fix: update arch guards for process_idle_timeout_ms implementation

- Add execution/test_headless_execute.py to LAYER_CASCADE_CONSERVATIVE['pipeline']
  in tests/_test_filter.py (uses minimal_ctx fixture which imports pipeline)
- Bump _headless_execute.py budget from 610 to 616 lines (4 new lines for
  spec-based idle override logic)
- Bump codex.py exemption from 1045 to 1060 lines (8 new lines for
  process_idle_timeout_ms wiring through both CmdSpec constructors)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Trecek

tests/_test_filter.py

@@ -649,7 +649,7 @@ class ImportContext(enum.StrEnum):
             "execution/test_headless_result_write_reconciliation.py",
             "execution/test_planner_write_isolation.py",
             "execution/test_session_log_flush.py",
-            # execution/ — fixture-mediated pipeline dependents (15 files):
+            # execution/ — fixture-mediated pipeline dependents (16 files):
             # These use minimal_ctx or tool_ctx fixtures which import
             # autoskillit.pipeline at call time. Validated by REQ-GUARD-007.
             "execution/test_backend_dispatch.py",
@@ -662,6 +662,7 @@ class ImportContext(enum.StrEnum):
             "execution/test_headless_dispatch.py",
             "execution/test_headless_env_injection.py",
             "execution/test_headless_env_scrub.py",
+            "execution/test_headless_execute.py",
             "execution/test_headless_provider_fallback.py",
             "execution/test_headless_synthesis.py",
             "execution/test_idle_output_env.py",

tests/arch/test_execution_source_split.py

@@ -18,7 +18,7 @@
 HEADLESS_SIZE_BUDGETS = {
     "headless/__init__.py": 490,
     "headless/_headless_helpers.py": 220,
-    "headless/_headless_execute.py": 610,
+    "headless/_headless_execute.py": 616,
     "headless/_headless_recovery.py": 370,
     "headless/_headless_path_tokens.py": 190,
     "headless/_headless_result.py": 865,

tests/arch/test_subpackage_isolation.py

@@ -979,7 +979,7 @@ def test_data_directories_are_not_python_packages() -> None:
         "dispatch gate add defense-in-depth checks",
     ),
     "execution/backends/codex.py": (
-        1045,
+        1060,
         "REQ-CNST-010-E9: Codex backend — skill_sigil capability threading adds multi-line "
         "keyword args to _ensure_skill_prefix call sites and _has_prefix guard; "
         "write_guard_tool_names env injection adds 7 lines to _codex_exec_extras; "
@@ -989,7 +989,9 @@ def test_data_directories_are_not_python_packages() -> None:
         "promoted from locate_session parameter to frozen dataclass field (3 net lines: "
         "field declaration, blank line between field and method, SessionLocator in import block)"
         "; project_log_dir method added to CodexSessionLocator (+3 net lines)"
-        "; session_log_path method added to CodexSessionLocator (+5 net lines)",
+        "; session_log_path method added to CodexSessionLocator (+5 net lines)"
+        "; process_idle_timeout_ms field wired through build_skill_session_cmd and "
+        "build_food_truck_cmd CmdSpec constructors (+8 net lines)",
     ),
 }