docs: add Sync-From-Code rule + Activity Log

- AGENTS.md: mandate Activity Log entry + section updates after every code push
- 09 - Audits/Activity Log.md: new append-only log, seeded with this session's
  frontend fixes (Docker build unblock, request template debug improvements,
  429 storm fix) and the cross-repo rule rollout

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -4,11 +4,39 @@ This documentation workspace uses Taskmaster as the source of truth for agent wo
 
 ## Repository Rules
 
-- Repository-wide operating rules live in `../RTK.md`; follow them in addition to this file.
+- Repository-wide operating rules live in `RTK.md` at this vault root; follow them in addition to this file.
 - For product or code changes that affect frontend or backend, keep `frontend` and `backend` package versions/build numbers bumped together and synchronized unless the user explicitly asks otherwise.
 - Preserve Telegram Mini App auth retry behavior: `/api/auth/telegram` must accept repeated valid `initData` for the same launch session; replay rejection belongs only on one-time routes such as webhook/session creation.
 - In the final response, mention version/build bumps and verification commands when they were part of the work.
 
+## Sync-From-Code Rule (MANDATORY)
+
+Whenever an agent finishes a commit-push in `../backend` or `../frontend`, this
+vault MUST be updated **in the same working session**:
+
+1. Add a new entry to `09 - Audits/Activity Log.md` — newest at the top.
+   Use this template:
+
+   ```markdown
+   ### YYYY-MM-DD — <repo>@<short-sha> — <one-line summary>
+
+   **Commits:** `<sha1>` `<sha2>` …
+   **Touched:** path/one.ts, path/two.tsx
+   **Why:** <motivation — bug, feature, PRD link, incident #>
+   **Verification:** <build status, smoke result, manual check>
+   **Linked docs updated:** [[03 - API Reference/Foo]], [[04 - Flows/Bar]]
+   ```
+
+2. If the change affects API surface, data models, flows, architecture, ops,
+   env vars, or design, update the matching numbered section in this vault
+   in addition to the Activity Log entry (do not just log it).
+
+3. Commit with message: `docs: sync from <repo> <short-sha> — <summary>` and
+   push to `origin/main`.
+
+The companion `AGENTS.md` files at `../backend/AGENTS.md` and
+`../frontend/AGENTS.md` carry the same rule from the code-side.
+
 ## Taskmaster Workflow
 
 - Before choosing implementation or documentation work, run `task-master next` from the repository root.
@@ -35,5 +63,5 @@ Do not hand-edit `.taskmaster/tasks/tasks.json` or generated task markdown files
 - Treat pending Taskmaster tasks as the prioritized backlog.
 - Respect task dependencies shown by `task-master next` and `task-master show`.
 - Update the relevant task whenever edits, findings, verification results, or blockers materially change the state of the work.
-- Before the final response, confirm that Taskmaster reflects the current task status.
+- Before the final response, confirm that Taskmaster reflects the current task status AND that the Activity Log has the latest push entry (if a push happened in this session).
 - If `task-master` is unavailable, mention that in the final response and summarize the Taskmaster update that should be applied manually.