fix(gitea): direct REST comment/review with fail-closed read-back (#865)

Closes #865

Mos (id-11) Gate-16 merge: fresh confirmatory independent APPROVE @8ac7e70f (1241-case fuzz 0 fail-open), author id2 != approver id11, clean commit-author, CI green wp1966.

Co-authored-by: jason.woltje <jason@diversecanvas.com>
Co-committed-by: jason.woltje <jason@diversecanvas.com>

packages/mosaic/framework/tools/git/README.md

@@ -4,6 +4,32 @@ These scripts provide host-aware GitHub and Gitea issue, pull-request, milestone
 
 ## 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 count as durable provenance only after the wrapper reads the created provider record back and verifies that it belongs to the intended repository and pull request and contains the exact submitted body (or verifies the provider-returned record ID).
+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.
 
-`pr-review.sh` therefore fails closed when a Gitea comment cannot be written, its created comment ID cannot be identified, or provider read-back does not match. It reports comment success only after that read-back verification passes.
+**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`), falling back to the repo host's credential when no login is named. 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.