test: use subprocesses for each test file (#29016)

* ci(tests): install ripgrep from prebuilt tarball instead of apt

apt-get update + install of ripgrep takes ~4 min on the GHA Ubuntu
runners (the apt-get update against archive.ubuntu.com is the slow
part; ripgrep itself is small). Switching to the upstream musl
binary tarball cuts the step to a few seconds.

- Pinned to ripgrep 15.1.0 with sha256 verification (same hash as
  published in the releases sha256 sidecar file).
- Drops the `rg` binary into /usr/local/bin so it is on PATH for
  every subsequent step without GITHUB_PATH manipulation.
- Applied to both the test and e2e jobs in tests.yml.

* fix(cli): compile syntax check to tempdir, not source __pycache__

`_validate_critical_files_syntax` runs `py_compile.compile()` on each
critical bootstrap file after a successful `git pull`. The default
`py_compile` writes the resulting `.pyc` next to the source under
`__pycache__/`, which causes two real problems:

1. Parallel test workers walking the same source tree (e.g. running
   the suite under per-file process isolation) can race against each
   other on the `__pycache__` write — manifests as flaky 'directory
   not empty' errors during teardown.
2. In production, the post-pull syntax check leaves a `.pyc` behind
   that the next interpreter run might pick up — fine when the
   interpreter version matches, sketchy if it doesn't.

Fix: write the compiled output to a `tempfile.TemporaryDirectory()`
that's discarded on function exit. We only care about the compile-or-not
signal, not the artifact.

* test(runner): per-file process isolation, drop manual state reset + xdist

Replace fragile manual _reset_module_state test fixtures with robust
per-file subprocess isolation. Each test file runs in a fresh
`python -m pytest <file>` subprocess via ThreadPoolExecutor. No xdist,
no custom pytest plugin, no shared worker state.

Key changes:
  * scripts/run_tests_parallel.py — new runner: discovers test files,
    runs N in parallel via ThreadPoolExecutor, captures stdout per file,
    treats exit code 5 (no tests collected) as pass, kills all children
    on exit. Change from cpu_count to cpu_count*2. The runner is
    I/O-bound (waiting on subprocess.communicate() from pytest children)
    The parent process does almost no CPU work, so 2x oversubscription
    keeps more pipes full. When a file fails, immediately show the last
    30 lines of pytest output (stack traces + FAILED summary) plus a
    ready-to-copy repro command:
      python -m pytest tests/agent/test_auxiliary_client.py
  * scripts/run_tests.sh — delegates to run_tests_parallel.py
  * .github/workflows/tests.yml — test step: python
scripts/run_tests_parallel.py
  * pyproject.toml — drop pytest-xdist, pytest-split; simplify addopts
  * tests/conftest.py — remove ~200 lines of manual state-reset fixtures
  * AGENTS.md — update Testing section for per-file design

* test(runner): speed gateway test antipattern scan up

* fix(test): web search provider plugin test missing xai

* fix(tests): make 14 test files pass under per-file subprocess isolation

Tests that relied on cross-file state pollution from xdist workers
fail when run in isolation (per-file subprocess model). Root causes
and fixes:

Tool registry not populated:
  - test_video_generation_tool_surface_matrix: add discover_builtin_tools()
  - test_web_providers_brave_free/ddgs/searxng/general: autouse fixtures
    registering all 8 bundled web providers, reset after each test
  - test_website_policy: same provider registration pattern
  - test_web_tools_tavily: same pattern across 3 dispatch test classes
  - Also add is_safe_url/check_website_access mocks where SSRF check
    blocks example.com (DNS resolution fails in isolated envs)

Stale check_fn cache:
  - test_kanban_tools: invalidate_check_fn_cache() + _clear_tool_defs_cache()
    in both kanban guidance tests (prior test cached False for kanban_show)
  - test_discord_tool: cache invalidation in setup/teardown
  - test_homeassistant_tool: invalidate_check_fn_cache() before registry queries

Module-level state pollution:
  - test_auxiliary_client: autouse fixture clearing _aux_unhealthy_until cache
  - test_skill_commands: set_session_vars() instead of patch.dict(os.environ)
    (ContextVar takes precedence over os.environ)
  - test_dm_topics: overwrite sys.modules + separate telegram.constants mock
    + force-reimport of gateway.platforms.telegram
  - test_terminal_tool_requirements: removed duplicate class declaration,
    autouse _clear_caches fixture

* change(tests): run_tests.sh explicitly includes env vars

instead of manually dropping some vars, now we just only include some

* fix(tests): 5 more isolation/NixOS fixes

- test_approval_plugin_hooks: isolate HERMES_HOME so real user's
  command_allowlist doesn't short-circuit the approval path
- test_google_chat: skipif when Platform.GOOGLE_CHAT not in enum
  (feature not merged on this branch)
- test_write_deny: test systemd prefix against tmp_path instead of
  /etc/systemd which resolves to /nix/store on NixOS
- test_pty_bridge: use shutil.which('cat') instead of /bin/cat
  (doesn't exist on NixOS)
- profiles.py: rmtree onexc handler chmod's parent dirs too, fixing
  profile deletion when copytree preserved read-only modes from
  nix store

* fix(tests): clear unhealthy cache in autouse fixture for auxiliary_client

* fix(tests): skip send_message when telegram not installed; handle missing worker_id in browser_supervisor

* fix: py3.11 rmtree onexc compat + belt-and-suspenders unhealthy cache clear for expired codex test

* fix: address PR #29016 review feedback

- Remove tracked .pytest-cache/ artifact and add to .gitignore
- Fix stale 'xdist worker' comment in conftest.py
- Deduplicate web provider registration into tests/tools/conftest.py
  shared helper (register_all_web_providers), replacing 8 copy-pasted
  blocks across 6 test files
- Update PR description: remove stale recovered-test-files claim,
  fix worker count to match code (cpu_count*2)

* fix: eliminate race in stale-cache achievements test

The background scan thread could complete and overwrite _SNAPSHOT_CACHE
before evaluate_all() returned the stale data — only 10 fake sessions
made the scan finish instantly. Added scan_delay param to _FakeSessionDB
and set it to 2s in the stale-cache test so the background thread can't
win the race.

tests/agent/test_auxiliary_client.py

@@ -40,6 +40,16 @@ def _clean_env(monkeypatch):
         "ANTHROPIC_API_KEY", "ANTHROPIC_TOKEN", "CLAUDE_CODE_OAUTH_TOKEN",
     ):
         monkeypatch.delenv(key, raising=False)
+    # Module-level unhealthy cache (10-min TTL) leaks between tests;
+    # earlier tests that call _mark_provider_unhealthy() poison the
+    # cache for later ones, causing _resolve_auto to skip providers
+    # that the test patched to return valid clients.
+    import agent.auxiliary_client as _aux_mod
+    _aux_mod._aux_unhealthy_until.clear()
+    _aux_mod._aux_unhealthy_logged_at.clear()
+    yield
+    _aux_mod._aux_unhealthy_until.clear()
+    _aux_mod._aux_unhealthy_logged_at.clear()
 
 
 @pytest.fixture
@@ -461,6 +471,17 @@ class TestExpiredCodexFallback:
         import base64
         import time as _time
 
+        # Belt-and-suspenders: _try_openrouter marks openrouter unhealthy
+        # when OPENROUTER_API_KEY is absent (which the preceding test in
+        # this class exercises).  The file-level _clean_env autouse fixture
+        # clears the cache, but fixture ordering with the conftest
+        # _hermetic_environment autouse can leave a narrow window where
+        # the mark reappears.  Explicitly clear here so this test is
+        # independent of run order.
+        import agent.auxiliary_client as _aux_mod
+        _aux_mod._aux_unhealthy_until.clear()
+        _aux_mod._aux_unhealthy_logged_at.clear()
+
         header = base64.urlsafe_b64encode(b'{"alg":"RS256","typ":"JWT"}').rstrip(b"=").decode()
         payload_data = json.dumps({"exp": int(_time.time()) - 3600}).encode()
         payload = base64.urlsafe_b64encode(payload_data).rstrip(b"=").decode()
@@ -1047,6 +1068,20 @@ class TestGetProviderChain:
 class TestTryPaymentFallback:
     """_try_payment_fallback skips the failed provider and tries alternatives."""
 
+    @pytest.fixture(autouse=True)
+    def _clear_unhealthy_cache(self):
+        """Earlier tests in this file call _mark_provider_unhealthy() which
+        pollutes the module-level ``_aux_unhealthy_until`` dict (10-min TTL).
+        Without this cleanup the fallback chain skips providers we've patched
+        to return valid clients — the patched function is never called.
+        """
+        from agent.auxiliary_client import _aux_unhealthy_until, _aux_unhealthy_logged_at
+        _aux_unhealthy_until.clear()
+        _aux_unhealthy_logged_at.clear()
+        yield
+        _aux_unhealthy_until.clear()
+        _aux_unhealthy_logged_at.clear()
+
     def test_skips_failed_provider(self):
         mock_client = MagicMock()
         with patch("agent.auxiliary_client._try_openrouter", return_value=(None, None)), \

tests/agent/test_skill_commands.py

@@ -556,10 +556,11 @@ Generate some audio.
             raising=False,
         )
 
-        with patch.dict(
-            os.environ, {"HERMES_SESSION_PLATFORM": "telegram"}, clear=False
-        ):
-            with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            from gateway.session_context import clear_session_vars, set_session_vars
+
+            tokens = set_session_vars(platform="telegram")
+            try:
                 _make_skill(
                     tmp_path,
                     "test-skill",
@@ -571,6 +572,8 @@ Generate some audio.
                 )
                 scan_skill_commands()
                 msg = build_skill_invocation_message("/test-skill", "do stuff")
+            finally:
+                clear_session_vars(tokens)
 
         assert msg is not None
         assert "local cli" in msg.lower()