slice-plan-refinement git:20260904.6a7ff9aA

Immutable. This exact content is served forever at /api/v1/blob/b22e79ac34c6628d.

---
name: slice-plan-refinement
description: >-
  Refine an existing slice PLAN in place into smaller commit-sized
  Behavior/Structure leaves. Use after slice-planning when slices are complex or
  sizing confidence is low, and whenever execution overruns the five/ten-minute
  budget. Creates no new plan. Skip when the existing plan is already simple and
  plausibly commit-sized.
---

<objective>
Edit an existing PLAN in place so each remaining slice is plausibly completable
within the execution-leaf target and has no unexplained path beyond its hard
limit, including focused verification. The thresholds are defined in
`problem-decomposition.mdc`. This is a planning hypothesis; execution enforces
the budget.

Apply `.cursor/rules/problem-decomposition.mdc` and
`.cursor/rules/planning.mdc`. Do not create another plan file or change the
selected story outcome.
</objective>

<input_gate>
Require an existing PLAN under `.planning/phases/` or `.planning/quick/`.

- No PLAN yet → use **slice-planning**.
- Story outcome, value, or boundary must change → use **story-decomposition**.
- Existing slices are already clear, cohesive, single-proof-loop, meet the
  target, and have no unexplained hard-limit path → execute directly;
  refinement is optional.
</input_gate>

<refinement_triggers>
Refine when any remaining slice:

- contains multiple independent post-conditions or proof loops;
- requires several separable implementation beats before any green result;
- hides preparation not tied to the immediate next Behavior;
- has low sizing confidence because the execution path or integration boundary
  is unclear;
- is likely to exceed the target or could plausibly exceed the hard limit,
  excluding a focused test whose runtime alone explains the duration;
- has already exceeded the target without converging; or
- has exceeded the hard limit without a stated exception.
</refinement_triggers>

<process>

<step name="inspect_the_existing_plan">
Read the PLAN and only the code/tests needed to judge execution boundaries.
Preserve completed slices and the selected story contract.

Classify each remaining slice:

| Result | Decision |
|--------|----------|
| **Ready** | One Behavior/Structure gate, one proof loop, cohesive change, meets the target |
| **Refine** | Same story, but the leaf violates its gate, has multiple beats, has low confidence, or could exceed the budget |
| **Escalate** | A smaller viable cut would change the selected story or sibling-story order |

Route **Escalate** to story-decomposition. Refine every **Refine** slice in this
skill.
</step>

<step name="split_remaining_slices">
Use the permitted splitting moves in `problem-decomposition.mdc`.

For every replacement leaf:

1. Keep one Behavior, or one Structure immediately before its Behavior.
2. Keep one outside-in proof loop and a CI-safe commit boundary.
3. Include implementation, focused verification, and slice-local cleanup in the
   sizing hypothesis.
4. Preserve value/learning order and genuine prerequisites.
5. Split again when the leaf still has separable beats or a plausible
   hard-limit path.

Do not split tests from the Behavior they prove, end a leaf on red, or create
horizontal layer slices.
</step>

<step name="handle_execution_overrun">
When refinement follows an execution attempt:

1. Record elapsed time, completed evidence, failure/thrash point, and the sizing
   assumption that proved false.
2. Confirm attempt-owned WIP was safely parked or reverted before editing the
   PLAN. Preserve developer changes; if ownership is unclear, stop for human
   judgment.
3. Return the failed slice to `planned` and replace it with smaller leaves.
4. Refine later slices only when the same disproved assumption applies to them.
5. Keep a stated exception when elapsed time came from one focused test or
   external wait that decomposition cannot reduce.
</step>

<step name="update_in_place">
Edit the same PLAN using the slice format in `planning.mdc`.

- Do not create a new file or directory.
- Preserve completed-slice history needed for resume.
- Replace obsolete planned detail rather than appending a second competing
  breakdown.
- Record only learnings that changed the refinement.
- Do not implement, commit, or push unless the invoking workflow separately
  authorizes those actions.
</step>

</process>

<success_criteria>
- The same PLAN was updated in place.
- Every remaining leaf passes the Behavior/Structure gate and has one proof
  loop.
- Each remaining leaf is a plausible target-sized hypothesis with no
  unexplained hard-limit path; execution time is not claimed as guaranteed.
- Completed slices and the selected story outcome are unchanged.
- Final response ends with `## SLICE PLAN REFINED`.
</success_criteria>

<output>
Report the PLAN path, replaced slices, resulting leaves, sizing exceptions, and
whether execution can resume.

```text
## SLICE PLAN REFINED
```
</output>

<out_of_scope>
- Creating a plan or decomposition artifact.
- Changing the selected story outcome or sibling-story order.
- Implementing or verifying product code.
</out_of_scope>