Process Tune

/skill:process-tune — Cross-Run Process Tuning

Purpose: consume the postmortem index, surface recurring recommendations, and propose concrete artefact edits. This is the write side of the auto-improve loop that /skill:postmortem and the ## Postmortem section of claude/execute-plan/SKILL.md feed.

The skill is proposal-only by default. It writes a tuning report listing edits and the evidence behind them; the operator (or a follow-on /skill:execute-plan run) makes the actual changes.

When to Use

• At least 5 postmortems have landed in docs/postmortems/index.json and you want to act on the patterns.
• You suspect a specific gate, rubric, or closed-decision area is drifting and want the index queried for evidence.
• Periodically (monthly, quarterly) as part of a process-health review.

When NOT to Use

• Fewer than ~3–5 postmortems exist for the recommendations being considered. A single postmortem flagging an issue is not signal — it may be a one-off run pathology. Wait for recurrence.
• You want to analyse a single run — use /skill:postmortem instead.
• You want to apply edits the proposal already names — that's /skill:execute-plan work; feed it a plan that wraps the edits.

Arguments

Workflow

1. Load the index

Read docs/postmortems/index.json (or --index=<path>). If it doesn't exist or is empty, halt:

No postmortems to tune from. /skill:postmortem hasn't run yet, or the index
is at a different path.

Apply the --since, --target, --type filters before grouping.

2. Group recommendations

Group every recommendation row across the filtered runs by the composite key (target, type). Within each group, count distinct runs (deduplicate by run field — repeated postmortems on the same run still count once) and aggregate the evidence.

Discard groups with fewer than --min-runs distinct runs.

3. Score each group

For each surviving group, compute:

• frequency — number of distinct runs flagging this (target, type) pair.
• mean confidence — average of the confidence values (high=3, medium=2, low=1).
• actionability ratio — fraction of recommendations in the group with actionable: true.
• recency — number of runs in the most recent 5 that flagged it.

These are scoring inputs, not user-facing fields. The skill picks the surfacing order from them; the report ranks groups by frequency × mean-confidence × actionability-ratio, with recency as the tiebreaker.

4. Emit a tuning report

Write the markdown report at --report-path. Structure:

# Process Tuning Report

## Summary
- **Index:** docs/postmortems/index.json
- **Window:** <since>..<latest>  (<N> runs)
- **Filters:** target=<...> type=<...>
- **Surfaced groups:** <K>

## Recommendations

### Group 1: <target> / <type>  (<frequency> runs)

**Pattern:** <one sentence summarising the recurring complaint>

**Evidence:**
| Run | Recommendation summary | Confidence |
|---|---|---|
| 2026-04-12-091200 | ... | high |
| 2026-04-19-141500 | ... | high |
| 2026-05-02-082000 | ... | medium |

**Proposed edit:**
<Concrete change, naming the file and the operation. Examples:
- "Lower `adversarial_triggers` threshold from 200 → 150 lines in
  the repo's CLAUDE.md ## Commands."
- "Add a closed decision at
  `closed-decisions/auth/session-cookie-name.md` with the value the
  last three plans re-debated."
- "Tighten domain-review profile `breakpoint` to also run the
  `tests-cover-changed-paths` check.">

**Risk of acting:** <one line — what could go wrong if applied>

**Confidence to act:** high | medium | low

Group order: highest score first.

5. Optional: emit an actionable plan

When --apply is set, also write a _internal/plan-format-shaped file at docs/plans/process-tune-<YYYYMMDD-HHMMSS>.md containing one Task per confidence: high group. Each task names the file to edit, the operation, and an acceptance bullet that's mechanically verifiable (a grep, a numeric value, a closed-decision file exists). The plan does NOT auto-execute — the operator chooses whether to feed it to /skill:execute-plan.

This split (proposal-only vs. plan emission) is deliberate. Process edits land in the same artefacts that govern future runs; an auto-applied edit changes the rules of engagement without an auditable approval. The plan path keeps the human in the loop while removing the busy-work of authoring tasks from a known list of groups.

6. Report

Tuning report: <report-path>
Surfaced groups: <K>  (<H> high-confidence, <M> medium, <L> low)
[--apply]    Plan emitted: <plan-path>  Run /skill:execute-plan to apply.
[--schedule] Routine registered: process-tune-<slug>  Next run: <datetime>

Scheduling guidance: If the project has an active execution pipeline (running /skill:execute-prd or /skill:kickoff regularly), --schedule "0 9 * * 1" establishes a weekly Monday morning tuning pass. The Dreaming feature (Claude Code's background session review) can surface raw signal automatically between runs; process-tune then acts on that accumulated signal in a structured way. At minimum one --min-runs=3 cycle is needed before a scheduled run produces useful output.

Hard rules

• Read-only by default. The skill writes a report and (when --apply is set) a plan file. It does NOT edit _internal/, closed-decisions/, CLAUDE.md, or any other governing artefact directly.
• Frequency is the primary filter. A single postmortem flagging an issue is below threshold, even if its confidence is high. Drift fixes that overfit to one run are themselves drift.
• Recommendations the index can't ground go in a separate Unsurfaced section. If a group has target: other, surface it in a tail section labelled "Recommendations needing taxonomy extension" so the taxonomy itself can be improved. Do not silently drop them.
• The taxonomy is owned by the ## Postmortem section of claude/execute-plan/SKILL.md. If /skill:process-tune keeps proposing taxonomy changes, the change goes into that section's "Recommendation taxonomy" subsection, not into a parallel definition here.

Things you must not do

• Do not synthesise recommendations the index doesn't contain. Every surfaced group must trace back to ≥--min-runs distinct postmortems.
• Do not edit governing artefacts directly, even when --apply is set. --apply produces a plan; the plan goes through /skill:execute-plan like any other change. Process edits get the same scrutiny as feature edits.
• Do not delete or rewrite rows in docs/postmortems/index.json. The index is append-only (see the ## Postmortem section of claude/execute-plan/SKILL.md). Outdated recommendations stay as evidence; the scoring logic naturally weights recency.
• Do not run on an empty or near-empty index. The --min-runs=3 default exists to prevent overfitting; lowering it is a smell.