| name | adr-writing |
| description | Architecture Decision Record format and rules for the developer agent. Load when the implementation introduces a structural decision worth remembering 6 months later — new pattern, new dependency, deliberate departure from convention, non-obvious schema choice. Skip for naming and file-layout micro-choices. No ADR is the default. |
ADR — Architecture Decision Record
Load only when you have a structural decision to record. Default behaviour for any developer is no ADR.
When to write one
Yes:
- New pattern introduced into the codebase (not just used once — recurring).
- New runtime dependency (npm package, new Supabase extension, external service).
- Deliberate departure from an existing convention.
- Non-obvious schema choice (denormalisation, computed column, soft-delete strategy).
No:
- File naming, folder placement.
- A bug fix or refactor with no structural impact.
- Style decisions already captured by lint/prettier.
File naming — namespaced by session + ticket
Path: <WORKTREE_PATH>/adr/ADR-<SESSION_SHORT_ID>-<TASK-XXX>-<slug>.md
<SESSION_SHORT_ID> is your session id — the prefix of your BRANCH_NAME before the / (e.g. BRANCH_NAME=58e4ec51/TASK-004 → 58e4ec51). It scopes the ADR to this session.<TASK-XXX> is the literal ticket id. Together with the session id it forms the namespace — there is no separate sequence number (e.g. ADR-58e4ec51-TASK-004-supabase-rls-strategy.md).<slug> is kebab-case, ASCII, ≤ 40 chars.- One ADR per ticket is the common case. If the same ticket genuinely needs two ADRs, the distinct slugs keep them apart.
Why the session+ticket namespace: in a wave, N developers run in parallel on worktrees branched from the same base. A monotonically-incremented ADR-NNN-… scheme makes every worker independently pick the same next number (e.g. all land on ADR-003); different slugs hide the collision from git merge, so duplicate numbers land in $CLAUDE_PROJECT_DIR/adr/ silently. <TASK-XXX> removes the intra-wave collision; the <SESSION_SHORT_ID> prefix removes the cross-session one — ticket numbering restarts at TASK-001 each session, so two sessions both producing a TASK-004 would otherwise overwrite each other's ADR in the shared $CLAUDE_PROJECT_DIR/adr/.
Source-code reference
One comment at the most representative line of the change, pointing at the ADR you just wrote:
- TS/JS/CSS:
// See adr/ADR-<SESSION_SHORT_ID>-<TASK-XXX>-<slug>.md
- Python/SQL/shell:
# See adr/ADR-<SESSION_SHORT_ID>-<TASK-XXX>-<slug>.md
No need for more than one reference; reviewers follow the link.
Commit
The ADR + its reference comment go in the same commit as the code they describe (WORKFLOW step 3). Subject:
docs(TASK-XXX): ADR-<SESSION_SHORT_ID>-<TASK-XXX> <title>
Reviewers see the ADR alongside the implementation.
Template (≤ 25 lines)
# ADR-<SESSION_SHORT_ID>-<TASK-XXX> — <decision title>
- **Date**: YYYY-MM-DD
- **Ticket**: TASK-XXX
- **Session**: <SESSION_SHORT_ID>
## Context
2–4 lines on what made this decision necessary.
## Decision
1–3 lines on what was chosen.
## Consequences
- Up to 4 bullets: what this enables, costs, locks in.
## Alternatives considered
- Up to 3, one line each, with reason for rejection. If none were captured, write `- _Not captured at decision time._` — never invent.
Keep it short. An ADR longer than 25 lines is a sign that the decision either belongs in code comments or is actually several decisions that should be split.
Red Flags
- An ADR written for a naming, file-placement, or pure-style choice (no ADR is the default).
- A monotonic
ADR-NNN-… filename instead of the ADR-<SESSION_SHORT_ID>-<TASK-XXX>-<slug> namespace parallel workers collide on the same number.
- An ADR file written outside the worktree, or committed separately from the code it describes.
Alternatives considered invented after the fact instead of - _Not captured at decision time._.- An ADR past 25 lines likely belongs in code comments or is several decisions.
Verification
