Fix: Resolve open cache-isolation and config-provenance issues

[ModeSevenIndustrialSolutions]

Closes #385
Closes #386

Note

#392 has merged, so this no longer stacks — the diff is now just the two commits below. Still marked draft; say the word and I'll mark it ready.

Fix: Reset process-wide caches between tests — #385

The autouse fixture clearing gerrit_urls._BASE_PATH_CACHE landed in #384; the sibling caches that issue named were left to a follow-up. This is that follow-up.

ssh_config_parser memoises four values, each derived from state tests routinely monkeypatch:

Cache	Key	Value derived from
_get_respect_user_ssh_setting	none — zero-arg lru_cache(maxsize=1)	G2G_RESPECT_USER_SSH
_get_cached_git_user_email	none — zero-arg lru_cache(maxsize=1)	git config user.email
derive_gerrit_credentials	(host, organization, port)	the two above, plus ~/.ssh/config and env — none of which are in the key
_ssh_config_cache	config path, never its contents	the parsed SSH config

The first two are the worst: with no arguments there is a single cache slot, so any two tests collide and the second receives the first one's environment — including the git identity that isolate_git_environment works to control.

The module already exposed clear_credential_cache(), which resets all four, but only two test modules called it and only from setup_method — guarding those files on the way in while leaving the caches populated for whatever runs next. Calling it from an autouse fixture covers every test, and clearing on both sides stops a dirty cache reaching a test as well as leaving one behind. No src/ change was needed.

Honest scoping: no leak between existing tests is demonstrable. Every test reaching derive_gerrit_credentials either patches it wholesale or clears in setup_method, which is why this has held. The exposure is latent, exactly like the base-path bug — it bites when someone adds a test that derives credentials for real, and surfaces far from its cause. No leak is claimed that could not be shown.

The explicit clear in test_gerrit_urls_more.py at module scope is now redundant and goes. The one mid-test survives, because it is not a test boundary: without it the second half of that test never probes at all and its assertions pass off the value cached by the first half. Its comment claimed the fixture covered it, which was wrong; the comment is now accurate.

Fix: Separate derived Gerrit config from explicit — #386

Duplicate detection short-circuited on GERRIT_SERVER / GERRIT_PROJECT from the environment, but by then those are usually derived fallbacks, not operator intent — _load_effective_inputs derives them and writes them to the environment first.

Two consequences: the .gitreview resolution below that early return was effectively dead on the normal path, including the base-ref pinning added in #384 for fork PRs; and the derived project is a guess taken from the repository name, so OpenDaylight's integration-distribution yielded that same string where Gerrit holds integration/distribution. Detection queried a project that does not exist and reported no duplicates, silently.

Config values now carry provenance. mark_derived_keys records which keys hold a derived fallback and is_derived_key reports it, backed by G2G_DERIVED_KEYS.

On why an environment variable is acceptable here: this is process-scoped configuration, settled once before the bulk ThreadPoolExecutor starts — deliberately unlike the per-PR state that cli.py:289 already documents as unsafe to hold globally.

Marking applies only to keys whose environment value is empty, matching the test apply_config_to_env applies moments later, so a key derivation supplies but the environment already defines explicitly stays explicit. The cli.py:767 call site opts out via mark_derived=False: it persists to the org config file after successful submission and never touches the environment.

Detection now short-circuits only when both host and project are explicit, field by field, letting the per-PR .gitreview fill only what is not explicitly configured — and only where .gitreview actually carries a value. Where it yields nothing the derived pair still applies, because returning None would disable detection entirely wherever it previously ran against a derived project. The fork-trust handling from #384 is untouched.

Review round

Copilot found five issues across this PR, all genuine, all fixed. Three were bugs I introduced; two were pre-existing problems the provenance work exposed. Worth recording, since two of them were worse than the bug this PR set out to fix:

1. Partial-pair precedence. Collapsing both keys into one derived flag meant one derived key made the whole pair non-explicit, so .gitreview replaced an explicitly configured value too. Now tracked per field.
2. Host-only .gitreview. parse_gitreview requires only host= and returns project = "". Taking that empty project dropped the project: qualifier from the query — _build_duplicate_query_path logs it as project=(any) — so detection searched every project on the server, letting an unrelated same-title change block a legitimate submission. Now falls back to the environment value per field.
3. Per-repository value in per-organization config. save_derived_parameters_to_config writes into the org section, so one repository's GERRIT_PROJECT was handed to every sibling repository. Now filtered out before writing.
4. Legacy config entries. Values auto-saved by earlier releases still loaded as explicit. Rather than a migration, a GERRIT_PROJECT from the config file is now treated as derived outright — the file is sectioned per-organization while a project is per-repository, so such a value is misscoped whoever wrote it. It stays usable as a last resort, so nothing breaks and no user file is rewritten.
5. A substring check in my own test helper. "raw.githubusercontent.com" in url accepted lookalike hosts, path segments, query strings and plain HTTP. Now parsed and compared as an origin.

One deliberate behaviour change from (2): when .gitreview is host-only and no project is configured anywhere, the resolver returns None and the check is skipped, where it previously issued the unscoped query. A missed duplicate is recoverable; a false positive blocking a legitimate submission is not.

Validation

Gate	Result
pytest	1549 passed, 0 failed, 0 errors, 0 skipped (from 1518)
basedpyright (124 files)	0 errors, 0 warnings
ruff check / format	clean
aislop ci	100 / 100, 0 findings
prek run --all-files	every hook passed
CI	24 success, 3 skipped, 0 failures

Every fix was verified by deleting it and watching the tests fail, not by observing them pass. Representative:

# detector reverted
FAILED test_duplicate_query_uses_gitreview_path_not_derived_name
  AssertionError: Gerrit was not queried for the .gitreview project:
  ['...changes/?q=project:integration-distribution status:open...']

# host-only .gitreview fix reverted
AssertionError: Gerrit query was not scoped to a project:
  ['...changes/?q=status:open after:2026-08-19&n=50&...']

# autouse fixtures disabled
FAILED test_base_path_cache_does_not_leak_into_later_test
FAILED test_respect_user_ssh_setting_does_not_leak_into_later_test
FAILED test_git_user_email_cache_does_not_leak_into_later_test
FAILED test_credential_cache_does_not_leak_into_later_test
FAILED test_ssh_config_cache_does_not_leak_into_later_test

Two of the provenance tests pass with and without their fix — with the block absent nothing marks the key, so "not marked" is trivially true. They guard against a plausible mis-fix rather than proving the fix, and are flagged as such rather than counted as regression tests.

A note on the aislop gate

The first cut of #386 added 47 lines to duplicate_detection.py and tripped complexity/file-too-large. Rather than add an ignore directive, I measured the real budget — the gate warns at 991 lines, a 10% grace band over the configured max: 900, and the file sat at 978 — then expressed the same logic, twice over as review findings landed, by moving rationale into the docstring and condensing comments. Final: 989 lines, gate at 100/100. No threshold lowered, no exclusion added.

Deliberately not done

• core._resolve_gerrit_info still returns .gitreview unconditionally, ahead of an explicitly configured GERRIT_SERVER — the "arguably backwards" precedence Duplicate detection cannot distinguish derived config #386 calls out. is_derived_key is now the tool to fix it, but it touches the push path and deserves its own change.
• config._read_gitreview_host still reads the local working-directory file — the residual exposure from Duplicate detection cannot distinguish derived config #386's comment thread, needing PR provenance at derivation time.
• derive_gerrit_credentials' memo is unsound in production, not merely in tests. Its real inputs — an env var, git config, ~/.ssh/config — are absent from its key, and cli.py:2329 mutates G2G_RESPECT_USER_SSH at runtime, so whether that mutation is visible depends on call ordering.
• Verify pull_request_review runs are privileged #391 remains blocked on deciding whether to probe pull_request_review privileges or skip to the two-stage workflow_run redesign.

[Copilot]

Pull request overview

Resets process-wide caches between tests and tracks derived Gerrit configuration so duplicate detection can prefer .gitreview. The diff also contains stacked #392 static-analysis changes.

Changes:

• Adds cache/provenance isolation fixtures and regression tests.
• Tracks derived configuration and adjusts duplicate-detection precedence.
• Updates stacked test typing and static-analysis configuration.

Reviewed changes

Copilot reviewed 28 out of 29 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/github2gerrit/config.py	Adds derived-key provenance tracking.
src/github2gerrit/duplicate_detection.py	Prefers .gitreview over derived values.
src/github2gerrit/cli.py	Controls provenance during config persistence.
tests/conftest.py	Resets global caches and provenance.
tests/test_cache_isolation.py	Tests cache isolation regressions.
tests/test_config_helpers.py	Tests provenance behavior.
tests/test_duplicate_detection.py	Tests duplicate resolution precedence.
tests/test_gerrit_urls_more.py	Removes redundant cache fixture.
tests/test_ssh_artifact_prevention.py	Adds type-narrowing assertions.
tests/test_reconciliation_plan_and_orphans.py	Uses typed test models.
tests/test_reconciliation_extracted_module.py	Uses typed test models.
tests/test_pr_content_filter_integration.py	Corrects port type.
tests/test_pr_commands.py	Adds type annotations.
tests/test_orphan_rest_side_effects.py	Uses typed Gerrit information.
tests/test_mapping_comment_digest_and_backref.py	Corrects model argument types.
tests/test_mapping_comment_additional.py	Uses typed test models.
tests/test_gerrit_pr_closer.py	Narrows parsed result type.
tests/test_gerrit_change_id_footer.py	Corrects port type.
tests/test_core_ssh_setup.py	Corrects port types.
tests/test_core_prepare_commits.py	Corrects port type.
tests/test_core_integration_fixture_repo.py	Corrects port type.
tests/test_composite_action_coverage.py	Adds missing-step assertions.
tests/test_cli.py	Targets Click 8.2 output behavior.
tests/test_action_outputs.py	Adds missing-step assertion.
tests/test_action_environment_mapping.py	Adds missing-step assertions.
tests/fixtures/make_repo.py	Simplifies byte-output decoding.
pyproject.toml	Extends static analysis and dev dependencies.
.pre-commit-config.yaml	Broadens Python hook coverage.
uv.lock	Locks updated development dependencies.

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[Copilot]

Pull request overview

Copilot reviewed 28 out of 29 changed files in this pull request and generated no new comments.

Suppressed comments (1)

src/github2gerrit/config.py:828

• This provenance block is skipped when G2G_ENABLE_DERIVATION=false, because apply_parameter_derivation returns at lines 770–775 first. A legacy org-level GERRIT_PROJECT is then exported without a derived mark, so duplicate detection treats it as explicit and again short-circuits before .gitreview, reproducing #386 for a supported configuration. Record provenance for config-sourced projects independently of whether new derivation is enabled, and add the disabled-derivation regression case.

    if (
        mark_derived
        and cfg.get("GERRIT_PROJECT", "").strip()
        and (os.getenv("GERRIT_PROJECT") or "").strip() == ""
    ):
        mark_derived_keys(["GERRIT_PROJECT"])

The merge-base changed after approval.