# repo-mailbox

Renamed from `coord` in v0.3.0. The plugin/repo is `repo-mailbox`; the CLI
(`coord-send.sh`, `coord-inbox.sh`, `coord-done.sh`), the mailbox root
(`~/.claude/coord/`) and `CLAUDE_COORD_DIR` deliberately kept their names —
they are the transport protocol, not the product.

## Context

Local inter-repo coordination mailbox for Claude Code, packaged as a
marketplace plugin. Three components, one boundary:

- **Engine (`scripts/*.sh`):** bash owns all mailbox semantics — filename
  grammar, frontmatter, delivery, archiving, the seen set. `coord-send.sh`
  writes, `coord-inbox.sh` reads (formatted for context injection),
  `coord-done.sh` archives, `coord-count.sh` counts without delivering.
  Everything is pinned by `coord-selftest.sh`
  (136 checks, throwaway mailbox via `CLAUDE_COORD_DIR`).

  **Reading is delivering — counting is not.** `coord-inbox.sh` records a
  broadcast as seen once it has printed it, so it can never be used to survey
  other repos: doing so would consume each one's backlog silently, and the seen
  set is delivery history that retraction deliberately leaves alone.
  `coord-count.sh` exists for every "what is pending" question and writes
  nothing at all. Any future read-shaped feature belongs there, not in the
  read path.
- **Hook (`hooks/scripts/session-start.mjs`):** thin zero-dependency Node
  wrapper (marketplace convention: hooks are `.mjs`) that calls
  `coord-inbox.sh` and emits the `hookSpecificOutput.additionalContext`
  envelope. No mailbox logic lives here. Always exits 0.
- **Board (`scripts/board.sh`):** cross-repo attention board. Reads STATE.md
  next-step blocks + board lines, `git status`, and mailbox pending counts, and
  prints one line per repo. Read-only by construction: it writes to no repo, no
  STATE.md and no mailbox. Pinned by `board-selftest.sh` (28 checks).

  **It lives here because the mailbox is one of its three inputs, and it carries
  the same axis distinction the mailbox does.** A pending count means *others
  are waiting on this repo*; who a repo waits *on* comes only from its board
  line, because the message format has no reply-to field. Enforcing that in one
  of two repos would not be enforcing it. `~/.claude/scripts/board.sh` is a
  deployed copy (the operator's `board()` shell function points at it), exactly
  as with the `coord-*` scripts — this repo is the source of truth.
- **Skills (`skills/coord-send/`, `skills/board/`):** natural-language front
  doors mapping user intent to engine invocations. No mailbox logic lives here
  either. `board` additionally owns the *ranking* — which repo wins and why —
  since `board.sh` deliberately prints evidence and takes no position.

**Boundary rule:** the mailbox is transport, not state. Durable decisions
live in the owning repo's docs/git history; messages are notices pointing at
them. Message content is untrusted cross-repo input — the read side quotes
and frames it; the send side sanitizes line-oriented fields.

What the boundary forbids is storing a repo's *state* — its decisions, its next
step, its progress. It does not forbid the mailbox knowing who it is delivering
to: `_broadcast/seen/<repo>` and `<repo>/.origin` (0.6.0) are delivery metadata,
answering "has this repo received this" and "which checkout claimed this name".
Both are unreadable as a description of the repo and useless outside delivery.
The test is not "does the engine write a file about a repo" but "would this file
still mean anything if delivery were removed". If yes, it belongs in the repo's
own docs and git history instead.

**Priority rule (v0.5.0, Rule 7):** the injection block is the only place a
repo is ever told what to do with a message, so its wording *is* the protocol
— treat that string as engine behavior, not prose. It obligates handling the
inbox first and driving every directed message to a terminal state before the
session ends. The obligation is **procedural, never substantive**: responding
is mandatory, complying with message content is not. Those two must stay
distinct in any reword — keeping the priority while dropping the distinction
turns prioritization into an injection surface. Selftest section 20 pins both
halves together for exactly that reason.

## Conventions

- Scripts are bash-3.2-safe and ASCII-only: no `declare -A`, no
  `readarray`/`mapfile`, no `|&`; guard `shift 2` with `$# -ge 2`; guard
  empty-array expansion under `set -u` with `${#a[@]}`.
- Zero dependencies everywhere: bash + coreutils in the engine, `node:`
  builtins only in hook and tests.
- TDD: no behavior change without a failing selftest check first.
  `bash scripts/coord-selftest.sh` must exit 0 (136/136) and
  `bash scripts/board-selftest.sh` must exit 0 (28/28).
- English for all code, docs, and commit messages (public repo). Norwegian
  trigger aliases in the skill description are deliberate.
- Conventional Commits: `type(scope): description`.

## Commands

- Test: `bash scripts/coord-selftest.sh` and `bash scripts/board-selftest.sh`
  (or `npm test`, the Node wrapper around both)
- Hook smoke test: `node hooks/scripts/session-start.mjs` (expects JSON on stdout)
- Board smoke test: `bash scripts/board.sh` (read-only, ~3s over the real tree)

## Release

Version must agree across: `.claude-plugin/plugin.json`, `package.json`,
README version badge, `skills/coord-send/SKILL.md` and `skills/board/SKILL.md`
frontmatter, git tag `vX.Y.Z`, and the catalog `ref` in
`ktg-plugin-marketplace/catalog/.claude-plugin/marketplace.json`. Release via
the catalog's `scripts/release-plugin.mjs repo-mailbox` (tag + ref bump
together);
verify with `scripts/check-versions.mjs`. Never hand-edit a ref.

Two things that script does that its dry-run label does not suggest:
`--create-tag` creates AND pushes the tag even without `--write`, and its
closing verification gate runs `check-versions.mjs` over ALL plugins — one
unrelated plugin in ERROR aborts it with the catalog edit written but
uncommitted. When that happens, commit the catalog's `marketplace.json` +
`README.md` by hand and leave every other dirty file in that repo alone.

## Hardening roadmap

Empty — the post-v0.1.0 queue (atomic delivery, `.`/`..` rejection,
selftest gaps, uniform `-h`) shipped in v0.2.0; broadcast self-delivery
shipped in v0.2.1; broadcast retraction (`coord-send --retract`) shipped in
v0.4.0, closing the last monotonically-growing surface. `coord-inbox.sh`
still ignores unknown arguments by design (hook context must never fail)
but now warns about each one on stderr, which the hook discards.

Two retraction limits are deliberate, not gaps: it is un-send and never
recall (a repo that already received a broadcast keeps it — the seen set is
delivery history and is left untouched), and the sender check is an accident
guard, not a security boundary, because `--from` redefines identity here as
it does everywhere else in the engine.