Add Convention

---
name: add-convention
description: Assess and add a CONVENTION (a reusable rule, practice, or naming/process standard) to a documentation-led repo — decides FIRST whether it is worth codifying at all, then routes it to the right home (AGENTS.md hard rule, CONVENTIONS.md guidance, GLOSSARY term, or to /new-adr if it is really a one-off decision). Pushes back on premature or duplicate conventions. Use when the user says "add a convention", "make this a rule", "document this practice", "we should always X", or invokes /add-convention. NOT for recording a single architectural/product decision (use /new-adr) and NOT for queueing work (use /new-plan).
---

# add-convention

Add a convention — but only after assessing whether it should exist and
where it belongs. This skill is a gatekeeper and a router, not a
stenographer.

## Step 0 — Preconditions and context

1. Confirm the repo is bootstrapped.
2. Read `CONVENTIONS.md` and `AGENTS.md` in full so you can detect
   overlap with existing rules and judge fit.

## Step 0.5 — Assessment (run first)

Run the shared assessment protocol; the triage (Step 1) and routing
(Step 2) questions are asked under it:

- **Reuse supplied answers first.** Treat applicable choices already supplied
  in the request or this session, including depth, as answered. Summarise
  them without asking again; defaults never replace explicit choices. If
  every material choice is supplied, proceed. Ask only about a material
  missing or conflicting choice. A repository preference alone is not a
  current answer or execution grant.
- **Depth selector for unresolved choices.** If depth is not supplied and
  choices remain, ask how deep this assessment should go:
  **express** — every choice takes its recommended default; only
  questions with no derivable default (the free-text essentials) are
  still asked; **guided** — only the questions marked high-impact
  below, plus the free-text essentials; **full** — every question
  below. If the repo's `CONVENTIONS.md` records an `Assessment depth:`,
  pre-select it as the recommended option when asking; a recorded depth
  is never applied silently. Otherwise
  recommend **full** when the request arrived with little or no
  context and **express** when it is already fully specified. At any
  question the operator may answer "defaults from here" or "go
  deeper"; honour the switch immediately.

- Ask questions **one at a time**, each with a **recommended option** and
  a one-line reason; wait for each answer.
- Use **structured selection** (single- or multiple-choice). If the host
  exposes a structured single-/multi-select question tool, use it and
  mark the recommended option; otherwise list options A/B/C in plain text
  and name the recommended one. Use **free text only** where an
  enumerable set is impossible (e.g. the exact wording).
- **The operator decides.** Never proceed past a question without an
  answer, and never guess scope when invoked with no context.

Questions (skip any the request already answers):
1. **Worth codifying?** — yes (recurring, stable, testable) or no
   (one-off, duplicate, churn-prone, vague). *Recommended: per the Step 1
   triage; this question gates the rest.* *(High-impact — asked in
   guided.)*
2. **Home** — `AGENTS.md` hard rule / `CONVENTIONS.md` guidance /
   `GLOSSARY.md` term / actually a decision (hand off to the **new-adr**
   skill). *Recommended: per the rule's nature (see Step 2).*
   *(High-impact — asked in guided: the wrong home is churn to move.)*
3. **Enforce in the verify gate?** — yes / no. *Recommended: no, unless
   the rule is mechanically checkable.*
4. **Wording** — free text (the rule statement itself; asked at every
   depth).

## Step 1 — Assess: is this worth codifying?

Apply triage. Recommend **against** adding when:
- It is already covered (explicitly or implicitly) by an existing
  convention — point to it instead of duplicating.
- It is a one-off, not a recurring decision — codifying it adds noise.
- It is likely to churn — premature rules become stale cruft.
- It is too vague to be testable or actionable as written.

Recommend **for** adding when it is a recurring decision whose ambiguity
causes rework, it is stable, and it can be stated so an agent can follow
it without further interpretation. State your recommendation and the
reason before doing anything.

## Step 2 — Route: where does it belong?

Decide the home, and explain the choice:
- **Hard rule agents must obey** → a bullet in `AGENTS.md` §Hard rules,
  with the substance in `CONVENTIONS.md`. Use for non-negotiable
  constraints.
- **Authoring / process guidance** → a section in `CONVENTIONS.md`.
  Use for "how we do things" that informs but doesn't gate.
- **Shared term / definition** → `GLOSSARY.md` (create it if absent —
  adding the first term enables the glossary layer; place it at the
  recorded artefact root). Read the repo's `CONVENTIONS.md` §Glossary and
  inspect the rule it actually declares; the canonical structure is an
  optional H1 heading and optional introductory prose, then exactly one
  two-column Markdown table whose header is `Term | Definition`. Every
  term is its own row. Never record a term as a heading, a bullet or a
  paragraph, and never add a second table or a different column shape. A
  §Glossary that states an older or unrelated glossary convention is not
  adoption of this table: use the canonical shape and offer the audit
  skill's separately consented rule-and-file migration rather than copying
  the old shape. An absent `GLOSSARY.md` remains a valid state; this skill
  creates one only because a term is actually being added.
- **It is actually a decision, not a convention** (an architectural,
  product, or technology choice with alternatives and consequences) →
  this is an ADR. Stop and offer the **new-adr** skill; do not bury a
  decision in
  CONVENTIONS.

If a convention is a triage/process rule (e.g. how incoming work is
triaged), prefer `CONVENTIONS.md` with a hard-rule bullet in AGENTS.md
only for the parts that are non-negotiable.

## Step 3 — Draft and confirm

Draft the exact wording for its home file. Keep it tight, testable, and
in the repo's language. Show the diff. Confirm before writing.

## Step 4 — Write and commit

Apply the edit(s). If a convention rises to a hard rule, ensure
`AGENTS.md` and `CONVENTIONS.md` stay consistent. Conventional Commit
(`docs: ...`); no ADR touched means no `Rationale:` footer is required,
but add one if the repo's contract asks for it on convention changes.

**Adding or extending a glossary.** Use the canonical structure defined
below and the declared-rule checks; the shape must not drift between runs.

- **Where the rule comes from.** If `CONVENTIONS.md` has no §Glossary
  section (a legacy repo that predates it, or a layer enabled before the
  rule was recorded), fall back to the product default canonical shape
  above: optional `# Glossary` heading and intro prose, then one
  `Term | Definition` table. Do not invent a different shape for that
  repo, and do not silently edit unrelated conventions.
- **Reading the declared rule.** When a §Glossary exists, read what it
  actually declares. If it describes the canonical two-column
  `Term | Definition` table, follow it and change it only on an explicit
  request. If it states a different or older glossary convention (bullets,
  prose, another column shape), the repo has **not** adopted this table:
  do not copy the old shape, and do not silently rewrite the rule. Use the
  canonical shape for the term and offer the audit skill's migration, which
  covers the rule and the file together as one separately consented diff.
- **Recording the convention.** When a §Glossary is absent, offer — as its
  own confirmed edit, separate from the term being added — to record a
  `## Glossary` section in `CONVENTIONS.md` stating the shape actually
  used. Show that diff and write it only if the user accepts; never rewrite
  or reorder other `CONVENTIONS.md` sections to make room, and if the user
  declines, keep the glossary canonical but leave `CONVENTIONS.md`
  unchanged.
- **Creating the file.** Write the optional `# Glossary` heading and any
  short introductory prose the repo needs, then the single two-column
  table with header `Term | Definition` and the new term as its first
  row. Do not invent placeholder terms.
- **Extending an existing file.** Preserve the heading, introductory
  prose, entry order and every existing row byte for byte. Append the new
  term as one new row; never rebuild, re-sort or reformat the file, and
  never introduce a second table.
- **Anchors.** If the new term's row is reachable from a heading anchor an
  incoming link already uses, keep that anchor on the row rather than
  dropping the target; if the anchor cannot be preserved, stop and flag it
  instead of guessing.
- **Preserve meaning.** Keep the term's spelling, aliases, links and
  inline code exactly as supplied. Escape a literal pipe as `\|`. If a
  definition is genuinely multiline, keep it in one cell with `<br>` for
  the hard break rather than spilling into extra rows.
- **Duplicates and ambiguity.** If the term already exists, show the
  existing and proposed definitions and ask whether to update or leave the
  existing row. Never silently merge, replace or add a second row for the
  same term, and never guess a definition.
- **Non-canonical file.** If the existing `GLOSSARY.md` is bullets, prose,
  headings or a mixed shape, do not append a competing row and do not
  rewrite the file as a side effect of adding a term. Surface the
  non-canonical structure and offer the audit skill's consented migration;
  apply it only if the user accepts the concrete diff. A declined
  migration leaves the file as the user keeps it.

Name the rule and propagation performed; list repositories not updated.

<!-- docflow:closing-report -->
## Closing report

End every run, including blocked, failed and stopped runs, with a section
headed exactly **Status at a glance**, containing these three labels:

- **This run:** only actions actually attempted and their outcomes; quote each verify gate's exact output and exit code, including timeouts or interruptions.
- **Overall:** implemented, partially verified, verified, blocked, failed or unknown. A passing sub-step is not an overall pass; incomplete or missing evidence never becomes success.
- **Yet to do:** every remaining action, unresolved finding, verification, cleanup or required input. Write None only when the whole task is verifiably complete; never omit work because a budget ended.

Routine progress messages need no block. Keep final results brief and
distinguish work prepared on a PR from work confirmed shipped.
<!-- /docflow:closing-report -->