Dev

---
name: dev
description: Implement a feature. Supports resuming interrupted work and team mode (--team flag). Reads spec/feature/[name]/spec.md and design.md, generates PLAN.md inside the feature directory, waits for user confirmation, then implements and verifies the feature.
argument-hint: "[feature name] [--team]"
context: fork
---

## Prerequisite check

Before parsing arguments, verify `/init` has been run:

- Check if `spec/PROJECT.md` exists
- If NOT exists → output: "Project not initialized. Run `/init` first to analyze your codebase and set up the spec directory." → **STOP**

## Argument Parsing

Parse `$ARGUMENTS` before anything else:

1. If `$ARGUMENTS` contains `--team`:
   - Remove `--team` from arguments → remaining text = feature name (trimmed)
   - Set **MODE = team**
2. Otherwise:
   - Feature name = `$ARGUMENTS` as-is
   - Set **MODE = solo**

## Resume Protocol

Before starting, read `spec/STATE.md` and find the target feature's phase under `## Features`.

### Feature name resolution:

- If feature name (after parsing) is provided, use it.
- If feature name is empty, look for features with non-idle phases in `spec/STATE.md`.
  - If exactly one non-idle feature exists, use it.
  - If multiple non-idle features exist, list them and ask the user which to continue.
  - If all features are idle, ask the user which feature to work on.

### Auto-generated spec check

After resolving the feature name:

- Read the first 10 lines of `spec/feature/[feature-name]/spec.md`
- If the file contains `> DRAFT`:
  - Output: "Warning: The spec for \"[feature-name]\" was auto-generated by /init and is marked as DRAFT. Run `/spec [feature-name]` to review and finalize before developing. Proceed anyway? (yes/no)"
  - If "no" → **STOP**
- If the file contains `> REFORGED`:
  - Output: "Warning: The spec for \"[feature-name]\" was auto-generated by /reforge. Review with `/spec [feature-name]` if refinement needed. Proceed anyway? (yes/no)"
  - If "no" → **STOP**
- If spec.md doesn't exist → skip (planner handles this)

### Mode detection on resume:

When resuming (phase is not `idle`), MODE is determined by the existing PLAN.md:

- If `spec/feature/[name]/PLAN.md` contains `## Team Composition` → MODE = team
- Otherwise → MODE = solo

The `--team` flag is only needed for fresh starts. Resume auto-detects from PLAN.md.

## Approval gate contract

Planning must not transition to execution without explicit user approval.

Accepted approval replies:

- `approve`
- `approved`
- `yes`
- `proceed`

Rules:

- If response is not an accepted approval reply, keep PLAN.md as `Status: pending`.
- Do not spawn `lead-engineer` while status is pending.
- If user requests changes, route back to planner and keep phase `planning`.

### Model selection

The planner writes a `## Model Assignment` section in the feature's PLAN.md with the recommended model for each agent.
When spawning agents, read PLAN.md and use the assigned model:

- **planner**: always sonnet (no PLAN.md exists yet at this point)
- **lead-engineer**: read `lead-engineer:` from PLAN.md `## Model Assignment`
- **verifier**: always haiku (fixed — see `spec/rules/_model-routing.md`)

If `## Model Assignment` is missing for lead-engineer, default to sonnet.

### Phase-based routing:

- **`existing`** → Feature already has code but no formal spec.
  Output:

  ```
  Feature "[feature-name]" was detected as existing code during /init.
  Before modifying, create a formal spec:
    /spec [feature-name] "brief description"
  After running /spec, the phase updates to idle and you can run /dev normally.
  ```

  **STOP** — do not spawn any agent.

- **`idle` (or no entry)** → Fresh start. Spawn `planner` (sonnet) with HANDOFF:
  - TASK: `Create [team?] implementation plan for feature "[feature-name]"`
  - If MODE = team: add `MODE: team` and include Team Composition in DONE-WHEN
  - DONE-WHEN: PLAN.md approved, CONTEXT.md created, lead-engineer spawned
  - MUST-NOT: Start implementation before user confirms, create plan without reading spec.md and design.md
  - READS: `spec/feature/[feature-name]/spec.md`, `design.md`

- **`planning`** → Planner was interrupted. Check `spec/feature/[name]/PLAN.md`:
  - If `Status: approved`: staleness check (compare spec.md mod time vs PLAN.md Created date). If stale, warn user. If proceeding, update phase to `executing` and spawn lead-engineer (same as `executing` below).
  - If `Status: pending`: spawn `planner` (sonnet) — TASK: present pending plan for approval. MUST-NOT rewrite from scratch. READS: PLAN.md only.
  - If PLAN.md missing: spawn `planner` same as `idle` above.

- **`executing`** → Lead-engineer was interrupted. Read model from PLAN.md, spawn `lead-engineer` ({model}) with HANDOFF:
  - TASK: `Resume implementing feature "[feature-name]" (skip completed tasks)`
  - DONE-WHEN: all tasks `[x]`, tsc passes, verifier L1-3
  - MUST-NOT: re-do `[x]` tasks, modify spec.md/design.md
  - READS: `spec/feature/[feature-name]/PLAN.md`, `CONTEXT.md`

- **`verifying`** → Verifier was interrupted. Spawn `lead-engineer` ({model from PLAN.md}) — not verifier directly, because lead-engineer manages the auto-fix budget across sessions.
  - TASK: `Resume verification for feature "[feature-name]" (re-run verifier)`
  - DONE-WHEN: verifier L1-3 pass, L4 human-verify presented
  - MUST-NOT: re-implement completed tasks, modify spec.md/design.md
  - READS: `spec/feature/[feature-name]/PLAN.md`, `CONTEXT.md`
- **`looping`** → Feature is in a `/loop` cycle. Do NOT start `/dev` flow.
  Report to the user:
  ```
  Feature "[feature-name]" is currently in looping phase (managed by /loop).
  - To continue the loop: run `/loop [feature-name]`
  - To restart from scratch: manually set the phase to idle in spec/STATE.md, then run `/dev [feature-name]`
  ```
  Stop here — do not spawn any agent.

---

Implement the following feature:

$ARGUMENTS