[a1f52d13] Rebuild evidence-assembly timeout fix on current main (#796)

* [a1f52d13] feat(gateway): re-apply evidence-assembly timeout fix on current main

Rebuilds the bounded-timeout fix for claim_review/evidence()/roboco_git_diff
that PR #765 carried as contaminated pre-Board-Programs file copies. The
rebase restored the current-main baseline; this commit re-applies ONLY the
validated timeout-fix hunks on top of that baseline:

- config.py: evidence_assembly_timeout_seconds (90.0s) and
  conventions_validator_timeout_seconds (45s) Settings fields
- envelope.py: Envelope.gateway_timeout classmethod for structured
  timeout errors naming the stalled component
- git.py: GitService.diff_and_files (single resolution, concurrent
  diff+--name-only subprocesses), settings-backed conventions-validator
  timeout, and changed_files passthrough to conventions_check_for_task
- qa.py: claim_review bounded-timeout wrapper around
  _build_qa_claim_evidence, split into _qa_git_and_conventions and
  _qa_db_reads concurrent segments (pass_review signature and gate
  untouched)
- content_actions.py: evidence() bounded wrapper with _evidence_git_and_fetch
  and _evidence_db_reads concurrent split (all other methods untouched)
- git routes: GET /diff bounded asyncio.wait_for guard with 504 on trip

The pre-existing methods (sync_env_branch, open_sync_pr, pass_review with
criteria_verified gate, all propose_*/request_render methods) are preserved
and untouched. The test files already exist on current main.

* [a1f52d13] fix(git-routes): wrap workspace resolution in bounded timeout for GET /diff

The bounded asyncio.wait_for must cover the workspace resolution step too,
not just the diff+stat subprocesses — the integration test makes
get_workspace slow (not _run_git), so the timeout guard needs to enclose
the entire resolve-and-diff path to return a structured 504 on trip.

* [a1f52d13] test: update mock setups from git.diff/list_changed_files to diff_and_files

Tests that exercise claim_review and evidence() paths need their git
mocks to return a tuple from diff_and_files instead of separate diff
and list_changed_files return values, matching the new combined accessor
introduced by the evidence-assembly timeout fix.

* [a1f52d13] test: configure diff_and_files mock in lifecycle parity test _make_deps

The spec-parity test test_claim_review_matches_spec[qa-awaiting_qa] failed
with ValueError at qa.py:330 because _make_deps set git=AsyncMock() without
configuring diff_and_files.return_value, so the await resolved to a MagicMock
instead of a (diff_summary, files_changed) 2-tuple. Adds the same
return_value = ("", []) configuration that commit 014a0d03 applied to the
other 4 test files.

* [a1f52d13] docs(evidence-assembly-timeout): correct GET /diff guard scope and _qa_git_and_conventions timing field

---------

Co-authored-by: Backend Developer 2 <be-dev-2@roboco.tech>
Co-authored-by: Backend Documenter <be-doc@roboco.tech>

docs/backend/services/evidence-assembly-timeout-fix.md

@@ -22,7 +22,7 @@ A new `settings.evidence_assembly_timeout_seconds` (default 90s, well under the
 
 - `ContentActions.evidence()` — wraps the `asyncio.gather` of the git-diff coroutine and `_evidence_db_reads`.
 - `QAMixin.claim_review()` — wraps the call to `_build_qa_claim_evidence`; the claim itself (`qa_claim` + `mark_evidence_inspected`) has already committed by this point, so a trip here means only evidence assembly is slow, not that the claim failed.
-- `GET /api/git/diff` (`roboco/api/routes/git.py`, `roboco_git_diff`) — wraps the diff + `--stat` subprocess pair.
+- `GET /api/git/diff` (`roboco/api/routes/git.py`, `roboco_git_diff`) — wraps workspace resolution *plus* the diff + `--stat` subprocess pair in one bounded guard, so a slow workspace fetch trips the 504 too — not just a slow diff. (The workspace resolution is enclosed because an unbounded `get_workspace` is the step the integration test makes slow; leaving it outside the guard would let the whole request hang past the timeout anyway.)
 
 On a trip, each site returns a structured `Envelope.gateway_timeout(component, timeout_seconds, remediate)` (new classmethod on `roboco/services/gateway/envelope.py`'s `Envelope`) naming which segment stalled (e.g. `"git diff/fetch or a journal/ancestor/findings DB read"`) and a remediation hint, instead of the outer 120s rollback with no indication of which piece stuck. The route's HTTP path raises a `504 Gateway Timeout` with the equivalent detail message.
 
@@ -40,7 +40,7 @@ Each segment logs its own duration (structlog `.info()` calls) so a slow request
 - `GitService.diff_and_files` logs `resolve_ms` (workspace/token/head/base resolution) and `diff_ms` (the concurrent diff subprocesses) as "evidence diff_and_files timing".
 - `conventions_check_for_task` logs `total_ms` plus whether it reused the passed-in file list, as "conventions_check_for_task timing".
 - `evidence()` logs `git_diff_and_fetch_ms` ("evidence git diff/fetch timing") and the DB-reads batch logs `db_reads_ms` ("evidence db reads timing").
-- `claim_review`'s two segment helpers (`_qa_git_and_conventions`, `_qa_db_reads`) log `git_diff_and_fetch_ms`/`conventions_ms` ("claim_review git+conventions timing") and `db_reads_ms` ("claim_review db reads timing") respectively.
+- `claim_review`'s two segment helpers (`_qa_git_and_conventions`, `_qa_db_reads`) log `git_diff_and_fetch_ms` ("claim_review git+conventions timing", covering the whole git+conventions block as one measurement) and `db_reads_ms` ("claim_review db reads timing") respectively.
 
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