diff --git a/CHANGELOG.md b/CHANGELOG.md
index b56ae4b..d0863e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,61 @@ skip versions are the composition of each intervening adjacent
 release's steps in order — no A-to-B path is pre-computed beyond
 that.
 
+## 0.43.0 — 2026-06-06
+
+**Minor (non-breaking) — §22 three-tier refactor, slice S4: *invitation
+surfaces + role-aware empty states.* An Owner can now grant scope roles from the
+UI, and each tier shows a role-appropriate empty state. Purely additive over S3:
+new endpoints and UI, no schema migration, and no change to existing read or
+write semantics. Completes acceptance scenarios `@S4` (C2.1–C2.7: invitation
+reach, bounding, supersession, and the pending-account floor; C3.3–C3.5: the
+create-first-collection and propose-first empty states).**
+
+See [`docs/design/2026-06-05-three-tier-projects-collections.md`](./docs/design/2026-06-05-three-tier-projects-collections.md)
+(Part E slice S4, Part C.2 and C.3). The in-app create-project flow and the
+global-directory empty states (C3.1–C3.2) remain S5.
+
+Added:
+
+- **Scope-role invitation surface (§22 C.2)** — `POST
+  /api/projects/<id>/members` grants `{owner, contributor}` to an existing
+  account (looked up by email) at the project, or at one collection (with
+  `collection_id`). The grant writes a `memberships` row immediately and emits a
+  §15 personal-direct notification (`scope_role_granted`) naming the project and
+  role — a direct grant, not an accept round-trip. `GET` lists the project
+  subtree's grants (project-Owner view); `DELETE
+  /api/projects/<id>/members/<user_id>` (optionally `?collection_id=`) revokes.
+- **Invitation gates** — `auth.can_invite_at_project` /
+  `can_invite_at_collection`: managing membership is an Owner capability bounded
+  by the inviter's reach. A project Owner grants at the project or any collection
+  within it; a collection Owner grants only at that collection (never the project
+  or globally); an RFC Contributor manages no membership.
+- **Broader-scope-supersedes (§22 C.2.6)** — granting at a broader scope removes
+  the grantee's narrower rows that the new grant subsumes (same-or-lower role
+  rank within the subtree); a stronger child grant survives a weaker parent grant
+  (no negative override).
+- **Pending-account floor (§22 C.2.7)** — a grant to a `pending` deployment
+  account is recorded but confers no write until the account is granted at the
+  deployment (the §6 admission floor in `effective_scope_role`).
+- **Viewer capability flags** — `GET /api/projects/<id>/collections` carries a
+  `viewer` block (`can_create_collection`, `can_invite`, `role`); `GET
+  /api/projects/<id>/collections/<cid>` carries `viewer.can_contribute /
+  can_invite / role`. These drive the role-aware UI without a second round-trip.
+- **Role-aware empty states (§22 C.3.3–C.3.5)** — a project Owner landing on an
+  empty project sees a "Create your first collection" CTA (opening the
+  create-collection modal — surfacing the S2 endpoint, previously UI-less); a
+  contributor without create rights sees the bare empty directory; a collection
+  contributor landing on an empty collection sees "Propose the first entry"
+  (anonymous readers keep the S2 sign-in prompt). The directory also gains an
+  Owner-only **Members** control opening the invitation modal.
+
+Upgrade steps:
+
+1. No operator action is required. S4 adds endpoints and UI only — there is no
+   migration and no change to existing authorization outcomes. A deployment that
+   was managing `memberships` rows directly (the S3 administrative path) keeps
+   working; the new UI is an additional way to write the same rows.
+
 ## 0.42.0 — 2026-06-05
 
 **Minor (breaking — upgrade steps below) — §22 three-tier refactor, slice S3:
diff --git a/VERSION b/VERSION
index 787ffc3..8298bb0 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.42.0
+0.43.0
diff --git a/docs/design/2026-06-05-three-tier-projects-collections.md b/docs/design/2026-06-05-three-tier-projects-collections.md
index 4592e3f..6498e6a 100644
--- a/docs/design/2026-06-05-three-tier-projects-collections.md
+++ b/docs/design/2026-06-05-three-tier-projects-collections.md
@@ -581,13 +581,17 @@ means the deployment runs and either gains a capability or provably loses none
   hidden from the public. **Completes:** `@S3` (all of C.1 — role usage,
   inheritance, union, no-negative-override).
 
-- **S4 — Invitation surfaces + role-aware empty states.** The invite UI
+- **S4 — Invitation surfaces + role-aware empty states.** *(Shipped v0.43.0.)*
+  The invite UI
   (Owner-only) granting Owner/RFC Contributor at a scope or any scope beneath it,
   with §15 notifications and the broader-scope-supersedes rule; the
   create-first-collection / propose-first empty states keyed to the actor's role.
-  **Usable end-state:** an Owner invites collaborators at the right scope from
-  the UI. **Completes:** `@S4` (all of C.2 — invitation; plus the project/
-  collection empty states C3.3–C3.5).
+  Modelled as a **direct grant** to an existing account looked up by email (the
+  C.2 scenarios write the membership row immediately and §15-notify an existing
+  user — no accept round-trip; inviting a not-yet-account email is out of S4
+  scope, handled by the admin-create-invite path). **Usable end-state:** an Owner
+  invites collaborators at the right scope from the UI. **Completes:** `@S4` (all
+  of C.2 — invitation; plus the project/collection empty states C3.3–C3.5).
 
 - **S5 — In-app create-project + the global directory.** The global-Owner
   **create-project** action (bot provisions a Gitea content repo + commits to
diff --git a/frontend/package.json b/frontend/package.json
index 1bb033b..29152e4 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "rfc-app-frontend",
   "private": true,
-  "version": "0.42.0",
+  "version": "0.43.0",
   "type": "module",
   "scripts": {
     "dev": "vite",