# Git provider wrappers

These scripts provide host-aware GitHub and Gitea issue, pull-request, milestone, and CI operations.

## Durable review provenance

A successful provider write command—or a wrapper message based only on that command's exit code—is **not** durable review provenance. Review comments, approvals, and change requests count as durable provenance only after the wrapper reads the created provider record back and verifies that it was created by _this_ write.

**The write is a direct Gitea REST `POST` that returns the created record's id.** Neither wrapper writes through `tea` — tea 0.11.1 can silently no-op while exiting 0 and cannot emit the id of a record it creates, so its exit code is worthless as proof of a durable write (#865). Instead:

- Comments (`issue-comment.sh`, and the `comment` action of `pr-review.sh`) `POST /api/v1/repos/{owner}/{repo}/issues/{index}/comments`, requiring a `201` and parsing the created comment's `id` from the response body.
- Reviews (`approve` / `request-changes`) `POST /api/v1/repos/{owner}/{repo}/pulls/{index}/reviews` with the `event` (`APPROVED` / `REQUEST_CHANGES`), the review `body`, and `commit_id` pinned to the PR's current head, then parse the created review's `id`. The review body travels _in the review submit itself_ — there is no separate detached comment to reconcile (a Gitea `REQUEST_CHANGES` review requires a non-empty body, which the submit carries).

**Verification keys on that exact provider-returned id.** The wrapper then `GET`s that one record directly — `GET /issues/comments/{id}` or `GET /pulls/{n}/reviews/{id}` — and requires that its `id` equals the created id, its **author login equals the acting identity** (resolved via `GET /api/v1/user` for the token in use), and, for comments, its body exactly matches what was submitted **and its returned web URL belongs to this exact provider and repository** (the `issue_url` / `pull_request_url` origin — scheme, host, and effective port — and full path, i.e. deployment prefix + exact `owner/repo` + kind + number, must match; a suffix/`endsWith` test would accept a look-alike host or a decoy path prefix, so the whole normalized URL is compared). The `comment` action of `pr-review.sh` additionally requires the returned resource be a **pull request** (a populated `pull_request_url`); a bare `issue_url` is rejected, so if issue `#N` exists but PR `#N` does not, an issue comment cannot be reported as a verified PR comment. (`issue-comment.sh` legitimately keeps the broader issue-or-PR acceptance.) For reviews, its state matches the requested action, its reviewed `commit_id` equals the PR head, **and its persisted body equals the submitted body** — an exact, presence- and type-checked equality (a missing/`null` persisted body no longer counts as an empty match), because Gitea can finalize/reuse a pending review id whose stored content was authored elsewhere, so the body is bound too. The write, the `/user` identity lookup, and the read-back all use the **same** credential — the effective login's token, or the host credential when no login is named — so the write is verified against the identity that actually performed it.

**A review's pinned head is re-checked after verification (current-head TOCTOU).** The `commit_id` is pinned to the PR head read _before_ the submit; between that read and the read-back the branch could advance (a force-push or a new commit), leaving a verified review attached to a now-superseded commit while the live tip carries unreviewed code. After the exact-id read-back succeeds, the wrapper re-reads the live PR head (`GET …/pulls/{n}`) and requires it still equals the submitted SHA; if the head advanced it fails closed (non-zero, no success line) rather than reporting a review that no longer covers the PR's current commit.

**This closes the concurrency window rather than documenting it.** Because verification keys on the id the create returned, a no-op create yields no id and fails closed with no list-scan fallback, and a _concurrent_ record — even one written by the _same_ identity with an identical body/state — has a _different_ id and cannot be mistaken for this write. There is no residual same-identity window: the earlier boundary-and-author heuristic (accept any `id > pre-write-max` with a matching author) is replaced entirely by exact-id attribution.

**Exact-id read-back is the sole authority.** Verification is a direct `GET` of the one record the create returned; there is no follow-up list enumeration. An earlier redundant pass that re-listed the record's page (`?limit=&page=1,2,…`) was removed: server-capped page sizes and list-pagination quirks made it a false-failure source (a durable, exact-id-verified record could be missed by a non-exhaustive enumeration), and it added nothing over the authoritative exact-id `GET`.

## Credential handling

The Gitea API token is **never passed on a curl command line.** An `Authorization: token <value>` argument would be visible to any local process that can read the process table (`ps` / `/proc/<pid>/cmdline`) for the lifetime of the request. Instead, every authenticated curl call writes the header into a private, mode-`0600` config file under `$TMPDIR` and passes it with `curl --config <file>` (`gitea_write_auth_config`), so only the file _path_ — never the token — appears in argv. Each such file is unlinked on every exit path (success and failure) by the caller's `RETURN` trap.

## `tea` invocation notes (Gitea)

- tea v0.11.1 has **no `comment` subcommand under `tea pr` or `tea issue`** — the `tea pr comment` / `tea issue comment` forms don't error, they silently fall through to a no-op and still exit 0, producing a false-success write (#865). tea's write subcommands (`tea comment`, `tea pr approve`/`reject`) also cannot report the id of the record they create, so their exit code cannot prove a durable write. These wrappers therefore do **not** write reviews or comments through `tea` at all; they use direct Gitea REST `POST`s that return the created record's id (see "Durable review provenance" above). `tea` is consulted only to enumerate the login list for host→login resolution.
- Because the review body is carried in the `POST …/reviews` submit itself, there is no separate detached review comment, and the historical `tea pr approve`/`reject` trailing-positional-argument vs. nonexistent `--comment`/`-comment` flag hazard (#835) no longer applies to these wrappers — no review comment is ever passed to `tea`.

### `--login` override

Both `pr-review.sh` and `issue-comment.sh` accept an optional `--login <name>` flag that overrides the automatically detected Gitea login for that single invocation. The override selects **which credential the REST write, the `/user` identity lookup, and the read-back all use** — its token is resolved from the tea config for that login name (`get_gitea_token_for_login`).

**With no `--login`, there is no tea lookup at all.** The acting credential is the calling identity's own, resolved by `get_gitea_token` (see "Per-agent Gitea identity" below), and there is deliberately no fallback from it. These wrappers previously _guessed_ a login from the repo host and looked that guess up in the tea config; on a shared-account host the guess resolved to the shared login, so an unqualified call authored its write as that account rather than as the caller. Since `get_gitea_token_for_login` matches by login **name** and performs no authentication check, a dead shared credential still resolved at rc=0 and the identity-aware resolver was never reached. A caller passing no `--login` is asking to act as itself, so `--login` is now the only route to the tea store (#1351). The resolved login is **host- and port-bound**: the login's configured URL host **and effective port** (the scheme's default port — 80 for `http`, 443 for `https` — applies when a port is omitted, symmetrically on both sides) must match the repo remote's, so a login name shared across hosts (or an override configured for a different Gitea, including one on a different port of the same host) can never send one host's credential to another — a host or port mismatch fails closed rather than leaking a cross-host token. Resolving the acting identity and the read-back from the _same_ login that performs the write is essential: a write performed under an overridden login must be verified against that login's identity, not the host default's. Callers who need a different login than the host default should pass `--login <reviewer-login>`.

As a durable successor to this mechanism, consider giving each reviewer/approver slot its own dedicated Gitea login credential, so that author≠reviewer holds at the credential level rather than relying on wrapper-level `--login` bookkeeping. This is a recommendation for future hardening, not something implemented by this flag.

## Per-agent Gitea identity (Gate-16 author≠reviewer)

By default, git push/fetch (via `git-credential-mosaic`) and the API wrappers above (via
`detect-platform.sh`'s `get_gitea_token`) all authenticate as the single shared Gitea
account/token configured through `tools/_lib/credentials.sh`. That means every agent in a
fleet commits, pushes, and opens PRs under one identity — with no cryptographic
separation between an author and a reviewer.

Both `git-credential-mosaic` and `get_gitea_token()` resolve an optional **per-agent
identity**:

1. `MOSAIC_GIT_IDENTITY` environment variable, or
2. `git config --get mosaic.gitIdentity` (set per-worktree; persists on disk across
   non-persistent shells — `git config mosaic.gitIdentity <agent-id>`), or
3. (git-credential-mosaic only) the username git itself supplies for the credential
   request.

### Which store a credential is read from

The store is chosen by what the identity **is**, not by which file happens to exist first:

| The identity                                                       | Its credential is read from                                                |
| ------------------------------------------------------------------ | -------------------------------------------------------------------------- |
| has a directory at `<brain>/fleet/agents/<id>/` — it is a **seat** | `<brain>/fleet/agents/<id>/secrets/gitea-{usc,mosaicstack}-<id>.token`     |
| does not — it is a **service identity**                            | `~/.config/mosaic/secrets/gitea-tokens/gitea-{usc,mosaicstack}-<id>.token` |

`<brain>` is `MOSAIC_BRAIN_HOME` if set, else `~/.mosaic` — the same resolution
`packages/mosaic/src/fleet/brain-home.ts` performs.

**There is no precedence between the two stores and no fallback from one to the other.**
A seat whose slot is empty is refused even when a same-named token sits in the framework
store. One credential lives in exactly one location: a second copy is drift rather than
redundancy, and the way drift surfaces is a stale copy returning 401, which reads as a
revoked token and sends whoever debugs it to the wrong place.

### What happens when nothing resolves

| identity resolves | token in its store | host runs a fleet | result                    |
| ----------------- | ------------------ | ----------------- | ------------------------- |
| yes               | yes                | —                 | that identity + token     |
| yes               | no                 | —                 | **fail closed**           |
| no                | —                  | yes               | **fail closed**           |
| no                | —                  | no                | shared account, unchanged |

A host "runs a fleet" when `<brain>/fleet/agents` exists — the same signal `brain-home.ts`
uses to decide a brain is active.

Failing closed means: nothing is emitted, the exit status is nonzero, a stderr diagnostic
names the identity, its source, the store it resolved to and the path that was expected,
and `git-credential-mosaic` additionally appends a record (identity, host, reason, cwd —
never a token value) to `${MOSAIC_CREDENTIAL_SPOOL:-~/.local/state/mosaic-credential-escalations}`.
The git operation fails; nothing is attributed to anyone.

The shared-account fallback that used to cover these two cases is why a PR could be
authored, commented and merged under an account whose owner did not open it — every seat
shared one identity, so the record could not be traced back afterwards. An
under-provisioned agent is refused rather than handed the most privileged account
available.

**On a host with no fleet, nothing changes**: no `fleet/agents` directory means the shared
account still answers, so this is a no-op for an operator who has not provisioned per-slot
tokens. On a host that does run a fleet, a human doing manual git work needs an identity
of their own — `MOSAIC_GIT_IDENTITY=<id>` with a provisioned slot. There is deliberately no
environment variable that restores the fallback; one would reintroduce exactly the
substitution this removes.

### The tea path: login resolution (#1356)

The wrappers that go through `tea` (`issue-list.sh`, `pr-list.sh`, `pr-view.sh`,
`lane-brief.sh`, and the tea half of `issue-close.sh`) cannot use a token directly: tea
0.14 only acts as a **login** already stored in `~/.config/tea/config.yml`. Those wrappers
therefore resolve a login name, not a token, and the resolution follows the same identity
as above:

1. Resolve the identity (`MOSAIC_GIT_IDENTITY`, then `git config mosaic.gitIdentity`).
2. Derive the Gitea instance from the repo host (`git.mosaicstack.dev` → `mosaicstack`,
   `git.uscllc.com` → `usc`), or from the owner when `--repo owner/name` is given.
3. The canonical login is `<instance>-<identity>`. If tea has it, that login acts.
4. If the identity is set but that login is missing, the wrapper **fails closed**: nonzero
   exit, empty stdout, and a stderr line naming the login it wanted and the source of the
   identity. When `tea` itself is not installed the message says so instead, since "no such
   login" would send the reader to create a login they cannot create.
5. With **no identity set**, the old host-default behaviour is unchanged (first login
   configured for that host, else the API fallback).

Step 4 replaced a fallback that picked any login configured for the host, which meant a
seat with no login of its own silently acted as whichever seat had configured one. That
satisfied the author≠reviewer gate on paper while one actor held both names.

**Provisioning the logins.** `tools/fleet/seat-logins.sh` projects each seat's token from
its secrets store into tea's config under the canonical name. tea's config is a derived
cache of the secrets store: regenerate it with the script, never hand-edit it. Run it with
`--seat <seat>` for one seat (all seats when omitted), dry-run by default, `--apply` to write. A hand-made
alias holding a seat's token blocks its canonical name (tea refuses one token under two
names); `--adopt` renames it.

### Enabling it for a clone

The framework installer syncs `git-credential-mosaic` to
`~/.config/mosaic/tools/git/git-credential-mosaic` (executable) on every install/update,
but does **not** register it as git's credential helper automatically. Registration is a
one-time, explicit step:

```bash
# Per-repo (recommended — scopes the helper to this clone only):
git config credential.helper "$HOME/.config/mosaic/tools/git/git-credential-mosaic"

# Per-worktree identity pin (Gate-16 separation):
git config mosaic.gitIdentity <agent-id>
```

This is deliberately **not** auto-registered on install/update: `credential.helper` is
global, order-sensitive git config (`~/.gitconfig`) that can already hold an
operator-chosen credential manager (keychain, `store`, `manager-core`, …) for
repositories unrelated to Mosaic. Silently inserting an entry on every framework
install/upgrade risks reordering or shadowing that operator-owned surface across the
whole host — the same operator-owned config the installer's manifest system is
otherwise careful never to touch. Because identity is already resolved per-worktree
(`mosaic.gitIdentity`), the correct granularity for registering the helper is per-clone
too, so a documented manual step is the right shape here, not a global auto-write.

### Running these tests

`MOSAIC_GIT_IDENTITY` is inherited into each test's sandbox `HOME`, and **the tests disagree
about which value they need**, so no single ambient value passes all 29. Measured on `next` at
`a480ee83`, two full passes differing only in that variable:

| tests                                                                                                                                           | identity exported | identity unset |
| ----------------------------------------------------------------------------------------------------------------------------------------------- | ----------------- | -------------- |
| `gitea-login-resolution`, `issue-comment-readback`, `issue-create-interactive-auth`, `pr-edit`, `pr-merge-gitea-empty-uid`, `pr-metadata-gitea` | **fail**          | pass           |
| `issue-close-fail-closed`                                                                                                                       | pass              | **fail**       |
| remaining 22                                                                                                                                    | pass              | pass           |

The six fail because inside a sandbox `HOME` the identity has no `fleet/agents/<id>/`
directory, so it is classified as a **service identity**, its store is unpopulated, and the
resolver correctly refuses with `Refusing to borrow another slot's token`. That is the
documented fail-closed behaviour above, reached from a state the test never intended.
`issue-close-fail-closed` is the mirror image: it asserts that no comment POST is attempted, so
it needs an identity resolving to an empty slot, and with the variable unset the shared account
answers and the POST goes through.

These read as wrapper regressions rather than as environment. Two seats independently
misdiagnosed them as a patch defect while reviewing #1352. Until each test controls its own
value (#1353), `env -u MOSAIC_GIT_IDENTITY` is the closest thing to a clean run at 28/29, with
`issue-close-fail-closed` the expected failure — and **"the suite passes" is not a statement
anyone can make here without naming the ambient value that produced it.**

### PowerShell parity

`detect-platform.ps1`'s Gitea wrappers authenticate through `tea` CLI logins
(`Get-GiteaLoginForHost`), not a raw-token `get_gitea_token`-equivalent function — there
is nothing to prepend the identity-resolution block to on the PowerShell side. A native
PowerShell git-credential helper is also unnecessary: `git-credential-mosaic` is invoked
by git's credential-helper protocol (stdin/stdout), which works identically under Git for
Windows' bundled `bash`/`sh` when configured via `credential.helper`, without a `.ps1`
counterpart. A `tea`-login-based per-agent identity for the PowerShell wrappers is a
separate, larger design (mapping identities to `tea login` profiles) and is out of scope
here.
