Decide

/decide

You are the author of a single Architectural Decision Record (ADR) under ai-docs/decisions/. The decision registry is the substrate that makes prior reasoning recallable — every meaningful choice that constrains future work, excludes an alternative explicitly, or sets an expiration gets recorded so future engineers and AI agents can trace it.

You do NOT edit production code in this skill. The only artifact you write is the new or amended ADR file. Backref suggestions to canonical-patterns.md / architectural-smells.md are recommended in your summary, not executed by you (an explicit edit task lands those backrefs after human review).

How success is judged

• The new/amended ADR passes Stage 3 verification: .venv/bin/python scripts/decisions.py audit and link-check come back clean, with the real output reported.
• Stage 1 confirmed no existing decision already covers the topic — a duplicate aborts into --amend or supersession, never a second ADR for the same choice.
• related_smell / related_pattern backrefs are set where one applies, and the summary recommends the matching Decided in: NNNN lines — recommended, not self-executed.
• Nothing outside ai-docs/decisions/ was written. Write toward these gates from Stage 0.

Core beliefs

1. The threshold for a decision is real. Any choice that (a) constrains a future skill or refactor, (b) excludes an alternative explicitly, or (c) sets an expiration date is a candidate. Surprises, debugging notes, and project status are NOT decisions — those go in .claude/tasks/lessons.md, commit messages, or task lists.
2. One ADR per choice. If the work spans two coupled choices, write two ADRs. A single ADR documenting two independent forks is hard to supersede, hard to link, and turns into a graveyard entry.
3. Backrefs make the registry navigable. Every ADR should set related_smell and/or related_pattern frontmatter when one applies, AND your summary recommends adding Decided in: NNNN backrefs to the matching canonical-patterns.md / architectural-smells.md entries. Without backrefs the registry is write-only.
4. Supersession over deletion. A superseded decision stays in the registry with status: superseded and superseded_by: NNNN. Never delete an ADR — the chain is the audit trail.
5. Target cadence: 2-5/quarter. More than that across a single project signals over-recording — the ledger turns into a junk drawer. If you find yourself drafting the third ADR in a week, pause and ask whether the latter ones are really decisions or just preferences.
6. Retro-authored ADRs are valid. A long-standing convention that constrains future work deserves an ADR even if it predates the registry. Mark it as such in the body (> Retro-authored ADR.).

Argument parsing

Four forms — pick exactly one.

Form A — New ADR (default)

/decide <slug>

<slug> is a short kebab-case topic identifier (e.g. textchoices-for-state, spec-first-refactor, celery-safe-dispatch). The orchestrator picks the next available 4-digit id (the lowest unused integer, zero-padded), stems the title from the slug, and scaffolds a proposed-status ADR.

Form B — Supersede an existing ADR

/decide --supersede <existing-id> --slug <new-slug>

Writes a new ADR (next id, status proposed) with supersedes: [<existing-id>]. Also stages an edit to the superseded ADR's frontmatter (status: superseded, superseded_by: <new-id>) but does NOT commit it — the new ADR must be human-approved first.

Form C — Amend an existing ADR

/decide --amend <id>

Edit one of: status, superseded_by, applies_to, tags, related_smell, related_pattern. Body edits are out of scope (open the file directly for those — amending an ADR's decision is itself a decision, so it should usually be a supersession instead).

Form D — List

/decide --list

Shorthand for .venv/bin/python scripts/decisions.py list. No new file written.

Present the parsed spec back to the user (intent + target id + related_smell/related_pattern candidates surfaced from canonical-patterns.md / architectural-smells.md) and wait for approval before writing in Forms A and B. Form C / D execute immediately.

The approval-token contract matches /extract-enum and /fix-workflow: first non-whitespace token must be approved, approve, go, lgtm, proceed, or yes.

Pipeline

Stage 0 — Setup

Pre: argument parsed. Post: next-id resolved (Forms A, B); target file path resolved (Form C); ${REPO_ROOT}/ai-docs/decisions/ exists.

# Find next id (Forms A, B)
NEXT_ID=$(.venv/bin/python -c "
import pathlib, re
ids = []
for p in pathlib.Path('ai-docs/decisions').glob('[0-9][0-9][0-9][0-9]-*.md'):
    m = re.match(r'(\d{4})-', p.name)
    if m: ids.append(int(m.group(1)))
print(f'{(max(ids)+1) if ids else 1:04d}')
")
NEW_PATH="ai-docs/decisions/${NEXT_ID}-${SLUG}.md"

If the slug already exists at any id, abort and recommend --amend on the existing ADR.

Stage 1 — Context gathering

Pre: target id known. Post: related-pattern and related-smell candidates identified.

Read these files (small, fast, scoped to the topic):

• ai-docs/decisions/README.md — registry conventions
• .claude/docs/canonical-patterns.md — search for pattern names that match the decision topic (case-insensitive grep on slug words)
• .claude/docs/architectural-smells.md — same search for smell names
• .venv/bin/python scripts/decisions.py list --json — full registry (so you don't accidentally re-decide an already-decided question)

For Form B (supersede), also read the superseded ADR's body so the new ADR can name what changed. Quote the superseded decision's Decision sentence directly, then explain the divergence.

Stage 2 — Draft the ADR

Pre: context gathered. Post: ${NEW_PATH} written (Forms A, B) or --amend'd field updated (Form C).

Scaffold Forms A/B with the registry script, then edit the generated file. The scaffold is the executable source of truth for frontmatter shape:

.venv/bin/python scripts/decisions.py init "${SLUG}"

ADR shape emitted by scripts/decisions.py init — keep these frontmatter fields present, even when a value is empty:

---
id: "<NNNN>"
namespace: core
title: "<Capitalized title sentence — verb-led if possible>"
status: proposed              # proposed | accepted | superseded | deprecated
date: <YYYY-MM-DD today>
deciders: []                  # ask if uncertain before filling
supersedes: []                # populated only in Form B
superseded_by: null
applies_to: []
embodied_by: []               # required once accepted; see ADR 0033
tags: []
related_smell: <smell-anchor or null>      # from architectural-smells.md
related_pattern: <pattern-anchor or null>  # from canonical-patterns.md
---

# <title>

<Optional retro-authored disclaimer>

## Context

<2-4 paragraphs explaining the prior state, the recurring problem, and
the trigger for this decision. Be specific — cite real files, real
incidents, real failure modes. Vague context = un-supersedable later.>

## Decision

<One short paragraph stating the rule, then bullet points if there are
multiple sub-rules. The Decision section is the single load-bearing
sentence; everything else exists to support it.>

## Alternatives considered

- **<Alt 1 name>.** <One-line statement>. Rejected: <reason>.
- **<Alt 2 name>.** <One-line statement>. Rejected: <reason>.
- (At least two alternatives; "no decision" usually counts as one.)

## Consequences

**Easier:**
- <durable improvement>

**Harder:**
- <trade-off the decision accepts>

**Now expected / now disallowed:**
- <new constraint that lints, reviewers, or future agents will enforce>

## Verification

- **Tooling**: <lint rule / test / audit command, with file path>
- **Doc backref**: <which canonical-patterns.md / architectural-smells.md
  entry will carry `Decided in: <NNNN>`>
- **Existing artifacts**: <pointer to specs / commits / PRs that
  already conform>

After scaffolding, fill title/body and any known deciders, applies_to, tags, related_smell, and related_pattern values. For Form B, edit supersedes: [<existing-id>] in the new ADR.

For Form C (amend), edit only the requested frontmatter field via the Edit tool. Do NOT touch the body. If the amend would set status: superseded without a superseded_by, abort and ask for the superseding id.

Stage 3 — Verify

Pre: ADR written. Post: decisions.py audit and link-check exit 0.

.venv/bin/python scripts/decisions.py audit && \
  .venv/bin/python scripts/decisions.py link-check

If either fails, surface the diagnostic and STOP — the ADR is on disk but not registered. Common failures:

• proposed > 30 days — only relevant for older ADRs (won't happen on a freshly-authored one)
• broken supersedes — Form B's superseded-ADR edit didn't land
• applies_to path missing — fix the applies_to glob

Stage 4 — Effectiveness log

Pre: verify passed. Post: one line appended to reports/_meta/effectiveness.jsonl.

.venv/bin/python scripts/log_effectiveness.py \
  --skill decide \
  --scan-id "decision-${NEXT_ID}" \
  --target "${NEW_PATH}" \
  --findings-total 1 \
  --buckets "{\"new_decision\": 1}"

For Form C (amend), bucket is {"amended_decision": 1} and findings- total stays 1.

Stage 5 — Summarize

Report to the user in ≤8 lines:

• Path to the new (or amended) ADR.
• ID and title.
• Related-pattern and related-smell backref candidates surfaced in Stage 1, with the exact line each entry should grow: Decided in: ${NEXT_ID} under the matching pattern/smell.
• Suggested next command:
  • Form A/B: human review → mark status: accepted via /decide --amend ${NEXT_ID} once approved.
  • Form C: nothing — the amend is the work.

Do NOT edit canonical-patterns.md / architectural-smells.md yourself. Surfacing the backref candidate is the work; the human decides whether to land it.

Non-goals

• Editing canonical-patterns.md or architectural-smells.md (recommend the backref, don't write it — that's a separate review).
• Adding a lint rule (that's /prevent-regression's job; the ADR may recommend one in its Verification section).
• Building a new feature / refactor (the ADR motivates the work; the work is /plan-feature or /refactor-subsystem).
• Recording lessons or surprises (those go in .claude/tasks/lessons.md).
• Exceeding 2-5 ADRs/quarter without a corresponding spike in real cross-cutting choices — pause and reassess.

When things go sideways

Repository layout

.claude/skills/decide/
├── SKILL.md                  # this file — orchestrator
└── knowledge/
    └── rules.md              # ADR threshold heuristics, anti-patterns

The orchestrator (you) does NOT read knowledge/rules.md — that file is an offline reference for designers / future maintainers explaining the threshold rules and common ADR anti-patterns the skill is architected to avoid. Future scout sub-agents (if added) would read it.