# Task: Generate the Implementation Plan

> Canonical Planner task. Convert one reviewed PRD, its verified feature-owned prototype when current, and repository evidence into executable vertical stages without creating another specification layer.

## Required input

- `.aioson/context/project.context.md`
- `.aioson/context/prd-{slug}.md` (or project-level `prd.md`)
- `product_scope: approved`, `prd_ready: approved`, `sheldon_review: approved`, and a current hash-bound Sheldon PASS
- the approved prototype only when `prototype:check --strict` verifies the active feature owner; with `prototype_status: none`, the current repository behavior is the baseline
- the PRD's repository-backed `## Current System Fit`
- nearest implementation patterns in the codebase

If observable behavior is missing or contradictory, return to Product and require a renewed Sheldon review before planning resumes. Never substitute another or closed feature's prototype. Do not invent `requirements`, `spec`, `architecture`, `design-doc`, `readiness`, `conformance`, or harness documents as substitutes.

## Output

Write exactly one `.aioson/context/implementation-plan-{slug}.md` with:

1. frontmatter containing `status: approved`, feature, classification, and PRD path;
2. a short delivery strategy tied to existing boundaries;
3. `Engineering Controls` containing only repository/PRD-triggered concerns, phase verification, and recovery where state can persist or escape;
4. an `Implementation Delta` classifying every exact path as `reuse`, `modify`, `create`, or `retire` from inspected evidence;
5. vertical phases, each producing visible/usable behavior;
6. a `Capability Delivery Plan` mapping every `CAP-*`/`AC-*` to a phase;
7. exact behavior and support paths expected per phase;
8. stack-native executable checks and production-path smoke evidence;
9. dependencies, migrations, rollback/risk notes only when applicable;
10. explicit optional-specialist triggers, normally none.

The first implementation phase must prove a real end-to-end slice early. Detached fixtures, a second mock application, or screenshots of an unconnected prototype do not count as production-path evidence.

## Depth

- MICRO feature: terse one/few-phase plan; Simple Plan is a separate non-feature lane and may go directly to `@dev`.
- SMALL: concise phases and representative negative paths.
- MEDIUM: same artifact shape, with deeper failure modes, integration checks, migration/rollback detail, and ownership boundaries.

## Done gate

Run the plan/completeness checks, confirm every required capability has a current-system fit, implementation delta, exact phase/path/check, update the dossier/pulse best-effort, then hand off only to `@dev`. Evidence-backed recommended technical choices do not add a human confirmation gate.