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.

.github/workflows/tests.yml

@@ -23,13 +23,24 @@ concurrency:
 jobs:
   test:
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 60
     steps:
       - name: Checkout code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
 
-      - name: Install system dependencies
-        run: sudo apt-get update && sudo apt-get install -y ripgrep
+      - name: Install ripgrep (prebuilt binary)
+        run: |
+          set -euo pipefail
+          RG_VERSION=15.1.0
+          RG_SHA256=1c9297be4a084eea7ecaedf93eb03d058d6faae29bbc57ecdaf5063921491599
+          RG_TARBALL=ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl.tar.gz
+          curl -sSfL -o "$RG_TARBALL" \
+            "https://github.com/BurntSushi/ripgrep/releases/download/${RG_VERSION}/${RG_TARBALL}"
+          echo "${RG_SHA256}  ${RG_TARBALL}" | sha256sum -c -
+          tar -xzf "$RG_TARBALL"
+          sudo mv "ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl/rg" /usr/local/bin/rg
+          rm -rf "$RG_TARBALL" "ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl"
+          rg --version
 
       - name: Install uv
         uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86  # v5
@@ -44,9 +55,26 @@ jobs:
           uv pip install -e ".[all,dev]"
 
       - name: Run tests
+        # Per-file isolation via scripts/run_tests_parallel.py: discovers
+        # every test_*.py file under tests/ (excluding integration/ + e2e/),
+        # then runs `python -m pytest <file>` in a freshly-spawned subprocess
+        # with bounded parallelism. No xdist, no shared workers, no
+        # module-level state leakage between files.
+        #
+        # Why per-file (not per-test): per-test spawn cost (~250ms × 17k
+        # tests = 70min CPU minimum) blew the wall-clock budget. Per-file
+        # spawn (~250ms × ~850 files = ~3.5min) fits while still giving
+        # every file a fresh interpreter — the only isolation boundary
+        # that matters in practice (cross-file leakage was the original
+        # flake source; intra-file is the test author's responsibility).
+        #
+        # Why drop xdist entirely: xdist's persistent workers accumulate
+        # state across files, which is exactly the leakage we wanted to
+        # fix. ThreadPoolExecutor + subprocess.run is ~60 lines and does
+        # the job with cleaner semantics.
         run: |
           source .venv/bin/activate
-          python -m pytest tests/ -q --ignore=tests/integration --ignore=tests/e2e --tb=short -n auto --timeout=30 --timeout-method=signal
+          python scripts/run_tests_parallel.py
         env:
           # Ensure tests don't accidentally call real APIs
           OPENROUTER_API_KEY: ""
@@ -60,8 +88,19 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
 
-      - name: Install system dependencies
-        run: sudo apt-get update && sudo apt-get install -y ripgrep
+      - name: Install ripgrep (prebuilt binary)
+        run: |
+          set -euo pipefail
+          RG_VERSION=15.1.0
+          RG_SHA256=1c9297be4a084eea7ecaedf93eb03d058d6faae29bbc57ecdaf5063921491599
+          RG_TARBALL=ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl.tar.gz
+          curl -sSfL -o "$RG_TARBALL" \
+            "https://github.com/BurntSushi/ripgrep/releases/download/${RG_VERSION}/${RG_TARBALL}"
+          echo "${RG_SHA256}  ${RG_TARBALL}" | sha256sum -c -
+          tar -xzf "$RG_TARBALL"
+          sudo mv "ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl/rg" /usr/local/bin/rg
+          rm -rf "$RG_TARBALL" "ripgrep-${RG_VERSION}-x86_64-unknown-linux-musl"
+          rg --version
 
       - name: Install uv
         uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86  # v5