Ln 400 Story Executor

> **Paths:** File paths (`references/`, `../ln-*`) are relative to this skill directory.

**Type:** L2 Coordinator
**Category:** 4XX Execution

# Story Execution Orchestrator

Runtime-backed coordinator for Story execution. Owns task ordering, worktree lifecycle, task/group checkpoints, and the final Story transition to `To Review`.

## Inputs

| Input | Required | Source | Description |
|-------|----------|--------|-------------|
| `storyId` | Yes | args, git branch, kanban, user | Story to process |
| `--rework-focus` | No | ln-1000 | Comma-separated blocking categories from prior quality gate FAIL |

**Resolution:** Story Resolution Chain.  
**Status filter:** Todo, In Progress, To Rework, To Review

## Purpose & Scope

- Load Story and task metadata once per loop
- Execute in order: `To Review -> To Rework -> Todo`
- Launch `Todo` parallel groups only when explicitly marked
- Force immediate review after every executor/rework step
- Persist resumable runtime state in `.hex-skills/story-execution/runtime/`
- Move Story only to `To Review`; never to `Done`

## Runtime Contract

**MANDATORY READ:** Load `references/environment_state_contract.md`, `references/storage_mode_detection.md`, `references/input_resolution_pattern.md`
**MANDATORY READ:** Load `references/coordinator_runtime_contract.md`, `references/story_execution_runtime_contract.md`, `references/coordinator_summary_contract.md`, `references/loop_health_contract.md`
**MANDATORY READ:** Load `references/git_worktree_fallback.md` — use the Story execution row

Runtime CLI:

```bash
node references/scripts/story-execution-runtime/cli.mjs start --story {storyId} --manifest-file .hex-skills/story-execution/manifest.json
node references/scripts/story-execution-runtime/cli.mjs status
node references/scripts/story-execution-runtime/cli.mjs checkpoint --phase PHASE_3_SELECT_WORK --payload '{...}'
node references/scripts/story-execution-runtime/cli.mjs record-worker --task-id {taskId} --payload '{...}'
node references/scripts/story-execution-runtime/cli.mjs record-group --group-id {groupId} --payload '{...}'
node references/scripts/story-execution-runtime/cli.mjs record-stage-summary --story {storyId} --payload '{...}'
node references/scripts/story-execution-runtime/cli.mjs record-loop-health --scope task --scope-id {taskId} --payload '{...}'
node references/scripts/story-execution-runtime/cli.mjs advance --to PHASE_4_TASK_EXECUTION
```

## Workflow

### Phase 0: Config

1. Resolve `storyId`.
2. Detect `task_provider` from task-management config.
3. Build execution manifest:
   - `story_id`
   - `task_provider`
   - `project_root`
   - planned `worktree_dir`
   - branch name
   - `parallel_group_policy`
   - `status_transition_policy`
4. Start runtime and checkpoint `PHASE_0_CONFIG`.

### Phase 1: Discovery

1. Resolve Story title and current Story status.
2. Load child task metadata only:
   - Use the configured tracker provider's `listTasksByStory(storyId)` operation (transport per `references/provider_file.md, references/provider_github.md, references/provider_linear.md`).
3. Build `processable_counts` for:
   - `to_review`
   - `to_rework`
   - `todo`
4. Checkpoint `PHASE_1_DISCOVERY`.

### Phase 2: Worktree Setup

1. Detect current branch.
2. If already inside `feature/*`, treat current directory as active worktree.
3. Otherwise create `.hex-skills/worktrees/story-{identifier}` and branch `feature/{identifier}-{slug}` per worktree fallback guide.
4. Checkpoint `PHASE_2_WORKTREE_SETUP` with:
   - `worktree_ready`
   - `worktree_dir`
   - `branch`
5. Advance only after `worktree_ready=true`.

### Phase 3: Select Work

Selection order is deterministic:

1. Any `To Review` task first, sequentially
2. Then any `To Rework` task, sequentially
3. Then `Todo` tasks:
   - tasks with `**Parallel Group:** {N}` may run as one group
   - tasks without a group are single-task sequential units

Checkpoint `PHASE_3_SELECT_WORK` with:
- `current_task_id` or `current_group_id`
- fresh `processable_counts`

If all processable counts are zero, skip execution and advance to `PHASE_7_STORY_TO_REVIEW`.

When `rework_focus` is provided:
- Tasks whose title or AC keywords match any `blocking_categories` entry are selected first within the same priority tier.
- This does not override the To Review > To Rework > Todo ordering — it reorders within each tier.

### Phase 4: Task Execution

Used for:
- `To Review` -> `ln-402`
- `To Rework` -> `ln-403`, then immediate `ln-402`
- single `Todo` test task -> `ln-404`, then immediate `ln-402`
- single `Todo` impl/refactor task -> `ln-401`, then immediate `ln-402`

Flow:

1. Compute executor `childRunId = {parent_run_id}--{worker}--{taskId}`.
2. Compute executor artifact path `.hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--{worker}.json`.
3. Materialize executor manifest at `.hex-skills/story-execution/{worker}--{taskId}_manifest.json`.
4. Start `task-worker-runtime` and checkpoint executor `child_run` metadata before invocation.
5. Execute the worker through Agent or Skill with `--run-id` and `--summary-artifact-path`.
6. Read the executor summary artifact from `.hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--{worker}.json`.
7. Record task loop health before retrying the same task/worker/error:
   - Action: compare current worker output with previous task loop health.
   - Key point: retry only when new artifact, new `ln-402` summary, task status delta, `files_changed` delta, or scenario improvement exists.
   - Why: repeated identical worker failures create retry storms without adding evidence.
   - Evidence: `record-loop-health --scope task --scope-id {taskId}` result.
   - Exception: if `pause.pause=true`, stop and surface `paused_reason`.
   - Automation/guard: story-execution runtime pauses after same-error/no-progress threshold.
8. When review is required, repeat the same runtime-backed sequence for `ln-402`.
9. Read the latest `ln-402` review summary artifact for the same task from `.hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--ln-402.json`.
10. Record worker artifacts with `record-worker`.
11. Checkpoint `PHASE_4_TASK_EXECUTION`.
12. Advance to `PHASE_6_VERIFY_STATUSES`.

### Phase 5: Group Execution

Used only for `Todo` groups with more than one task.

1. For each task, compute worker-specific child `runId`, artifact path, and manifest path.
2. Start one `task-worker-runtime` per executor and checkpoint all child metadata before spawning Agents.
3. Spawn all group executors in parallel via Agent tool.
4. Wait for all executors to finish.
5. Read each executor summary artifact.
6. Start one `ln-402` runtime per task, review each task sequentially, and read the latest review artifact for every task.
7. Record each worker artifact with `record-worker`, then record the group summary with `record-group`.
8. Checkpoint `PHASE_5_GROUP_EXECUTION`.
9. Advance to `PHASE_6_VERIFY_STATUSES`.

### Phase 6: Verify Statuses

1. Re-read task metadata from source of truth.
2. Refresh `processable_counts`.
3. Validate that every task touched in this run has a latest `ln-402` machine-readable summary.
4. If any worker leaves an unexpected transition, pause runtime.
5. If any task hits `To Rework` for the third consecutive time, pause runtime with escalation reason.
6. Checkpoint `PHASE_6_VERIFY_STATUSES`.
7. If processable work remains -> advance back to `PHASE_3_SELECT_WORK`.
8. If no processable work remains -> advance to `PHASE_6B_SCENARIO_VALIDATION`.

### Scenario Validation

Runs once when all tasks are Done. Delegates to an external agent to trace the user scenario end-to-end against implemented code. The executor has completion bias after shepherding tasks through implementation — an external agent has no investment in the story being done.

1. Load the Story ACs and the traceability table (from `.hex-skills/task-planning/{identifier}_traceability.md`). If the traceability artifact is missing, reconstruct an equivalent trace from the Story ACs and task Implementation Plans — do not fail scenario validation solely because the planner artifact is absent.
2. Run agent health check. If an advisor agent is available:
   a. Build validation prompt from `references/agents/prompt_templates/scenario_validator.md`
   b. Fill with: Story ACs, traceability table, architecture context, project root path (agent reads code directly)
   c. Save prompt to `.hex-skills/story-execution/{identifier}_scenario_prompt.md`
   d. Launch agent:

   ```bash
   node references/agents/agent_runner.mjs \
     --agent {agent} \
     --prompt-file .hex-skills/story-execution/{identifier}_scenario_prompt.md \
     --output-file .hex-skills/story-execution/{identifier}_scenario_result.md \
     --cwd {project_dir}
   ```

   e. Parse result JSON for broken segments
3. If no agent available: run self-check as fallback (trace 5 segments via code inspection).
4. If any segment is broken or missing:
   - Identify the responsible task from traceability table layer mapping
   - Record scenario loop health keyed by broken segment before setting another rework
   - If the same broken segment returns without code/artifact delta, pause instead of reworking blindly
   - Set that task back to `To Rework` with scenario findings as rework context
   - Advance back to `PHASE_3_SELECT_WORK`
5. Max 2 scenario validation loops. If still failing after 2 rework cycles, `PAUSE` for user review.
6. If all segments pass -> advance to `PHASE_7_STORY_TO_REVIEW`.

Checkpoint `PHASE_6B_SCENARIO_VALIDATION` with:
- `scenario_pass`: true/false
- `segments_traced`: count
- `segments_passed`: count
- `rework_tasks`: list of task IDs sent back (empty if pass)
- `validation_mode`: `agent_validated` or `self_check_only`

### Phase 7: Story To Review

1. Verify no tasks remain in `Todo`, `To Review`, or `To Rework`.
2. Update Story status to `To Review`.
3. Update kanban to `To Review`.
4. Checkpoint `PHASE_7_STORY_TO_REVIEW` with:
   - `story_transition_done=true`
   - `story_final_status="To Review"`
   - `final_result="READY_FOR_GATE"`
5. Write Stage 2 coordinator artifact with:
   - `summary_kind=pipeline-stage`
   - `stage=2`
   - `story_id`
   - `status=completed`
   - `final_result="READY_FOR_GATE"`
   - `story_status="To Review"`
   - `warnings`

### Phase 8: Self-Check

Build final checklist from runtime state, not memory:

- [ ] Config checkpoint exists
- [ ] Discovery checkpoint exists
- [ ] Worktree checkpoint exists and `worktree_ready=true`
- [ ] Every executed task has a latest `ln-402` summary artifact
- [ ] Every processed group has a recorded runtime result
- [ ] Rework loop guard did not trip
- [ ] Story moved to `To Review`
- [ ] Stage 2 coordinator artifact recorded

Checkpoint `PHASE_8_SELF_CHECK` with `pass=true|false`.
Complete runtime only after `pass=true`.

## Worker Invocation (MANDATORY)

**Host Skill Invocation:** `Skill(skill: "...", args: "...")` is mandatory delegation.
- Claude: call the Skill tool exactly as shown.
- Codex: if no Skill tool exists, locate the named skill in available skills, read its `SKILL.md`, treat `args` as `$ARGUMENTS`, execute that skill workflow, then return here with its result/artifact.
- Do not inline worker logic or mark the worker complete without executing the target skill.

| Status | Worker | Invocation |
|--------|--------|------------|
| `To Review` | `ln-402-task-reviewer` | Inline via `Skill()` |
| `To Rework` | `ln-403-task-rework` | Agent, then immediate `ln-402` |
| `Todo` tests | `ln-404-test-executor` | Agent, then immediate `ln-402` |
| `Todo` impl/refactor | `ln-401-task-executor` | Agent, then immediate `ln-402` |

Executors and reworkers run isolated:

```javascript
node references/scripts/task-worker-runtime/cli.mjs start --skill {worker} --task-id {taskId} --manifest-file .hex-skills/story-execution/{worker}--{taskId}_manifest.json --run-id {childRunId} --summary-artifact-path .hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--{worker}.json
node references/scripts/story-execution-runtime/cli.mjs checkpoint --phase PHASE_4_TASK_EXECUTION --payload '{"child_run":{"worker":"{worker}","task_id":"{taskId}","run_id":"{childRunId}","summary_artifact_path":".hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--{worker}.json"}}'
Agent(
  description: "Execute task {taskId}",
  prompt: "Execute task worker.\n\nStep 1: Invoke worker:\n  Skill(skill: \"{worker}\", args: \"{taskId} --run-id {childRunId} --summary-artifact-path .hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--{worker}.json\")\n\nCONTEXT:\nTask ID: {taskId}",
  subagent_type: "general-purpose"
)
```

Reviewer runs inline:

```javascript
node references/scripts/task-worker-runtime/cli.mjs start --skill ln-402 --task-id {taskId} --manifest-file .hex-skills/story-execution/ln-402--{taskId}_manifest.json --run-id {reviewRunId} --summary-artifact-path .hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--ln-402.json
node references/scripts/story-execution-runtime/cli.mjs checkpoint --phase PHASE_4_TASK_EXECUTION --payload '{"child_run":{"worker":"ln-402","task_id":"{taskId}","run_id":"{reviewRunId}","summary_artifact_path":".hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--ln-402.json"}}'
Skill(skill: "ln-402-task-reviewer", args: "{taskId} --run-id {reviewRunId} --summary-artifact-path .hex-skills/runtime-artifacts/runs/{parent_run_id}/task-status/{taskId}--ln-402.json")
```

## TodoWrite format (mandatory)

```
- Start ln-400 runtime (pending)
- Load Story/task metadata (pending)
- Setup or detect worktree (pending)
- Select next task/group (pending)
- Start child runtime(s) and checkpoint child metadata (pending)
- Execute task/group with managed transport inputs (pending)
- Review task results immediately (pending)
- Re-read statuses and record checkpoint (pending)
- Validate user scenario end-to-end (pending)
- Move Story to To Review (pending)
- Run runtime self-check and complete (pending)
```

## Critical Rules

- Runtime state is the orchestration SSOT; kanban is the task-status SSOT.
- Never batch reviews.
- Never move Story to `Done`.
- Every worker outcome must be read from summary JSON, not from prose-only chat.
- `record-worker` is the primary runtime ingestion path for worker outcomes.
- `record-loop-health` is the primary retry-usefulness ingestion path before repeating task/group/scenario work.
- Every managed worker run must be started through `task-worker-runtime` before invocation.
- `ln-1000` consumes the Stage 2 coordinator artifact, not free-text stage output.
- Reviews remain sequential even when execution groups are parallel.
- `ln-402` remains the only worker that can accept a task as `Done`.

## Definition of Done

- [ ] Runtime started and `PHASE_0_CONFIG` checkpointed
- [ ] Discovery and worktree setup checkpointed
- [ ] Every executed task/group recorded in runtime
- [ ] Rework-loop escalation handled deterministically (`PAUSED`) when needed
- [ ] Final status verification checkpointed
- [ ] Scenario validation passed or PAUSED for user review
- [ ] Story moved to `To Review`, not `Done`
- [ ] Self-check passed and runtime completed

## Phase 9: Meta-Analysis

Optional reference: load `references/meta_analysis_protocol.md` only when the user asks for post-run meta-analysis or protocol-formatted run reflection.

Skill type: `execution-orchestrator`. When requested, run after phases complete. Output to chat using the `execution-orchestrator` format.

## Reference Files

- `references/coordinator_runtime_contract.md`
- `references/story_execution_runtime_contract.md`
- `references/coordinator_summary_contract.md`
- `references/git_worktree_fallback.md`
- `../ln-401-task-executor/SKILL.md`
- `../ln-402-task-reviewer/SKILL.md`
- `../ln-403-task-rework/SKILL.md`
- `../ln-404-test-executor/SKILL.md`

---
**Version:** 4.0.0
**Last Updated:** 2026-01-29