gstack/docs/ship-policy.md

# The repo ship policy: `.gstack/ship-policy.json`

`/ship` reads one machine-readable file per repository that says how releases
are stamped and merged: the bump level, the queue mode, the repo's own release
tool, the paths where version mentions are rewritten, the CHANGELOG, a paired
mirror, the history policy and the preregistered evals. Without the file
nothing changes: every key has a default that reproduces today's behavior.

The file is **read from the committed copy on the base branch**
(`origin/<base>`), never from the PR's working tree, so a PR cannot smuggle a
command into its own gate. **File presence never authorizes execution:**
`gstack-restamp` runs `release_tool` only under `/ship` or with
`--allow-repo-commands`; standalone it lists the commands and exits 3 with
`repo commands not executed (pass --allow-repo-commands)`. A PR that
introduces or changes the policy runs under the reviewed bootstrap path
(`--policy-from head --allow-repo-commands`) and its receipt says
`policy: head (unreviewed)`.

Tools: `gstack-ship-policy init|validate|show-effective|check-history`,
`gstack-restamp`, `gstack-tree-receipt`, `gstack-ship-receipt`,
`gstack-ship-queue` ([shared merge queue](#run-a-shared-merge-queue)),
`gstack-evidence bundle|ancestor`. They share the exit table (`0` ok, `1`
fail, `2` usage, `3` refused or needs a flag) and end every error line with a
code from [troubleshooting.md](troubleshooting.md#queue-aware-ship-policy-restamp-tree-receipt-ship-receipt).

<a id="schema-v1"></a>
## Schema v1

`gstack-ship-policy init` writes every key at its default; `init --explain`
prints this table. JSON carries no comments, so examples live in
`.gstack/ship-policy.example.json`. Unknown keys are errors, and there is no
extension mechanism: a key from a newer gstack, or a misspelled one, fails
closed (`POLICY_INVALID`) instead of being ignored. Every key has an
introducing version (`init --explain` and `validate` print it). A key newer
than 1.91.98.0 set to a non-default value requires `min_gstack_version` at
least at its introducing version, and a gstack older than `min_gstack_version`
refuses the file (`POLICY_GSTACK_TOO_OLD`). `validate` ends with
`MIN_READER: gstack <version>`, the floor every lane reading the policy needs.

| Key | Values | Default | Meaning |
|---|---|---|---|
| `bump` | `patch` \| `ask` | `ask` | `patch` skips the MINOR/MAJOR prompt in `/ship` Step 12 and `gstack-restamp --next` bumps PATCH; `ask` keeps the prompt. |
| `queue_mode` | `claim-at-open` \| `stamp-at-merge` | `claim-at-open` | See [stamp-at-merge](#stamp-at-merge). `claim-at-open` is today's queue (`gstack-next-version` claims a slot when the PR opens). |
| `release_tool` | command or `null` | `null` | The repo's own release command (`bun run release:restamp`). Runs in an isolated staging worktree under the [release-tool contract](#release-tool-contract). |
| `release_outputs` | globs | `[]` | Paths the release tool may write beyond the version files, lockfiles, CHANGELOG and `stamp_paths`. Anything else is `RESTAMP_OUTPUT_OUTSIDE_ALLOWED`. |
| `stamp_paths` | globs | `[]` | Where exact `(was X)`, `since: X` and `vX` mentions of the branch's tentative version are rewritten on a restamp. |
| `changelog` | path or `null` | `CHANGELOG.md` | Re-headed on a restamp: the PR's `## [Unreleased]` (or old-version) section moves to the top as `## [<version>] - <date>`. |
| `mirror` | relative path or `null` | `null` | A paired checkout to restamp identically (tier 2: validated and confined today, not yet run). |
| `history` | `merge-only` \| `squash-ok` | `squash-ok` | `merge-only` makes `/ship` refuse a squash or rebase plan; `gstack-ship-policy check-history` reports a rewritten branch (`HISTORY_POLICY_VIOLATION`). |
| `preregistration_shas` | commit ids | `[]` | Each must be an ancestor of HEAD before push: `gstack-evidence ancestor --from-policy`; the ship receipt records the result. |
| `stamp_sensitive_gates` | evidence labels | `[]` | Gates that read VERSION or generated bytes (gstack's own `tests` lane does, through the agents-digest freshness test). The tree receipt never marks them reusable. |
| `pr_count` | `{ default_pr_count, split_requires_owner }` | `{1, true}` | The PR-count row in plan reviews. |
| `maintainers` | GitHub logins | `[]` | Maintainer set for `/review` contributor mode; empty means repository push permission. |
| `stamp_files` | globs | `[]` | The repo's stamp rule: when set, only these files may differ by a stamp (list the version file, manifests, plugin trees and the files holding the PR's own `since:` rows). It applies before every other stamp rule, so a doc `vX` mention outside it is a difference. |
| `stamp_patterns` | literal templates | `[]` | At most 16 templates of at most 128 characters, each with exactly one `{version}` slot (`"version": "{version}"`, `since: '{version}'`, `<!-- x-stamp: {version} -->`); matched literally at a version boundary, never as a regex. The restamp writer and the tree receipt use them beside the built-in forms. |
| `restamp_command` | command or `null` | `null` | The repo's own restamp, run first in the staging worktree; see [restamp_command](#restamp-command). |
| `migrations` | `{ dir, id }` or `null` | `null` | The migration directory and a regex with exactly one capture group for the number in a file name (`"^v(\\d+)-"`); `gstack-pregate regate` reports `MIGRATION_COLLISION`. |
| `gate_command` | command or `null` | `null` | The repo's full pre-merge gate. `gstack-ship-queue gate-ahead` and `ready` print it for the caller to run (in the background or in CI); gstack never executes it. Needs `min_gstack_version`. |
| `full_e2e` | `true` \| `false` | `false` | `true`: every merge needs a passing full-gate result bound to a tree equal to the merging one modulo stamps; `gstack-ship-queue ready`, `stamp` and `verify` refuse without one (`QUEUE_GATE_MISSING`): a gate-ahead record, or the lane's `--gate-exit 0 --gate-log <file>` from its run on the gated head. Needs `min_gstack_version`. |
| `min_gstack_version` | version or `null` | `null` | The oldest gstack that may read the file; see the compatibility rule above. |

Containment, checked by `validate` and again at write time: paths and globs are
repo-relative with no `..` segment, under 256 characters, at most 64 per list,
and a glob's regex expansion under 512 characters; `release_tool` is under 512
characters with no newline; a matched file that resolves through a symlink to
outside the repository is refused (`POLICY_CONTAINMENT`). A mirror may start
with `..` (a sibling checkout) but has no interior `..`; mirror writes are
confined to that directory.

## gstack's own files

gstack's policy (`.gstack/ship-policy.json`, tracked beside `generated.json`
and `pregate.json` under the otherwise ignored `.gstack/`) runs the repo on
stamp-at-merge: the version is allocated once, when the PR is next in the queue,
every bump is PATCH, and `/review` reads the maintainer set from the file. It
names the one release tool `gstack-version-bump --regen-digest` used to
hard-code:

```json
{
  "bump": "patch",
  "queue_mode": "stamp-at-merge",
  "release_tool": "bun scripts/gen-agents-digest.ts",
  "release_outputs": ["agents-digest/gstack-AGENTS.md"],
  "stamp_paths": [],
  "changelog": "CHANGELOG.md",
  "history": "squash-ok",
  "stamp_sensitive_gates": ["tests"]
}
```

`.gstack/ship-policy.example.json` shows every key set the way a serial-merge
repo with a release script, docs mentions and a mirror would set them.

### Queue-side procedure for gstack

Who does what under `stamp-at-merge`, for the PR author and for the thread
running the merge queue:

1. **Open.** The branch carries a tentative stamp of the base's version plus
   PATCH (`gstack-version-bump write --version <base+patch> --regen-digest`)
   and its CHANGELOG section headed with that version directly under
   `# Changelog`; `## [Unreleased]` is also accepted. Nothing is claimed and
   `gstack-next-version` is not consulted; the tentative version is only the
   guess that makes the common case free. CI runs on this head as usual.
2. **Register.** The queue records the PR and its intended order.
3. **Stamp when next.** With every check green on the current head and
   `origin/main` at the SHA the queue assumed, the PR owner (never the queue)
   runs on the branch:
   `gstack-restamp --next --base main --allow-repo-commands --pr <n> --expect-base <main-sha> --expect-order <pr,...>`.
   When the base has not moved past the tentative stamp it prints
   `RESTAMP: X -> X (noop)` and `FILES: (none)`, and the green head is the
   merge candidate with no further CI. When the base moved, it stamps base +
   PATCH, re-heads the CHANGELOG above the base's top entry, reruns the
   release tool, prints `STAMP_VERSION: <X>` and the stamp diff, and refuses
   with `QUEUE_STALE` (nothing written) when the base or order moved after
   `--expect-base` was read. The owner commits and pushes the stamp commit,
   lets CI run on it, and reports `READY #<n> <sha> STAMP_VERSION=<X>`.
4. **Merge.** The queue verifies on that exact SHA: `VERSION` equals
   `STAMP_VERSION`, the CHANGELOG's top heading is `[<X>]` and the heading
   below it is the base's current version, every check is green on that SHA,
   and, when a stamp commit was pushed, it changed only `VERSION`,
   `package.json`, `CHANGELOG.md` and the release outputs
   (`gstack-tree-receipt --gated <green-head> --current <sha>` prints the
   per-file verdict). It then squash-merges with the merge API's expected-head
   `sha` set to that SHA, so a late push is rejected by the server. "VERSION
   above main" is replaced by "VERSION equals the restamp's STAMP_VERSION on
   the SHA being merged, and that version is base + PATCH at merge time".
5. **Not next.** A PR waiting behind another may gate ahead locally with
   `gstack-restamp --after <predecessor-pr>`; it pushes nothing. When the
   predecessor lands, the waiting PR merges `origin/main` in (never a rebase),
   keeping its own CHANGELOG section above the newly merged one, and step 3
   runs.

Until this policy is on `origin/main`, `gstack-restamp --next` reads the base's
`bump: ask` and falls back to a MICRO bump; pass `--bump patch` on the first
PR stamped after the flip if its base predates it.

<a id="run-a-shared-merge-queue"></a>
## Run a shared merge queue

`gstack-ship-queue` strings `gstack-restamp`, `gstack-tree-receipt` and the
ship receipt into the coordinator protocol, so nobody proves a stamp diff by
hand. Lanes own their PRs and never merge; the coordinator owns the order and
every merge. Each step ends in a line the other side acts on, then
`GSTACK_RESULT: skill=ship-queue status=complete|refused run=<path>`. Nothing
here pushes.

**1. Lane: report ready (unstamped).** After the gate and pregate pass on the
pushed head:

```bash
gstack-pregate run --allow-repo-commands
git push
gstack-ship-queue ready --pr 42
```

```
READY #42 <head> STAMP_VERSION=unstamped
pr: https://github.com/<owner>/<repo>/pull/42
head: <head>
version: unstamped
base: origin/main@<sha>
ci: green at <head12> (passed=31 failed=0 pending=0 skipped=2)
PREGATE: pass tree=<tree12> head=<head12> checks=6
gate: command="<gate_command>" full_e2e=no gate-ahead=none
SHIP_RECEIPT: pr=42 head=<head12> …
```

It refuses (`QUEUE_NOT_READY`) when the working tree has tracked edits, HEAD
is not the PR's pushed head, CI at that exact head is not green, or the pregate
result is not a current pass. Send the block as printed.

**2. Lane behind another PR: gate ahead.** Gate the tree the queue will have
once the predecessor lands, while it is still open:

```bash
git fetch origin pull/41/head
gstack-ship-queue gate-ahead --after 41 --pr 42 --predecessor-ref FETCH_HEAD --allow-repo-commands
```

prints `GATE_AHEAD: pr=42 attempt=<id> gated=<sha> tree=<tree> merge_tree=<tree>
predecessor=#41@<sha12> version=<N+1>`, the attempt's own `worktree:`, its
`record:` file, `GATE_COMMAND:` (the policy's `gate_command`) and the exact
`next:` line. Run the gate there, in the background or in CI, then bind it:

```bash
(cd <worktree> && <gate command>) > gate.log 2>&1
gstack-ship-queue gate-ahead --record --pr 42 --attempt <id> --exit $? --log gate.log
```

`GATE_RECORD: pr=42 attempt=<id> exit=0 gated_tree=<tree> log_sha256=<sha256>
current=yes`. The record keeps the log and removes only that attempt's
worktree, and refuses (`GATE_AHEAD_ATTEMPT_INVALID`) when the worktree no
longer holds the gated commit. If the predecessor moves, prepare a new
attempt; attempts never share a worktree, the newest is current, and
recording an older one later prints `current=no (superseded by <id>)`.
`gate-ahead --list --pr 42` shows them all. Send the record file with READY.

**3. Coordinator: call the slot.** Name the version, the base sha and the
order: "#42 next at 1.2.7.0, base `<sha>`, order 41,42".

**4. Lane: stamp.** A gate-ahead lane first merges `origin/main` (with the
predecessor in it) into its branch, never a rebase. Then:

```bash
gstack-ship-queue stamp --pr 42 --version 1.2.7.0 --expect-gated <gated> \
  --expect-base <sha> --expect-order 41,42 --allow-repo-commands
```

`<gated>` is the head the gate ran on: the pushed head the lane gated, or the
record's `gated=` after a gate-ahead. The preflight refuses before anything is
written unless the tree to stamp equals the gated one modulo stamps, the base
is `<sha>` and, under `full_e2e`, a passing gate result is bound to the gated
head. Then it runs the restamp, commits, reruns the tree receipt and prints

```
QUEUE_STAMP: 42 1.2.7.0 head=<sha> gated=<sha> tree=same-modulo-stamps receipt=<sha256>
```

Each stage is journaled in `.gstack/tmp/ship-queue/stamp-42.json`; the
identical command resumes at the first unfinished stage, or returns the stored
`QUEUE_STAMP` when it already finished. A refusal prints
`QUEUE_STAMP_REFUSED: 42 head=<sha> committed=no|yes <sha> stage=<stage>`
and the coded line (`QUEUE_STALE` carries a `recompute:` command). Push the
stamp commit, wait for CI on it, run `ready` again
(`READY #42 <head> STAMP_VERSION=1.2.7.0`) and send it with the
`QUEUE_STAMP` line.

**5. Coordinator: verify, then merge.** From the coordinator's own clone:

```bash
gstack-ship-queue verify --pr 42 --gated <gated> --receipt <sha256> --expect-head <head> [--gate-exit 0 --gate-log <file>]
gstack-ship-queue verify --pr 42 --record <gate-ahead record> --receipt <sha256> --expect-head <head>
```

It fetches `refs/pull/42/head` and reruns the tree receipt there, so
`QUEUE_STAMP` is never a pasted claim: `VERIFY: 42 1.2.7.0 head=<sha>
gated=<sha> tree=same-modulo-stamps receipt=<same sha256>`. Under `full_e2e`,
`--gated` also needs the lane's passing gate log from its run on that head
(`--gate-exit 0 --gate-log <file>`), else `QUEUE_GATE_MISSING`. With a gate-ahead
record, whose gated commit never left the lane's machine, it first recomputes
the merge with `git merge-tree --write-tree <branch head> <predecessor head>`
and compares it with the recorded merge tree, rebuilds the gated tree from
the recorded stamp patch and compares it with the recorded `gated_tree`,
proves that patch is stamps only, checks the predecessor did not move, and
prints `merge_tree:`, `gated_tree:` and `gate:` lines. The last line is
`MERGE_CONDITION: sha=<head>`: merge with that expected head. Any
`QUEUE_VERIFY_MISMATCH` means do not merge.

**Rolling out `gate_command` and `full_e2e`.** Commit them (with
`min_gstack_version` at their introducing version, which `init --explain`
prints) only after every lane's gstack is at least that version, the crew's
install floor (`GSTACK_MIN_REVISION`). A lane on an older gstack refuses the
policy by name rather than reading it differently.

<a id="ship"></a>
## What `/ship` reads from it

`/ship` Step 3 runs `show-effective --base <base>` and follows its `ship:` lines,
which carry the workflow consequences the skill prose would otherwise spell out:

| Line | Effect |
|---|---|
| `ship: history merge-only: …` | never rebase, squash or force-push; `check-history --plan <merge\|squash\|rebase>` refuses a rewrite plan (`HISTORY_POLICY_VIOLATION`, exit 3) |
| `ship: queue_mode stamp-at-merge: …` | Step 12 items 1–4 are replaced by `gstack-restamp --next --base <base> --pr <n> --expect-base <sha>` when the PR is next, `--after <predecessor-pr>` when it is not; the restamp's own `next:` line says what follows (NEW_VERSION, CHANGELOG entry text only, the merge's expected head) |
| `ship: shared merge queue: …` | in a coordinator-run queue, `gstack-ship-queue ready`, `gate-ahead` and `stamp` replace the restamp calls; see [Run a shared merge queue](#run-a-shared-merge-queue) |
| `ship: gate-ahead: …` | with `.gstack/tmp/gate-ahead.json` present, Step 16 reuses only the lanes `gstack-tree-receipt … --json > .gstack/tmp/tree-receipt.json` marks reusable; stamp-sensitive and not-eligible lanes run live; `--force-gate <reason>` is the coordinator's call |
| `ship: bump patch: …` | Step 12 never asks for MINOR or MAJOR; PATCH or MICRO by size |
| `ship: preregistration: …` | `gstack-evidence ancestor --from-policy --base <base>` must print only `ANCESTOR: ok` before push |
| `ship: release_tool: …` | the command runs only inside `gstack-restamp` (staging worktree, outputs confined to `release_outputs`) |

The PR body's first section is the ship receipt (`gstack-ship-receipt write … --body`),
written by the pr-body section of `/ship` after the body is composed.

<a id="stamp-at-merge"></a>
## `queue_mode: stamp-at-merge`

Under `stamp-at-merge` nothing is claimed when a PR opens. The stamp happens
when the PR is next, from the base branch's version at that moment, through
the repo's own release tool, across every stamp location at once:

```bash
gstack-restamp --next --base main --allow-repo-commands --pr 42 \
  --expect-base <sha of origin/main the queue assumed> --expect-order 40,41,42
```

prints `ship, next in queue at <version>`, `STAMP_VERSION: <version>`, one
line per stage, the diff limited to stamp files, `MERGE_CONDITION: sha=<head>`
(pass it to the merge API's expected-head `sha` so a check-to-merge race is
rejected by the server) and the `GSTACK_RESULT:` line. `claims: ignored
(stamp-at-merge)` says the legacy claim reader was not consulted. When the base
or the order moved, the result is `QUEUE_STALE` (exit 3) with the exact
`recompute` command; nothing is written.

Stages, each journaled in `.gstack/tmp/restamp-journal.json`:

0. **restamp_command** (only when the policy sets it): the repo's own restamp, see [restamp_command](#restamp-command).
1. **version**: `gstack-version-bump write --version <X>` in the staging worktree (VERSION, the manifest, npm lockfiles); skipped when `restamp_command` owns the version.
2. **release_tool**: the policy command, under the contract below.
3. **changelog**: the PR's `[Unreleased]` or old-version section moves to the top under `<X>`, above its predecessor's entry. Duplicate headings (`CHANGELOG_DUPLICATE_HEADING`) and a top entry that is not `<X>` (`CHANGELOG_TOP_MISMATCH`) are errors.
4. **stamp_paths**: exact `(was X)`, `since: X` and `vX` rewrites, plus every `stamp_patterns` template, within `stamp_paths` and `stamp_files`. `X` is the branch's own tentative stamp (its VERSION when it moved past base), else `--was <X>`, else the version an unstamped branch would have taken next (`base + bump`); mentions of a version the base never released (not a CHANGELOG heading at base, not a tag) are rewritten too, so a queue reorder that moves the base under a branch still finds its `since:` fields. Only the repo's own version width counts, so a 3-digit dependency pin in a 4-digit repo is never a candidate.
5. **mirror**: tier 2; declared and validated, reported as not run.
6. **apply**: every changed file is written to the branch only after all stages validated, each against the fingerprinted preimage; a file edited meanwhile is `RESTAMP_CONFLICT` and the applied writes roll back (rollback refuses to overwrite a file whose bytes differ from the recorded postimage).

Idempotent: a second run with the same version is `noop`. `--dry-run` prints
the full diff and writes nothing (not even the journal). `--version <X>` stamps
exactly X; `--bump` overrides the level; `--queue-mode` overrides the policy.

### Gate-ahead: `--after <pr>`

A reorder is cheap only when the gate can run before the predecessor merges.
`gstack-restamp --after <pr> --predecessor-ref <ref>` merges HEAD and the
predecessor's head in a throwaway worktree (`.gstack/tmp/gate-ahead-worktree`),
resolving only version-file and CHANGELOG-ordering conflicts, stamps N+1
relative to the predecessor's version there, commits, and records
`.gstack/tmp/gate-ahead.json` (`predecessor_head`, `branch_head`,
`gated_head`, `gated_tree`, `version`, `evidence_branch_key`). The PR branch's
history is never touched, so squash-history PRs stay clean. The gate runs in
that worktree; `gstack-evidence bundle` there exports the evidence.

<a id="release-tool-contract"></a>
### The release-tool contract

The release tool runs in an isolated staging worktree seeded from the working
tree's content fingerprint (`gstack-wtree`), with the repo's ignored
`node_modules` linked in. Its outputs are enumerated: the version files,
lockfiles, the CHANGELOG, `stamp_paths` and `release_outputs`. A write outside
that set refuses the whole restamp before anything reaches the branch
(`RESTAMP_OUTPUT_OUTSIDE_ALLOWED`); a non-zero exit is
`RESTAMP_RELEASE_TOOL_FAILED`. Preimages and postimages of every write are
recorded in the journal. Pinning the command string does not freeze its
implementation (`bun run release:restamp` still runs the PR's package script),
so the receipt names the policy revision, the command, its working directory
and the trust scope (`policy: base origin/main@<sha>` or `head (unreviewed)`).

<a id="restamp-command"></a>
### `restamp_command`: the repo owns the stamp

A repo whose own tool knows its stamp locations sets `restamp_command`.
`gstack-restamp` runs it as the first stage inside its staging worktree, a
clean checkout of HEAD, with the allocated version as the last argument and in
`GSTACK_RESTAMP_VERSION`. The caller's HEAD, index and worktree must be clean
first (`RESTAMP_CONFLICT`, nothing written); the generic path keeps its
working-tree fingerprint seed. Anything the command stages or commits in the
staging worktree is folded back into plain edits; then output confinement
applies as for the release tool (`RESTAMP_OUTPUT_OUTSIDE_ALLOWED`), the
version file must hold the target version (`RESTAMP_VERSION_SOURCE`), and a
non-zero exit is `RESTAMP_RELEASE_TOOL_FAILED`. In every failure nothing
reaches the branch. gstack's version writer is skipped; the CHANGELOG and
`stamp_paths` stages still run (a no-op when the tool already did the work).
Read from the base branch and run only with `--allow-repo-commands`, like
`release_tool`. A tool that fetches, merges the base branch or needs a version
of its own choosing cannot run here; give it a mode that takes the version and
writes only stamps.

<a id="tree-receipt"></a>
## The tree receipt

```bash
gstack-tree-receipt --from .gstack/tmp/gate-ahead.json --predecessor-pr 41 --bundle evidence-bundle.json
gstack-tree-receipt --gated <sha> --current HEAD --json
```

Compares two **committed heads** (a working-tree fingerprint can name objects
unreachable once the gate VM is gone) and prints the gated and current heads,
both tree ids, the version pair, the predecessor the gate assumed, the diff
limited to stamp files, one line per file with its rule and verdict, one line
per gate, then two verdict lines:

```
TREE: same-modulo-stamps | changed (<residual paths>)
gate-reuse: eligible (reusable: tests; rerun: digest) | not-eligible (<what changed>) — fix: <rerun command> (GATE_REUSE_NOT_ELIGIBLE)
```

Hunks are classified per file type: the version file (old → new only), the
manifest (`version` key only), npm and bun lockfiles (root `version` keys
only, where `gstack-version-bump` writes; a dependency entry is `changed`),
the CHANGELOG (a heading move or re-heading, compared as an order-independent
multiset of entries), `stamp_paths` and `release_outputs` (every
removed/added pair must be an exact `(was X)` / `since: X` / `vX` rewrite with
X the gated version and the replacement the current one, so a dependency pin
that happens to equal the old version is `changed`; `stamp_patterns`
templates count as stamp forms too). With `stamp_files` set, a file outside it
is `changed (stamp_files: not in the repo's stamp_files allowlist)` whatever
its diff. Any other byte is a change.

Equivalence is decided per gate. A lane in `stamp_sensitive_gates` always
`rerun`s; a verified lane is `reusable` only when the tree is same-modulo-stamps
and the execution identity in the bundle equals the current one: Bun and Node
versions, OS and arch, every lockfile's identity (root version normalized
away), the `.github/workflows` tree id, runtime pin files and
`package.json#engines`, and the runner image when either side knows it. Without
a bundle the identity is unknown and the receipt is `not-eligible`. When the
recorded predecessor head is no longer the predecessor PR's head (checked
through `--predecessor-ref` or `gh pr view --predecessor-pr`) the receipt
prints `PREDECESSOR MOVED <old> -> <new> — fix: gstack-restamp --after <pr>
again (RESTAMP_PREDECESSOR_MOVED)` and refuses `eligible`.

`/ship` Step 16 consults the receipt; when it says `eligible`, a repeated full
gate needs `--force-gate <reason>`, and the coordinator makes the call.

### The evidence bundle

`gstack-evidence` is machine-local by design, so the portable form is a bundle:

```bash
gstack-evidence bundle --out evidence-bundle.json --label tests --label e2e --require tests,e2e \
  --selection tests='bun run test' --run-url tests=https://github.com/.../actions/runs/1
```

A bundle binds to a committed head (`repo.commit`, `repo.tree`) and carries the
comparison material (version source, CHANGELOG path, `stamp_paths`,
`release_outputs`), the execution identity above, the required-lane manifest,
and per lane the command, `cmd_sha256`, exit, timestamp, executed selection,
run URL, log hash and whether it is `verified` (produced by the ledger on a
clean committed tree at this head) or not (dirty tree, other commit, or an
`--import`ed assertion). A fresh coordinator machine reads it with
`gstack-tree-receipt --bundle` after the gate VM is gone; the receipt refuses
reuse when the bundle was produced on another tree or lacks the identity
(`EVIDENCE_IDENTITY_UNKNOWN`).

<a id="ship-receipt"></a>
## The ship receipt

The handoff record is a fenced block, identifiers first, validated against
`gstack-artifact schema ship-receipt`:

````
```gstack-ship-receipt
{ "schema_version": 1, "pr": 42, "head": "<sha>", "version": "1.2.7.0", "base": "main",
  "gated_tree": "<tree>", "predecessor": "<sha>", "tree": "same-modulo-stamps",
  "gate_reuse": "eligible (reusable: tests; rerun: digest)", "gate": { "tests": { "pass": 10, "fail": 0, "skip": 1 } },
  "ci": { "checks": 3, "failed": 0 }, "spend_usd": 0.42, "session_kind": "unattended",
  "artifacts_consumed": "1/1", "run": "<run id>", "thread": "<thread id>", "policy": "base origin/main@<sha>" }
```
````

`gstack-ship-receipt write --pr <n> --receipt <tree-receipt.json> --gate '<json>' --ci '<json>' --body <pr-body.md>`
makes it the first section of the PR body (`/ship` Step 18) and prints
`SHIP_RECEIPT: pr=… head=… version=…` for the first line of the completion
message. `/land-and-deploy` reads it with `gstack-ship-receipt read --pr <n>
--json` (`RECEIPT_MISSING`, `RECEIPT_INVALID`).

### The adoption census (P7)

```bash
gstack-ship-receipt census --repo garrytan/gstack --since v1.91.70.0 --cohort threads.txt
```

reads merged PRs since the tag through `gh`, parses each receipt, deduplicates
by `run` and `thread`, and prints `CENSUS: … unattended=<n> consumed=<n>
adoption=<consumed threads>/<cohort> durable=yes`. The cohort file lists one
thread id per line (threads that never invoke gstack count in the
denominator); without it the denominator is the threads the receipts name.

## History policy and preregistration (C7)

Under `history: merge-only`, `/ship` refuses a squash or rebase plan and merges
the base branch instead: `gstack-ship-policy check-history --plan squash`
prints `HISTORY: refused (…) (HISTORY_POLICY_VIOLATION)` with exit 3, and
without `--plan` it prints `HISTORY: ok` or `HISTORY: rewritten …
(HISTORY_POLICY_VIOLATION)` (exit 1) when the pushed branch is no longer an
ancestor of HEAD. `gstack-evidence ancestor
--from-policy --base main` prints one `ANCESTOR: ok|missing <sha>` line per
`preregistration_shas` entry (`PREREGISTRATION_NOT_ANCESTOR`, exit 1), and the
ship receipt records the result in `preregistration`.

## Contributor mode

`/review` runs `gstack-contributor-mode detect` at Step 1 (decision D10). The PR
author is outside the maintainer set when `maintainers` in `.gstack/ship-policy.json`
on the base branch is non-empty and does not list the login (`source=policy`);
with an empty list, when `gh api repos/<owner>/<repo>/collaborators/<login>/permission`
reports less than push permission (`source=collaborators`, an egress receipt
`contributor-mode` precedes the call); when neither is available the mode is off
and `CONTRIBUTOR_SOURCE_UNAVAILABLE` names what was missing. `--contributor`
forces it on (`source=flag`). `CODEOWNERS` is file ownership, not maintenance
authority, and is never read. The printed line is
`CONTRIBUTOR_MODE: on|off author=<login> source=flag|policy|collaborators|off`,
followed when on by the evidence-first instructions: a table per change
(evidence value, risk surfaces, `accept` / `supersede` / `decline`), where
`accept` keeps a direct path for a correct outside implementation judged by the
same bar as a maintainer change, `supersede` rewrites from our own plan only after
a plain-language approval, and the credit lines (`Contributed by @handle`,
`Co-Authored-By:`, `Supersedes #N`) appear only when a diagnosis or a test carried
over. `gstack-contributor-mode instructions` prints the same text without detecting.

## Banned terms

`.gstack/banned-terms.json` lists terms the repository forbids outside named
locations: `terms` (a string, or `{ "term", "allowed_paths", "reason" }`) and a
top-level `allowed_paths` that every term inherits. Globs follow the same
containment rules as the ship policy (repo-relative, no `..`, under 256
characters). `gstack-banned-terms check --base <ref>` scans the lines the branch
adds since its merge base (or whole files with `--files <csv>`), reading the term
list from the committed copy on the base by default (`--policy-from head` reads
the working tree). Each finding is one line,
`BANNED_TERM: "<term>" <file>:<line> allowed: <locations> — <text>`, and the
last line is `BANNED_TERMS: ok | found=<n> | none` (`none`: the repository keeps
no list). Exit 0 for ok or none, 1 when found, 3 when the file is invalid
(`BANNED_TERMS_INVALID`, also from `validate`). `/review` turns each finding into
a Step 4 finding and `/document-release` into a documentation finding;
`gstack-banned-terms init` writes a commented example.

<a id="approval-classes"></a>
## Approval classes

`.gstack/approval-classes.json` names the changes that need the owner's
approval before they ship: upgrade-time data rewrites, trust or visibility
changes, existing-user default changes, data repairs, anything the owner wants
cited. Each entry in `classes` has a `name` (lowercase, dashes) and at least
one matcher: `paths` (globs of changed files), `patterns` (literal text in an
added line, case-sensitive) or `migrations: true` (the files the ship policy's
`migrations` key describes). `allowed_paths` exempts files, such as tests;
`description` is for people. Globs follow the ship policy's containment rules.

Classes come only from the copy committed on `origin/<base>`, so a branch can
neither declare nor drop its own; `gstack-approval-classes validate` checks the
working-tree copy before you commit it, and `init` writes an example.
`gstack-approval-classes check --base <ref>` scans the branch's changes since
the merge base and prints one `APPROVAL_CLASS: <class> <file>:<line>` line per
hit, one `APPROVAL_SCOPE: <class>@<digest12>` line per declared class with hits,
and `APPROVAL_CLASSES: ok | found=<n> | none` last (exit 0, 1 when found, 3 when
the base file is invalid or `origin/<base>` does not resolve). Built-in
detectors only report: the ship policy's migration files, when no class sets
`migrations: true`, print as `(built-in, report-only)` and need no citation.

The digest covers the class's effects: each matched file with its blob at the
scanned head, and each matched added line. The scan reads git's native diff
(`--no-ext-diff --no-textconv`), so a configured external diff driver or text
conversion cannot hide a line; when the content diff cannot be read, or its
added lines disagree with git's own count, `check` and the receipt refuse with
`APPROVAL_SOURCE_UNAVAILABLE` instead of passing. Adding, removing or editing an
effect changes the token, so an approval given earlier no longer binds.

**Enforcement.** `gstack-ship-receipt write` refuses with
`APPROVAL_CITATION_MISSING`, writing nothing, unless each declared class with
hits has a line in the `--body` file (or an `--approval` value) of the form

```
Approved by <owner> <YYYY-MM-DD> via <ref> [for <class>@<digest12>[,<class>@<digest12>]]
```

that resolves and binds:

- A plan sha (7 to 64 hex characters) must match the plan of an autoplan run
  passed with `--approval-run <run dir>` whose gate is APPROVED, and the plan
  must name the scope token, or the class and every effect path.
- A GitHub comment or review URL must be written by a `maintainers` login from
  the base's ship policy that equals the cited owner. A review must be in
  state `APPROVED`; a comment-only, dismissed or changes-requested review is
  not an approval. The evidence is the body's first non-blank line only. It
  must start at column 0 with `Approved` or `Approve` (any case, optionally
  in `**` bold; no list marker, quote or indent) and name the token, or the
  class and every effect path. Nothing later in the body counts, so a
  rejection that quotes or nests an example approval approves nothing. For
  example, a comment whose first line is
  `Approved data-repair@0123456789ab: preview-first, never at upgrade.`
  verifies; one that opens with any other line does not.
- A token is authoritative. Evidence that names the class with a different
  digest approved earlier effects: it does not bind, and it never falls back
  to matching the class and paths.
- Anything else (a thread code, a chat message, a URL gstack cannot read) is
  recorded `citation: unverified` for the coordinator, and only when the line
  attests which scope it covers with `for <class>@<digest12>` matching the
  current token.

The receipt's `approval` object records the source, `status` (`checked`, or
`unavailable` when `origin/<base>` does not resolve), one record per class
(scope token, effects, `citation: verified | unverified`, owner, date, ref,
`binding: token | paths | attested`, evidence) and any report-only hits; the
`SHIP_RECEIPT:` line ends with `approval=verified`, `approval=unverified:<classes>`,
`approval=none` or `approval=unchecked`. A repository without the file gets no
`approval` object unless a built-in detector reported.

A data repair is a class to declare, and /review checks its shape: explicit,
preview-first, and never reachable from an upgrade or migration path.