message=body.custom_message,
+        )
+
+        return {
+            "ok": True,
+            "invite_id": outcome.invite_id,
+            "invited_user_id": outcome.invited_user_id,
+            "email": email_clean,
+            "role": body.role,
+        }
+
+    @router.get("/api/admin/users/invites")
+    async def list_user_invites(request: Request) -> dict[str, Any]:
+        """List active (not claimed, not expired) admin-issued invites.
+
+        Powers the admin's "I sent these but they haven't been claimed
+        yet" view. The frontend uses this alongside `list_users` —
+        the user-listing's `pending_invite` field carries the per-row
+        flag; this endpoint carries the full invite shape for a
+        dedicated drill-in surface.
+        """
+        auth.require_admin(request)
+        rows = invites.list_pending_invites()
+        # Join through to the admin display names so the surface can
+        # render "invited by @ben" without a second client call.
+        admin_ids = {r.created_by_admin_id for r in rows}
+        admin_lookup: dict[int, dict[str, str]] = {}
+        if admin_ids:
+            placeholders = ",".join("?" * len(admin_ids))
+            admin_rows = db.conn().execute(
+                f"SELECT id, gitea_login, display_name FROM users "
+                f"WHERE id IN ({placeholders})",
+                tuple(admin_ids),
+            ).fetchall()
+            admin_lookup = {
+                ar["id"]: {
+                    "gitea_login": ar["gitea_login"] or "",
+                    "display_name": ar["display_name"] or "",
+                }
+                for ar in admin_rows
+            }
+        return {
+            "items": [
+                {
+                    "id": r.id,
+                    "email": r.email,
+                    "role": r.role,
+                    "first_name": r.first_name,
+                    "last_name": r.last_name,
+                    "custom_message": r.custom_message,
+                    "created_at": r.created_at,
+                    "expires_at": r.expires_at,
+                    "invited_user_id": r.invited_user_id,
+                    "created_by_admin_id": r.created_by_admin_id,
+                    "created_by_login": admin_lookup.get(
+                        r.created_by_admin_id, {}
+                    ).get("gitea_login", ""),
+                    "created_by_display": admin_lookup.get(
+                        r.created_by_admin_id, {}
+                    ).get("display_name", ""),
                 }
                 for r in rows
             ]
@@ -408,6 +672,73 @@ def make_router(config: Config) -> APIRouter:
             "has_more": len(rows) == limit,
         }
 
+    @router.get("/api/admin/outbound-emails")
+    async def list_outbound_emails(
+        request: Request,
+        kind: str | None = None,
+        status: str | None = None,
+        to_address: str | None = None,
+        limit: int = Query(default=100, ge=1, le=500),
+        before_id: int | None = None,
+    ) -> dict[str, Any]:
+        """v0.18.0 Slice 4: read-only inspection of the
+        `outbound_emails` audit table.
+
+        Answers questions like "did this person ever get their
+        invite?" without grepping VM logs. Filterable by kind
+        ('otc' | 'invite' | 'notification' | 'bundle' | 'digest'),
+        status ('sent' | 'failed' | 'deferred' | 'bounced'), and
+        to_address; the latter is exact-match because the audit
+        question is usually "the specific person who said they
+        didn't receive it." Per the proposal, no admin UI ships
+        with v0.18.0 — operator queries via curl + jq for now.
+        """
+        auth.require_admin(request)
+        clauses: list[str] = []
+        args: list[Any] = []
+        if kind:
+            clauses.append("kind = ?")
+            args.append(kind)
+        if status:
+            clauses.append("status = ?")
+            args.append(status)
+        if to_address:
+            clauses.append("LOWER(to_address) = LOWER(?)")
+            args.append(to_address)
+        if before_id is not None:
+            clauses.append("id < ?")
+            args.append(before_id)
+        where = ("WHERE " + " AND ".join(clauses)) if clauses else ""
+        rows = db.conn().execute(
+            f"""
+            SELECT id, to_address, from_address, subject, kind, sent_at,
+                   status, error, notification_id, message_id
+              FROM outbound_emails
+             {where}
+             ORDER BY id DESC
+             LIMIT ?
+            """,
+            (*args, limit),
+        ).fetchall()
+        return {
+            "items": [
+                {
+                    "id": r["id"],
+                    "to_address": r["to_address"],
+                    "from_address": r["from_address"],
+                    "subject": r["subject"],
+                    "kind": r["kind"],
+                    "sent_at": r["sent_at"],
+                    "status": r["status"],
+                    "error": r["error"],
+                    "notification_id": r["notification_id"],
+                    "message_id": r["message_id"],
+                }
+                for r in rows
+            ],
+            "has_more": len(rows) == limit,
+        }
+
     @router.get("/api/admin/permission-events")
     async def list_permission_events(
         request: Request,

backend/app/api_notifications.py

@@ -73,6 +73,13 @@ class MarkReadBody(BaseModel):
 class BounceBody(BaseModel):
     email: str = Field(min_length=3, max_length=320)
     kind: str = Field(default="hard")  # 'hard' or 'complaint'
+    # v0.18.0 Slice 5: when the bounce provider includes the
+    # original Message-ID, the framework correlates it back to
+    # the matching `outbound_emails` row and stamps
+    # `status='bounced'`. Optional — providers that don't surface
+    # the Message-ID still flip the global opt-out via the email
+    # match, but lose the per-message attribution.
+    message_id: str | None = Field(default=None, max_length=1000)
 
 
 class CookieConsentBody(BaseModel):
@@ -443,6 +450,40 @@ def make_router(config: Config) -> APIRouter:
 
     # ----- Email: one-click unsubscribe + bounce webhook -----
 
+    # v0.18.0: the category → column map. The `all` synthetic
+    # category lands the bundle's one-click on the global opt-out
+    # flag (per `email._send_bundle` in v0.18.0 Slice 2 — a bundle
+    # spans multiple categories, so a per-category flip wouldn't
+    # honor the user's intent).
+    _CATEGORY_COLUMN: dict[str, str] = {
+        "personal-direct": "email_personal_direct",
+        "structural": "email_watched_structural",
+        "admin-actionable": "email_admin_actionable",
+        "all": "email_opt_out_all",
+    }
+
+    def _apply_unsubscribe(user_id: int, category: str) -> bool:
+        """Flip the matching column. Returns True on success, False
+        if the category is unknown. Idempotent — running twice on
+        the same (user, category) is harmless (it sets the column
+        to its current value)."""
+        column = _CATEGORY_COLUMN.get(category)
+        if column is None:
+            return False
+        # `all` sets the flag to 1 (opt out); per-category sets to 0
+        # (turn that category off). The column semantic is "1 means
+        # don't send"; the per-category booleans are "1 means do
+        # send". Different polarities, hence the case split.
+        if category == "all":
+            db.conn().execute(
+                f"UPDATE users SET {column} = 1 WHERE id = ?", (user_id,)
+            )
+        else:
+            db.conn().execute(
+                f"UPDATE users SET {column} = 0 WHERE id = ?", (user_id,)
+            )
+        return True
+
     @router.get("/api/email/unsubscribe")
     async def email_unsubscribe(t: str = Query(..., description="Signed token from the email footer")) -> HTMLResponse:
         try:
@@ -453,20 +494,51 @@ def make_router(config: Config) -> APIRouter:
                 "<p>Open the app to manage your notification preferences directly.</p>",
                 status_code=400,
             )
-        column = {
-            "personal-direct": "email_personal_direct",
-            "structural": "email_watched_structural",
-            "admin-actionable": "email_admin_actionable",
-        }.get(category)
-        if column is None:
+        if not _apply_unsubscribe(user_id, category):
             return HTMLResponse(
                 f"<h1>Unknown category</h1><p>{category}</p>", status_code=400
             )
-        db.conn().execute(f"UPDATE users SET {column} = 0 WHERE id = ?", (user_id,))
-        return HTMLResponse(
-            f"<h1>Unsubscribed</h1><p>You will no longer receive {category} emails. "
-            f"You can re-enable them in your notification preferences.</p>"
-        )
+        if category == "all":
+            body = (
+                "<h1>Unsubscribed</h1><p>You will no longer receive any email "
+                "from this app. You can re-enable individual categories from "
+                "your notification preferences after signing in.</p>"
+            )
+        else:
+            body = (
+                f"<h1>Unsubscribed</h1><p>You will no longer receive {category} emails. "
+                f"You can re-enable them in your notification preferences.</p>"
+            )
+        return HTMLResponse(body)
+
+    @router.post("/api/email/unsubscribe")
+    async def email_unsubscribe_post(
+        request: Request,
+        t: str = Query(..., description="Signed token from the List-Unsubscribe header"),
+    ) -> dict[str, Any]:
+        """v0.18.0: RFC 8058 one-click endpoint.
+
+        Gmail and Yahoo POST `List-Unsubscribe=One-Click` (as a
+        form-encoded body) to the URL in the `List-Unsubscribe`
+        header when the user clicks their MUA's "Unsubscribe"
+        button. The endpoint MUST accept POST (per the
+        `List-Unsubscribe-Post` header we advertise) and MUST be
+        idempotent.
+
+        The body content is checked loosely — RFC 8058 says it
+        SHOULD be exactly `List-Unsubscribe=One-Click`, but some
+        intermediaries strip / re-encode the body, so the
+        framework accepts any POST to the URL once the token
+        verifies. The bar is that the token signature carries the
+        authority; the body is hint-only.
+        """
+        try:
+            user_id, category = email_mod.verify_unsubscribe_token(t)
+        except BadSignature:
+            raise HTTPException(400, "Invalid or expired token")
+        if not _apply_unsubscribe(user_id, category):
+            raise HTTPException(400, f"Unknown category: {category}")
+        return {"ok": True, "category": category}
 
     @router.post("/api/webhooks/email-bounce")
     async def email_bounce(body: BounceBody, request: Request) -> dict[str, Any]:
@@ -490,16 +562,46 @@ def make_router(config: Config) -> APIRouter:
             import hmac as _hmac
             if not received or not _hmac.compare_digest(expected, received):
                 raise HTTPException(401, "Invalid webhook signature")
+        # v0.18.0 Slice 5: correlate the bounce back to the
+        # matching outbound_emails row if the provider supplied
+        # the Message-ID. The hard-bounce -> global-opt-out
+        # logic below still fires regardless; this is an
+        # additional audit signal.
+        correlated_row_id: int | None = None
+        if body.message_id:
+            correlated = db.conn().execute(
+                "SELECT id FROM outbound_emails WHERE message_id = ?",
+                (body.message_id,),
+            ).fetchone()
+            if correlated is not None:
+                correlated_row_id = correlated["id"]
+                db.conn().execute(
+                    "UPDATE outbound_emails SET status = 'bounced', "
+                    "error = COALESCE(error, '') || ? WHERE id = ?",
+                    (f"bounce ({body.kind})", correlated_row_id),
+                )
+                log.info(
+                    "email-bounce: correlated message_id=%s -> outbound_emails.id=%s",
+                    body.message_id, correlated_row_id,
+                )
+            else:
+                log.info(
+                    "email-bounce: message_id=%s did not match any "
+                    "outbound_emails row (provider may be replaying an old bounce, "
+                    "or the row was pruned)",
+                    body.message_id,
+                )
+
         row = db.conn().execute(
             "SELECT id FROM users WHERE LOWER(email) = LOWER(?)", (body.email,),
         ).fetchone()
         if row is None:
-            return {"ok": True, "matched": False}
+            return {"ok": True, "matched": False, "correlated_id": correlated_row_id}
         db.conn().execute(
             "UPDATE users SET email_opt_out_all = 1 WHERE id = ?", (row["id"],),
         )
         log.info("email-bounce: opted out user %s (%s)", row["id"], body.kind)
-        return {"ok": True, "matched": True}
+        return {"ok": True, "matched": True, "correlated_id": correlated_row_id}
 
     return router
 

backend/app/config.py

@@ -60,6 +60,20 @@ def load_config() -> Config:
 
     enabled = [m.strip() for m in _optional("ENABLED_MODELS", "claude").split(",") if m.strip()]
 
+    # v0.18.0: `GITEA_WEBHOOK_SECRET` is now mandatory (per the
+    # email + webhook hygiene proposal). An empty value used to
+    # silently accept unsigned webhook POSTs — that was the
+    # invisible-failure shape the proposal targets. Now the
+    # framework refuses to start when the secret is empty unless
+    # the operator opts into the dev-bypass with
+    # `RFC_APP_INSECURE_WEBHOOKS=1`. Local-dev deployments without
+    # a wired Gitea hook set the bypass; production MUST NOT.
+    insecure_webhooks = os.environ.get("RFC_APP_INSECURE_WEBHOOKS", "").strip() == "1"
+    if insecure_webhooks:
+        webhook_secret = _optional("GITEA_WEBHOOK_SECRET")
+    else:
+        webhook_secret = _required("GITEA_WEBHOOK_SECRET")
+
     return Config(
         gitea_url=_required("GITEA_URL").rstrip("/"),
         gitea_bot_user=_required("GITEA_BOT_USER"),
@@ -72,7 +86,7 @@ def load_config() -> Config:
         secret_key=_required("SECRET_KEY"),
         database_path=database_path,
         owner_gitea_login=_optional("OWNER_GITEA_LOGIN"),
-        webhook_secret=_optional("GITEA_WEBHOOK_SECRET"),
+        webhook_secret=webhook_secret,
         enabled_models=enabled,
         anthropic_api_key=_optional("ANTHROPIC_API_KEY"),
         google_api_key=_optional("GOOGLE_API_KEY"),

backend/app/digest.py

@@ -180,7 +180,19 @@ def assemble_for_user(
 
     subject = _subject(eligible, cadence)
     body = _body(eligible, cadence, cfg)
-    sent = email_mod._deliver(cfg, email, subject, body)
+    # v0.18.0: the digest is the bulk-adjacent surface par excellence
+    # (it can carry weeks of accumulated activity), so it gets the
+    # full one-click unsubscribe to the global opt-out. Per-category
+    # opt-outs are managed from the preferences page; this footer is
+    # the "stop sending me anything" escape hatch Gmail and Yahoo
+    # expect for senders at this tier.
+    unsubscribe_url = email_mod.make_unsubscribe_url(user_id, "all")
+    sent = email_mod._deliver(
+        cfg, email, subject, body,
+        unsubscribe_mailto=cfg.unsubscribe_mailto,
+        unsubscribe_url=unsubscribe_url,
+        kind="digest",
+    )
     if not sent:
         return False
     ids = [r["id"] for r, _ in eligible]

backend/app/email.py

@@ -24,7 +24,6 @@ import os
 import smtplib
 from dataclasses import dataclass
 from datetime import datetime, time, timezone
-from email.message import EmailMessage
 from email.utils import formataddr
 from itertools import groupby
 from typing import Any
@@ -33,6 +32,7 @@ from urllib.parse import urlencode
 from itsdangerous import BadSignature, URLSafeSerializer
 
 from . import db
+from .email_envelope import build_envelope
 
 log = logging.getLogger(__name__)
 
@@ -69,6 +69,7 @@ class EmailConfig:
     app_url: str
     bundle_threshold: int
     enabled: bool
+    unsubscribe_mailto: str
 
     @classmethod
     def from_env(cls) -> "EmailConfig":
@@ -84,6 +85,16 @@ class EmailConfig:
             app_url=os.environ.get("APP_URL", "http://localhost:8000").rstrip("/"),
             bundle_threshold=int(os.environ.get("EMAIL_BUNDLE_THRESHOLD", "5")),
             enabled=os.environ.get("EMAIL_ENABLED", "1") not in ("0", "false", "False"),
+            # v0.18.0: the `List-Unsubscribe: <mailto:…>` target on
+            # invite + notification mail. Defaults to the From
+            # address when unset; a deployment can route opt-out
+            # mail to a separate mailbox (e.g., a humans-monitored
+            # account distinct from the no-reply notifications
+            # sender) by setting this explicitly.
+            unsubscribe_mailto=os.environ.get(
+                "EMAIL_UNSUBSCRIBE_MAILTO",
+                os.environ.get("EMAIL_FROM", "notifications@wiggleverse.local"),
+            ).strip(),
         )
 
 
@@ -98,6 +109,14 @@ def _signer() -> URLSafeSerializer:
 
 
 def make_unsubscribe_url(user_id: int, category: str) -> str:
+    """Build the §15.4 per-category one-click URL.
+
+    `category` is one of `personal-direct`, `structural`,
+    `admin-actionable` (the three per-category flags) or `all`
+    (v0.18.0: the bundle path, which sets `email_opt_out_all = 1`
+    because a bundle covers multiple categories and a per-category
+    opt-out wouldn't honor the user's intent).
+    """
     cfg = EmailConfig.from_env()
     token = _signer().dumps({"u": user_id, "c": category})
     qs = urlencode({"t": token})
@@ -250,7 +269,21 @@ def _send_one(user: Any, notif_id: int, payload: dict, category: str) -> None:
         return
     subject = _subject(payload)
     body = _body(payload, user["id"], category, cfg)
-    sent = _deliver(cfg, user["email"], subject, body)
+    # v0.18.0: notification mail is bulk-adjacent (a watcher can
+    # accumulate dozens of structural events on a busy RFC), so it
+    # carries the full one-click unsubscribe — Gmail and Yahoo
+    # require this for senders at OHM's volume tier per RFC 8058.
+    unsubscribe_url = make_unsubscribe_url(user["id"], category)
+    sent = _deliver(
+        cfg,
+        user["email"],
+        subject,
+        body,
+        unsubscribe_mailto=cfg.unsubscribe_mailto,
+        unsubscribe_url=unsubscribe_url,
+        kind="notification",
+        notification_id=notif_id,
+    )
     if not sent:
         return
     db.conn().execute(
@@ -305,23 +338,65 @@ def _deep_link(payload: dict, cfg: EmailConfig) -> str:
     return cfg.app_url
 
 
-def _deliver(cfg: EmailConfig, to_address: str, subject: str, body: str) -> bool:
+def _deliver(
+    cfg: EmailConfig,
+    to_address: str,
+    subject: str,
+    body: str,
+    *,
+    unsubscribe_mailto: str | None = None,
+    unsubscribe_url: str | None = None,
+    kind: str = "notification",
+    notification_id: int | None = None,
+) -> bool:
+    """Build the envelope via the shared `build_envelope` helper and
+    hand it to SMTP.
+
+    The `_SENT` buffer carries the helper's `EmailMessage` under
+    `message` plus the legacy `to`/`from`/`subject`/`body` keys for
+    backward-compatibility with tests that read those directly.
+    Newer tests can assert on the header surface by inspecting
+    `envelope["message"]`.
+
+    v0.18.0 Slice 4: also writes one row to `outbound_emails`
+    capturing the attempt. status='sent' on success, 'failed' on
+    SMTP exception, 'deferred' on the dev-fallback path (no
+    SMTP_HOST configured — the send didn't happen, but the row
+    records the attempt so the admin endpoint can answer "did the
+    framework try?").
+    """
+    msg = build_envelope(
+        to_address=to_address,
+        from_address=cfg.from_address,
+        from_name=cfg.from_name,
+        subject=subject,
+        body_plain=body,
+        unsubscribe_mailto=unsubscribe_mailto,
+        unsubscribe_url=unsubscribe_url,
+    )
     envelope = {
         "to": to_address,
         "from": formataddr((cfg.from_name, cfg.from_address)),
         "subject": subject,
         "body": body,
+        "message": msg,
+        "kind": kind,
     }
     _SENT.append(envelope)
+    message_id = msg["Message-ID"]
     if not cfg.smtp_host:
         log.info("email (stdout fallback): to=%s subject=%s", to_address, subject)
+        record_outbound(
+            to_address=to_address,
+            from_address=cfg.from_address,
+            subject=subject,
+            kind=kind,
+            status="deferred",
+            message_id=message_id,
+            notification_id=notification_id,
+        )
         return True
     try:
-        msg = EmailMessage()
-        msg["From"] = envelope["from"]
-        msg["To"] = to_address
-        msg["Subject"] = subject
-        msg.set_content(body)
         smtp = smtplib.SMTP(cfg.smtp_host, cfg.smtp_port, timeout=30)
         try:
             if cfg.smtp_starttls:
@@ -331,12 +406,78 @@ def _deliver(cfg: EmailConfig, to_address: str, subject: str, body: str) -> bool
             smtp.send_message(msg)
         finally:
             smtp.quit()
+        record_outbound(
+            to_address=to_address,
+            from_address=cfg.from_address,
+            subject=subject,
+            kind=kind,
+            status="sent",
+            message_id=message_id,
+            notification_id=notification_id,
+        )
         return True
-    except Exception:
+    except Exception as exc:
         log.exception("email send failed: to=%s subject=%s", to_address, subject)
+        record_outbound(
+            to_address=to_address,
+            from_address=cfg.from_address,
+            subject=subject,
+            kind=kind,
+            status="failed",
+            error=f"{type(exc).__name__}: {exc}",
+            message_id=message_id,
+            notification_id=notification_id,
+        )
         return False
 
 
+def record_outbound(
+    *,
+    to_address: str,
+    from_address: str,
+    subject: str,
+    kind: str,
+    status: str,
+    error: str | None = None,
+    notification_id: int | None = None,
+    message_id: str | None = None,
+) -> int | None:
+    """v0.18.0 Slice 4: write one row to `outbound_emails`.
+
+    Returns the inserted row's id, or `None` if the DB connection
+    isn't initialized (which happens in unit tests that don't boot
+    the full app — the write is best-effort and never raises).
+    """
+    try:
+        cur = db.conn().execute(
+            """
+            INSERT INTO outbound_emails
+                (to_address, from_address, subject, kind, sent_at, status,
+                 error, notification_id, message_id)
+            VALUES (?, ?, ?, ?, datetime('now'), ?, ?, ?, ?)
+            """,
+            (
+                to_address,
+                from_address,
+                subject,
+                kind,
+                status,
+                error,
+                notification_id,
+                message_id,
+            ),
+        )
+        return cur.lastrowid
+    except RuntimeError:
+        # db.conn() raises RuntimeError if init() hasn't been called.
+        # Pure-helper unit tests for build_envelope hit this path; the
+        # audit row is best-effort and not part of the contract.
+        return None
+    except Exception:
+        log.exception("outbound_emails write failed: to=%s subject=%s", to_address, subject)
+        return None
+
+
 # ---------------------------------------------------------------------------
 # Quiet-hours release pass — called from the digest job
 # ---------------------------------------------------------------------------
@@ -440,13 +581,27 @@ def _send_bundle(cfg: EmailConfig, user: Any, emailable: list) -> int:
         for r, _cat, extras in group_rows:
             summary = _summary_for(r["event_kind"], r["actor_display"], r["rfc_title"], extras)
             sections.append(f"  · {summary}")
+    # v0.18.0: the bundle covers multiple categories, so a
+    # per-category opt-out can't honor the user's intent. The
+    # `all` category lands at the §15.4 endpoint and sets
+    # `email_opt_out_all = 1`.
+    unsubscribe_url = make_unsubscribe_url(user["id"], "all")
     body = (
         "Activity on RFCs you watch, accumulated during your quiet hours:\n"
         + "\n".join(sections)
         + f"\n\nOpen your inbox: {cfg.app_url}/inbox\n"
         + f"Manage all preferences: {cfg.app_url}/settings/notifications\n"
+        + f"Unsubscribe from all email: {unsubscribe_url}\n"
+    )
+    sent = _deliver(
+        cfg,
+        user["email"],
+        subject,
+        body,
+        unsubscribe_mailto=cfg.unsubscribe_mailto,
+        unsubscribe_url=unsubscribe_url,
+        kind="bundle",
     )
-    sent = _deliver(cfg, user["email"], subject, body)
     if not sent:
         return 0
     ids = [r["id"] for r, _, _ in emailable]

backend/app/email_envelope.py

@@ -0,0 +1,143 @@
+"""v0.18.0 / roadmap items #18 + #20: a shared envelope builder.
+
+Every outbound mail in rfc-app today (OTC, admin-invite, watcher
+notification, "while you were away" bundle, per-RFC invite) constructs
+its own `email.message.EmailMessage` ad-hoc. The four sites diverged
+just enough to be a deliverability hazard: missing `Date`, missing
+`Message-ID`, no `Auto-Submitted`, no `List-Unsubscribe` on the
+bulk-adjacent paths, no `multipart/alternative` body.
+
+This module is the one place an `EmailMessage` is constructed. Every
+send path imports `build_envelope` and calls it; the headers that
+matter for inbox placement (Date, Message-ID, Auto-Submitted) land
+uniformly, and the per-kind variations (unsubscribe semantics,
+HTML alternative) are explicit arguments rather than buried in
+each call site.
+
+Per the v0.18.0 proposal at `~/git/ohm-infra/RFC-APP-EMAIL-HYGIENE-PROPOSAL.md`,
+the per-kind unsubscribe matrix is:
+
+  * OTC: no `List-Unsubscribe` (the recipient explicitly requested
+    the code; advertising an unsubscribe header would imply OHM has
+    them on a list, which it doesn't).
+  * Admin invite / per-RFC invite: `mailto:` form only (the
+    recipient isn't a user yet, so there's no per-user opt-out row
+    to flip; the operator handles ad-hoc opt-outs manually).
+  * Watcher notification / bundle: full `mailto:` + signed-URL
+    `List-Unsubscribe` plus `List-Unsubscribe-Post:
+    List-Unsubscribe=One-Click` per RFC 8058 (Gmail and Yahoo
+    enforce this for bulk-adjacent senders).
+
+The `is_transactional` flag governs `Auto-Submitted: auto-generated`,
+which prevents auto-responder loops on every kind of mail we send.
+All five mail kinds today are transactional in the SMTP sense (no
+human is at the From mailbox watching for replies), so the default
+is True; the argument is exposed for future symmetry.
+"""
+from __future__ import annotations
+
+from email.message import EmailMessage
+from email.utils import formataddr, formatdate, make_msgid
+
+
+def build_envelope(
+    *,
+    to_address: str,
+    from_address: str,
+    from_name: str,
+    subject: str,
+    body_plain: str,
+    body_html: str | None = None,
+    reply_to: str | None = None,
+    unsubscribe_mailto: str | None = None,
+    unsubscribe_url: str | None = None,
+    is_transactional: bool = True,
+    msgid_domain: str | None = None,
+) -> EmailMessage:
+    """Compose an `EmailMessage` with hardened headers.
+
+    `to_address` / `from_address` are bare RFC 5322 addresses;
+    `from_name` is the display label that goes through `formataddr`
+    so spaces / commas in the display string are encoded correctly.
+
+    `body_plain` is mandatory. `body_html`, if supplied, lands as the
+    second part of a `multipart/alternative` body — mail clients
+    that prefer HTML render it; clients that don't fall back to the
+    plain part. The text/plain part comes first per RFC 2046, so a
+    plain-text client that picks the first body gets the readable
+    text.
+
+    `reply_to`, when set, lets a send path point replies at a
+    different mailbox than the From line (e.g., a watcher
+    notification with From=notifications@... but Reply-To=
+    ohm@... so a confused recipient who hits Reply lands at a
+    monitored mailbox).
+
+    `unsubscribe_mailto` / `unsubscribe_url` populate
+    `List-Unsubscribe`. If `unsubscribe_url` is set, the helper also
+    emits `List-Unsubscribe-Post: List-Unsubscribe=One-Click` per
+    RFC 8058 — Gmail and Yahoo POST that payload on the user's
+    one-click action. (Send paths that wire `unsubscribe_url`
+    therefore MUST also expose a matching POST endpoint that accepts
+    the same token; see `api_notifications.py:email_unsubscribe`.)
+
+    `msgid_domain` defaults to the @-domain of `from_address` so
+    Message-IDs are aligned with the sending domain by default. A
+    deployment that wants the Message-ID domain to track a different
+    surface (e.g., a tracking-domain that's separate from the From
+    domain) can override.
+
+    `Date` is RFC 5322 formatted via `email.utils.formatdate`; the
+    `localtime=True` setting picks the running process's local
+    timezone, which is what every popular MUA does too. (A
+    deployment running in UTC stamps UTC; that's correct, not a
+    bug.)
+    """
+    msg = EmailMessage()
+    msg["From"] = formataddr((from_name, from_address))
+    msg["To"] = to_address
+    msg["Subject"] = subject
+    msg["Date"] = formatdate(localtime=True)
+    # If the caller didn't pin a Message-ID domain, derive it from the
+    # From address. `make_msgid` accepts None and falls back to the
+    # local hostname, which is the wrong shape for a deliverable
+    # message (the hostname might be `gke-pool-xxx`); a deployment
+    # without a configured From would surface that as a build-time
+    # config error elsewhere, so the fallback here is just defensive.
+    if msgid_domain is None:
+        if "@" in from_address:
+            msgid_domain = from_address.split("@", 1)[1]
+        else:
+            msgid_domain = "localhost"
+    msg["Message-ID"] = make_msgid(domain=msgid_domain)
+    if reply_to:
+        msg["Reply-To"] = reply_to
+    if is_transactional:
+        # RFC 3834: prevents auto-responders (vacation replies, etc.)
+        # from triggering on this message. Every kind of mail rfc-app
+        # sends today is transactional in this sense.
+        msg["Auto-Submitted"] = "auto-generated"
+    if unsubscribe_mailto or unsubscribe_url:
+        parts: list[str] = []
+        if unsubscribe_mailto:
+            parts.append(f"<mailto:{unsubscribe_mailto}>")
+        if unsubscribe_url:
+            parts.append(f"<{unsubscribe_url}>")
+        msg["List-Unsubscribe"] = ", ".join(parts)
+        if unsubscribe_url:
+            # RFC 8058 one-click. Gmail and Yahoo POST the payload
+            # `List-Unsubscribe=One-Click` to the URL on the user's
+            # one-click action; the matching POST endpoint must be
+            # idempotent and not require auth. See
+            # `api_notifications.py` for the receiver.
+            msg["List-Unsubscribe-Post"] = "List-Unsubscribe=One-Click"
+    if body_html:
+        # multipart/alternative: text/plain first, text/html second.
+        # `set_content` sets the first part (and the message's main
+        # body); `add_alternative` adds the second part and
+        # restructures the message as multipart/alternative.
+        msg.set_content(body_plain)
+        msg.add_alternative(body_html, subtype="html")
+    else:
+        msg.set_content(body_plain)
+    return msg

backend/app/email_invite.py

@@ -0,0 +1,166 @@
+"""Outbound admin-invite email — a thin wrapper over the existing SMTP layer.
+
+v0.17.0 / roadmap item #16: when an admin uses `POST /api/admin/users` to
+create-with-invite, this module composes and sends the invite envelope.
+
+Structurally distinct from:
+
+  * `email_otc.py` (v0.7.0) — that one carries a credential the user
+    just requested; this one carries a credential the admin is sending
+    unsolicited.
+  * `email.py` (§15.4 notification mailer) — that one is inbox-driven,
+    bundled, with category opt-outs; this one is a single transactional
+    outbound to a person who does not yet have an inbox.
+  * v0.9.0's `new_beta_request` admin notification — that one is
+    invitee-to-admin (an existing pending user asking to be let in);
+    this one is admin-to-invitee (an admin reaching out to seed access).
+
+So this module reuses `EmailConfig.from_env()` for the SMTP plumbing
+and the From identity, but writes its own envelope. In dev (no
+SMTP_HOST set), the envelope is logged at INFO level and pushed to
+the same `_SENT` buffer the notification mailer uses, so the
+integration tests can assert on the outbound shape without standing
+up an SMTP server.
+
+The send is synchronous. The admin endpoint returns 200 on the
+create-row half regardless of send outcome — a transient SMTP
+failure should not roll back the invite (an admin can re-send via a
+future "resend invite" gesture, deferred to a follow-up release).
+"""
+from __future__ import annotations
+
+import logging
+import smtplib
+from email.utils import formataddr
+
+from .email import EmailConfig, _SENT, record_outbound
+from .email_envelope import build_envelope
+
+log = logging.getLogger(__name__)
+
+
+def send_invite_email(
+    *,
+    to_address: str,
+    claim_url: str,
+    inviter_display: str,
+    inviter_email: str,
+    custom_message: str = "",
+) -> bool:
+    """Compose and send the admin-invite email. Returns True on the
+    happy path; False on SMTP failure. The notifier-side buffer
+    `_SENT` is appended either way so tests can assert on content.
+
+    The body names the inviting admin, embeds the optional custom
+    message in a clearly delimited block if present, and ships the
+    claim link. The subject names the inviter so the recipient can
+    recognize the sender at a glance in their inbox preview.
+    """
+    cfg = EmailConfig.from_env()
+    subject = _subject(inviter_display, cfg)
+    body = _body(claim_url, inviter_display, inviter_email, custom_message, cfg)
+    # v0.18.0: invite mail carries a `List-Unsubscribe: <mailto:…>`
+    # only (no signed URL) — the invitee isn't a user yet, so there
+    # is no per-user opt-out row to flip. The operator handles
+    # ad-hoc opt-outs from the mailto: target. Per the proposal's
+    # "Tradeoff discussion": the invite was unsolicited from the
+    # recipient's perspective, so the courtesy header is right;
+    # but it can't be a one-click URL because the row doesn't
+    # exist yet.
+    msg = build_envelope(
+        to_address=to_address,
+        from_address=cfg.from_address,
+        from_name=cfg.from_name,
+        subject=subject,
+        body_plain=body,
+        unsubscribe_mailto=cfg.unsubscribe_mailto,
+    )
+    envelope = {
+        "to": to_address,
+        "from": formataddr((cfg.from_name, cfg.from_address)),
+        "subject": subject,
+        "body": body,
+        "kind": "invite",
+        "message": msg,
+    }
+    _SENT.append(envelope)
+
+    message_id = msg["Message-ID"]
+    if not cfg.enabled:
+        log.info("invite email disabled (EMAIL_ENABLED=0): to=%s", to_address)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="invite", status="deferred", message_id=message_id,
+        )
+        return True
+    if not cfg.smtp_host:
+        # Dev fallback: surface the claim URL at INFO so the operator can
+        # complete a claim flow without an SMTP relay. In production
+        # SMTP_HOST is always set per OHM's overlay.
+        log.info("invite email (stdout fallback): to=%s claim_url=%s", to_address, claim_url)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="invite", status="deferred", message_id=message_id,
+        )
+        return True
+
+    try:
+        smtp = smtplib.SMTP(cfg.smtp_host, cfg.smtp_port, timeout=30)
+        try:
+            if cfg.smtp_starttls:
+                smtp.starttls()
+            if cfg.smtp_user:
+                smtp.login(cfg.smtp_user, cfg.smtp_password)
+            smtp.send_message(msg)
+        finally:
+            smtp.quit()
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="invite", status="sent", message_id=message_id,
+        )
+        return True
+    except Exception as exc:
+        log.exception("invite email send failed: to=%s", to_address)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="invite", status="failed",
+            error=f"{type(exc).__name__}: {exc}", message_id=message_id,
+        )
+        return False
+
+
+def _subject(inviter_display: str, cfg: EmailConfig) -> str:
+    """e.g. "You're invited to Wiggleverse by Ben Stull"."""
+    inviter = inviter_display or "an admin"
+    return f"You're invited to {cfg.from_name} by {inviter}"
+
+
+def _body(
+    claim_url: str,
+    inviter_display: str,
+    inviter_email: str,
+    custom_message: str,
+    cfg: EmailConfig,
+) -> str:
+    inviter = inviter_display or "An admin"
+    inviter_suffix = f" ({inviter_email})" if inviter_email else ""
+    message_block = ""
+    if custom_message.strip():
+        # Indent the custom message so it reads as a clearly-delimited
+        # quote rather than running together with the framework's
+        # framing text. Per-line indent keeps multi-line messages
+        # visually grouped in plain-text mail clients.
+        indented = "\n".join(f"    {line}" for line in custom_message.strip().splitlines())
+        message_block = f"\nA personal note from {inviter}:\n\n{indented}\n"
+
+    return (
+        f"{inviter}{inviter_suffix} has invited you to {cfg.from_name}.\n"
+        f"{message_block}\n"
+        f"Click the link below to claim your account and sign in.\n"
+        f"This link is single-use and expires in 7 days.\n\n"
+        f"    {claim_url}\n\n"
+        f"If you weren't expecting this invitation, you can ignore this\n"
+        f"email — no account becomes active until you click the link.\n\n"
+        f"---\n"
+        f"{cfg.from_name} · {cfg.app_url}\n"
+    )

backend/app/email_otc.py

@@ -23,10 +23,10 @@ from __future__ import annotations
 
 import logging
 import smtplib
-from email.message import EmailMessage
 from email.utils import formataddr
 
-from .email import EmailConfig, _SENT
+from .email import EmailConfig, _SENT, record_outbound
+from .email_envelope import build_envelope
 
 log = logging.getLogger(__name__)
 
@@ -44,31 +44,48 @@ def send_otc_email(to_address: str, code: str) -> bool:
     cfg = EmailConfig.from_env()
     subject = f"Your sign-in code for {cfg.from_name}"
     body = _body(code, cfg)
+    # v0.18.0: OTC mail carries NO List-Unsubscribe — the recipient
+    # explicitly requested the code; advertising an unsubscribe
+    # header would imply OHM has them on a list, which it doesn't.
+    # See the proposal's "Tradeoff discussion" for the binding
+    # rationale.
+    msg = build_envelope(
+        to_address=to_address,
+        from_address=cfg.from_address,
+        from_name=cfg.from_name,
+        subject=subject,
+        body_plain=body,
+    )
     envelope = {
         "to": to_address,
         "from": formataddr((cfg.from_name, cfg.from_address)),
         "subject": subject,
         "body": body,
         "kind": "otc",
+        "message": msg,
     }
     _SENT.append(envelope)
 
+    message_id = msg["Message-ID"]
     if not cfg.enabled:
         log.info("otc email disabled (EMAIL_ENABLED=0): to=%s", to_address)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="otc", status="deferred", message_id=message_id,
+        )
         return True
     if not cfg.smtp_host:
         # Dev fallback: surface the code at INFO so the operator can
         # complete a sign-in flow without an SMTP relay. In production
         # SMTP_HOST is always set per OHM's overlay.
         log.info("otc email (stdout fallback): to=%s code=%s", to_address, code)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="otc", status="deferred", message_id=message_id,
+        )
         return True
 
     try:
-        msg = EmailMessage()
-        msg["From"] = envelope["from"]
-        msg["To"] = to_address
-        msg["Subject"] = subject
-        msg.set_content(body)
         smtp = smtplib.SMTP(cfg.smtp_host, cfg.smtp_port, timeout=30)
         try:
             if cfg.smtp_starttls:
@@ -78,9 +95,18 @@ def send_otc_email(to_address: str, code: str) -> bool:
             smtp.send_message(msg)
         finally:
             smtp.quit()
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="otc", status="sent", message_id=message_id,
+        )
         return True
-    except Exception:
+    except Exception as exc:
         log.exception("otc email send failed: to=%s", to_address)
+        record_outbound(
+            to_address=to_address, from_address=cfg.from_address,
+            subject=subject, kind="otc", status="failed",
+            error=f"{type(exc).__name__}: {exc}", message_id=message_id,
+        )
         return False
 
 

backend/app/invites.py

@@ -0,0 +1,425 @@
+"""§6.1 / v0.17.0: admin-create user with role + invite email (roadmap item #16).
+
+Distinguishes from the v0.8.0 self-serve beta-access flow:
+
+  * **Self-serve (v0.8.0)** — anyone with an email can request OTC sign-in;
+    a fresh `users` row lands in `permission_state='pending'`; an admin
+    grants or revokes via the v0.9.0 user-management page.
+
+  * **Admin-create (v0.17.0)** — an admin types first/last/email/role
+    *before* the invitee has signed in. The framework provisions the
+    `users` row with the chosen role and `permission_state='granted'`
+    (the admin's hand is the grant) and `last_seen_at IS NULL` as the
+    "invited but not yet arrived" discriminator. An invite-token row
+    lands in `user_invite_tokens`; the admin's chosen `custom_message`
+    (if any) rides in the email body alongside the claim link.
+
+  * **Claim flow** — the invitee clicks the link, which lands them at
+    `/invites/claim?token=…`. The page POSTs `/api/invites/claim` with
+    the token. The framework verifies the token (not expired, not
+    claimed, hash matches), marks the row claimed, signs the user in,
+    and returns a payload telling the frontend whether to route to
+    passcode-set (if v0.10.0 passcode flow is in play and the user has
+    no passcode yet) or to `/`. **No OTC roundtrip** — clicking the
+    unique token in the email is itself proof of email control, per
+    the roadmap. This is the intentional UX shortcut for first
+    sign-in; subsequent sign-ins use the standard OTC / passcode
+    paths.
+
+The shape:
+
+  * `create_invite(...)` — provision the invitee `users` row + the
+    `user_invite_tokens` row, return the raw token for the admin
+    endpoint to put in the outbound email link.
+  * `claim(raw_token)` — validate the token, mark it claimed, return
+    the `SessionUser` the endpoint signs in. Distinguishes the failure
+    modes (`expired`, `claimed`, `unknown`, `invalid`) so the endpoint
+    can map them to HTTP 410 vs HTTP 404 cleanly.
+  * `list_pending_invites()` — return active invites for the admin
+    listing surface. Filters out claimed + expired rows so the surface
+    only shows live invites.
+
+Token shape: opaque DB token (256 bits of CSPRNG entropy via
+`secrets.token_urlsafe(32)`), bcrypt-hashed at rest. Opaque chosen
+over JWT because revocation is then a single SQL UPDATE — a JWT
+would be stateless but harder to invalidate, and admin-issued
+invites are exactly the kind of thing an admin should be able to
+yank back. The raw token only ever lives in the outbound email link
+and the inbound claim body; server-side storage is the hash.
+
+TTL: hard-coded to 7 days via `INVITE_TOKEN_TTL_DAYS`. Env-var
+configurability is a §19.2 candidate — the constant is exposed
+here as a single point of edit if a deployment wants to override.
+
+The 500-char ceiling on `custom_message` is enforced at the
+Pydantic body level in `api_admin.py`; this module trusts what
+the endpoint hands it.
+"""
+from __future__ import annotations
+
+import logging
+import secrets
+from dataclasses import dataclass
+
+import bcrypt
+
+from . import db
+from .auth import SessionUser
+
+log = logging.getLogger(__name__)
+
+
+# ---------------------------------------------------------------------------
+# Tunables — intentionally hard-coded in v0.17.0 (§19.2 candidate to env-ify).
+# ---------------------------------------------------------------------------
+
+INVITE_TOKEN_TTL_DAYS = 7
+# 256 bits of CSPRNG entropy. `secrets.token_urlsafe(32)` yields ~43
+# URL-safe characters; the bcrypt hash is what's stored, so the raw
+# token only ever lives in the outbound email link.
+TOKEN_BYTES = 32
+# Free-text ceiling for the admin's optional custom message. Matched
+# at the Pydantic body bound in `api_admin.py`; mentioned here so the
+# bound is documented in one place.
+CUSTOM_MESSAGE_MAX_LENGTH = 500
+
+
+# ---------------------------------------------------------------------------
+# Token + hash helpers (mirror device_trust.py shape)
+# ---------------------------------------------------------------------------
+
+
+def _new_token() -> str:
+    return secrets.token_urlsafe(TOKEN_BYTES)
+
+
+def _hash(token: str) -> str:
+    return bcrypt.hashpw(token.encode("utf-8"), bcrypt.gensalt()).decode("ascii")
+
+
+def _check(token: str, token_hash: str) -> bool:
+    try:
+        return bcrypt.checkpw(token.encode("utf-8"), token_hash.encode("ascii"))
+    except (ValueError, TypeError):
+        return False
+
+
+# ---------------------------------------------------------------------------
+# Create
+# ---------------------------------------------------------------------------
+
+
+@dataclass
+class CreateOutcome:
+    """The shape returned from `create_invite`.
+
+    `raw_token` is what the admin endpoint puts in the outbound email
+    link; it never appears in storage. `invite_id` is the surrogate
+    key for the admin's "invites I've sent" listing. `invited_user_id`
+    is the freshly-provisioned `users` row id so the admin surface can
+    join through to the user-management page.
+    """
+    raw_token: str
+    invite_id: int
+    invited_user_id: int
+
+
+def create_invite(
+    *,
+    email: str,
+    first_name: str,
+    last_name: str,
+    role: str,
+    custom_message: str,
+    created_by_admin_id: int,
+) -> CreateOutcome:
+    """Provision the invitee `users` row + the `user_invite_tokens` row.
+
+    Caller (`api_admin.py`) is responsible for the admin-only auth check,
+    the self-email refusal (422), and the duplicate-email refusal (409).
+    This function trusts what it's handed and writes both rows
+    transactionally — the v0.10.0 `passcode.py` / v0.11.0 `device_trust.py`
+    helpers follow the same separation-of-concerns pattern.
+
+    The invitee `users` row is provisioned with:
+      * `permission_state='granted'` — the admin's hand is the grant;
+        the v0.8.0 self-serve `pending` queue is for the other path.
+      * `last_seen_at = NULL` — the discriminator for "invited but
+        not yet arrived" per the §16 / roadmap design. Every sign-in
+        path stamps `last_seen_at` to now, so a NULL value means the
+        invited user has not clicked through yet.
+      * `gitea_id = NULL`, `gitea_login = NULL` — same as a v0.7.0
+        OTC-provisioned user; the OAuth identity is grandfathered if
+        the user ever lands through that path.
+      * `display_name` defaults to "<first> <last>" (or local-part of
+        email if both are empty) so the user-management page reads a
+        sensible label before the user has signed in.
+      * `first_name` / `last_name` / `beta_request_reason` — the
+        first two from the admin's typed values; reason stays blank
+        (this user did not self-request access).
+    """
+    email_clean = email.strip()
+    first_clean = (first_name or "").strip()
+    last_clean = (last_name or "").strip()
+    display = " ".join(p for p in (first_clean, last_clean) if p).strip()
+    if not display:
+        display = email_clean.split("@", 1)[0] or email_clean
+
+    # 1. Provision the invitee users row. The grant is the admin's
+    # hand; no permission_events row is necessary for the grant itself
+    # (we are not transitioning from pending → granted, we are landing
+    # a fresh row directly into granted).
+    #
+    # Note on the "pending invite" discriminator: the brief floated
+    # `first_sign_in_at NULL` / `last_seen_at NULL` as the marker the
+    # admin user-management page reads off the row to render the
+    # "(pending invite)" badge. The schema didn't cooperate — the
+    # existing `users.last_seen_at` column is NOT NULL with a
+    # `datetime('now')` default (see `migrations/001_users_and_audit.sql`),
+    # and there is no `first_sign_in_at` column. Rather than introduce
+    # a schema migration to add one (the brief explicitly said "likely
+    # no `users` table changes"), the discriminator is the existence of
+    # an active row in `user_invite_tokens` joined on `invited_user_id`.
+    # The admin listing's `pending_invite` field joins through that
+    # table; the claim flow stamps `claimed_at` on the invite row,
+    # which clears the badge naturally. This shape keeps the
+    # discriminator scoped to the v0.17.0 surface and avoids
+    # double-tracking against an existing column.
+    cur = db.conn().execute(
+        """
+        INSERT INTO users (
+            gitea_id, gitea_login, email, display_name, avatar_url,
+            role, permission_state, first_name, last_name
+        )
+        VALUES (NULL, NULL, ?, ?, '', ?, 'granted', ?, ?)
+        """,
+        (email_clean, display, role, first_clean, last_clean),
+    )
+    invited_user_id = cur.lastrowid
+
+    # 2. Mint the token, hash it, write the invite row.
+    raw = _new_token()
+    h = _hash(raw)
+    cur = db.conn().execute(
+        f"""
+        INSERT INTO user_invite_tokens (
+            email, role, first_name, last_name, custom_message,
+            token_hash, expires_at, created_by_admin_id, invited_user_id
+        )
+        VALUES (?, ?, ?, ?, ?, ?, datetime('now', '+{INVITE_TOKEN_TTL_DAYS} days'), ?, ?)
+        """,
+        (
+            email_clean,
+            role,
+            first_clean,
+            last_clean,
+            (custom_message or "").strip(),
+            h,
+            created_by_admin_id,
+            invited_user_id,
+        ),
+    )
+    invite_id = cur.lastrowid
+    return CreateOutcome(
+        raw_token=raw,
+        invite_id=invite_id,
+        invited_user_id=invited_user_id,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Claim
+# ---------------------------------------------------------------------------
+
+
+@dataclass
+class ClaimOutcome:
+    """The result of `claim`.
+
+    `user` is populated only on success. `reason` distinguishes the
+    failure modes so the endpoint can return distinct HTTP statuses
+    (HTTP 410 for expired/claimed — the token is dead; HTTP 400 for
+    unknown/invalid — the request shape is wrong).
+    """
+    ok: bool
+    user: SessionUser | None
+    reason: str  # 'ok' | 'invalid' | 'unknown' | 'expired' | 'claimed'
+    invite_id: int | None = None
+
+
+def claim(raw_token: str) -> ClaimOutcome:
+    """Validate the presented token and consume it.
+
+    Walks the active invite rows looking for a bcrypt hash match.
+    Mirrors `device_trust.lookup`: bcrypt's per-row salt means we
+    cannot SELECT by hash, but the set is small (a deployment's
+    outstanding invites at any moment) and bcrypt is cheap on the
+    order of milliseconds.
+
+    On a hit:
+      * Mark the row claimed (stamp `claimed_at = now`,
+        `claimed_by_user_id = invited_user_id` — the admin's
+        pre-provisioned row is the claimant).
+      * Stamp `last_seen_at = now` on the user row so the v0.9.0
+        admin user-management page no longer shows "(pending invite)".
+      * Return a populated `SessionUser` for the endpoint to sign in.
+
+    On a miss:
+      * `unknown` — no row matched. The token may have been forged or
+        the invite was admin-revoked.
+      * `expired` — row matched but `expires_at` is in the past.
+      * `claimed` — row matched but `claimed_at` is non-NULL. The
+        token was already consumed; the user must contact the admin
+        for a fresh invite.
+      * `invalid` — the token string itself was empty or unparseable.
+    """
+    raw = (raw_token or "").strip()
+    if not raw:
+        return ClaimOutcome(ok=False, user=None, reason="invalid")
+
+    rows = db.conn().execute(
+        """
+        SELECT id, token_hash, expires_at, claimed_at, invited_user_id, role
+          FROM user_invite_tokens
+         ORDER BY id DESC
+        """
+    ).fetchall()
+
+    matched = None
+    for row in rows:
+        if _check(raw, row["token_hash"]):
+            matched = row
+            break
+
+    if matched is None:
+        return ClaimOutcome(ok=False, user=None, reason="unknown")
+
+    if matched["claimed_at"] is not None:
+        return ClaimOutcome(
+            ok=False, user=None, reason="claimed", invite_id=matched["id"],
+        )
+
+    expired = db.conn().execute(
+        "SELECT datetime(?) < datetime('now') AS expired",
+        (matched["expires_at"],),
+    ).fetchone()["expired"]
+    if expired:
+        return ClaimOutcome(
+            ok=False, user=None, reason="expired", invite_id=matched["id"],
+        )
+
+    # Consume the row before signing in so a parallel claim of the same
+    # token cannot double-sign-in. (Mirrors `otc.verify_code`'s consume-
+    # before-provision shape.)
+    db.conn().execute(
+        """
+        UPDATE user_invite_tokens
+           SET claimed_at = datetime('now'),
+               claimed_by_user_id = invited_user_id
+         WHERE id = ?
+        """,
+        (matched["id"],),
+    )
+    # Stamp last_seen_at on the user row so the user's activity stamp
+    # is current after the claim (mirroring otc.verify_code's
+    # last-seen update on the provision path). The "(pending invite)"
+    # badge's clear is driven by the invite row's `claimed_at`
+    # transition above; this update is for the general user-listing's
+    # recency ordering.
+    db.conn().execute(
+        "UPDATE users SET last_seen_at = datetime('now') WHERE id = ?",
+        (matched["invited_user_id"],),
+    )
+
+    user_row = db.conn().execute(
+        """
+        SELECT id, gitea_id, gitea_login, email, display_name, avatar_url,
+               role, permission_state
+          FROM users
+         WHERE id = ?
+        """,
+        (matched["invited_user_id"],),
+    ).fetchone()
+    if user_row is None:
+        # The invitee user row was deleted between create_invite and
+        # claim (shouldn't happen under the FK ON DELETE CASCADE — the
+        # cascade would drop the invite row too — be defensive anyway).
+        return ClaimOutcome(
+            ok=False, user=None, reason="unknown", invite_id=matched["id"],
+        )
+
+    return ClaimOutcome(
+        ok=True,
+        user=SessionUser(
+            user_id=user_row["id"],
+            gitea_id=user_row["gitea_id"] or 0,
+            gitea_login=user_row["gitea_login"] or "",
+            display_name=user_row["display_name"],
+            email=user_row["email"] or "",
+            avatar_url=user_row["avatar_url"] or "",
+            role=user_row["role"],
+            permission_state=user_row["permission_state"] or "granted",
+        ),
+        reason="ok",
+        invite_id=matched["id"],
+    )
+
+
+# ---------------------------------------------------------------------------
+# List pending invites — for the admin's review surface
+# ---------------------------------------------------------------------------
+
+
+@dataclass
+class PendingInviteRow:
+    """The shape the `GET /api/admin/users/invites` endpoint returns.
+
+    Note the absence of `token_hash` — the hash is structurally private,
+    and the surface has no use for it. The raw token is also not on
+    the listing; it lives only in the email link.
+    """
+    id: int
+    email: str
+    role: str
+    first_name: str
+    last_name: str
+    custom_message: str
+    created_at: str
+    expires_at: str
+    created_by_admin_id: int
+    invited_user_id: int
+
+
+def list_pending_invites() -> list[PendingInviteRow]:
+    """Active invites (not claimed, not expired), freshest first.
+
+    The admin's "I sent these but they haven't been claimed yet" view.
+    Filters mirror the `device_trust.list_for_user` shape: the surface
+    only shows live records the framework would actually accept on a
+    presented token.
+    """
+    rows = db.conn().execute(
+        """
+        SELECT id, email, role, first_name, last_name, custom_message,
+               created_at, expires_at, created_by_admin_id, invited_user_id
+          FROM user_invite_tokens
+         WHERE claimed_at IS NULL
+           AND datetime(expires_at) > datetime('now')
+         ORDER BY created_at DESC, id DESC
+        """
+    ).fetchall()
+    return [
+        PendingInviteRow(
+            id=row["id"],
+            email=row["email"],
+            role=row["role"],
+            first_name=row["first_name"] or "",
+            last_name=row["last_name"] or "",
+            custom_message=row["custom_message"] or "",
+            created_at=row["created_at"],
+            expires_at=row["expires_at"],
+            created_by_admin_id=row["created_by_admin_id"],
+            invited_user_id=row["invited_user_id"],
+        )
+        for row in rows
+    ]

backend/app/main.py

@@ -24,6 +24,7 @@ from . import (
     digest,
     email_otc,
     hygiene,
+    invites as invites_mod,
     otc,
     passcode as passcode_mod,
     providers as providers_mod,
@@ -72,6 +73,25 @@ class PasscodeVerifyBody(BaseModel):
     trust_device: bool = False
 
 
+class InviteClaimBody(BaseModel):
+    """v0.17.0 / roadmap item #16 — claim an admin-issued invite token.
+
+    The frontend `/invites/claim?token=…` page reads the token from
+    the URL and POSTs it here. The body bound matches the
+    `secrets.token_urlsafe(32)` output shape (~43 URL-safe chars);
+    the upper bound stays generous in case `TOKEN_BYTES` is ever
+    raised. The token-shape is opaque to this layer — `invites.claim`
+    bcrypt-checks it against the active candidate set.
+    """
+    token: str = Field(min_length=1, max_length=512)
+    # v0.11.0-style opt-in: the claim flow's "trust this device" gesture
+    # is bundled here so the invitee can land trusted on first sign-in
+    # without an extra roundtrip. Defaults to false so the gesture is
+    # explicit (the frontend modal renders a checkbox alongside the
+    # claim CTA).
+    trust_device: bool = False
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     config = load_config()
@@ -382,6 +402,95 @@ def _oauth_router(config) -> APIRouter:
             },
         }
 
+    # ---------------------------------------------------------------
+    # v0.17.0: admin-create user + invite claim (§6.1, roadmap item #16).
+    #
+    # The admin-create surface lives at POST /api/admin/users (see
+    # api_admin.py); this endpoint is the corresponding claim path the
+    # invitee hits when they click the link in their invite email.
+    # The frontend route `/invites/claim?token=…` reads the token from
+    # the URL and POSTs it here.
+    #
+    # The claim itself is the first-sign-in for the invitee: clicking
+    # the unique token in the email is proof of email control per the
+    # roadmap, so this endpoint skips the OTC step entirely on first
+    # sign-in. The session cookie lands; the response tells the
+    # frontend whether to route to passcode-set (if v0.10.0 passcode
+    # flow is in play and the user has not yet set a passcode) or to
+    # home.
+    #
+    # The endpoint is anonymous-reachable: the entire point is to
+    # establish the session, so we do not gate it on `require_user`.
+    # The trust-device opt-in mirrors the v0.11.0 OTC/passcode verify
+    # contract (the body's `trust_device` flag, when true, mints a
+    # fresh device-trust row on the same response so the invitee
+    # lands trusted on their first device).
+    # ---------------------------------------------------------------
+
+    @router.post("/api/invites/claim")
+    async def invites_claim(body: InviteClaimBody, request: Request, response: Response):
+        result = invites_mod.claim(body.token)
+        if result.reason == "expired":
+            # The token's TTL window passed without a claim. HTTP 410
+            # (Gone) so the frontend can render a "this invite has
+            # expired — please contact the admin for a fresh one"
+            # message distinct from the generic invalid-token shape.
+            raise HTTPException(410, "This invite has expired")
+        if result.reason == "claimed":
+            # The token was already consumed. HTTP 410 for the same
+            # reason — the row is dead either way.
+            raise HTTPException(410, "This invite has already been claimed")
+        if not result.ok or result.user is None:
+            # 'unknown' / 'invalid' — the token does not match any
+            # active invite row. HTTP 400 so it reads distinct from
+            # the dead-token shape above.
+            raise HTTPException(400, "Invalid invite token")
+
+        # Establish the session. From here on the invitee is signed
+        # in as the pre-provisioned user row carrying their
+        # pre-assigned role.
+        auth.store_session(request, result.user)
+
+        # v0.11.0 — opt-in device trust on the claim response. Same
+        # contract as OTC/passcode verify: when the body's flag is
+        # true, the server mints a fresh device-trust row and sets
+        # the long-lived cookie, so the invitee skips the email step
+        # on subsequent visits to the same browser.
+        if body.trust_device:
+            ua = request.headers.get("user-agent", "")
+            outcome = device_trust_mod.issue(result.user.user_id, ua)
+            _set_device_trust_cookie(response, outcome.raw_token)
+
+        # Has the user already set a passcode? (Could only happen via
+        # an admin pre-population path that doesn't exist yet, but
+        # the response shape mirrors `/api/auth/me` so the frontend
+        # can read it without a second call.) If `needs_passcode` is
+        # true and v0.10.0 passcode flow is in play, the frontend
+        # routes to /settings/notifications#sign-in to set a passcode
+        # immediately; otherwise it routes to /.
+        row = db.conn().execute(
+            "SELECT passcode_hash FROM users WHERE id = ?",
+            (result.user.user_id,),
+        ).fetchone()
+        has_passcode = bool(row and row["passcode_hash"])
+
+        return {
+            "ok": True,
+            "user": {
+                "id": result.user.user_id,
+                "display_name": result.user.display_name,
+                "email": result.user.email,
+                "role": result.user.role,
+                "permission_state": result.user.permission_state,
+            },
+            # Roadmap §16: the claim flow skips OTC entirely; the
+            # natural next step is passcode-set (so the invitee can
+            # sign back in without needing an email roundtrip on their
+            # second visit). The frontend uses this hint to decide
+            # whether to route to the passcode-set screen or to home.
+            "needs_passcode": not has_passcode,
+        }
+
     # ---------------------------------------------------------------
     # v0.11.0: trust device for 30 days (§6.2, roadmap item #9).
     #

backend/app/webhooks.py

@@ -12,6 +12,7 @@ import hashlib
 import hmac
 import json
 import logging
+import os
 
 from fastapi import APIRouter, Header, HTTPException, Request
 
@@ -40,7 +41,27 @@ def make_router(config: Config, gitea: Gitea) -> APIRouter:
         x_gitea_signature: str = Header(default=""),
     ):
         body = await request.body()
-        if config.webhook_secret:
+        # v0.18.0: defense in depth. config.py refuses to start
+        # when the secret is empty unless `RFC_APP_INSECURE_WEBHOOKS=1`
+        # is set; this branch catches the dev-bypass case (the only
+        # path where `config.webhook_secret` can be empty) and surfaces
+        # it loudly to the client. A POST that lands here with an
+        # empty secret on a production deployment indicates a
+        # mis-configuration (somebody flipped the bypass in prod),
+        # and the loud 500 is the proposal's whole point.
+        insecure = os.environ.get("RFC_APP_INSECURE_WEBHOOKS", "").strip() == "1"
+        if not config.webhook_secret:
+            if not insecure:
+                log.error(
+                    "webhook receiver misconfigured: GITEA_WEBHOOK_SECRET is empty "
+                    "and RFC_APP_INSECURE_WEBHOOKS=1 is not set"
+                )
+                raise HTTPException(status_code=500, detail="Webhook receiver misconfigured")
+            log.warning(
+                "webhook receiver running with RFC_APP_INSECURE_WEBHOOKS=1 — "
+                "signature verification is DISABLED. Production deployments MUST NOT set this."
+            )
+        else:
             if not _verify_signature(body, x_gitea_signature, config.webhook_secret):
                 raise HTTPException(status_code=401, detail="Invalid signature")
 
@@ -68,6 +89,17 @@ def make_router(config: Config, gitea: Gitea) -> APIRouter:
                 slug = _slug_for_repo(repo_full)
                 if slug:
                     await cache.refresh_rfc_repo(config, gitea, slug)
+                else:
+                    # v0.18.0: the proposal's "unknown-repo logging"
+                    # gesture — a hook on a fork or a stale repo binding
+                    # used to silently 200-OK here, hiding the
+                    # misconfiguration. Now the operator sees it in
+                    # the log.
+                    log.info(
+                        "webhook received for unknown repo: repo_full=%s event=%s "
+                        "(no cached_rfcs row matched; hook may be on a fork or stale)",
+                        repo_full, event,
+                    )
         except Exception:
             log.exception("webhook refresh failed")
             raise HTTPException(status_code=500, detail="Refresh failed")

backend/migrations/019_user_invite_tokens.sql

@@ -0,0 +1,105 @@
+-- §6.1 / v0.17.0: admin-create user with role + invite email (roadmap item #16).
+--
+-- Distinguishes from the v0.8.0 / v0.9.0 self-serve beta-access shape:
+-- here an *admin* creates a `users` row *before* the invited person has
+-- ever signed in, assigns them a role at creation time, and sends them
+-- an invite email carrying a claim link. The invitee clicks the link,
+-- the claim flow consumes the token (which is itself proof of email
+-- control), the row is marked claimed, and the user is signed in
+-- inheriting the pre-set role.
+--
+-- Migration slot 019 is allocated to this release. Slot 018 is reserved
+-- for the parallel #12 release (per-RFC invitation, owner-only) shipping
+-- in the same wave; the two features live in distinct tables
+-- (`user_invite_tokens` here vs. `rfc_invitations` there) so they
+-- coexist cleanly. Slot 016 was reserved+skipped by Session K during
+-- v0.9.0 integration; slot 017 is the v0.11.0 device-trust table.
+--
+-- Open-question decisions settled in this release (see CHANGELOG):
+--   * No `users` table changes — the brief floated `first_sign_in_at`
+--     / `last_seen_at IS NULL` as the "(pending invite)" discriminator,
+--     but the existing `users.last_seen_at` is NOT NULL with a
+--     `datetime('now')` default (migrations/001) and there is no
+--     `first_sign_in_at` column. Rather than land a schema migration to
+--     introduce one, the discriminator is the existence of an active
+--     (not-claimed, not-expired) row in `user_invite_tokens` joined on
+--     `invited_user_id`. The admin user-listing carries a
+--     `pending_invite` field populated via that join; on claim, the
+--     invite row's `claimed_at` populates and the badge clears.
+--     No new `permission_state` value is introduced either.
+--   * The token is opaque (random URL-safe string, bcrypt-hashed at
+--     rest), not a JWT, so admin revocation by row UPDATE works
+--     without distributing a key-rotation gesture.
+--   * The TTL is a constant (`INVITE_TOKEN_TTL_DAYS = 7` in
+--     `backend/app/invites.py`); env-var configurability is a follow-up.
+--   * Immediate-send (no admin-review-then-send queue) ships in this
+--     release; admin-preview is a future enhancement.
+--   * Bulk-invite (CSV paste) is deferred to a follow-up release;
+--     v0.17.0 is one-at-a-time.
+--
+-- Storage shape:
+--
+--   * `id` — surrogate key. Lets the admin "pending invites" listing
+--     address a row without leaking the token shape.
+--   * `email` — the address the invite was sent to (case-insensitive
+--     match at claim time, persisted verbatim for the audit trail).
+--   * `role` — the role the invitee inherits on first sign-in. Pinned
+--     via CHECK to the same set the §6.1 role flip accepts
+--     (`owner` / `admin` / `contributor`) so a future role-set drift
+--     fails loudly at insert rather than provisioning a ghost role.
+--   * `first_name` / `last_name` — captured at create time so the
+--     invitee skips the v0.8.0 capture-form step on first sign-in.
+--   * `custom_message` — optional free-text from the admin (max 500
+--     chars enforced at the API layer); embedded verbatim in the
+--     email body if present.
+--   * `token_hash` — bcrypt hash of the random opaque token. The
+--     raw token only ever lives in the outbound email link and the
+--     inbound claim body; server-side storage is the hash.
+--   * `expires_at` — `created_at + 7 days` (default at the app layer
+--     via `INVITE_TOKEN_TTL_DAYS`). A row past this stamp is dead;
+--     the claim path refuses with HTTP 410.
+--   * `created_at` — when the admin issued the invite.
+--   * `created_by_admin_id` — FK into users(id) for the admin who
+--     created the invite (no cascade; if the admin's row is deleted
+--     the invite history stays so the audit trail survives).
+--   * `claimed_at` — non-NULL once the invitee successfully claims.
+--     A second claim attempt against an already-claimed row returns
+--     HTTP 410.
+--   * `claimed_by_user_id` — FK into users(id) for the user row
+--     that consumed the token. In the common case this equals the
+--     freshly-provisioned row that was created at invite time; the
+--     FK lets the admin's "claimed" list join through.
+--   * `invited_user_id` — FK into users(id) for the pre-provisioned
+--     row. Created at invite time with `last_seen_at IS NULL` so the
+--     v0.9.0 admin user-management page can render a "(pending
+--     invite)" badge alongside existing users.
+--
+-- Indexing:
+--   * Unique index on `token_hash` documents the no-collision
+--     invariant (256 bits of CSPRNG entropy; collision is
+--     structurally impossible, the unique constraint catches a
+--     bug at insert time).
+--   * Index on `(email, claimed_at)` so the "is this email already
+--     invited?" pre-check the admin endpoint runs is a covering walk.
+--   * Index on `(created_by_admin_id, created_at DESC)` for the
+--     admin's "invites I've sent" listing.
+
+CREATE TABLE user_invite_tokens (
+    id                   INTEGER PRIMARY KEY AUTOINCREMENT,
+    email                TEXT NOT NULL,
+    role                 TEXT NOT NULL CHECK (role IN ('owner', 'admin', 'contributor')),
+    first_name           TEXT NOT NULL DEFAULT '',
+    last_name            TEXT NOT NULL DEFAULT '',
+    custom_message       TEXT NOT NULL DEFAULT '',
+    token_hash           TEXT NOT NULL,
+    expires_at           TEXT NOT NULL,
+    created_at           TEXT NOT NULL DEFAULT (datetime('now')),
+    created_by_admin_id  INTEGER NOT NULL REFERENCES users(id),
+    claimed_at           TEXT,
+    claimed_by_user_id   INTEGER REFERENCES users(id),
+    invited_user_id      INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE
+);
+
+CREATE UNIQUE INDEX idx_user_invite_tokens_hash ON user_invite_tokens (token_hash);
+CREATE INDEX idx_user_invite_tokens_email ON user_invite_tokens (email, claimed_at);
+CREATE INDEX idx_user_invite_tokens_admin ON user_invite_tokens (created_by_admin_id, created_at DESC);

backend/migrations/020_outbound_emails.sql

@@ -0,0 +1,30 @@
+-- v0.18.0 Slice 4: outbound_emails audit table.
+--
+-- Per the v0.18.0 email + webhook hygiene proposal §3, every send
+-- helper writes a row to this table before returning, regardless
+-- of outcome. status='sent' on success, 'failed' on exception,
+-- 'deferred' on the dev-fallback path (no SMTP_HOST configured).
+--
+-- The table is queried by `GET /api/admin/outbound-emails` to
+-- answer "did this person ever get their invite?" without having
+-- to grep VM logs, and by the v0.18.0 Slice 5 bounce-correlation
+-- hook (which looks up message_id when a POST lands at
+-- /api/webhooks/email-bounce and marks the matching row
+-- status='bounced').
+
+CREATE TABLE IF NOT EXISTS outbound_emails (
+    id              INTEGER PRIMARY KEY,
+    to_address      TEXT NOT NULL,
+    from_address    TEXT NOT NULL,
+    subject         TEXT NOT NULL,
+    kind            TEXT NOT NULL,     -- 'otc' | 'invite' | 'notification' | 'bundle' | 'digest' | 'rfc-invite'
+    sent_at         TEXT NOT NULL,     -- ISO 8601, time the send was attempted
+    status          TEXT NOT NULL,     -- 'sent' | 'failed' | 'deferred' | 'bounced'
+    error           TEXT,              -- exception class + message if status='failed'
+    notification_id INTEGER,           -- nullable FK to notifications.id for the watcher path
+    message_id      TEXT               -- the Message-ID header value, for bounce correlation
+);
+
+CREATE INDEX IF NOT EXISTS idx_outbound_emails_to        ON outbound_emails(to_address);
+CREATE INDEX IF NOT EXISTS idx_outbound_emails_sent_at   ON outbound_emails(sent_at);
+CREATE INDEX IF NOT EXISTS idx_outbound_emails_message   ON outbound_emails(message_id);

backend/tests/test_admin_create_user_invite_vertical.py

@@ -0,0 +1,728 @@
+"""End-to-end integration tests for v0.17.0's admin-create user +
+invite-email + claim-flow vertical (roadmap item #16, §6.1).
+
+The release lands three halves of the same surface:
+
+  * **Admin-create user** at `POST /api/admin/users`. The admin types
+    email, first/last name, role, and an optional custom message. The
+    framework provisions the invitee `users` row (granted, with the
+    chosen role) and writes a `user_invite_tokens` row carrying the
+    bcrypt-hashed opaque token. The "pending invite" discriminator is
+    the active `user_invite_tokens` row joined on `invited_user_id`,
+    not a NULL column on `users` (the existing `last_seen_at` column
+    is NOT NULL). An invite email dispatches via the existing SMTP
+    relay.
+
+  * **Pending-invite admin listing** at `GET /api/admin/users/invites`.
+    Lists active (not claimed, not expired) invites for the admin's
+    "I sent these but they haven't been claimed yet" view.
+
+  * **Claim** at `POST /api/invites/claim`. The invitee POSTs the token
+    they got via email; the framework verifies, marks the row claimed,
+    signs them in (skipping OTC on first sign-in per the roadmap), and
+    returns a `needs_passcode` hint for the frontend to route to the
+    passcode-set screen.
+
+The tests prove:
+
+  * The happy path: admin creates → invite row + email envelope land →
+    invitee claims with the token → session is established.
+  * Non-admin caller is refused 403.
+  * Self-invite is refused 422.
+  * Duplicate email is refused 409.
+  * Owner-grant by non-owner is refused 422.
+  * Malformed role is refused 422 (pydantic regex).
+  * Custom message over 500 chars is refused 422 (pydantic max_length).
+  * Claim with valid token: signs in + marks row claimed.
+  * Claim with expired token: HTTP 410.
+  * Claim with already-claimed token: HTTP 410.
+  * Claim with unknown token: HTTP 400.
+  * The admin-create gesture writes a `permission_events` row with
+    event_kind='user_invited'.
+  * The user listing surfaces the `pending_invite` field for invited-
+    but-not-yet-claimed users, and clears it after claim.
+"""
+from __future__ import annotations
+
+import json
+
+from test_propose_vertical import (  # noqa: F401 — fixtures land via import
+    FakeGitea,
+    app_with_fake_gitea,
+    provision_user_row,
+    sign_in_as,
+    tmp_env,
+)
+
+
+def _reset_outbound():
+    from app import email as email_mod
+    email_mod.reset_sent_envelopes()
+
+
+def _outbound_invite_envelopes(to_address: str | None = None) -> list[dict]:
+    """Pull the invite-kind envelopes off the shared notifier buffer.
+
+    Mirrors the OTC code-extraction helper in
+    test_admin_users_vertical.py — invite emails land in the same
+    `_SENT` buffer with `kind='invite'`.
+    """
+    from app import email as email_mod
+    out = []
+    for env in email_mod.sent_envelopes():
+        if env.get("kind") != "invite":
+            continue
+        if to_address is not None and env["to"] != to_address:
+            continue
+        out.append(env)
+    return out
+
+
+def _extract_claim_url(envelope: dict) -> str:
+    """Pull the claim URL out of the invite email body."""
+    for line in envelope["body"].splitlines():
+        line = line.strip()
+        if line.startswith("http") and "/invites/claim" in line:
+            return line
+    raise AssertionError(f"no claim URL in envelope body: {envelope['body']!r}")
+
+
+def _extract_claim_token(envelope: dict) -> str:
+    """Pull the `token` query-string param out of the claim URL."""
+    from urllib.parse import urlparse, parse_qs
+    url = _extract_claim_url(envelope)
+    qs = parse_qs(urlparse(url).query)
+    return qs["token"][0]
+
+
+# ---------------------------------------------------------------------------
+# Admin create + invite — happy path
+# ---------------------------------------------------------------------------
+
+
+def test_admin_create_user_invite_happy_path(app_with_fake_gitea):
+    """Admin creates → user row + invite-token row + email envelope all
+    land; the response carries the created ids and the inviter is the
+    admin who issued the gesture."""
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=100, login="adminzero", role="admin")
+        sign_in_as(
+            client, user_id=100, gitea_login="adminzero",
+            display_name="Admin Zero", role="admin",
+            email="adminzero@test",
+        )
+        _reset_outbound()
+
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "invitee@example.com",
+                "first_name": "Inv",
+                "last_name": "Tee",
+                "role": "contributor",
+                "custom_message": "We chatted at the conference — welcome!",
+            },
+        )
+        assert r.status_code == 200, r.text
+        body = r.json()
+        assert body["ok"] is True
+        assert body["email"] == "invitee@example.com"
+        assert body["role"] == "contributor"
+        assert body["invite_id"] > 0
+        assert body["invited_user_id"] > 0
+
+        # User row exists with the chosen role + granted. The "pending
+        # invite" discriminator is the active `user_invite_tokens` row,
+        # not a NULL column on `users` — see the invites.create_invite
+        # docstring for the reasoning.
+        row = db.conn().execute(
+            "SELECT role, permission_state, first_name, last_name "
+            "FROM users WHERE email = ? COLLATE NOCASE",
+            ("invitee@example.com",),
+        ).fetchone()
+        assert row is not None
+        assert row["role"] == "contributor"
+        assert row["permission_state"] == "granted"
+        assert row["first_name"] == "Inv"
+        assert row["last_name"] == "Tee"
+
+        # Invite-token row exists with the matching ids and the custom
+        # message persisted verbatim.
+        invite = db.conn().execute(
+            "SELECT email, role, custom_message, created_by_admin_id, "
+            "invited_user_id, claimed_at FROM user_invite_tokens WHERE id = ?",
+            (body["invite_id"],),
+        ).fetchone()
+        assert invite is not None
+        assert invite["email"] == "invitee@example.com"
+        assert invite["role"] == "contributor"
+        assert invite["custom_message"] == "We chatted at the conference — welcome!"
+        assert invite["created_by_admin_id"] == 100
+        assert invite["invited_user_id"] == body["invited_user_id"]
+        assert invite["claimed_at"] is None
+
+        # Email envelope landed with the invite kind and embeds the
+        # custom message + claim URL. The inviter display name comes
+        # off the DB row (which provision_user_row sets to
+        # login.capitalize()), not the sign_in_as cookie payload.
+        envelopes = _outbound_invite_envelopes(to_address="invitee@example.com")
+        assert len(envelopes) == 1
+        env = envelopes[0]
+        assert "Adminzero" in env["subject"] or "Adminzero" in env["body"]
+        assert "We chatted at the conference — welcome!" in env["body"]
+        # Claim URL is well-formed.
+        url = _extract_claim_url(env)
+        assert "/invites/claim?token=" in url
+
+        # `permission_events` row landed with event_kind='user_invited'.
+        ev = db.conn().execute(
+            "SELECT actor_user_id, subject_user_id, event_kind, details "
+            "FROM permission_events WHERE event_kind = 'user_invited'"
+        ).fetchall()
+        assert len(ev) == 1
+        assert ev[0]["actor_user_id"] == 100
+        assert ev[0]["subject_user_id"] == body["invited_user_id"]
+        details = json.loads(ev[0]["details"])
+        assert details["email"] == "invitee@example.com"
+        assert details["role"] == "contributor"
+
+
+# ---------------------------------------------------------------------------
+# Refusals on the admin-create endpoint
+# ---------------------------------------------------------------------------
+
+
+def test_admin_create_user_invite_refuses_non_admin(app_with_fake_gitea):
+    """A contributor caller is refused 403; an anonymous caller 401."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=110, login="contrib", role="contributor")
+        sign_in_as(
+            client, user_id=110, gitea_login="contrib",
+            display_name="Contrib", role="contributor",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={"email": "x@y.com", "role": "contributor"},
+        )
+        assert r.status_code == 403, r.text
+
+        client.cookies.clear()
+        r = client.post(
+            "/api/admin/users",
+            json={"email": "x@y.com", "role": "contributor"},
+        )
+        assert r.status_code == 401
+
+
+def test_admin_create_user_invite_refuses_self_email(app_with_fake_gitea):
+    """An admin trying to invite their own email is refused 422 —
+    self-invite is the wrong channel; the role-change endpoint exists
+    for self-edits."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=120, login="adm", role="admin")
+        # Manually set the admin's email since provision_user_row's
+        # fixture uses login@test; this is what we'll try to self-invite.
+        from app import db
+        db.conn().execute(
+            "UPDATE users SET email = ? WHERE id = ?",
+            ("selfinviter@example.com", 120),
+        )
+        sign_in_as(
+            client, user_id=120, gitea_login="adm",
+            display_name="Adm", role="admin",
+            email="selfinviter@example.com",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "selfinviter@example.com",
+                "role": "contributor",
+            },
+        )
+        assert r.status_code == 422, r.text
+        assert "yourself" in r.json()["detail"].lower()
+
+
+def test_admin_create_user_invite_refuses_duplicate_email(app_with_fake_gitea):
+    """An admin trying to invite an email that already maps to a users
+    row is refused 409 — the existing role / grant gestures are the
+    right surface for an existing user."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=130, login="adminD", role="admin")
+        provision_user_row(user_id=131, login="existingone", role="contributor")
+        sign_in_as(
+            client, user_id=130, gitea_login="adminD",
+            display_name="Admin D", role="admin",
+        )
+        # provision_user_row sets email to <login>@test, so:
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "existingone@test",
+                "role": "contributor",
+            },
+        )
+        assert r.status_code == 409, r.text
+
+
+def test_admin_create_user_invite_owner_grant_refused_for_non_owner(app_with_fake_gitea):
+    """An admin (not owner) trying to invite a fresh user as `owner` is
+    refused 422 — §6.1's owner-zero is the only bootstrap path."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=140, login="adminNoOwner", role="admin")
+        sign_in_as(
+            client, user_id=140, gitea_login="adminNoOwner",
+            display_name="Admin", role="admin",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "wouldbeowner@example.com",
+                "role": "owner",
+            },
+        )
+        assert r.status_code == 422, r.text
+
+
+def test_admin_create_user_invite_owner_can_invite_as_owner(app_with_fake_gitea):
+    """A sitting owner can invite a fresh user as `owner` — the §6.1
+    role-grant channel. Sanity check that the owner-grant path itself
+    works, paired with the refusal above."""
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=150, login="ownerzero", role="owner")
+        sign_in_as(
+            client, user_id=150, gitea_login="ownerzero",
+            display_name="Owner Zero", role="owner",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "newowner@example.com",
+                "role": "owner",
+            },
+        )
+        assert r.status_code == 200, r.text
+        row = db.conn().execute(
+            "SELECT role FROM users WHERE email = ? COLLATE NOCASE",
+            ("newowner@example.com",),
+        ).fetchone()
+        assert row["role"] == "owner"
+
+
+def test_admin_create_user_invite_refuses_malformed_role(app_with_fake_gitea):
+    """The pydantic regex refuses any role outside the §6.1 set."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=160, login="adminR", role="admin")
+        sign_in_as(
+            client, user_id=160, gitea_login="adminR",
+            display_name="Admin R", role="admin",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "ok@example.com",
+                "role": "superuser",
+            },
+        )
+        assert r.status_code == 422
+
+
+def test_admin_create_user_invite_refuses_long_custom_message(app_with_fake_gitea):
+    """Custom message over the 500-char ceiling is refused 422."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=170, login="adminM", role="admin")
+        sign_in_as(
+            client, user_id=170, gitea_login="adminM",
+            display_name="Admin M", role="admin",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "ok@example.com",
+                "role": "contributor",
+                "custom_message": "x" * 501,
+            },
+        )
+        assert r.status_code == 422
+
+
+# ---------------------------------------------------------------------------
+# Claim flow
+# ---------------------------------------------------------------------------
+
+
+def test_claim_with_valid_token_signs_in_and_marks_claimed(app_with_fake_gitea):
+    """End-to-end: admin creates → invitee posts the token to
+    /api/invites/claim → session lands + row marked claimed +
+    last_seen_at stamps on the user row (the pending-invite
+    discriminator clears)."""
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=200, login="adminC", role="admin")
+        sign_in_as(
+            client, user_id=200, gitea_login="adminC",
+            display_name="Admin C", role="admin",
+        )
+        _reset_outbound()
+
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "claimant@example.com",
+                "first_name": "Clai",
+                "last_name": "Mant",
+                "role": "contributor",
+            },
+        )
+        assert r.status_code == 200
+        invite_id = r.json()["invite_id"]
+        invited_user_id = r.json()["invited_user_id"]
+
+        env = _outbound_invite_envelopes("claimant@example.com")[0]
+        token = _extract_claim_token(env)
+
+        # The invitee's request is anonymous (they have no session
+        # yet). We clear the admin's session cookie to simulate this.
+        client.cookies.clear()
+
+        r = client.post(
+            "/api/invites/claim",
+            json={"token": token},
+        )
+        assert r.status_code == 200, r.text
+        body = r.json()
+        assert body["ok"] is True
+        assert body["user"]["id"] == invited_user_id
+        assert body["user"]["role"] == "contributor"
+        assert body["user"]["permission_state"] == "granted"
+        # The user has no passcode set yet → frontend should route to
+        # passcode-set per the roadmap.
+        assert body["needs_passcode"] is True
+
+        # Row marked claimed; last_seen_at populated.
+        invite = db.conn().execute(
+            "SELECT claimed_at, claimed_by_user_id FROM user_invite_tokens "
+            "WHERE id = ?",
+            (invite_id,),
+        ).fetchone()
+        assert invite["claimed_at"] is not None
+        assert invite["claimed_by_user_id"] == invited_user_id
+
+        user_row = db.conn().execute(
+            "SELECT last_seen_at FROM users WHERE id = ?",
+            (invited_user_id,),
+        ).fetchone()
+        assert user_row["last_seen_at"] is not None
+
+
+def test_claim_with_expired_token_returns_410(app_with_fake_gitea):
+    """A token whose `expires_at` has passed surfaces as HTTP 410."""
+    from fastapi.testclient import TestClient
+    from app import db, invites
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=210, login="adminE", role="admin")
+        sign_in_as(
+            client, user_id=210, gitea_login="adminE",
+            display_name="Admin E", role="admin",
+        )
+        _reset_outbound()
+
+        # Create the invite, then back-date the expires_at to the past.
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "expired@example.com",
+                "role": "contributor",
+            },
+        )
+        assert r.status_code == 200
+        invite_id = r.json()["invite_id"]
+        db.conn().execute(
+            "UPDATE user_invite_tokens SET expires_at = datetime('now', '-1 day') "
+            "WHERE id = ?",
+            (invite_id,),
+        )
+        env = _outbound_invite_envelopes("expired@example.com")[0]
+        token = _extract_claim_token(env)
+
+        client.cookies.clear()
+        r = client.post("/api/invites/claim", json={"token": token})
+        assert r.status_code == 410, r.text
+        assert "expired" in r.json()["detail"].lower()
+
+
+def test_claim_with_already_claimed_token_returns_410(app_with_fake_gitea):
+    """Re-claiming an already-consumed token surfaces as HTTP 410."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=220, login="adminA", role="admin")
+        sign_in_as(
+            client, user_id=220, gitea_login="adminA",
+            display_name="Admin A", role="admin",
+        )
+        _reset_outbound()
+
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "twice@example.com",
+                "role": "contributor",
+            },
+        )
+        assert r.status_code == 200
+        env = _outbound_invite_envelopes("twice@example.com")[0]
+        token = _extract_claim_token(env)
+
+        client.cookies.clear()
+        # First claim succeeds.
+        r = client.post("/api/invites/claim", json={"token": token})
+        assert r.status_code == 200
+        # Second claim, with the same token, refuses with 410.
+        client.cookies.clear()
+        r = client.post("/api/invites/claim", json={"token": token})
+        assert r.status_code == 410, r.text
+        assert "already" in r.json()["detail"].lower()
+
+
+def test_claim_with_unknown_token_returns_400(app_with_fake_gitea):
+    """A token that doesn't match any active invite is HTTP 400."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        # No invite ever created; the token is whatever the attacker
+        # types in. The endpoint should refuse without disclosing
+        # whether the token "looked" right.
+        r = client.post(
+            "/api/invites/claim",
+            json={"token": "totally-made-up-token-string-that-is-not-real"},
+        )
+        assert r.status_code == 400, r.text
+
+
+# ---------------------------------------------------------------------------
+# Pending-invite admin listing
+# ---------------------------------------------------------------------------
+
+
+def test_pending_invites_listing_shows_active_invites_only(app_with_fake_gitea):
+    """The `GET /api/admin/users/invites` listing filters to active
+    invites — claimed and expired rows do not surface here (the admin
+    user-listing carries the per-row pending-invite badge for the
+    living rows; once claimed, the badge clears)."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=300, login="adminL", role="admin")
+        sign_in_as(
+            client, user_id=300, gitea_login="adminL",
+            display_name="Admin L", role="admin",
+        )
+        _reset_outbound()
+
+        # Create three invites: one stays pending, one we'll claim, one
+        # we'll back-date to expired.
+        for email in ("alive@ex.co", "claimed@ex.co", "expired@ex.co"):
+            r = client.post(
+                "/api/admin/users",
+                json={"email": email, "role": "contributor"},
+            )
+            assert r.status_code == 200
+
+        # Claim the middle one.
+        env = _outbound_invite_envelopes("claimed@ex.co")[0]
+        token_claim = _extract_claim_token(env)
+
+        # Expire the third one.
+        from app import db
+        db.conn().execute(
+            "UPDATE user_invite_tokens SET expires_at = datetime('now', '-1 day') "
+            "WHERE email = 'expired@ex.co'"
+        )
+
+        # The admin's session is still on the cookie. Claim works
+        # anonymously; we clear and restore.
+        admin_cookie = client.cookies.get("rfc_session")
+        client.cookies.clear()
+        r = client.post("/api/invites/claim", json={"token": token_claim})
+        assert r.status_code == 200
+        client.cookies.set("rfc_session", admin_cookie)
+
+        r = client.get("/api/admin/users/invites")
+        assert r.status_code == 200, r.text
+        items = r.json()["items"]
+        emails = sorted(i["email"] for i in items)
+        assert emails == ["alive@ex.co"]
+
+
+def test_pending_invite_badge_clears_after_claim(app_with_fake_gitea):
+    """The `/api/admin/users` listing surfaces `pending_invite` while
+    the invite is unclaimed; after the invitee claims, the row's
+    pending_invite is null."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=310, login="adminB", role="admin")
+        sign_in_as(
+            client, user_id=310, gitea_login="adminB",
+            display_name="Admin B", role="admin",
+        )
+        _reset_outbound()
+
+        r = client.post(
+            "/api/admin/users",
+            json={"email": "badgey@ex.co", "role": "contributor"},
+        )
+        assert r.status_code == 200
+        invited_id = r.json()["invited_user_id"]
+
+        # Before claim — pending_invite is populated.
+        r = client.get("/api/admin/users")
+        assert r.status_code == 200
+        row = next(u for u in r.json()["items"] if u["id"] == invited_id)
+        assert row["pending_invite"] is not None
+        assert row["pending_invite"]["invite_id"] > 0
+
+        # Claim.
+        env = _outbound_invite_envelopes("badgey@ex.co")[0]
+        token = _extract_claim_token(env)
+        admin_cookie = client.cookies.get("rfc_session")
+        client.cookies.clear()
+        r = client.post("/api/invites/claim", json={"token": token})
+        assert r.status_code == 200
+        client.cookies.set("rfc_session", admin_cookie)
+
+        # After claim — pending_invite is null.
+        r = client.get("/api/admin/users")
+        assert r.status_code == 200
+        row = next(u for u in r.json()["items"] if u["id"] == invited_id)
+        assert row["pending_invite"] is None
+
+
+def test_pending_invites_listing_admin_only(app_with_fake_gitea):
+    """The listing requires admin/owner; contributor gets 403."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=320, login="contribL", role="contributor")
+        sign_in_as(
+            client, user_id=320, gitea_login="contribL",
+            display_name="Contrib L", role="contributor",
+        )
+        r = client.get("/api/admin/users/invites")
+        assert r.status_code == 403
+
+
+# ---------------------------------------------------------------------------
+# v0.18.0: invite-envelope header shape — Slice 2
+#
+# Invite mail goes through `build_envelope` and MUST land Date,
+# Message-ID, Auto-Submitted, AND a `List-Unsubscribe: <mailto:…>`
+# (no URL — the invitee isn't a user yet, so no per-user opt-out
+# row exists). The mailto: target is the operator's `EMAIL_FROM`
+# by default; the operator can override via `EMAIL_UNSUBSCRIBE_MAILTO`.
+# ---------------------------------------------------------------------------
+
+
+def _provision_admin_and_send_invite(client, app_with_fake_gitea_fixture, *, to: str = "headers@ex.co"):
+    provision_user_row(user_id=400, login="adminH", role="admin")
+    sign_in_as(
+        client, user_id=400, gitea_login="adminH",
+        display_name="Admin H", role="admin",
+        email="adminh@test",
+    )
+    _reset_outbound()
+    r = client.post(
+        "/api/admin/users",
+        json={
+            "email": to,
+            "first_name": "Header",
+            "last_name": "Test",
+            "role": "contributor",
+            "custom_message": "",
+        },
+    )
+    assert r.status_code == 200, r.text
+    return _outbound_invite_envelopes(to)[-1]
+
+
+def test_invite_envelope_sets_date_messageid_autosubmitted(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+    from email.utils import parsedate_to_datetime
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        env = _provision_admin_and_send_invite(client, (app, _fake))
+        msg = env["message"]
+        assert parsedate_to_datetime(msg["Date"]) is not None
+        assert msg["Message-ID"].startswith("<") and msg["Message-ID"].endswith(">")
+        assert msg["Auto-Submitted"] == "auto-generated"
+
+
+def test_invite_envelope_has_mailto_list_unsubscribe_only(app_with_fake_gitea):
+    """The invitee isn't a user yet — no per-user opt-out URL is
+    available. The `List-Unsubscribe` MUST be a mailto: form, and
+    the `List-Unsubscribe-Post` header MUST be absent (the
+    one-click semantic requires a URL the MUA can POST to)."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        env = _provision_admin_and_send_invite(client, (app, _fake))
+        msg = env["message"]
+        lu = msg["List-Unsubscribe"]
+        assert lu is not None and lu.startswith("<mailto:")
+        # No URL part — invite is mailto-only.
+        assert "https://" not in lu and "http://" not in lu
+        assert msg["List-Unsubscribe-Post"] is None
+
+
+def test_invite_envelope_respects_email_unsubscribe_mailto_override(app_with_fake_gitea, monkeypatch):
+    """When `EMAIL_UNSUBSCRIBE_MAILTO` is set, the mailto: target on
+    `List-Unsubscribe` honors it (lets a deployment route opt-outs
+    to a humans-monitored mailbox distinct from the no-reply
+    sender)."""
+    from fastapi.testclient import TestClient
+
+    monkeypatch.setenv("EMAIL_UNSUBSCRIBE_MAILTO", "ohm@wiggleverse.org?subject=remove")
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        env = _provision_admin_and_send_invite(client, (app, _fake))
+        msg = env["message"]
+        assert "ohm@wiggleverse.org?subject=remove" in msg["List-Unsubscribe"]

backend/tests/test_e2e_smoke.py

@@ -231,13 +231,17 @@ def test_bounce_webhook_refuses_unsigned_when_secret_configured(app_with_fake_gi
 
         # With the right header, the call passes the guard. (No matching
         # user exists, so we get {matched: False} — that's the v1 contract.)
+        # v0.18.0 Slice 5: the response now includes `correlated_id`
+        # (the outbound_emails row id that matched the bounce's
+        # `message_id`, if one was supplied). The body didn't pass a
+        # message_id, so correlated_id is None.
         r = client.post(
             "/api/webhooks/email-bounce",
             json={"email": "stranger@example.com", "kind": "hard"},
             headers={"X-Webhook-Secret": "shhh"},
         )
         assert r.status_code == 200, r.text
-        assert r.json() == {"ok": True, "matched": False}
+        assert r.json() == {"ok": True, "matched": False, "correlated_id": None}
 
 
 def test_bounce_webhook_open_when_secret_unset(app_with_fake_gitea):

backend/tests/test_email_envelope.py

@@ -0,0 +1,173 @@
+"""Unit tests for `app.email_envelope.build_envelope` (v0.18.0 Slice 1).
+
+These tests don't spin up the FastAPI app or touch the DB — they
+exercise the helper directly. The integration tests in
+test_otc_vertical / test_admin_create_user_invite_vertical /
+test_notifications_vertical exercise the helper's *use* via the
+shared `_SENT` buffer (the send path appends the envelope dict
+before invoking the helper).
+"""
+from __future__ import annotations
+
+from email.utils import parsedate_to_datetime
+
+from app.email_envelope import build_envelope
+
+
+def _base_kwargs(**overrides):
+    base = dict(
+        to_address="recipient@example.com",
+        from_address="notifications@ohm.wiggleverse.org",
+        from_name="OHM",
+        subject="A test subject",
+        body_plain="Hello, world.\n",
+    )
+    base.update(overrides)
+    return base
+
+
+# ---------------------------------------------------------------------------
+# Always-present headers
+# ---------------------------------------------------------------------------
+
+
+def test_envelope_sets_from_to_subject():
+    msg = build_envelope(**_base_kwargs())
+    assert msg["To"] == "recipient@example.com"
+    assert msg["Subject"] == "A test subject"
+    # `From` is the display-form: "OHM <notifications@ohm.wiggleverse.org>".
+    assert "OHM" in msg["From"]
+    assert "<notifications@ohm.wiggleverse.org>" in msg["From"]
+
+
+def test_envelope_sets_date_header_parseable():
+    msg = build_envelope(**_base_kwargs())
+    raw = msg["Date"]
+    assert raw, "Date header must be set"
+    # parsedate_to_datetime raises ValueError on malformed input.
+    dt = parsedate_to_datetime(raw)
+    assert dt is not None
+
+
+def test_envelope_sets_message_id_with_from_domain_by_default():
+    msg = build_envelope(**_base_kwargs())
+    mid = msg["Message-ID"]
+    assert mid, "Message-ID must be set"
+    # Shape per RFC 5322 / make_msgid: <random@domain>
+    assert mid.startswith("<") and mid.endswith(">")
+    assert "@ohm.wiggleverse.org>" in mid
+
+
+def test_envelope_message_id_domain_override():
+    msg = build_envelope(**_base_kwargs(msgid_domain="example.test"))
+    assert "@example.test>" in msg["Message-ID"]
+
+
+def test_envelope_message_id_falls_back_to_localhost_if_from_has_no_at():
+    # Defensive: a malformed from_address shouldn't crash the helper.
+    msg = build_envelope(**_base_kwargs(from_address="bare-no-at-sign"))
+    assert "@localhost>" in msg["Message-ID"]
+
+
+# ---------------------------------------------------------------------------
+# Auto-Submitted (RFC 3834)
+# ---------------------------------------------------------------------------
+
+
+def test_envelope_sets_auto_submitted_for_transactional_default():
+    msg = build_envelope(**_base_kwargs())
+    assert msg["Auto-Submitted"] == "auto-generated"
+
+
+def test_envelope_omits_auto_submitted_when_transactional_is_false():
+    msg = build_envelope(**_base_kwargs(is_transactional=False))
+    assert msg["Auto-Submitted"] is None
+
+
+# ---------------------------------------------------------------------------
+# Reply-To
+# ---------------------------------------------------------------------------
+
+
+def test_envelope_sets_reply_to_when_provided():
+    msg = build_envelope(**_base_kwargs(reply_to="ohm@wiggleverse.org"))
+    assert msg["Reply-To"] == "ohm@wiggleverse.org"
+
+
+def test_envelope_omits_reply_to_when_absent():
+    msg = build_envelope(**_base_kwargs())
+    assert msg["Reply-To"] is None
+
+
+# ---------------------------------------------------------------------------
+# List-Unsubscribe (the headers RFC 8058 / Gmail-Yahoo care about)
+# ---------------------------------------------------------------------------
+
+
+def test_envelope_no_list_unsubscribe_when_neither_given():
+    """OTC mail: the recipient explicitly requested the code; no
+    unsubscribe semantics. The header MUST be absent (presence would
+    imply OHM has the recipient on a list, which it doesn't)."""
+    msg = build_envelope(**_base_kwargs())
+    assert msg["List-Unsubscribe"] is None
+    assert msg["List-Unsubscribe-Post"] is None
+
+
+def test_envelope_mailto_only_list_unsubscribe():
+    """Admin invite / per-RFC invite: `mailto:` form only, no URL.
+    The recipient isn't a user yet, so there's no per-user opt-out
+    URL to flip; the operator handles ad-hoc opt-outs manually."""
+    msg = build_envelope(**_base_kwargs(
+        unsubscribe_mailto="ohm@wiggleverse.org?subject=remove",
+    ))
+    assert msg["List-Unsubscribe"] == "<mailto:ohm@wiggleverse.org?subject=remove>"
+    # NO List-Unsubscribe-Post when only a mailto is present — the
+    # one-click semantic requires a URL the MUA can POST to.
+    assert msg["List-Unsubscribe-Post"] is None
+
+
+def test_envelope_full_one_click_list_unsubscribe():
+    """Watcher notification / bundle: `mailto:` + signed-URL +
+    `List-Unsubscribe-Post: List-Unsubscribe=One-Click`. Gmail and
+    Yahoo enforce this for bulk-adjacent mail per RFC 8058."""
+    msg = build_envelope(**_base_kwargs(
+        unsubscribe_mailto="ohm@wiggleverse.org?subject=remove",
+        unsubscribe_url="https://ohm.wiggleverse.org/api/email/unsubscribe?t=abc",
+    ))
+    lu = msg["List-Unsubscribe"]
+    assert "<mailto:ohm@wiggleverse.org?subject=remove>" in lu
+    assert "<https://ohm.wiggleverse.org/api/email/unsubscribe?t=abc>" in lu
+    assert msg["List-Unsubscribe-Post"] == "List-Unsubscribe=One-Click"
+
+
+def test_envelope_url_only_list_unsubscribe_still_sets_post():
+    msg = build_envelope(**_base_kwargs(
+        unsubscribe_url="https://ohm.wiggleverse.org/api/email/unsubscribe?t=abc",
+    ))
+    assert msg["List-Unsubscribe"] == "<https://ohm.wiggleverse.org/api/email/unsubscribe?t=abc>"
+    assert msg["List-Unsubscribe-Post"] == "List-Unsubscribe=One-Click"
+
+
+# ---------------------------------------------------------------------------
+# Body shape — plain-only vs multipart/alternative
+# ---------------------------------------------------------------------------
+
+
+def test_envelope_plain_only_body_is_text_plain():
+    msg = build_envelope(**_base_kwargs())
+    # No HTML alternative -> single-part text/plain.
+    assert msg.get_content_type() == "text/plain"
+    assert msg.get_content().strip() == "Hello, world."
+
+
+def test_envelope_with_html_is_multipart_alternative():
+    msg = build_envelope(**_base_kwargs(body_html="<p>Hello, <b>world</b>.</p>"))
+    assert msg.get_content_type() == "multipart/alternative"
+    # Two parts: text/plain first (so plain-text clients picking the
+    # first part get the readable text), text/html second.
+    parts = list(msg.iter_parts())
+    assert len(parts) == 2
+    assert parts[0].get_content_type() == "text/plain"
+    assert parts[1].get_content_type() == "text/html"
+    assert "Hello, world." in parts[0].get_content()
+    assert "<b>world</b>" in parts[1].get_content()

backend/tests/test_notifications_vertical.py

@@ -612,3 +612,127 @@ def test_explicit_watch_set_overrides_auto(app_with_fake_gitea):
         # the user put them.
         assert row["set_by"] == "explicit"
         assert row["state"] == "following"
+
+
+# ---------------------------------------------------------------------------
+# v0.18.0 — envelope headers + RFC 8058 one-click POST endpoint
+#
+# Watcher notifications are bulk-adjacent (a busy RFC can produce
+# dozens of structural events); per the proposal, they MUST carry
+# `Date`, `Message-ID`, `Auto-Submitted`, full `List-Unsubscribe`
+# (mailto + signed URL), AND `List-Unsubscribe-Post:
+# List-Unsubscribe=One-Click` per RFC 8058. Gmail and Yahoo
+# enforce this for senders at OHM's volume tier.
+# ---------------------------------------------------------------------------
+
+
+def test_notification_envelope_carries_full_one_click_headers(app_with_fake_gitea):
+    """A `proposal_merged` event lands a watcher notification email
+    with the full one-click unsubscribe shape."""
+    from fastapi.testclient import TestClient
+    from email.utils import parsedate_to_datetime
+    from app import db, email as email_mod
+
+    app, fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=2, login="alice", role="contributor")
+        provision_user_row(user_id=1, login="ben", role="owner")
+
+        sign_in_as(client, user_id=2, gitea_login="alice", display_name="Alice", role="contributor", email="alice@test")
+        r = client.post("/api/rfcs/propose", json={"title": "OHM", "slug": "ohm", "pitch": PITCH, "tags": []})
+        assert r.status_code == 200
+        email_mod.reset_sent_envelopes()
+        sign_in_as(client, user_id=1, gitea_login="ben", display_name="Ben", role="owner", email="ben@test")
+        merge_r = client.post(f"/api/proposals/{r.json()['pr_number']}/merge")
+        assert merge_r.status_code == 200, merge_r.text
+
+        envelopes = [e for e in email_mod.sent_envelopes() if e["to"] == "alice@test"]
+        assert envelopes, "watcher notification did not fire"
+        msg = envelopes[-1]["message"]
+        # Always-present headers from the helper.
+        assert parsedate_to_datetime(msg["Date"]) is not None
+        assert msg["Message-ID"].startswith("<") and msg["Message-ID"].endswith(">")
+        assert msg["Auto-Submitted"] == "auto-generated"
+        # Full one-click unsubscribe.
+        lu = msg["List-Unsubscribe"]
+        assert lu is not None
+        assert "<mailto:" in lu
+        # URL part carries the signed token per make_unsubscribe_url.
+        assert "/api/email/unsubscribe?t=" in lu
+        assert msg["List-Unsubscribe-Post"] == "List-Unsubscribe=One-Click"
+
+
+def test_email_unsubscribe_post_one_click_flips_category_off(app_with_fake_gitea):
+    """RFC 8058: Gmail/Yahoo POST `List-Unsubscribe=One-Click` to the
+    URL in the List-Unsubscribe header. The endpoint MUST accept POST
+    + the same token shape as the GET handler + return 200 + flip the
+    flag."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=2, login="alice", role="contributor")
+        token = email_mod.make_unsubscribe_url(2, "personal-direct").split("t=", 1)[1]
+
+        r = client.post(
+            f"/api/email/unsubscribe?t={token}",
+            data={"List-Unsubscribe": "One-Click"},
+        )
+        assert r.status_code == 200, r.text
+        body = r.json()
+        assert body["ok"] is True
+        assert body["category"] == "personal-direct"
+
+        row = db.conn().execute(
+            "SELECT email_personal_direct FROM users WHERE id = 2"
+        ).fetchone()
+        assert row["email_personal_direct"] == 0
+
+
+def test_email_unsubscribe_post_all_sets_global_opt_out(app_with_fake_gitea):
+    """The v0.18.0 `all` synthetic category (used by the bundle +
+    digest paths) MUST set `email_opt_out_all = 1`."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=2, login="alice", role="contributor")
+        token = email_mod.make_unsubscribe_url(2, "all").split("t=", 1)[1]
+        r = client.post(f"/api/email/unsubscribe?t={token}")
+        assert r.status_code == 200
+        assert r.json() == {"ok": True, "category": "all"}
+        row = db.conn().execute(
+            "SELECT email_opt_out_all FROM users WHERE id = 2"
+        ).fetchone()
+        assert row["email_opt_out_all"] == 1
+
+
+def test_email_unsubscribe_get_all_sets_global_opt_out(app_with_fake_gitea):
+    """GET handler also accepts the `all` category and lands the
+    global opt-out (so an MUA that doesn't honor RFC 8058 POST and
+    just opens the URL in a browser still works)."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=2, login="alice", role="contributor")
+        token = email_mod.make_unsubscribe_url(2, "all").split("t=", 1)[1]
+        r = client.get(f"/api/email/unsubscribe?t={token}")
+        assert r.status_code == 200
+        assert "Unsubscribed" in r.text
+        row = db.conn().execute(
+            "SELECT email_opt_out_all FROM users WHERE id = 2"
+        ).fetchone()
+        assert row["email_opt_out_all"] == 1
+
+
+def test_email_unsubscribe_post_refuses_invalid_token(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        r = client.post("/api/email/unsubscribe?t=not-a-valid-token")
+        assert r.status_code == 400

backend/tests/test_otc_vertical.py

@@ -347,3 +347,53 @@ def test_otc_re_request_invalidates_prior_unused_code(app_with_fake_gitea, monke
         # The new code still works.
         r = client.post("/auth/otc/verify", json={"email": "alice@example.com", "code": second})
         assert r.status_code == 200
+
+
+# ---------------------------------------------------------------------------
+# v0.18.0: envelope headers — Slice 2
+#
+# OTC mail goes through `build_envelope` and MUST land Date,
+# Message-ID, and Auto-Submitted but MUST NOT carry a
+# List-Unsubscribe header (the recipient explicitly requested the
+# code; advertising a list semantic would be wrong).
+# ---------------------------------------------------------------------------
+
+
+def _last_otc_envelope():
+    from app import email as email_mod
+    otc = [e for e in email_mod.sent_envelopes() if e.get("kind") == "otc"]
+    assert otc, "no OTC envelope in the buffer"
+    return otc[-1]
+
+
+def test_otc_envelope_sets_date_messageid_autosubmitted(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+    from email.utils import parsedate_to_datetime
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        _reset_outbound()
+        client.post("/auth/otc/request", json={"email": "headers@example.com"})
+        msg = _last_otc_envelope()["message"]
+        # Date is RFC 5322 parseable.
+        assert parsedate_to_datetime(msg["Date"]) is not None
+        # Message-ID is bracketed and carries the From-address @-domain.
+        mid = msg["Message-ID"]
+        assert mid.startswith("<") and mid.endswith(">")
+        # Auto-Submitted prevents auto-responder loops.
+        assert msg["Auto-Submitted"] == "auto-generated"
+
+
+def test_otc_envelope_has_no_list_unsubscribe(app_with_fake_gitea):
+    """The recipient explicitly typed their email and asked for a
+    code; the framework MUST NOT advertise a list semantic on this
+    mail. Per the v0.18.0 proposal's tradeoff discussion."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        _reset_outbound()
+        client.post("/auth/otc/request", json={"email": "headers@example.com"})
+        msg = _last_otc_envelope()["message"]
+        assert msg["List-Unsubscribe"] is None
+        assert msg["List-Unsubscribe-Post"] is None

backend/tests/test_outbound_emails_vertical.py

@@ -0,0 +1,368 @@
+"""End-to-end integration tests for the v0.18.0 Slice 4
+outbound_emails audit table + admin endpoint.
+
+The release adds:
+  * `backend/migrations/020_outbound_emails.sql` — the audit table.
+  * `record_outbound()` in `email.py` — the write helper every send
+    path calls before returning, capturing status='sent' / 'failed'
+    / 'deferred' (the dev-fallback path when SMTP_HOST is unset).
+  * `GET /api/admin/outbound-emails` — admin-only listing, filterable
+    by kind / status / to_address.
+
+These tests prove:
+  * Sending OTC / invite / notification mail writes one row per send
+    (status='deferred' under tests since SMTP_HOST is unset).
+  * The Message-ID on the row matches the envelope's Message-ID
+    header (the seam Slice 5 uses for bounce correlation).
+  * `kind` is populated per send path.
+  * `GET /api/admin/outbound-emails` lists rows newest-first,
+    accepts filters, refuses non-admins.
+"""
+from __future__ import annotations
+
+from test_propose_vertical import (  # noqa: F401
+    FakeGitea,
+    app_with_fake_gitea,
+    provision_user_row,
+    sign_in_as,
+    tmp_env,
+)
+
+
+# ---------------------------------------------------------------------------
+# Write-on-send wiring
+# ---------------------------------------------------------------------------
+
+
+def test_otc_send_writes_outbound_row_with_message_id(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        email_mod.reset_sent_envelopes()
+        r = client.post("/auth/otc/request", json={"email": "newcomer@ex.co"})
+        assert r.status_code == 200
+
+        # Audit row landed.
+        rows = db.conn().execute(
+            "SELECT id, to_address, kind, status, message_id, error "
+            "FROM outbound_emails WHERE to_address = 'newcomer@ex.co'"
+        ).fetchall()
+        assert len(rows) == 1
+        row = rows[0]
+        assert row["kind"] == "otc"
+        # No SMTP_HOST in tests -> 'deferred', not 'sent'.
+        assert row["status"] == "deferred"
+        assert row["error"] is None
+        # Message-ID matches the envelope's header (the seam Slice 5 uses).
+        envelopes = [e for e in email_mod.sent_envelopes() if e.get("kind") == "otc"]
+        assert envelopes
+        envelope_mid = envelopes[-1]["message"]["Message-ID"]
+        assert row["message_id"] == envelope_mid
+
+
+def test_invite_send_writes_outbound_row(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=500, login="adminQ", role="admin")
+        sign_in_as(
+            client, user_id=500, gitea_login="adminQ",
+            display_name="Admin Q", role="admin",
+            email="adminq@test",
+        )
+        r = client.post(
+            "/api/admin/users",
+            json={
+                "email": "invitee@ex.co",
+                "first_name": "Inv", "last_name": "Itee",
+                "role": "contributor", "custom_message": "",
+            },
+        )
+        assert r.status_code == 200, r.text
+
+        rows = db.conn().execute(
+            "SELECT kind, status, message_id FROM outbound_emails "
+            "WHERE to_address = 'invitee@ex.co'"
+        ).fetchall()
+        assert len(rows) == 1
+        assert rows[0]["kind"] == "invite"
+        assert rows[0]["status"] == "deferred"
+        assert rows[0]["message_id"] is not None
+
+
+def test_notification_send_writes_outbound_row_with_notification_id(app_with_fake_gitea):
+    """Watcher notifications carry a `notification_id` FK so the
+    admin can join through to the notifications table to see what
+    triggered the send."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+    from test_notifications_vertical import PITCH
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=2, login="alice", role="contributor")
+        provision_user_row(user_id=1, login="ben", role="owner")
+        sign_in_as(
+            client, user_id=2, gitea_login="alice",
+            display_name="Alice", role="contributor", email="alice@test",
+        )
+        r = client.post("/api/rfcs/propose", json={
+            "title": "OHM", "slug": "ohm", "pitch": PITCH, "tags": [],
+        })
+        email_mod.reset_sent_envelopes()
+        # Wipe pre-merge audit rows so the assertion below is unambiguous.
+        db.conn().execute("DELETE FROM outbound_emails")
+        sign_in_as(
+            client, user_id=1, gitea_login="ben",
+            display_name="Ben", role="owner", email="ben@test",
+        )
+        merge_r = client.post(f"/api/proposals/{r.json()['pr_number']}/merge")
+        assert merge_r.status_code == 200, merge_r.text
+
+        rows = db.conn().execute(
+            "SELECT kind, status, notification_id, message_id "
+            "FROM outbound_emails WHERE to_address = 'alice@test'"
+        ).fetchall()
+        assert rows, "no outbound_emails row for alice@test"
+        # At least one notification kind, with a populated FK.
+        notif_rows = [r for r in rows if r["kind"] == "notification"]
+        assert notif_rows
+        for nr in notif_rows:
+            assert nr["status"] == "deferred"
+            assert nr["notification_id"] is not None
+            assert nr["message_id"] is not None
+
+
+# ---------------------------------------------------------------------------
+# Admin endpoint
+# ---------------------------------------------------------------------------
+
+
+def test_admin_outbound_emails_lists_rows(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        # Generate a few rows.
+        client.post("/auth/otc/request", json={"email": "one@ex.co"})
+
+        provision_user_row(user_id=600, login="adminR", role="admin")
+        sign_in_as(
+            client, user_id=600, gitea_login="adminR",
+            display_name="Admin R", role="admin", email="adminr@test",
+        )
+        client.post("/api/admin/users", json={
+            "email": "two@ex.co", "first_name": "T", "last_name": "Wo",
+            "role": "contributor", "custom_message": "",
+        })
+
+        r = client.get("/api/admin/outbound-emails")
+        assert r.status_code == 200, r.text
+        items = r.json()["items"]
+        kinds = {it["kind"] for it in items}
+        assert "otc" in kinds
+        assert "invite" in kinds
+        # Newest-first.
+        ids = [it["id"] for it in items]
+        assert ids == sorted(ids, reverse=True)
+
+
+def test_admin_outbound_emails_filters_by_kind(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        client.post("/auth/otc/request", json={"email": "filter1@ex.co"})
+
+        provision_user_row(user_id=601, login="adminS", role="admin")
+        sign_in_as(
+            client, user_id=601, gitea_login="adminS",
+            display_name="Admin S", role="admin", email="admins@test",
+        )
+        client.post("/api/admin/users", json={
+            "email": "filter2@ex.co", "first_name": "F", "last_name": "Two",
+            "role": "contributor", "custom_message": "",
+        })
+
+        r = client.get("/api/admin/outbound-emails?kind=otc")
+        assert r.status_code == 200
+        items = r.json()["items"]
+        assert items
+        assert all(it["kind"] == "otc" for it in items)
+
+
+def test_admin_outbound_emails_filters_by_to_address(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        client.post("/auth/otc/request", json={"email": "TARGET@ex.co"})
+        client.post("/auth/otc/request", json={"email": "other@ex.co"})
+
+        provision_user_row(user_id=602, login="adminT", role="admin")
+        sign_in_as(
+            client, user_id=602, gitea_login="adminT",
+            display_name="Admin T", role="admin", email="admint@test",
+        )
+
+        # to_address filter is case-insensitive.
+        r = client.get("/api/admin/outbound-emails?to_address=target@ex.co")
+        assert r.status_code == 200
+        items = r.json()["items"]
+        assert items
+        assert all(it["to_address"].lower() == "target@ex.co" for it in items)
+
+
+def test_admin_outbound_emails_refuses_non_admin(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=700, login="contribU", role="contributor")
+        sign_in_as(
+            client, user_id=700, gitea_login="contribU",
+            display_name="Contrib U", role="contributor",
+        )
+        r = client.get("/api/admin/outbound-emails")
+        assert r.status_code == 403
+
+
+# ---------------------------------------------------------------------------
+# v0.18.0 Slice 5: bounce correlation
+# ---------------------------------------------------------------------------
+
+
+def test_bounce_with_message_id_marks_outbound_row_bounced(app_with_fake_gitea):
+    """When the bounce body includes the original `message_id`, the
+    framework looks it up in outbound_emails and stamps
+    status='bounced' on the matching row. The hard-bounce ->
+    global-opt-out logic still fires."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=800, login="bouncey", role="contributor")
+        db.conn().execute("UPDATE users SET email = 'bouncey@ex.co' WHERE id = 800")
+
+        # Send something to bouncey to land an outbound_emails row.
+        email_mod.reset_sent_envelopes()
+        client.post("/auth/otc/request", json={"email": "bouncey@ex.co"})
+        row = db.conn().execute(
+            "SELECT id, message_id, status FROM outbound_emails "
+            "WHERE to_address = 'bouncey@ex.co'"
+        ).fetchone()
+        assert row is not None
+        original_id = row["id"]
+        message_id = row["message_id"]
+        assert row["status"] == "deferred"  # pre-bounce baseline
+
+        # Bounce comes in carrying that message_id.
+        r = client.post(
+            "/api/webhooks/email-bounce",
+            json={
+                "email": "bouncey@ex.co",
+                "kind": "hard",
+                "message_id": message_id,
+            },
+        )
+        assert r.status_code == 200
+        body = r.json()
+        assert body["matched"] is True
+        assert body["correlated_id"] == original_id
+
+        # Audit row stamped.
+        post = db.conn().execute(
+            "SELECT status, error FROM outbound_emails WHERE id = ?",
+            (original_id,),
+        ).fetchone()
+        assert post["status"] == "bounced"
+        assert "bounce (hard)" in (post["error"] or "")
+
+        # Hard-bounce global opt-out still fires.
+        urow = db.conn().execute(
+            "SELECT email_opt_out_all FROM users WHERE id = 800"
+        ).fetchone()
+        assert urow["email_opt_out_all"] == 1
+
+
+def test_bounce_with_unknown_message_id_does_not_crash(app_with_fake_gitea):
+    """A message_id the framework doesn't recognize logs but does
+    NOT 5xx — bounce providers replay old bounces, and the
+    framework can't refuse just because the row was pruned."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        r = client.post(
+            "/api/webhooks/email-bounce",
+            json={
+                "email": "nobody@ex.co",
+                "kind": "hard",
+                "message_id": "<not-in-our-db@ex.co>",
+            },
+        )
+        assert r.status_code == 200
+        assert r.json()["correlated_id"] is None
+
+
+def test_bounce_without_message_id_still_flips_opt_out(app_with_fake_gitea):
+    """Backward compat: providers that don't surface Message-ID
+    still get the legacy v1 behavior — match by email + flip the
+    global opt-out."""
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=801, login="legacybounce", role="contributor")
+        db.conn().execute("UPDATE users SET email = 'legacy@ex.co' WHERE id = 801")
+
+        r = client.post(
+            "/api/webhooks/email-bounce",
+            json={"email": "legacy@ex.co", "kind": "hard"},
+        )
+        assert r.status_code == 200
+        body = r.json()
+        assert body["matched"] is True
+        assert body["correlated_id"] is None
+
+        urow = db.conn().execute(
+            "SELECT email_opt_out_all FROM users WHERE id = 801"
+        ).fetchone()
+        assert urow["email_opt_out_all"] == 1
+
+
+def test_bounced_rows_show_in_admin_endpoint(app_with_fake_gitea):
+    """The admin endpoint surfaces bounced rows alongside the rest;
+    filtering by `status=bounced` isolates them."""
+    from fastapi.testclient import TestClient
+    from app import db, email as email_mod
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        provision_user_row(user_id=802, login="adminB", role="admin")
+        sign_in_as(
+            client, user_id=802, gitea_login="adminB",
+            display_name="Admin B", role="admin", email="adminb@test",
+        )
+        email_mod.reset_sent_envelopes()
+        client.post("/auth/otc/request", json={"email": "willbounce@ex.co"})
+        row = db.conn().execute(
+            "SELECT message_id FROM outbound_emails WHERE to_address = 'willbounce@ex.co'"
+        ).fetchone()
+        client.post(
+            "/api/webhooks/email-bounce",
+            json={"email": "willbounce@ex.co", "kind": "hard", "message_id": row["message_id"]},
+        )
+
+        r = client.get("/api/admin/outbound-emails?status=bounced")
+        assert r.status_code == 200
+        items = r.json()["items"]
+        assert items
+        assert all(it["status"] == "bounced" for it in items)
+        assert any(it["to_address"] == "willbounce@ex.co" for it in items)

backend/tests/test_propose_vertical.py

@@ -438,7 +438,11 @@ def tmp_env(monkeypatch):
         "SECRET_KEY": "test-secret-key-for-cookies",
         "DATABASE_PATH": str(db_path),
         "OWNER_GITEA_LOGIN": "ben",
-        "GITEA_WEBHOOK_SECRET": "",
+        # v0.18.0: `GITEA_WEBHOOK_SECRET` is now mandatory at startup
+        # per the email + webhook hygiene proposal. Tests bind a fake
+        # value so the framework boots; tests that want to exercise
+        # the dev-bypass path monkeypatch `RFC_APP_INSECURE_WEBHOOKS=1`.
+        "GITEA_WEBHOOK_SECRET": "test-webhook-secret-for-signature-verification",
         "ENABLED_MODELS": "claude",
     }
     for k, v in env.items():

backend/tests/test_webhooks_vertical.py

@@ -0,0 +1,205 @@
+"""End-to-end integration tests for the Gitea webhook receiver
+(v0.18.0 Slice 3 — webhook tightening per the email + webhook
+hygiene proposal).
+
+The release changes the receiver from "verifies the signature only
+when a secret is configured; silently accepts unsigned POSTs
+otherwise" to "requires the secret unless `RFC_APP_INSECURE_WEBHOOKS=1`
+is set as an explicit dev-bypass." The startup-time check lives in
+`config.load_config()`; the request-time check lives in
+`webhooks.receive`.
+
+These tests prove:
+
+  * The framework refuses to start when `GITEA_WEBHOOK_SECRET` is
+    empty and the dev-bypass is not set.
+  * The dev-bypass (`RFC_APP_INSECURE_WEBHOOKS=1`) lets the
+    framework boot with an empty secret AND lets webhook POSTs
+    land without signature verification (a loud-warning log line
+    surfaces, but the request is accepted).
+  * Default path (secret bound): a POST with a valid signature
+    lands; a POST with an invalid signature gets 401; a POST with
+    no signature gets 401.
+  * Unknown-repo POSTs surface in the log (the "stale Gitea hook"
+    case the proposal targets).
+"""
+from __future__ import annotations
+
+import hashlib
+import hmac
+import json
+import logging
+
+import pytest
+
+from test_propose_vertical import (  # noqa: F401
+    FakeGitea,
+    app_with_fake_gitea,
+    tmp_env,
+)
+
+
+# ---------------------------------------------------------------------------
+# Startup-time secret check (config.load_config)
+# ---------------------------------------------------------------------------
+
+
+def test_config_refuses_to_load_with_empty_secret_and_no_bypass(monkeypatch, tmp_path):
+    """The framework MUST refuse to start when `GITEA_WEBHOOK_SECRET`
+    is empty unless `RFC_APP_INSECURE_WEBHOOKS=1` is set. This is
+    the v0.18.0 startup-loud-failure shape — silent acceptance was
+    the bug."""
+    monkeypatch.setenv("GITEA_URL", "http://gitea.test")
+    monkeypatch.setenv("GITEA_BOT_USER", "rfc-bot")
+    monkeypatch.setenv("GITEA_BOT_TOKEN", "bot-token")
+    monkeypatch.setenv("GITEA_ORG", "wiggleverse")
+    monkeypatch.setenv("OAUTH_CLIENT_ID", "cid")
+    monkeypatch.setenv("OAUTH_CLIENT_SECRET", "csec")
+    monkeypatch.setenv("SECRET_KEY", "test-secret-key")
+    monkeypatch.setenv("DATABASE_PATH", str(tmp_path / "test.db"))
+    monkeypatch.setenv("GITEA_WEBHOOK_SECRET", "")
+    monkeypatch.delenv("RFC_APP_INSECURE_WEBHOOKS", raising=False)
+
+    from app.config import load_config
+    with pytest.raises(RuntimeError, match="GITEA_WEBHOOK_SECRET"):
+        load_config()
+
+
+def test_config_loads_with_empty_secret_when_bypass_is_set(monkeypatch, tmp_path):
+    """The explicit `RFC_APP_INSECURE_WEBHOOKS=1` opt-in lets the
+    framework boot with an empty webhook secret. This is the
+    local-dev escape hatch."""
+    monkeypatch.setenv("GITEA_URL", "http://gitea.test")
+    monkeypatch.setenv("GITEA_BOT_USER", "rfc-bot")
+    monkeypatch.setenv("GITEA_BOT_TOKEN", "bot-token")
+    monkeypatch.setenv("GITEA_ORG", "wiggleverse")
+    monkeypatch.setenv("OAUTH_CLIENT_ID", "cid")
+    monkeypatch.setenv("OAUTH_CLIENT_SECRET", "csec")
+    monkeypatch.setenv("SECRET_KEY", "test-secret-key")
+    monkeypatch.setenv("DATABASE_PATH", str(tmp_path / "test.db"))
+    monkeypatch.setenv("GITEA_WEBHOOK_SECRET", "")
+    monkeypatch.setenv("RFC_APP_INSECURE_WEBHOOKS", "1")
+
+    from app.config import load_config
+    cfg = load_config()  # MUST NOT raise
+    assert cfg.webhook_secret == ""
+
+
+def test_config_loads_with_secret_set(monkeypatch, tmp_path):
+    """Sanity: the happy path (secret bound, bypass not set) loads
+    cleanly."""
+    monkeypatch.setenv("GITEA_URL", "http://gitea.test")
+    monkeypatch.setenv("GITEA_BOT_USER", "rfc-bot")
+    monkeypatch.setenv("GITEA_BOT_TOKEN", "bot-token")
+    monkeypatch.setenv("GITEA_ORG", "wiggleverse")
+    monkeypatch.setenv("OAUTH_CLIENT_ID", "cid")
+    monkeypatch.setenv("OAUTH_CLIENT_SECRET", "csec")
+    monkeypatch.setenv("SECRET_KEY", "test-secret-key")
+    monkeypatch.setenv("DATABASE_PATH", str(tmp_path / "test.db"))
+    monkeypatch.setenv("GITEA_WEBHOOK_SECRET", "my-real-secret")
+    monkeypatch.delenv("RFC_APP_INSECURE_WEBHOOKS", raising=False)
+
+    from app.config import load_config
+    cfg = load_config()
+    assert cfg.webhook_secret == "my-real-secret"
+
+
+# ---------------------------------------------------------------------------
+# Request-time signature verification (webhooks.receive)
+#
+# The default `app_with_fake_gitea` fixture binds
+# `GITEA_WEBHOOK_SECRET=test-webhook-secret-for-signature-verification`,
+# so these tests exercise the production path.
+# ---------------------------------------------------------------------------
+
+
+_SECRET = "test-webhook-secret-for-signature-verification"
+
+
+def _sign(body: bytes) -> str:
+    return hmac.new(_SECRET.encode("utf-8"), body, hashlib.sha256).hexdigest()
+
+
+def test_webhook_post_with_valid_signature_accepted(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        body = json.dumps({"repository": {"full_name": "wiggleverse/meta"}}).encode()
+        sig = _sign(body)
+        r = client.post(
+            "/api/webhooks/gitea",
+            content=body,
+            headers={
+                "X-Gitea-Event": "push",
+                "X-Gitea-Signature": sig,
+                "Content-Type": "application/json",
+            },
+        )
+        assert r.status_code == 200, r.text
+
+
+def test_webhook_post_with_invalid_signature_refused_401(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        body = json.dumps({"repository": {"full_name": "wiggleverse/meta"}}).encode()
+        r = client.post(
+            "/api/webhooks/gitea",
+            content=body,
+            headers={
+                "X-Gitea-Event": "push",
+                "X-Gitea-Signature": "0" * 64,  # wrong signature
+                "Content-Type": "application/json",
+            },
+        )
+        assert r.status_code == 401
+
+
+def test_webhook_post_with_missing_signature_refused_401(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        body = json.dumps({"repository": {"full_name": "wiggleverse/meta"}}).encode()
+        r = client.post(
+            "/api/webhooks/gitea",
+            content=body,
+            headers={
+                "X-Gitea-Event": "push",
+                "Content-Type": "application/json",
+            },
+        )
+        assert r.status_code == 401
+
+
+# ---------------------------------------------------------------------------
+# Unknown-repo logging (the "stale hook on a fork" surface)
+# ---------------------------------------------------------------------------
+
+
+def test_webhook_unknown_repo_logs_at_info(app_with_fake_gitea, caplog):
+    """Per the proposal: a hook on a fork or a stale Gitea binding
+    used to silently 200-OK. v0.18.0 surfaces it as an INFO log."""
+    from fastapi.testclient import TestClient
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        body = json.dumps({"repository": {"full_name": "someone-else/unrelated"}}).encode()
+        sig = _sign(body)
+        with caplog.at_level(logging.INFO, logger="app.webhooks"):
+            r = client.post(
+                "/api/webhooks/gitea",
+                content=body,
+                headers={
+                    "X-Gitea-Event": "push",
+                    "X-Gitea-Signature": sig,
+                    "Content-Type": "application/json",
+                },
+            )
+        assert r.status_code == 200  # the handler still 200s; surface is the log line
+        assert any(
+            "unknown repo" in rec.message and "someone-else/unrelated" in rec.message
+            for rec in caplog.records
+        ), f"expected unknown-repo log line; got: {[r.message for r in caplog.records]}"

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "rfc-app-frontend",
   "private": true,
-  "version": "0.16.0",
+  "version": "0.18.0",
   "type": "module",
   "scripts": {
     "dev": "vite",

frontend/src/App.jsx

@@ -16,6 +16,7 @@ import Docs from './components/Docs.jsx'
 import NotificationSettings from './components/NotificationSettings.jsx'
 import Admin from './components/Admin.jsx'
 import AcceptInvitation from './components/AcceptInvitation.jsx'
+import InviteClaim from './components/InviteClaim.jsx'
 import ToastHost, { showToast } from './components/ToastHost.jsx'
 import CookieConsentBanner from './components/CookieConsentBanner.jsx'
 import Privacy from './pages/Privacy.jsx'
@@ -227,6 +228,10 @@ export default function App() {
           <Route path="/invitations/accept" element={
             <PolicyShell><AcceptInvitation viewer={viewer} /></PolicyShell>
           } />
+          {/* v0.17.0 — roadmap item #16. The claim landing page for
+              admin-issued invites. Anonymous-reachable; the call
+              itself establishes the session on success. */}
+          <Route path="/invites/claim" element={<InviteClaim />} />
           <Route path="/philosophy" element={<PhilosophyWithSidebar viewer={viewer} />} />
           <Route path="/docs" element={<DocsWithSidebar viewer={viewer} />} />
           {/* §14.5 / §14.6: cookie-consent companions to /philosophy.

frontend/src/api.js

@@ -799,6 +799,53 @@ export async function removeAllowlistEmail(email) {
   }))
 }
 
+// v0.17.0 — roadmap item #16. Admin-create user + invite email with
+// optional custom message. The frontend modal on /admin/users wires
+// these two helpers; the claim helper drives the /invites/claim page
+// that the invitee lands on when they click the email link.
+//
+// `createUserInvite` returns `{ ok, invite_id, invited_user_id, email,
+// role }`. The 409 path (duplicate email) and 422 path (self-invite,
+// owner-grant-by-non-owner, malformed input) surface as thrown errors
+// via `jsonOrThrow` so the modal can render the server's message.
+//
+// `listUserInvites` returns the active-invites list for the admin's
+// "I sent these but they haven't been claimed yet" view. Active means
+// not claimed and not expired; once the invitee clicks through, the
+// row clears here and the user-listing's `pending_invite` badge
+// vanishes alongside.
+
+export async function createUserInvite({ email, first_name, last_name, role, custom_message }) {
+  return jsonOrThrow(await fetch('/api/admin/users', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      email,
+      first_name: first_name || '',
+      last_name: last_name || '',
+      role,
+      custom_message: custom_message || '',
+    }),
+  }))
+}
+
+export async function listUserInvites() {
+  return jsonOrThrow(await fetch('/api/admin/users/invites'))
+}
+
+// Claim an admin-issued invite token. Anonymous endpoint — the invitee
+// is not yet signed in; this call establishes the session on success.
+// `trustDevice` mirrors the v0.11.0 OTC/passcode opt-in: when true,
+// the server mints a fresh device-trust row + sets the long-lived
+// cookie so the invitee skips OTC on their next visit.
+export async function claimInvite(token, { trustDevice = false } = {}) {
+  return jsonOrThrow(await fetch('/api/invites/claim', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ token, trust_device: !!trustDevice }),
+  }))
+}
+
 export async function searchUsers(q) {
   const params = new URLSearchParams()
   if (q) params.set('q', q)

frontend/src/components/Admin.jsx

@@ -23,9 +23,16 @@ import {
   listAllowlist,
   addAllowlistEmail,
   removeAllowlistEmail,
+  createUserInvite,
 } from '../api.js'
 import { EVENTS, track } from '../lib/analytics.js'
 
+// v0.17.0 — roadmap item #16. The max length the backend enforces
+// (Pydantic body bound + `invites.CUSTOM_MESSAGE_MAX_LENGTH`); kept
+// here so the modal's "remaining chars" counter stays in lockstep
+// with the server-side bound.
+const CUSTOM_MESSAGE_MAX_LENGTH = 500
+
 const TABS = [
   { path: 'users', label: 'Users' },
   { path: 'allowlist', label: 'Allowlist' },
@@ -90,6 +97,10 @@ function UsersTab() {
   const [busy, setBusy] = useState({})
   const [error, setError] = useState(null)
   const [stateFilter, setStateFilter] = useState('all')
+  // v0.17.0 — roadmap item #16. The "Create user + invite" modal's
+  // open/closed state. The modal is local to UsersTab (it only opens
+  // from the header button) and refreshes the listing on success.
+  const [inviteModalOpen, setInviteModalOpen] = useState(false)
 
   async function refresh() {
     setError(null)
@@ -179,8 +190,28 @@ function UsersTab() {
           retain their v0.7.0 semantics — promote to admin to remove a
           user's ability to write without silencing them.
         </p>
+        {/* v0.17.0 — roadmap item #16. The "Create user + invite"
+            affordance opens a modal that provisions a fresh users row
+            with the chosen role and sends an invite email with a
+            single-use claim link. */}
+        <div className="admin-tab-actions">
+          <button
+            type="button"
+            className="btn-primary"
+            onClick={() => setInviteModalOpen(true)}
+          >Create user + invite</button>
+        </div>
       </header>
       {error && <p className="settings-note warning">{error}</p>}
+      {inviteModalOpen && (
+        <CreateUserInviteModal
+          onClose={() => setInviteModalOpen(false)}
+          onSuccess={async () => {
+            setInviteModalOpen(false)
+            await refresh()
+          }}
+        />
+      )}
 
       <div className="admin-filter-chips">
         {STATE_CHIPS.map(chip => (
@@ -231,12 +262,26 @@ function UserRow({ user: u, busy, onChangeRole, onToggleMute, onFlipPermission }
   const state = u.permission_state || 'granted'
   const fullName = [u.first_name, u.last_name].filter(Boolean).join(' ').trim()
   const handle = u.gitea_login ? `@${u.gitea_login}` : (u.email || u.display_name)
+  // v0.17.0 — roadmap item #16. The user's row may also be the
+  // "(pending invite)" shape: admin-created via POST /api/admin/users,
+  // not yet claimed via /api/invites/claim. The backend's user-listing
+  // surfaces this via `pending_invite` (object with invite_id +
+  // expires_at) or null. The badge sits inline next to the handle so
+  // the admin sees at a glance which rows are real users vs. unclaimed
+  // invites.
+  const pendingInvite = u.pending_invite
   return (
     <>
       <tr>
         <td>
           <div className="user-cell">
             <span className="user-handle">{handle}</span>
+            {pendingInvite && (
+              <span
+                className="invite-badge"
+                title={`Admin-created invite; expires ${pendingInvite.expires_at}`}
+              >(pending invite)</span>
+            )}
             <span className="muted">
               {fullName || u.display_name}
               {u.email ? ` · ${u.email}` : ''}
@@ -326,6 +371,173 @@ function PermissionCell({ user: u, busy, onFlipPermission }) {
   )
 }
 
+// ── Create user + invite modal (v0.17.0 / roadmap item #16) ────────────────
+//
+// The "Create user + invite" affordance on the Users tab opens this
+// modal. Admin types email, first name, last name, role, and (optionally)
+// a custom message to embed in the invite email. On submit, calls
+// `POST /api/admin/users` which provisions the row + sends the email.
+// The 409 path (duplicate email) and 422 path (self-invite, owner-
+// grant-by-non-owner, malformed input) surface the server's message
+// inline; the success path closes the modal and refreshes the listing.
+//
+// The modal lives in this file rather than a separate component
+// because it has one caller (UsersTab), reuses the existing modal
+// stylesheet from /admin's chrome, and shares the
+// CUSTOM_MESSAGE_MAX_LENGTH constant defined at the top of the file.
+
+function CreateUserInviteModal({ onClose, onSuccess }) {
+  const [email, setEmail] = useState('')
+  const [firstName, setFirstName] = useState('')
+  const [lastName, setLastName] = useState('')
+  const [role, setRole] = useState('contributor')
+  const [customMessage, setCustomMessage] = useState('')
+  const [busy, setBusy] = useState(false)
+  const [error, setError] = useState(null)
+  const [success, setSuccess] = useState(null)
+
+  const remaining = CUSTOM_MESSAGE_MAX_LENGTH - customMessage.length
+
+  async function handleSubmit(event) {
+    event.preventDefault()
+    const trimmedEmail = email.trim()
+    if (!trimmedEmail) {
+      setError('Email is required')
+      return
+    }
+    setBusy(true)
+    setError(null)
+    setSuccess(null)
+    try {
+      const result = await createUserInvite({
+        email: trimmedEmail,
+        first_name: firstName.trim(),
+        last_name: lastName.trim(),
+        role,
+        custom_message: customMessage,
+      })
+      // v0.17.0 + #21 Part C — Amplitude wiring. target_user_id is
+      // the OHM user id the invite-create gesture provisioned;
+      // initial_role is what the invitee inherits on claim.
+      // custom_message_chars is a coarse signal of admin effort
+      // (0 = template-only, 1+ = personalized). No PII.
+      track(EVENTS.USER_INVITED, {
+        target_user_id: result.invited_user_id != null
+          ? String(result.invited_user_id) : null,
+        initial_role: result.role,
+        custom_message_chars: (customMessage || '').length,
+      })
+      setSuccess(`Invite sent to ${result.email} (${result.role}).`)
+      // Brief delay so the admin sees the success state, then close
+      // and let the parent refresh the listing.
+      setTimeout(() => { onSuccess?.() }, 600)
+    } catch (e) {
+      setError(e.message || 'Unable to send invite')
+    } finally {
+      setBusy(false)
+    }
+  }
+
+  return (
+    <div className="modal-backdrop" onClick={onClose}>
+      <div className="modal-panel" onClick={e => e.stopPropagation()}>
+        <header className="modal-header">
+          <h3>Create user + invite</h3>
+          <button
+            type="button"
+            className="btn-link-quiet"
+            onClick={onClose}
+            disabled={busy}
+            aria-label="Close"
+          >×</button>
+        </header>
+        <p className="muted">
+          Provisions a fresh user row with the chosen role and sends an
+          invite email carrying a single-use claim link. The link
+          expires in 7 days. The invitee clicks through to claim
+          their account — no OTC roundtrip is required on first sign-in.
+        </p>
+        <form onSubmit={handleSubmit} className="create-user-invite-form">
+          <label>
+            <span>Email</span>
+            <input
+              type="email"
+              value={email}
+              onChange={e => setEmail(e.target.value)}
+              required
+              disabled={busy}
+              autoFocus
+              maxLength={320}
+            />
+          </label>
+          <div className="form-row">
+            <label>
+              <span>First name</span>
+              <input
+                type="text"
+                value={firstName}
+                onChange={e => setFirstName(e.target.value)}
+                disabled={busy}
+                maxLength={120}
+              />
+            </label>
+            <label>
+              <span>Last name</span>
+              <input
+                type="text"
+                value={lastName}
+                onChange={e => setLastName(e.target.value)}
+                disabled={busy}
+                maxLength={120}
+              />
+            </label>
+          </div>
+          <label>
+            <span>Role</span>
+            <select
+              value={role}
+              onChange={e => setRole(e.target.value)}
+              disabled={busy}
+            >
+              <option value="contributor">Contributor</option>
+              <option value="admin">Admin</option>
+              <option value="owner">Owner (owner-only)</option>
+            </select>
+          </label>
+          <label>
+            <span>
+              Custom message (optional){' '}
+              <span className={`muted${remaining < 0 ? ' warning' : ''}`}>
+                {remaining} chars left
+              </span>
+            </span>
+            <textarea
+              value={customMessage}
+              onChange={e => setCustomMessage(e.target.value)}
+              disabled={busy}
+              rows={4}
+              maxLength={CUSTOM_MESSAGE_MAX_LENGTH}
+              placeholder="Optional — embedded in the invite email."
+            />
+          </label>
+          {error && <p className="settings-note warning">{error}</p>}
+          {success && <p className="settings-note success">{success}</p>}
+          <div className="modal-actions">
+            <button type="button" onClick={onClose} disabled={busy}>Cancel</button>
+            <button
+              type="submit"
+              className="btn-primary"
+              disabled={busy || !email.trim() || remaining < 0}
+            >
+              {busy ? 'Sending…' : 'Send invite'}
+            </button>
+          </div>
+        </form>
+      </div>
+    </div>
+  )
+}
+
 // ── Private-beta allowlist (`migrations/011_allowlist.sql`) ────────────────
 
 function AllowlistTab() {

frontend/src/components/InviteClaim.jsx

@@ -0,0 +1,173 @@
+// v0.17.0 — roadmap item #16. The claim flow's landing page.
+//
+// The admin's invite email carries a link to /invites/claim?token=…;
+// the invitee clicks through and lands here. The page reads the
+// token from the URL, posts it to /api/invites/claim, and on success
+// routes either to the passcode-set screen (if v0.10.0 passcode flow
+// is in play and the user has no passcode yet) or to home.
+//
+// Anonymous-reachable: the entire point of the call is to establish
+// the session; we do not pre-check authentication.
+//
+// Failure modes the backend distinguishes:
+//   * 410 — token is expired or already claimed (the row is dead).
+//   * 400 — token doesn't match any active invite (forged, revoked,
+//     or wiped).
+//
+// We surface both as the same "this invite link isn't valid" shape
+// for the invitee — the detail message from the server reads
+// distinctively enough that the admin can debug from logs, and the
+// invitee just needs to know they should contact the admin for a
+// fresh link.
+
+import { useEffect, useState } from 'react'
+import { useLocation, useNavigate } from 'react-router-dom'
+import { claimInvite } from '../api.js'
+import { EVENTS, identify, track } from '../lib/analytics.js'
+
+export default function InviteClaim() {
+  const location = useLocation()
+  const navigate = useNavigate()
+  const [status, setStatus] = useState('working') // 'working' | 'ok' | 'failed'
+  const [error, setError] = useState(null)
+  const [trustDevice, setTrustDevice] = useState(false)
+  const [submitted, setSubmitted] = useState(false)
+  const [user, setUser] = useState(null)
+  const [needsPasscode, setNeedsPasscode] = useState(false)
+
+  const params = new URLSearchParams(location.search)
+  const token = params.get('token') || ''
+
+  async function performClaim() {
+    if (!token) {
+      setStatus('failed')
+      setError('No invite token in the URL.')
+      return
+    }
+    setSubmitted(true)
+    setStatus('working')
+    setError(null)
+    try {
+      const result = await claimInvite(token, { trustDevice })
+      setUser(result.user)
+      setNeedsPasscode(!!result.needs_passcode)
+      // v0.17.0 + #21 Part C — identify the new user with their OHM
+      // user_id BEFORE firing any track() event, so the Amplitude
+      // user record is created with the OHM id from the first event
+      // rather than as an anonymous device that retroactively links.
+      // setOnce on invited_at + invited_by_admin_id + initial_role so
+      // these are immutable user-history markers on the Amplitude
+      // record.
+      if (result.user?.id != null) {
+        const setOnceProps = {
+          claim_method: 'admin-invite',
+        }
+        if (result.invited_at) setOnceProps.invited_at = ['__setOnce__', result.invited_at]
+        if (result.invited_by_admin_id != null) {
+          setOnceProps.invited_by_admin_id = ['__setOnce__', String(result.invited_by_admin_id)]
+        }
+        if (result.user.role) setOnceProps.initial_role = ['__setOnce__', result.user.role]
+        identify({
+          user_id: String(result.user.id),
+          properties: setOnceProps,
+        })
+      }
+      track(EVENTS.INVITE_CLAIMED, {
+        invited_by_admin_id: result.invited_by_admin_id != null
+          ? String(result.invited_by_admin_id) : null,
+        initial_role: result.user?.role,
+        needs_passcode: !!result.needs_passcode,
+        trust_device: trustDevice,
+      })
+      setStatus('ok')
+    } catch (e) {
+      setStatus('failed')
+      setError(e.message || 'Unable to claim invite')
+    }
+  }
+
+  // Pre-flight: if the URL has no token at all, fail fast so the
+  // invitee sees the missing-token shape immediately rather than
+  // an empty form.
+  useEffect(() => {
+    if (!token) {
+      setStatus('failed')
+      setError('This claim link is missing its token.')
+    }
+  }, [token])
+
+  // On a successful claim, route the user onward. The brief calls
+  // this out: route to passcode-set if v0.10.0 passcode flow is in
+  // play and the user has no passcode yet; otherwise route to home.
+  useEffect(() => {
+    if (status !== 'ok') return
+    const timeout = setTimeout(() => {
+      if (needsPasscode) {
+        navigate('/settings/notifications#sign-in', { replace: true })
+      } else {
+        navigate('/', { replace: true })
+      }
+    }, 1200)
+    return () => clearTimeout(timeout)
+  }, [status, needsPasscode, navigate])
+
+  return (
+    <div className="invite-claim-page">
+      <div className="invite-claim-panel">
+        <h1>Claim your account</h1>
+        {!submitted && status === 'working' && token && (
+          <>
+            <p>
+              You've been invited to this deployment. Click the button below
+              to claim your account and sign in. This link is single-use and
+              expires 7 days after it was sent.
+            </p>
+            <label className="claim-trust-toggle">
+              <input
+                type="checkbox"
+                checked={trustDevice}
+                onChange={e => setTrustDevice(e.target.checked)}
+              />
+              {' '}Trust this device for 30 days (skip the email step on
+              your next visit from this browser).
+            </label>
+            <div className="claim-actions">
+              <button
+                type="button"
+                className="btn-primary"
+                onClick={performClaim}
+              >Claim my account</button>
+            </div>
+          </>
+        )}
+        {submitted && status === 'working' && (
+          <p>Claiming…</p>
+        )}
+        {status === 'ok' && (
+          <>
+            <p className="settings-note success">
+              Welcome{user?.display_name ? `, ${user.display_name}` : ''}!
+              You're signed in.
+            </p>
+            <p className="muted">
+              {needsPasscode
+                ? 'Redirecting you to set a passcode so you can sign in without an email roundtrip next time…'
+                : 'Redirecting you to the home page…'}
+            </p>
+          </>
+        )}
+        {status === 'failed' && (
+          <>
+            <p className="settings-note warning">
+              {error || "This invite link isn't valid."}
+            </p>
+            <p className="muted">
+              If you believe this is a mistake, contact the admin who
+              sent you the invite — they can issue a fresh link.
+            </p>
+          </>
+        )}
+      </div>
+    </div>
+  )
+}