implement-next-phase

Invoking this skill

Use when the partner attaches this skill and provides the sketch plan path. That plan includes YAML todos (one per phase, each content matches the corresponding ### Phase N - … heading in ## Sketch) plus a ## Sketch section in the file body.

Non-negotiable: Until the partner explicitly approves proceeding (for example: "go ahead," "implement," "proceed with Phase 2"), you do not edit application code, tests, config, or assets for the work. Preparation (reading, searching, analysis, questions) is allowed; building is not, until that approval.

Chat during preparation: Do not deliver a research report, findings recap, or summary of what you learned. Do not restate or summarize the sketch, the plan, or the codebase in chat. The partner already has the plan. In chat, write only: concise questions when something blocks you or is unclear; brief asks when the plan or todos need fixing; and—when you have no further questions—a single short line requesting approval to implement, naming the active phase by its todo content (for example: ready to implement Phase 1 - … when you approve). No other preparation prose in chat.

Git staging (before each phase cycle)

Every time this skill starts a fresh phase cycle—the first pending phase in the plan, or the next pending phase after earlier ones were implemented—run git add -A, then read and prepare. Do not commit. Do not begin step 1 below until staging is done.

This checkpoints work from the prior phase (or any other unstaged edits) before new preparation or implementation begins.

First actions, in order

1. Read the sketch plan file the partner gave you. Parse YAML frontmatter and read the file body (## Sketch section).

1. Pick the active phase from todos: Take the first todo whose status is pending (or unset / not completed). That todo's content is the active phase label. If todos is missing, empty, or there is no pending item, stop and ask the partner to fix the plan or supply a proper solutionize sketch before continuing.

1. Orient to the sketch: In ## Sketch, open the ### Phase N - … section whose heading text matches the active todo content; read that section's Objective and bullets for implementation scope. If no heading matches, stop and ask the partner to align todos with the sketch. Skim earlier phases in the sketch for ordering and dependencies.

1. Gather context (read-only):

- Read completed-phase material the partner points to, or earlier sections of the same plan if they record what was done. - Open files linked or named in the sketch for this phase; follow callers/callees as needed. - Use search and repo reads until you could implement without guessing. Keep that picture internal; do not write it to chat.

1. Reconcile and question: If research contradicts the sketch, omits something the code requires, or surfaces anything odd (missing symbols, wrong paths, tests that no longer match), ask one tight question (or a minimal set) in chat—no surrounding narrative. If anything in the phase is vague or ambiguous, ask the same way rather than assume.

1. Handoff when ready: If you still have open questions, stay on step 5; do not ask for approval until they are resolved. When you have no further questions, send only the short approval-request line described under Chat during preparation (phase named by todo content). Stop. Do not implement until the partner explicitly approves.

After approval

When the partner approves, implement only that phase per the sketch and prior answers; keep scope tight. If approval was for a specific phase number, do not roll forward into the next phase without a new cycle of this skill or explicit instruction.

No new tests: Do not add net-new tests when implementing a phase. Update existing tests only when behavior changes require it.

No cross-phase scaffolding: Do not change code so this phase can stand alone when the sketch defers work to a later phase. Do not add defaults, placeholders, temporary checks, stubs, no-ops, or similar bridging work to paper over gaps between this phase and a future one—unless the sketch explicitly requires that in this phase.

Immediately after your implementation edits for that phase, edit the sketch plan file: set the active phase's todo status to completed in YAML frontmatter. Do this before any other follow-up work on the plan or codebase.