Pre-existing failures (verified via parent commit 4ab7c732):
1. tests/test_aggregate_flags.py::test_auto_aggregate_skip
- Gemini API 503 UNAVAILABLE on both parent and current
- Aggregate.build_tier3_context calls summarise.summarise_file which
calls Gemini API; under load, the API returns 503.
- Fix: mock the Gemini API call in summarise.summarise_file for tests.
2. tests/test_context_composition_phase6.py::test_view_mode_summary
- Same Gemini 503 flake (summarise_file returns traceback-formatted
error string; assert '**Python**' fails).
3. tests/test_context_composition_phase6.py::test_view_mode_default_summary
- Same Gemini 503 flake (different code path; same dependency).
4. tests/test_context_composition_phase6.py::test_view_mode_custom_empty_default_to_summary
- Same Gemini 503 flake (custom view_mode with empty slices defaults
to summary; same Gemini 503 dependency).
Per AGENTS.md skip-marker policy: documentation of a known failure,
not an excuse. The underlying issue is that these tests depend on the
live Gemini API which is network-dependent and rate-limited under load.
Fix would require mocking the Gemini API in summarise.summarise_file
for tests. Deferred to a follow-up track.
ed