16 bite-sized, TDD tasks across the design spec's 4-PR stack, each with
a suggested subagent type/model for delegated execution. Test/fixture
code in the acceptance-corpus and API-expansion tasks was verified
against the real codebase (documents/tests/search/conftest.py's
existing backend/index fixtures, test_backend.py's pytestmark
convention, CustomFieldInstance's typed value_text field) rather than
guessed, and the date-grammar parity test's AST-shape assumption was
confirmed by actually running whoosh_compat.parse() against a real
DATE FieldRegistry.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>