docs(19-06): complete participant-only send and GDPR reassignment plan

Record CR-01/CR-02 gap closure and mark the 19-06 ROADMAP checkbox. Plugin repos were committed separately and not pushed.

Co-authored-by: Cursor <cursoragent@cursor.com>

.planning/ROADMAP.md

@@ -1198,7 +1198,7 @@ Plans:
   3. Golden tests show that the serializers (`Message.toApiArray` with attachments, thread summaries, channel, category, pref, pin and mention arrays) and every realtime event (name, channel and payload) match PHP output captured from Wavepath. Route-level parity of `/_wave` is checked at the Wavepath port.
   4. The new code has unit tests, delivered in the phase's last plan.
 
-**Plans:** 5/7 plans executed
+**Plans:** 6/7 plans executed
 
 Plans:
 **Wave 1**
@@ -1215,7 +1215,7 @@ Plans:
 - [x] 19-05-PLAN.md — Unit tests LAST: goldens, PHP method map (59 chat + 106 chatchannels), scripts/check-phase19.sh
 
 **Wave 5** *(gap closure)*
-- [ ] 19-06-PLAN.md — Participant-only canSend (CR-01) and created_by reassignment on user.Deleting (CR-02)
+- [x] 19-06-PLAN.md — Participant-only canSend (CR-01) and created_by reassignment on user.Deleting (CR-02)
 
 **Wave 6** *(gap closure, tests last)*
 - [ ] 19-07-PLAN.md — TestTeammateDMWriteIDOR, TestDeletingCascade creator path, check-phase19.sh names

.planning/phases/19-chat-and-chatchannels/19-06-SUMMARY.md

@@ -0,0 +1,166 @@
+---
+phase: 19-chat-and-chatchannels
+plan: 06
+subsystem: chat
+tags: [chat, chatchannels, canSend, GDPR, user.Deleting, D-08, D-13, SC-19-1]
+
+requires:
+  - phase: 19-02
+    provides: ChatService SendMessage, GetOrCreateDm, GetGroupChat
+  - phase: 19-04
+    provides: user.Deleting, FireDeletingEvent, ChannelService.WithDB analog
+provides:
+  - "CR-01 / D-08 / SC-19-1: canSend is participant-only; teammate DM write is ErrNotParticipant"
+  - "CR-02 / D-13: chat-owned ReassignCreatedBy on user.Deleting so remaining members keep the conversation"
+  - "TestGapClosureSmoke (postgres, skipped under -short)"
+affects: [19-07, Wavepath port]
+
+actuals:
+  tokens: 3037
+  tasks: 3
+  commits: 1
+plan_head_before: 29d06bc70e0e1e4f0d24dcb72a3dd304863994cb
+plan_head_after: pending-summary-commit
+
+tech-stack:
+  added: []
+  patterns:
+    - "canSend returns s.isParticipant after nil/zero-id guards; host ChatEnabled stays on GetGroupChat / GetOrCreateDm"
+    - "Service.WithDB clones like ChannelService.WithDB so the deleting event Tx is the session"
+    - "Chat owns user.Deleting reassignment so DMs survive when chatchannels is not mounted"
+
+key-files:
+  created:
+    - ../sm-chat-plugin/gap_closure_test.go
+  modified:
+    - ../sm-chat-plugin/classes/service.go
+    - ../sm-chat-plugin/boot.go
+    - ../sm-chat-plugin/README.md
+    - ../sm-chatchannels-plugin/README.md
+    - .planning/ROADMAP.md
+
+key-decisions:
+  - "Chat owns ReassignCreatedBy; chatchannels SeverUserFromContext is unchanged"
+  - "canSend is participation-only; ChatEnabled is not folded into canSend"
+  - "GetGroupChat still ignores addParticipant errors (IN-01 stays open)"
+  - "TestGapClosureSmoke is not added to check-phase19.sh (19-07)"
+
+patterns-established:
+  - "Gap-closure smoke lives in the plugin repo and is skipped under -short via TestMain"
+  - "GDPR created_by reassignment is chat-owned so DMs and channel-backed groups both survive"
+
+requirements-completed: [SC-19-1, D-08, D-13]
+
+coverage:
+  - id: D1
+    description: "canSend is participant-only; a third teammate cannot SendMessage into a two-person DM (CR-01 / D-08 / SC-19-1)"
+    requirement: SC-19-1
+    verification:
+      - kind: integration
+        ref: "../sm-chat-plugin/gap_closure_test.go#TestGapClosureSmoke"
+        status: pass
+    human_judgment: false
+  - id: D2
+    description: "user.Deleting reassigns created_by to another remaining participant so the DM row survives GDPR delete (CR-02 / D-13)"
+    requirement: D-13
+    verification:
+      - kind: integration
+        ref: "../sm-chat-plugin/gap_closure_test.go#TestGapClosureSmoke"
+        status: pass
+    human_judgment: false
+  - id: D3
+    description: "READMEs document participant-only send and created_by reassignment; WR-01..WR-04 and IN-01..IN-02 stay open"
+    requirement: D-08
+    verification:
+      - kind: other
+        ref: "grep ReassignCreatedBy/participant/created_by in plugin READMEs"
+        status: pass
+    human_judgment: false
+
+duration: 4min
+completed: 2026-10-17
+status: complete
+---
+
+# Phase 19 Plan 06: Chat/ChatChannels Gap Closure Summary
+
+**Participant-only canSend and chat-owned created_by reassignment on user.Deleting so DMs and shared channels survive GDPR delete**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-10-17T20:28:09Z
+- **Completed:** 2026-10-17T20:32:00Z
+- **Tasks:** 3
+- **Files modified:** 5
+
+## Accomplishments
+
+- `canSend` now returns only `s.isParticipant` after nil/zero-id guards. A teammate who is not a DM participant gets `ErrNotParticipant` (HTTP 404 mapping unchanged).
+- `Service.WithDB` and `Service.ReassignCreatedBy` land; Boot Listens `user.Deleting` and reassigns `created_by` to another remaining participant before the user row is deleted. The IF NOT EXISTS baseline CASCADE is untouched.
+- `TestGapClosureSmoke` proves both post-fix behaviours on one postgres path (Carol refused on Alice/Bob DM; Alice send succeeds; Carol GetGroupChat lazy-join then send succeeds; after Alice delete the DM remains with `created_by` = Bob).
+
+## Task Commits
+
+Each task was committed atomically in the plugin repos; this SUMMARY is the summercms.go metadata commit.
+
+1. **Task 1 + 2 + 3 (sm-chat-plugin):** `0aee785` (feat) — participant-only send, ReassignCreatedBy, TestGapClosureSmoke, README
+2. **Task 2 + 3 (sm-chatchannels-plugin):** `7d49c3c` (docs) — GDPR bullet that chat reassigns created_by
+3. **Plan metadata (summercms.go):** this commit (docs)
+
+_Plugin SHAs are local only. No remotes were pushed. fonoteka submodule pointers were not bumped._
+
+## Files Created/Modified
+
+- `../sm-chat-plugin/classes/service.go` — participant-only `canSend`; `WithDB`; `ReassignCreatedBy`
+- `../sm-chat-plugin/boot.go` — `listeners` step; `Listen[*userclasses.DeletingEvent]`
+- `../sm-chat-plugin/gap_closure_test.go` — `TestGapClosureSmoke`
+- `../sm-chat-plugin/README.md` — send-rights, GetGroupChat lazy-join, user.Deleting / ReassignCreatedBy
+- `../sm-chatchannels-plugin/README.md` — remaining members keep the channel because chat reassigns created_by
+
+## Decisions Made
+
+- Chat owns `user.Deleting` reassignment so DMs survive even when chatchannels is not mounted. chatchannels `SeverUserFromContext` still only removes that user's members/prefs/participants/personal categories.
+- `canSend` is participation-only. Host `ChatEnabled` stays on `GetGroupChat` and `GetOrCreateDm`.
+- `GetGroupChat` keeps `_ = addParticipant(...)` (IN-01 stays open).
+- Named postgres tests `TestTeammateDMWriteIDOR` / `TestDeletingCascade` creator-delete assertions and `scripts/check-phase19.sh` list updates wait for 19-07.
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+**Total deviations:** 0 auto-fixed
+**Impact on plan:** None.
+
+## Issues Encountered
+
+None.
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Verification Results
+
+- `go -C ../sm-chat-plugin vet ./...` — PASS
+- `go -C ../sm-chat-plugin test -count=1 -short ./...` — PASS (Task 1 and Task 2)
+- `go -C ../sm-chatchannels-plugin test -count=1 -short ./...` — PASS
+- `go -C ../sm-chat-plugin test -count=1 -run '^TestGapClosureSmoke$' -v .` — PASS (`--- PASS: TestGapClosureSmoke (0.72s)`)
+- Baseline `golem15_chat_conversations_created_by_foreign` / `ON DELETE CASCADE` unchanged
+- WR-01..WR-04 and IN-01..IN-02 confirmed unread: GetGroupChat still ignores addParticipant errors; download Content-Disposition unchanged; JoinChannel / PinMessage unchanged; FormAfterDelete remains the only production `FireDeletingEvent` site
+- No remotes pushed (`sm-chat-plugin` and `sm-chatchannels-plugin` are `ahead 1`)
+
+## Next Phase Readiness
+
+Ready for 19-07: `TestTeammateDMWriteIDOR`, `TestDeletingCascade` creator-delete assertions, and `scripts/check-phase19.sh` required-name updates. Production CR-01 and CR-02 are closed.
+
+---
+*Phase: 19-chat-and-chatchannels*
+*Completed: 2026-10-17*
+
+## Self-Check: PASSED
+
+- FOUND: `.planning/phases/19-chat-and-chatchannels/19-06-SUMMARY.md`
+- FOUND: `../sm-chat-plugin/gap_closure_test.go`
+- FOUND: `../sm-chat-plugin` commit `0aee785`
+- FOUND: `../sm-chatchannels-plugin` commit `7d49c3c`