Phase 11.3.2. CONTEXT-MANAGER EXCEPTION.
The plan claimed 'StartupProfiler.phase() is NOT a context manager;
tier-2's claim is factually wrong.' This is incorrect. phase() IS a
context manager:
- Decorated with @contextmanager (src/startup_profiler.py:26)
- Used in 13 'with startup_profiler.phase(...)' call sites in
src/gui_2.py (lines 308, 311, 327, 338, 343, 627, 629, 631, 669,
672, 711, 729, 739)
It cannot return Result[None] because:
- @contextmanager requires the function to yield (not return)
- The except body is inside a finally block (which cannot return)
Best partial migration: extract _log_phase_output helper that returns
Result[None]; phase() calls it and ignores the Result (we're in a
finally block).
Audit post-migration:
- _log_phase_output L28 = INTERNAL_COMPLIANT (Heuristic A) ✓
- phase() L54 try/finally = INTERNAL_COMPLIANT (canonical cleanup) ✓
Tests: 12/12 pass (test_audit_allowlist_2d, test_gui_startup_smoke,
test_headless_service, test_startup_profiler, test_warmup_canaries).
This site is documented in the per-site report as a CONTEXT-MANAGER
EXCEPTION. The Heuristic #19 (catch+log) classification remains valid;
the partial migration adds explicit Result-returning helpers where
possible without breaking the context manager pattern.
hot_reloader.py (1 site - module reload with broad except):
- reload() returns Result[bool] now. The migration catches the
broad Exception, captures it as ErrorInfo with the traceback in
last_error, and returns Result(data=False, errors=[...]).
- reload_all() returns Result[bool]; aggregates per-module errors.
- The class still tracks last_error and is_error_state for
backwards-compat with any caller reading the class attributes.
warmup.py (5 sites):
- L139 (on_complete callback fire): was except ...: pass.
Now logs to sys.stderr with the exception.
- L215 (_record_success callback fire): same.
- L249 (_record_failure callback fire): same.
- L276 (_log_canary stderr.write): was except OSError: pass.
Now logs the OSError itself.
- L300 (_log_summary stderr.write): same.
startup_profiler.py (1 site - context manager):
- phase() is a context manager (yields); can't return Result.
The except inside the finally block now logs the OSError.
Tests updated for hot_reloader to check result.ok and result.data.
Tests verified:
- tests/test_hot_reloader.py (9 tests) PASS
- tests/test_hot_reload_integration.py (13 tests) PASS
- tests/test_warmup.py (10 tests) PASS
- tests/test_warmup_canaries.py (18 tests) PASS
- startup_profiler: StartupProfiler = StartupProfiler() at module bottom
so sloppy.py can import it without circular imports.
- phase() context manager now writes a [startup] <name>: <ms>ms line to
stderr in its finally block. Live visibility of every measured phase.
Lightweight, in-memory profiler for AppController init phases. Used by
the startup_speedup_20260606 track to measure where the time goes
during boot (config hydration, hook server start, subsystem init, etc.).
The profiler is exposed via /api/startup_profile (Phase 8 work) and
the Diagnostics panel so the user can see the exact per-phase cost.
Public API:
StartupProfiler() - create
.phase(name) - context manager
.snapshot() - {phases: {name: {start_ts, duration_ms}}, total_ms, count}
.reset() - clear recorded phases
.enable() / .disable() - toggle recording
Implementation:
- dataclass with list of _Phase(name, start_ts, end_ts)
- @contextmanager records wall-clock via time.perf_counter
- records duration even if the body raises (try/finally)
- snapshot is a copy, so consumers can't mutate the live state
TDD: 5 tests in tests/test_startup_profiler.py cover: basic
recording, total math, snapshot isolation, exception safety, empty
state.
ed