chore: gardener housekeeping 2026-03-21

Progressive disclosure split of AGENTS.md (487→152 lines):
- Extracted per-directory AGENTS.md files for all 8 agents + lib/
- Root AGENTS.md now serves as a table of contents with summary table
- All watermarks updated to 16e430e

Grooming results:
- Promoted #469 (WATCH flow missing curl) and #436 (idle_pane_count bug) to backlog
- 12 dust items classified, no groups ripe for bundling yet
- No blocked issues, no AD violations

dev/AGENTS.md

@@ -0,0 +1,27 @@
+<!-- last-reviewed: 16e430ebce905cf722f91ae1f873faea1c64d890 -->
+# Dev Agent
+
+**Role**: Implement issues autonomously — write code, push branches, address
+CI failures and review feedback.
+
+**Trigger**: `dev-poll.sh` runs every 10 min via cron. It scans for ready
+backlog issues (all deps closed) or orphaned in-progress issues and spawns
+`dev-agent.sh <issue-number>`.
+
+**Key files**:
+- `dev/dev-poll.sh` — Cron scheduler: finds next ready issue, handles merge/rebase of approved PRs, tracks CI fix attempts
+- `dev/dev-agent.sh` — Orchestrator: claims issue, creates worktree + tmux session with interactive `claude`, monitors phase file, injects CI results and review feedback, merges on approval
+- `dev/phase-test.sh` — Integration test for the phase protocol
+
+**Environment variables consumed** (via `lib/env.sh` + project TOML):
+- `CODEBERG_TOKEN` — Dev-agent token (push, PR creation, merge) — use the dedicated bot account
+- `CODEBERG_REPO`, `CODEBERG_API` — Target repository
+- `PROJECT_NAME`, `PROJECT_REPO_ROOT` — Local checkout path
+- `PRIMARY_BRANCH` — Branch to merge into (e.g. `main`, `master`)
+- `WOODPECKER_REPO_ID` — CI pipeline lookups
+- `CLAUDE_TIMEOUT` — Max seconds for a Claude session (default 7200)
+- `MATRIX_TOKEN`, `MATRIX_ROOM_ID`, `MATRIX_HOMESERVER` — Notifications (optional)
+
+**Lifecycle**: dev-poll.sh → dev-agent.sh → create Matrix thread + export
+`MATRIX_THREAD_ID` (streams Claude output to thread via Stop hook) → tmux
+`dev-{project}-{issue}` → phase file drives CI/review loop → merge → close issue.