Execute Plan

State machine that reads an execution plan document and mechanically executes it -- launching worktree agents, enforcing commit gates, merging, running validation, and tracking progress.

Invocation

/exec-plan [path to execution plan]

Examples:

• /exec-plan docs/brainstorms/EXECUTION_PLAN.md
• /exec-plan docs/brainstorms/WEBSOCKET_PLAN.md

Core Principle: Main Agent Does Nothing

Main is a coordinator. It:

• Reads the plan doc (once, at the start)
• Launches agents
• Receives status messages
• Routes decisions
• Reports to the user

Main does NOT:

• Read source files
• Run tests
• Resolve merge conflicts
• Grep or explore the codebase
• Write or edit code

ALL of that is delegated to specialized agents.

Pipeline

Step 0: Parse the Plan

Read the execution plan document. Extract:

• Team list with dependencies
• Session grouping
• File conflict table
• Per-team specs (files, validation, agent instructions)

If the plan is missing required sections (file conflict table, validation commands, "read these first" lists), STOP and tell the user: "This plan is missing [X]. Run /plan-features to generate a complete plan."

Step 1: Pre-Flight Check

Spawn a pre-flight agent (general-purpose type) to:

• Verify all files referenced in the plan actually exist
• Check no uncommitted changes in the working tree
• Run the full test suite on current main branch
• Update `docs/KNOWN_FAILURES.md` -- if the file exists, read it first, then add any NEW pre-existing failures and remove any that now pass. If the file doesn't exist, create it. This is a living reference file shared across all execution runs -- not regenerated from scratch each time.

Format for docs/KNOWN_FAILURES.md:

# Known Test Failures
> Last updated: [date] by pre-flight check

| Test | File | Reason | Since |
|------|------|--------|-------|
| test_name | path/to/test.py | One-line reason | [date first seen] |

Agent returns: READY + known failures count, or BLOCKED + reason.

If BLOCKED, report to user and stop. Known failures are pre-existing, not blockers -- execution proceeds.

Step 2: Execute Session Groups

For each session group in the plan:

#### Sequential Teams (shared file conflicts)

Process one at a time, in dependency order:

For each team in sequence:
  1. LAUNCH  -- spawn code agent in worktree
  2. VERIFY  -- spawn watchdog to check the worktree
  3. MERGE   -- spawn merge agent to bring changes to main
  4. GATE    -- spawn test agent to validate

1. LAUNCH: Code Agents + Live Watchdog

For each batch of agents (parallel or sequential), spawn:

• All code agents with isolation: "worktree" and their team specs
• One live watchdog agent that monitors the batch concurrently

Code agent prompt template:

You are [Team Name].

[Paste the team's spec from the plan: blocked-by, read-these-first,
files-touched, deliverable, validation, agent instructions]

CRITICAL RULES:
- Read `docs/KNOWN_FAILURES.md` first -- do NOT report these as issues
- Read the "Read these files first" list BEFORE writing any code
- Follow existing patterns in those files
- You MUST `git add` and `git commit` all your changes before finishing
- Your commit message must start with "[Team X]:"
- Run the validation commands from your spec before finishing
- If validation fails, fix the issue and re-commit

When done, report: DONE + commit hash + validation results
OR: BLOCKED + what went wrong

Live watchdog prompt:

You are the batch watchdog. Your job is to monitor code agents for this session.

Active agents: [list of agent names]

Every 3 minutes, check TaskList for tasks that are in_progress but whose
owner has gone idle. If an agent has gone idle without sending a report
to team-lead, send them a nudge:

"You appear idle without reporting. Please send your status to team-lead:
DONE + commit hash + validation results, or BLOCKED + what went wrong."

When all agents in the batch have reported DONE or BLOCKED, send a summary
to team-lead and wait for shutdown.

Do NOT do any code work. Your only job is monitoring and nudging.

Important: The watchdog is spawned WITH the code agents and shut down WITH them. Fresh watchdog per batch -- do not persist across sessions.

2. GATE: Test Agent (per-session, not per-team)

After all teams in a session complete, spawn a test gate agent to run the session's validation:

You are a test gate agent. Run these validation commands on main:

[paste validation commands from the session's team specs]

Read `docs/KNOWN_FAILURES.md` -- do NOT report pre-existing failures as regressions.

Report:
- PASS: all N tests passed, lint clean
- FAIL: [which command failed] + [error output summary] + whether failure is new or pre-existing

Do NOT attempt to fix failures. Just report.

If FAIL with NEW failures: report to user. Options:

• Spawn a fix agent
• Revert specific commits
• Continue anyway (user's call)

Step 3: Session Checkpoint

After all teams in a session complete:

1. Spawn a checkpoint agent to:

• Run the FULL test suite (not just per-team validation)
• Update the plan doc (mark completed teams)
• Report overall status

1. Report to user:

   Session N complete.
   Teams merged: [list]
   Tests: X passed, Y failed
   Next session: [teams] -- proceed? (y/n)

1. Wait for user confirmation before starting next session.

Step 4: Finalize

After all sessions complete:

1. Spawn a finalize agent to:

• Run full test suite one more time
• Run linter and type checker
• Update the plan doc (mark all COMPLETED, add completion date)
• Clean up any remaining worktrees (git worktree prune)
• List any orphaned branches

1. Spawn a doc update agent to update ALL affected project documentation. This is non-negotiable -- stale docs actively mislead future agents and humans. The agent must:

• Read architecture docs and update any sections affected by the execution
• Read task tracking docs and mark completed items, add newly discovered items
• Check if any non-trivial technical decisions were made -- if so, add/update decision records
• Update docs/KNOWN_FAILURES.md -- remove any failures that were fixed during execution
• Commit all doc changes with message: "Update docs after [plan name] execution"

1. Report final summary to user.

Agent Roster

Main agent spawns all of these. Main never does their work. Watchdog lifecycle: Spawned WITH each batch of code agents, shut down WITH them. Fresh watchdog per batch.

Error Recovery

Code agent doesn't commit

Watchdog catches this. Send message back to code agent: "You have uncommitted changes. Run git add -A && git commit -m '[Team X]: [deliverable]' now."

Merge conflict

Merge agent attempts resolution. If it can't:

• Report the conflicting files and both versions
• Ask user: resolve manually, or skip this team?

Test gate fails

Report the failure. Ask user:

• Revert the merge?
• Spawn a fix agent?
• Continue anyway?

Agent goes silent / times out

After 10 minutes with no response from a code agent:

• Spawn a watchdog to check the worktree state
• If changes exist but uncommitted: spawn a new agent to commit + finish
• If no changes: respawn the code agent

Main Context Budget

For a 6-team execution plan:

• Plan doc read: ~200 lines (once)
• Per team: ~10 lines (launch + status messages)
• Session checkpoints: ~20 lines each
• Total: ~300 lines

This leaves the vast majority of main's context window available for the user to request follow-up work in the same session.

Anti-Patterns

1. Main reading files. Never. That's what Explore agents and watchdogs are for.
2. Main running tests. Never. Test gate agents exist for this.
3. Main resolving conflicts. Never. Fix agents handle this.
4. Skipping the live watchdog. Agents go idle without reporting -- they don't choose to stop, their turn ends. A live watchdog catches this while there's still time to nudge them. Always spawn one per batch.
5. Persisting the watchdog across batches. All teammates must be shut down before spawning a new team. Fresh watchdog per batch -- spawn with the code agents, shut down with them.
6. Reporting known failures as regressions. Pre-flight generates docs/KNOWN_FAILURES.md. Every agent and gate must read it. If they keep reporting the same pre-existing failures, the system wastes context on noise.
7. Launching agents from stale base. Sequential teams must wait for the previous team to land on main before their worktree is created. Otherwise they fork from pre-merge code and produce conflicts.