rules-distill — promote environment-specific facts to rules

Scan installed skills, find principles that belong in the always-loaded rules layer, and distill them into rules — appending to, revising, or creating rule files. The skill produces candidates and verdicts; it never edits rules without your approval.

When to Use

• Periodic rules maintenance (monthly, or after installing new skills)
• After a skill-stocktake reveals patterns that should be rules
• When rules feel incomplete relative to the skills in use

Phase 1 — Inventory (Glob, exhaustive)

Enumerate with Glob (no script):

• Skills: ~/.claude/skills/*/SKILL.md
• Rules: read every ~/.claude/rules/**/*.md in full — the corpus is small, so no grep pre-filter is needed

Glob targets only skill definition files, so dependency markdown under .venv / .pytest_cache is excluded structurally.

Present the counts (skills scanned, rule files, headings) before analysis.

Phase 2 — Cross-read & Verdict (inline, holistic)

Read every skill body and every rule into one context and analyze them together — extraction and matching are a single pass. Seeing all skills at once is what makes the recurrence count exact and the "not already in rules" test reliable.

A principle is a candidate only if ALL of these hold:

1. Environment-specific — a fact, a wiring, or a trap particular to this machine, harness, or set of accounts. A general engineering principle is not a candidate no matter how many skills repeat it.
2. Substrate does not already do it — if the current model handles it natively, a written rule does not add behaviour; it freezes an older default and competes with the newer one.
3. Not a procedure — steps and workflows belong in a skill. Residency is for facts and wiring, which have to be true before any particular task starts.
4. Actionable behavior change — expressible as "do X" / "don't do Y", not "X is important"
5. Clear violation risk — what goes wrong if ignored, in one sentence
6. Not already in rules — check the full rules text, including the same idea in different words

Tests 1–3 are rules/README.md's admission criterion ("facts, wiring, and traps specific to this environment. Procedures for thinking and work belong to skills, checks that need a firing time belong to hooks, and general judgment belongs to the substrate"), established by ADR-0018 and ADR-0035.

Recurrence is evidence, not a gate — report the count, do not filter on it. Frequency and residency-worthiness diverge often enough to matter: a general principle repeated in ten skills fails tests 1–3 (substrate has it — ADR-0018 cut residency 60% removing exactly that class), while a one-off environment trap passes them.

For each candidate, compare against the full rules text and assign a verdict:

Verdict	Meaning	Present to user
Append	Add to an existing section of an existing rule file	Target + draft
Revise	Existing rule content is inaccurate/insufficient	Target + reason + before/after
New Section	Add a new section to an existing rule file	Target + draft
New File	Create a new rule file	Filename + full draft
Already Covered	Sufficiently covered (even if worded differently)	Reason (1 line)
Too Specific	Should stay at the skill level	Link to the relevant skill

Exclude: principles already in rules, language/framework-specific knowledge (belongs in language-specific rules or skills), and code examples / commands (belong in skills).

Verdict quality

Each verdict must be self-contained — target, evidence, and rationale on its own. Draft text links back to the detailed How with the pointer form the rules corpus uses: skill: `name` .

# Bad
Append to security.md: Add LLM security principle

Good example (the evidence is why it passes tests 1–3, not an occurrence count. Cite references by section heading — line numbers shift every time the referenced file grows):

# Good
New Section in rules/common/debugging.md:
"If rate limits fire repeatedly during bulk writes to an external platform, treat them as a
policy signal, not a transient error, and stop the burst. Do not push through with backoff; report to a human."

Test 1 (environment-specific): an event that actually happened on this author's account. On 2026-07-16,
  continuing with backoff resulted in an indefinite account block + deletion of all created content. Not general
  HTTP 429 etiquette, but a stop condition specific to this operation
Test 2 (not substrate-native): the substrate's default retries 429 as transient.
  The rule is needed to override that default
Test 3 (not a procedure): not a procedure but a declaration of fact: "repeated rate limits = policy signal"
Violation risk: pushing through loses the whole account (proven, unrecoverable)
Recurrence: 1 skill (evidence, not a gate)

Note that it passes even with a Recurrence of 1.

Phase 3 — User Review & Execution

Present a summary table (# | Principle | Verdict | Target | Confidence) as the overview, then confirm one by one: walk the candidates sequentially — for each, show its evidence, violation risk, and draft text, then ask [y/n/skip]. The user can modify the draft before approving, and can stop at any point. Never batch the approval ("apply all 5? [y/n]" defeats the design — one candidate, one decision); skipped candidates go to the ledger with status: skipped.

Never modify rules automatically. Always require user approval. This is the one hard gate — rules load every session, so a bad rule has outsized blast radius.

Paths below start at ${CLAUDE_SKILL_DIR}, the directory holding this SKILL.md; an agent that does not substitute the variable reads it as that directory.

Then update the ledger ${CLAUDE_SKILL_DIR}/results.json inline (Read → merge → Write):

{
  "distilled_at": "2026-03-18T10:30:42Z",
  "candidates": {
    "llm-output-trust-boundary": {
      "principle": "Treat LLM output as untrusted when stored or re-injected",
      "verdict": "Append",
      "target": "rules/common/security.md",
      "evidence": ["llm-memory-trust-boundary", "llm-social-agent-anti-pattern"],
      "status": "applied"
    }
  }
}

distilled_at is real UTC (date -u +%Y-%m-%dT%H:%M:%SZ); candidate IDs are kebab-case derived from the principle.

Related

• skill-stocktake — audits skill quality; rules-distill promotes recurring principles to rules. Run stocktake first, then distill what survives.
• rules-stocktake — audits the rules this skill produces (residency cost, staleness, absorption) and demotes back what stopped earning its always-loaded slot; the inverse direction over the same boundary.
• learn-eval — extracts per-session patterns into skills/memory; rules-distill later promotes the cross-cutting ones to rules.