[AEW E2E] Add case-insensitive task search

[chen-gdp]

Summary

Add an optional q query parameter to GET /tasks for case-insensitive substring matching on task titles. Composes with the existing completed filter.

Spec Source: specs/issue/1-aew-e2e-add-case-insensitive-task-search/spec.md

Key Changes

• Add q: str | None = Query(default=None) parameter to the list_tasks endpoint
• Strip leading/trailing whitespace from q; blank or whitespace-only q preserves current behavior
• Apply case-insensitive substring filter: q.lower() in task.title.lower()
• Compose q filter conjunctively with existing completed filter
• Add 6 test cases covering match, no match, blank, whitespace-only, case-insensitive, and composition with completed

Area	What changed	Reviewer focus
API	src/task_api/main.py:48 — list_tasks signature + filter logic	Correctness of filter composition, whitespace handling
Tests	tests/test_api.py — 6 new test functions	Coverage of edge cases, regression of existing behavior

How to Test

Step	Command	Expected result
1	uv run --extra test pytest -v	10/10 tests pass (4 existing + 6 new)
2	uv run --extra test pytest -v -k "test_search_q"	6/6 q-related tests pass
3	uv run --extra test python -c "from fastapi.testclient import TestClient; from task_api.main import create_app; api = TestClient(create_app()); api.post('/tasks', json={'title': 'Test item'}); r = api.get('/tasks', params={'q': 'test'}); assert len(r.json()) == 1; print('Manual check OK')"	Manual behavior check passes

Related Issues

Closes #1

Author Checklist

• Synced with latest main branch
• All tests pass (10/10)
• Spec validation passed

Additional Notes

• Backward-compatible: q defaults to None, existing callers unaffected.
• Single-slice PR (PR-001), no stacked dependencies.

[chen-gdp]

Review Summary — ✅ Approved

@chen-gdp Implementation is clean, correct, well-tested, and fully aligned with the approved spec.

Reviewed: c41857c39787f992e015e130f764924037d6db72 against main

Notes

• ✅ 10/10 tests passing (4 existing + 6 new)
• ✅ Backward compatible — existing tests pass without modification
• ✅ All 6 spec coverage categories are matched by dedicated test cases
• ✅ No scope expansion, no security concerns, minimal diff

Validation

• ✅ uv run --extra test pytest — 10/10 passed
• ✅ Spec alignment confirmed — implementation matches spec.md design exactly

[chen-gdp]

@chen-gdp implementation PR ready for human review

• Implementation PR: [AEW E2E] Add case-insensitive task search #3
• Spec PR: [AEW E2E] Add case-insensitive task search #2
• AI code review: [AEW E2E] Add case-insensitive task search #3 (review)

This implementation delivers case-insensitive task search as specified in the approved spec. Please review at your convenience.