v0.23.0: server-side sign-in state resume (roadmap #29)

Track each authenticated user's last-viewed route + light view state
server-side, and on next sign-in redirect them to that state, falling
back to the empty-state home only when there's no recorded state.

Backend:
- migration 022_user_session_state.sql: one row per user
  (user_id PK/FK, last_route, last_route_state JSON-as-TEXT,
  resume_enabled default 1, last_updated_at).
- PUT /api/me/last-state (require_user): upserts route + light state;
  no-ops when resume_enabled=0. Localized in the /me region.
- /api/auth/me payload now carries resume_enabled + last_route +
  decoded last_route_state (no extra round-trip).
- test_session_resume_vertical.py: auth-required, upsert/read-back,
  per-user isolation, resume_enabled=0 disable.

Frontend:
- lib/useLastState.js: debounced (~1s) route-change PUT for
  authenticated users; one-time resume redirect on sign-in, gated on
  identify having fired (preserves #21 Part C identify-then-track).
- api.js: putLastState() client call.
- App.jsx: import + call the hook; set identifyReady after identify.
  Header region untouched.

Per-user (not per-device); profile-settings opt-out toggle UI
deferred (column + default-on behavior ship now). Stored state is
route + light view state ONLY, never draft buffers — documented in
SPEC §6.8.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

SPEC.md

@@ -714,6 +714,47 @@ The lighter half ships the structural shape — frontmatter, consent,
 resolution, revocation. The heavier half ships the runtime
 hardening.
 
+### 6.8 Sign-in state resume (roadmap item #29, v0.23.0)
+
+Signing in lands the user back on their most recently-viewed app
+state instead of always on the empty-state home view. The model is
+**per-user**, not per-device — the safe default the roadmap calls
+for: a sign-in on any device resumes the most-recently-recorded
+route. A per-device split and a profile-settings toggle UI are
+follow-ups; v0.23.0 ships the column-level opt-out flag
+(`resume_enabled`, default on) and the default-on behavior.
+
+**Storage.** A single row per user in `user_session_state`
+(migration 022): `user_id` (PK, FK → `users.id`, cascade-delete),
+`last_route` (TEXT, the frontend pathname), `last_route_state`
+(TEXT, JSON-encoded — SQLite has no native JSONB, so JSON-as-TEXT
+matches how the app stores every other JSON blob), `resume_enabled`
+(INTEGER, default 1), and `last_updated_at`.
+
+**Wiring.** A debounced (~1s) frontend route-change hook posts the
+current route to `PUT /api/me/last-state` for authenticated users
+(anonymous: no-op). The stored `last_route` is folded onto the
+existing `/api/auth/me` payload (no extra round-trip); on sign-in,
+after the §21-Part-C Amplitude `identify` fires, the frontend
+`navigate()`s to it. The identify-then-redirect ordering is
+preserved: the redirect is gated on identify having fired.
+
+**Stale state.** If the stored route is an RFC since withdrawn or
+one the user lost rights to read, the redirect is a graceful no-op:
+`navigate(last_route)` lands on whatever that route renders today,
+and the existing routing already falls through to the
+catalog/empty-state for a missing/unreadable RFC. No special-casing
+on the server.
+
+**Privacy (binding).** The stored state is **route + light view
+state ONLY** — scroll anchors, open-tab selection, filter chips, and
+the like. It **MUST NOT** carry draft-buffer contents, PR/comment
+draft text, or any user-typed content. The frontend never sends such
+content; the `last_route_state` column comment in migration 022 and
+this paragraph are the contract. Resume state is purposely cheap to
+discard: a deliberate "clear" (or `resume_enabled = 0`) drops the
+user back to today's empty-state behavior.
+
 ---
 
 ## 7. The left pane

backend/app/api.py

@@ -67,6 +67,18 @@ class FunderCredentialBody(BaseModel):
     api_key: str = Field(min_length=1, max_length=2048)
 
 
+class LastStateBody(BaseModel):
+    # v0.23.0 / roadmap item #29: server-side sign-in state resume.
+    # `route` is a frontend pathname the user was last on (bounded so a
+    # hostile client can't stuff arbitrary blobs through). `state` is an
+    # optional bag of *light* view state (scroll anchors, open tab,
+    # filter chips). PRIVACY: it MUST NOT carry draft-buffer contents —
+    # the frontend only ever sends ephemeral view state, and the column
+    # comment in migration 022 + SPEC §6.2 are the binding contract.
+    route: str = Field(min_length=1, max_length=2048)
+    state: dict[str, Any] | None = None
+
+
 class BetaRequestBody(BaseModel):
     # v0.8.0 — captured on the first OTC sign-in. All three fields are
     # required so the admin queue has a coherent triage shape.
@@ -354,6 +366,28 @@ def make_router(
         )
         has_passcode = bool(row and row["passcode_hash"])
         passcode_set_at = row["passcode_set_at"] if (row and has_passcode) else None
+        # v0.23.0 / item #29: fold the sign-in-resume state onto the
+        # same round-trip the frontend already makes on boot. When
+        # resume is disabled (resume_enabled = 0) we hand back a null
+        # route so the client never redirects; the stored row stays put
+        # so re-enabling later resumes the last-known route.
+        state_row = db.conn().execute(
+            "SELECT last_route, last_route_state, resume_enabled "
+            "FROM user_session_state WHERE user_id = ?",
+            (user.user_id,),
+        ).fetchone()
+        resume_enabled = bool(state_row["resume_enabled"]) if state_row else True
+        last_route = (
+            state_row["last_route"]
+            if (state_row and resume_enabled)
+            else None
+        )
+        last_route_state = None
+        if state_row and resume_enabled and state_row["last_route_state"]:
+            try:
+                last_route_state = json.loads(state_row["last_route_state"])
+            except (ValueError, TypeError):
+                last_route_state = None
         return {
             "authenticated": True,
             "user": {
@@ -370,6 +404,10 @@ def make_router(
                 "needs_profile": needs_profile,
                 "has_passcode": has_passcode,
                 "passcode_set_at": passcode_set_at,
+                # v0.23.0 / item #29 — sign-in state resume.
+                "resume_enabled": resume_enabled,
+                "last_route": last_route,
+                "last_route_state": last_route_state,
             },
         }
 
@@ -439,6 +477,52 @@ def make_router(
             notify.fan_out_new_beta_request(requester_user_id=user.user_id)
         return {"ok": True}
 
+    # ---------------------------------------------------------------
+    # v0.23.0 (§6.2, roadmap item #29): server-side sign-in state
+    # resume. The frontend debounce-posts the user's current route +
+    # a small bag of light view state here on every route change; the
+    # next sign-in reads `last_route` off `/api/auth/me` and redirects.
+    #
+    # Per-user (NOT per-device) — one row per user, keyed on user_id.
+    # `resume_enabled` is the opt-out flag (default on); when it's 0
+    # this endpoint no-ops so a user who turned resume off doesn't keep
+    # silently rewriting their stored route. PRIVACY: the body carries
+    # route + light state ONLY, never draft-buffer contents (migration
+    # 022 column comment + SPEC §6.2 are the binding contract).
+    #
+    # `require_user` (not `require_contributor`) — a pending/granted
+    # distinction is irrelevant for "remember where I was", and a
+    # pending user navigating read-only surfaces should still resume.
+    # Anonymous callers get the 401 `require_user` raises.
+    # ---------------------------------------------------------------
+
+    @router.put("/api/me/last-state")
+    async def put_last_state(body: LastStateBody, request: Request) -> dict[str, Any]:
+        user = auth.require_user(request)
+        # Respect the opt-out: if a row already exists with resume
+        # disabled, leave it untouched and report the no-op. A first-
+        # ever POST (no row yet) defaults to enabled and stores.
+        existing = db.conn().execute(
+            "SELECT resume_enabled FROM user_session_state WHERE user_id = ?",
+            (user.user_id,),
+        ).fetchone()
+        if existing is not None and not existing["resume_enabled"]:
+            return {"ok": True, "stored": False}
+        state_json = json.dumps(body.state) if body.state is not None else None
+        db.conn().execute(
+            """
+            INSERT INTO user_session_state
+                (user_id, last_route, last_route_state, last_updated_at)
+            VALUES (?, ?, ?, datetime('now'))
+            ON CONFLICT(user_id) DO UPDATE SET
+                last_route = excluded.last_route,
+                last_route_state = excluded.last_route_state,
+                last_updated_at = excluded.last_updated_at
+            """,
+            (user.user_id, body.route, state_json),
+        )
+        return {"ok": True, "stored": True}
+
     # ---------------------------------------------------------------
     # v0.11.0: trust device for 30 days (§6.2, roadmap item #9).
     #

backend/migrations/022_user_session_state.sql

@@ -0,0 +1,54 @@
+-- v0.23.0 / roadmap item #29: server-side sign-in state resume.
+--
+-- Track each authenticated user's last-viewed route + a small bag of
+-- "light" component state so that the *next* sign-in can land the user
+-- back where they left off, rather than always dropping them on the
+-- empty-state home view.
+--
+-- Storage shape (one row per user — per-user, NOT per-device, per the
+-- #29 "safe default"):
+--
+--   * `user_id` — PRIMARY KEY and FK into users(id) with cascade on
+--     delete. INTEGER to match users.id (INTEGER PRIMARY KEY
+--     AUTOINCREMENT). A deleted user automatically loses their stored
+--     resume state. One row per user means a later sign-in on any
+--     device resumes the most-recently-recorded route — the per-user
+--     model the roadmap asks for.
+--
+--   * `last_route` — the frontend pathname the user was last on
+--     (e.g. "/rfc/open-human-model"). TEXT, nullable until the first
+--     route-change POST lands. NEVER contains draft-buffer contents —
+--     it is a route only. See SPEC §6.2 "Sign-in state resume
+--     (privacy)".
+--
+--   * `last_route_state` — a JSON-encoded bag of *light* component
+--     state (scroll anchors, open-tab selection, filter chips, etc.).
+--     SQLite has no native JSONB; we store JSON as TEXT exactly as the
+--     rest of the app stores its JSON blobs (json.dumps / json.loads,
+--     cf. permission_events.details, actions.details). Nullable.
+--     PRIVACY INVARIANT: this column MUST NOT carry draft-buffer text,
+--     PR bodies, comment drafts, or any user-typed content — only
+--     ephemeral view state safe to replay. The PUT handler is the
+--     enforcement point; the column comment is the contract.
+--
+--   * `resume_enabled` — the per-user opt-out flag. 1 (default) means
+--     "resume me where I left off"; 0 means "always land on home". The
+--     PUT handler no-ops the upsert when this is 0, and the read path
+--     refuses to hand back a stored route when this is 0. A
+--     profile-settings toggle UI to flip this is a follow-up (the
+--     column + default-on behavior ship now); see CHANGELOG v0.23.0.
+--
+--   * `last_updated_at` — TEXT timestamp, app convention
+--     `datetime('now')`, matching device_trust.last_seen_at /
+--     users.last_seen_at. Refreshed on every successful upsert.
+--
+-- No new env vars. The debounce interval for the frontend route-change
+-- POST is a frontend constant (~1s), not a server knob.
+
+CREATE TABLE user_session_state (
+    user_id          INTEGER PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,
+    last_route       TEXT,
+    last_route_state TEXT,                        -- JSON-encoded light state, nullable
+    resume_enabled   INTEGER NOT NULL DEFAULT 1,
+    last_updated_at  TEXT NOT NULL DEFAULT (datetime('now'))
+);

backend/tests/test_session_resume_vertical.py

@@ -0,0 +1,140 @@
+"""End-to-end integration tests for the v0.23.0 sign-in state-resume
+vertical (§6.2, roadmap item #29).
+
+New behavior: each authenticated user's last-viewed route + a small bag
+of light view state is tracked server-side, so the next sign-in can land
+them back where they left off rather than on the empty-state home view.
+
+The tests below prove:
+
+  * `PUT /api/me/last-state` requires auth — an anonymous client gets
+    401, and nothing is stored.
+  * An authenticated PUT upserts the route, and the stored route is
+    read back for that user off `GET /api/auth/me` (`last_route`).
+  * A second PUT overwrites (upsert, one row per user) — the latest
+    route wins.
+  * `last_route_state` round-trips as decoded JSON on `/api/auth/me`.
+  * Per-user isolation: user A's stored route is not visible to user B.
+  * `resume_enabled = 0` disables resume: the PUT no-ops (does not
+    rewrite the stored route) and `/api/auth/me` hands back a null
+    `last_route` even though a stored row exists.
+
+The fakes from `test_propose_vertical` give us a working app harness +
+the `sign_in_as` / `provision_user_row` seams.
+"""
+from __future__ import annotations
+
+from test_propose_vertical import (  # noqa: F401
+    FakeGitea,
+    app_with_fake_gitea,
+    provision_user_row,
+    sign_in_as,
+    tmp_env,
+)
+
+
+def test_put_last_state_requires_auth(app_with_fake_gitea):
+    from fastapi.testclient import TestClient
+    from app import db
+
+    app, _fake = app_with_fake_gitea
+    with TestClient(app) as client:
+        # Anonymous — no session cookie set.
+        r = client.put("/api/me/last-state", json={"route": "/rfc/open-human-model"})
+        assert r.status_code == 401
+        # Nothing landed in the table.
+        row = db.conn().execute("SELECT COUNT(*) AS n FROM user_session_state").fetchone()
+        assert row["n"] == 0
+
+
+def test_put_last_state_upserts_and_reads_back(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=2, login="alice", role="contributor")
+        sign_in_as(client, user_id=2, gitea_login="alice", display_name="Alice", role="contributor", email="alice@test")
+
+        # First POST stores a route + light state.
+        r = client.put(
+            "/api/me/last-state",
+            json={"route": "/rfc/open-human-model", "state": {"tab": "discussion", "scroll": 420}},
+        )
+        assert r.status_code == 200
+        assert r.json()["stored"] is True
+
+        # /api/auth/me hands the route + decoded state back.
+        me = client.get("/api/auth/me").json()
+        assert me["authenticated"] is True
+        assert me["user"]["resume_enabled"] is True
+        assert me["user"]["last_route"] == "/rfc/open-human-model"
+        assert me["user"]["last_route_state"] == {"tab": "discussion", "scroll": 420}
+
+        # A later POST overwrites — one row per user, latest wins.
+        r = client.put("/api/me/last-state", json={"route": "/proposals/7"})
+        assert r.status_code == 200
+        me = client.get("/api/auth/me").json()
+        assert me["user"]["last_route"] == "/proposals/7"
+        # state was omitted on the second POST → cleared to null.
+        assert me["user"]["last_route_state"] is None
+
+
+def test_last_state_is_per_user(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=2, login="alice", role="contributor")
+        provision_user_row(user_id=3, login="bob", role="contributor")
+
+        sign_in_as(client, user_id=2, gitea_login="alice", display_name="Alice", role="contributor", email="alice@test")
+        client.put("/api/me/last-state", json={"route": "/rfc/alice-route"})
+
+        # Switch to bob — he has no stored route yet.
+        sign_in_as(client, user_id=3, gitea_login="bob", display_name="Bob", role="contributor", email="bob@test")
+        me = client.get("/api/auth/me").json()
+        assert me["user"]["last_route"] is None
+
+        client.put("/api/me/last-state", json={"route": "/rfc/bob-route"})
+        me = client.get("/api/auth/me").json()
+        assert me["user"]["last_route"] == "/rfc/bob-route"
+
+        # Back to alice — her route is untouched by bob's write.
+        sign_in_as(client, user_id=2, gitea_login="alice", display_name="Alice", role="contributor", email="alice@test")
+        me = client.get("/api/auth/me").json()
+        assert me["user"]["last_route"] == "/rfc/alice-route"
+
+
+def test_resume_disabled_no_ops_put_and_hides_route(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=2, login="alice", role="contributor")
+        sign_in_as(client, user_id=2, gitea_login="alice", display_name="Alice", role="contributor", email="alice@test")
+
+        # Seed a stored row, then flip resume_enabled off directly (the
+        # profile-settings toggle UI to do this from the client is a
+        # follow-up; the column + behavior ship now).
+        client.put("/api/me/last-state", json={"route": "/rfc/before-disable"})
+        db.conn().execute(
+            "UPDATE user_session_state SET resume_enabled = 0 WHERE user_id = ?",
+            (2,),
+        )
+
+        # /api/auth/me reports resume off and hands back a null route
+        # even though a stored row exists.
+        me = client.get("/api/auth/me").json()
+        assert me["user"]["resume_enabled"] is False
+        assert me["user"]["last_route"] is None
+
+        # A PUT while disabled no-ops: stored=False and the stored route
+        # is NOT rewritten.
+        r = client.put("/api/me/last-state", json={"route": "/rfc/after-disable"})
+        assert r.status_code == 200
+        assert r.json()["stored"] is False
+        row = db.conn().execute(
+            "SELECT last_route FROM user_session_state WHERE user_id = ?", (2,)
+        ).fetchone()
+        assert row["last_route"] == "/rfc/before-disable"

frontend/src/App.jsx

@@ -2,6 +2,7 @@ import { useEffect, useRef, useState } from 'react'
 import { Routes, Route, Link, Navigate, useLocation, useNavigate } from 'react-router-dom'
 import { getMe, subscribeToNotifications } from './api'
 import { anonymize, EVENTS, identify, track } from './lib/analytics'
+import { useLastState } from './lib/useLastState'
 import Catalog from './components/Catalog.jsx'
 import Inbox from './components/Inbox.jsx'
 import RFCView from './components/RFCView.jsx'
@@ -42,6 +43,12 @@ export default function App() {
   // "Privacy & cookies" tab dispatches a `rfc-app:cookie-consent-reopen`
   // event that bumps this.
   const [consentReopenTick, setConsentReopenTick] = useState(0)
+  // v0.23.0 / item #29 — flips true once the #21-Part-C identify effect
+  // has fired (or once we've confirmed there's no authenticated user to
+  // identify). useLastState gates its resume redirect on this so the
+  // redirect always happens AFTER identify, preserving identify-then-
+  // track ordering.
+  const [identifyReady, setIdentifyReady] = useState(false)
   const navigate = useNavigate()
   const location = useLocation()
   // v0.15.0 — Page Viewed event taxonomy. We fire on every
@@ -86,6 +93,9 @@ export default function App() {
       if (viewer?.first_sign_in_at) props.first_sign_in_at = ['__setOnce__', viewer.first_sign_in_at]
       if (viewer?.created_at) props.account_created_at = ['__setOnce__', viewer.created_at]
       identify({ user_id: String(uid), properties: props })
+      // v0.23.0 / item #29 — identify has now fired for this sign-in;
+      // release useLastState's resume redirect (it waits on this).
+      setIdentifyReady(true)
     } else if (uid == null && lastUserIdRef.current != null) {
       // Sign-out edge — App-level reset is handled separately by the
       // sign-out gesture that fires User Signed Out. Clear our local
@@ -94,6 +104,14 @@ export default function App() {
     }
   }, [me?.authenticated, me?.user?.id, me?.user?.role, me?.user?.permission_state, me?.user?.passcode_set, me?.user?.device_trusted])
 
+  // v0.23.0 / item #29 — once `me` has resolved, if there's no
+  // authenticated user there is nothing to identify, so release the
+  // resume gate immediately (anonymous boots have no resume to do, but
+  // the hook still needs the gate resolved to be a clean no-op).
+  useEffect(() => {
+    if (me != null && !me.authenticated) setIdentifyReady(true)
+  }, [me])
+
   useEffect(() => {
     const handler = () => setConsentReopenTick(t => t + 1)
     window.addEventListener('rfc-app:cookie-consent-reopen', handler)
@@ -107,6 +125,18 @@ export default function App() {
       .finally(() => setLoading(false))
   }, [])
 
+  // v0.23.0 / item #29 — server-side sign-in state resume. The hook
+  // debounce-posts the current route for authenticated users and, once
+  // identify has fired, redirects a fresh sign-in (which hard-lands on
+  // "/") to the user's stored last route. Anonymous users: no-op.
+  useLastState({
+    authenticated: !!me?.authenticated,
+    pathname: location.pathname,
+    identifyReady,
+    lastRoute: me?.authenticated ? me.user?.last_route : null,
+    navigate,
+  })
+
   // §15.3 — subscribe to the live SSE stream for authenticated viewers
   // so the badge counter and the toast surface stay in lockstep with
   // the inbox. Tabs that miss an event because they were closed pick

frontend/src/api.js

@@ -25,6 +25,25 @@ export async function getMe() {
   return jsonOrThrow(res)
 }
 
+// ── v0.23.0: sign-in state resume (§6.2, roadmap item #29) ───────────────
+//
+// The route-change hook (useLastState) debounce-posts the user's current
+// route + a small bag of *light* view state here for authenticated users.
+// The next sign-in reads `last_route` off `/api/auth/me` and redirects.
+// Privacy: `state` carries ephemeral view state ONLY — never draft-buffer
+// contents (see SPEC §6.2). Best-effort: callers ignore failures (an
+// offline/401 POST must never disrupt navigation).
+export async function putLastState(route, state) {
+  const body = { route }
+  if (state != null) body.state = state
+  const res = await fetch('/api/me/last-state', {
+    method: 'PUT',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(body),
+  })
+  return jsonOrThrow(res)
+}
+
 // ── v0.7.0: email + one-time-code sign-in (§6.2) ─────────────────────────
 //
 // The legacy /auth/login → /auth/callback OAuth flow remains during the

frontend/src/lib/useLastState.js

@@ -0,0 +1,91 @@
+// useLastState — v0.23.0 / roadmap item #29: server-side sign-in state
+// resume. Two responsibilities, kept in one small hook so App.jsx's
+// surface stays minimal:
+//
+//   1. Debounce-post the authenticated user's current route to
+//      `PUT /api/me/last-state` on every route change (~1s debounce so
+//      a fast click-through doesn't spray the endpoint). Anonymous
+//      users: no-op. Best-effort: a failed POST never disrupts nav.
+//
+//   2. On the first authenticated load, read the stored `last_route`
+//      (handed back on `/api/auth/me`) and `navigate()` to it ONCE.
+//      Stale routes (a withdrawn RFC, a slug the user lost rights to)
+//      are not special-cased here: navigating lands on whatever that
+//      route renders today, and the existing routing already falls
+//      through to the catalog/empty-state for a missing RFC. Keeping
+//      this dumb is deliberate (see SPEC §6.2 + the #29 scope note).
+//
+// Ordering with #21 Part C (Amplitude identify): App.jsx fires
+// `identify` in its own effect when `me.user.id` first appears. This
+// hook's resume redirect is gated on `identifyReady` — App.jsx flips it
+// true only after the identify effect has run — so the redirect always
+// happens AFTER identify, preserving the identify-then-track ordering
+// the roadmap calls out.
+import { useEffect, useRef } from 'react'
+import { putLastState } from '../api'
+
+// ~1s debounce on the route-change POST. A frontend constant, not a
+// server knob — the backend takes whatever lands.
+const DEBOUNCE_MS = 1000
+
+// Routes we never want to resume *to* — auth/landing surfaces that
+// would be nonsensical or hostile to drop a returning user onto. We
+// still record them (cheap, and the user may legitimately be sitting on
+// /docs), but the resume redirect skips them and falls through to the
+// default landing. Anything not listed resumes normally.
+const NON_RESUMABLE_PREFIXES = ['/login', '/welcome', '/invites/', '/invitations/']
+
+function isResumable(route) {
+  if (!route || typeof route !== 'string') return false
+  if (route === '/') return false // "/" is already the default landing
+  return !NON_RESUMABLE_PREFIXES.some(p => route.startsWith(p))
+}
+
+/**
+ * @param {object}   opts
+ * @param {boolean}  opts.authenticated  whether a viewer is signed in
+ * @param {string}   opts.pathname       current location.pathname
+ * @param {boolean}  opts.identifyReady   App flips true after identify fires
+ * @param {string|null} opts.lastRoute    stored route from /api/auth/me
+ * @param {function} opts.navigate        react-router navigate()
+ */
+export function useLastState({ authenticated, pathname, identifyReady, lastRoute, navigate }) {
+  // ── 1. Debounced route-change POST ────────────────────────────────
+  const timerRef = useRef(null)
+  useEffect(() => {
+    if (!authenticated) return undefined
+    if (timerRef.current) clearTimeout(timerRef.current)
+    timerRef.current = setTimeout(() => {
+      // Best-effort — swallow failures so an offline/401 POST never
+      // surfaces as a navigation error.
+      putLastState(pathname).catch(() => {})
+    }, DEBOUNCE_MS)
+    return () => {
+      if (timerRef.current) clearTimeout(timerRef.current)
+    }
+  }, [authenticated, pathname])
+
+  // ── 2. One-time resume redirect ───────────────────────────────────
+  // Fires once, after identify is ready, when there's a resumable
+  // stored route AND the user is currently sitting on the default
+  // landing ("/"). We only redirect from "/" so we never yank a user
+  // who deep-linked somewhere specific (or refreshed mid-RFC) back to
+  // their last route.
+  const resumedRef = useRef(false)
+  useEffect(() => {
+    if (resumedRef.current) return
+    if (!authenticated || !identifyReady) return
+    // Only resume when the app booted on the default landing — a hard
+    // sign-in nav lands on "/", which is exactly the case we want.
+    if (pathname !== '/') {
+      resumedRef.current = true // user deep-linked; don't resume later either
+      return
+    }
+    if (isResumable(lastRoute)) {
+      resumedRef.current = true
+      navigate(lastRoute, { replace: true })
+    } else {
+      resumedRef.current = true // nothing to resume to; keep default landing
+    }
+  }, [authenticated, identifyReady, lastRoute, pathname, navigate])
+}