docs(prd-6): mark M5 complete — assignee trigger validated

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

prds/6-e2e-test-forgejo-triggers.md

@@ -79,12 +79,17 @@ Systematically exercise each untested scenario on the live Forgejo instance (git
     3. `baa007a`: Forgejo sends `label_updated` instead of `labeled` as `eventAction` for issue label events. Added `FORGEJO_EVENT_ACTION_MAP` in `context.ts` to normalize at parse time (same pattern as event name normalization).
   - **Key learning**: Forgejo's `issues` event action names differ from GitHub — `label_updated` not `labeled`. Normalize in `context.ts` at parse time so all downstream code works unchanged. Creating an issue with a label fires both `opened` and `label_updated` as separate events — do NOT check labels on `opened` to avoid duplicate runs.
 
-- [ ] **M5: Test assignee trigger**
+- [x] **M5: Test assignee trigger**
 
-  - Assign a user to an issue to trigger the action
-  - Verify: trigger detection, context fetching, Claude response
-  - Document any issues and fix them
-  - **Validation**: Claude responds when assigned to an issue
+  - Created test issue #20, assigned `claude` user via API ✓
+  - Verify: trigger detection, context fetching, Claude response ✓
+  - Document any issues and fix them ✓ (1 bug found and fixed, see below)
+  - **Validation**: Claude responds when assigned to an issue ✓ (run 52842, 2 turns, $0.09)
+  - **Bug found & fixed**:
+    1. `99624ef`: Forgejo's `issues/assigned` webhook payload lacks the top-level `assignee` object — `payload.assignee` is `undefined`. The assignee is only available at `payload.issue.assignee`. Added fallback in `trigger.ts` to check `issue.assignee.login` when `payload.assignee.login` is missing.
+  - **Also discovered**: Forgejo sends `assigned` as the event action (matching GitHub) — no normalization needed, unlike M4's `label_updated`.
+  - **Also discovered**: Forgejo's API `PATCH /issues/{index}` with `{"assignees": ["user"]}` (plural array) returns 404. Must use deprecated singular `{"assignee": "user"}` field instead.
+  - **Key learning**: On Forgejo, the `issues/assigned` webhook payload structure differs from GitHub — the assigned user is nested under `issue.assignee`, not at the top-level `assignee` field. Same pattern as M2's missing top-level `comment` object.
 
 - [ ] **M6: Test tag mode with code changes (branch creation)**
 
@@ -119,6 +124,8 @@ Systematically exercise each untested scenario on the live Forgejo instance (git
 | Workflow if: expression parser rejects # comments        | RESOLVED: moved comments outside if: block, use >- scalar    |
 | Forgejo event action names differ from GitHub            | RESOLVED: FORGEJO_EVENT_ACTION_MAP normalizes at parse time  |
 | Creating issue with label fires duplicate runs           | RESOLVED: label check only on labeled event, not on opened   |
+| Forgejo assigned payload lacks top-level assignee        | RESOLVED: fallback to issue.assignee.login in trigger.ts     |
+| Forgejo API assignees array field returns 404            | RESOLVED: use deprecated singular assignee field instead     |
 
 ## Success Criteria