aif-implement

# Implement - Execute Task Plan Execute tasks from the plan, track progress, and enable session continuation. ## Workflow ### Step 0 (pre): Detect Handoff Mode Determine Handoff mode. If the caller passed `HANDOFF_MODE` and `HANDOFF_SKIP_REVIEW` as explicit text in the prompt, use those values. Otherwise, use the Bash tool: ``` Bash: printenv HANDOFF_MODE || true Bash: printenv HANDOFF_SKIP_REVIEW || true ``` **Then check `HANDOFF_MODE`:** #### When `HANDOFF_MODE` is `1` (autonomous Handoff agent) The Handoff coordinator already manages status transitions and DB writes directly. Do NOT call MCP tools. Instead: - **No interactive questions:** Do not use `AskUserQuestion` — use sensible defaults (auto-commit at checkpoints, skip pause prompts). - **No pause/resume prompts:** Execute all tasks sequentially without stopping. #### When `HANDOFF_MODE` is NOT `1` (manual Claude Code session) Handoff sync is handled inline — see **Step 0.2** (after reading the plan file) for the task ID extraction and MCP sync trigger. The sync points are: - **On start (Step 0.2):** `handoff_sync_status` → `"implementing"` (with `paused: true`) - **On checklist update (Step 3.6):** `handoff_push_plan` with updated plan content - **On completion (Step 5):** `handoff_push_plan` with final plan, then `handoff_sync_status` → `"review"` (with `paused: true`) or `"done"` (with `paused: false` when `HANDOFF_SKIP_REVIEW=1`) **CRITICAL:** Always pass `paused: true` with every `handoff_sync_status...