---
id: T03
parent: S02
milestone: M014
provides: []
requires: []
affects: []
key_files: ["backend/pipeline/test_harness_compose.py", ".gsd/milestones/M014/slices/S02/tasks/T03-SUMMARY.md"]
key_decisions: ["Used MockKeyMoment NamedTuple directly without extra ORM fields"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "All 16 tests pass: cd backend && python -m pytest pipeline/test_harness_compose.py -v (0.41s). Compose subcommand accessible: python -m pipeline.test_harness compose --help exits 0."
completed_at: 2026-04-03T01:08:30.886Z
blocker_discovered: false
---

# T03: 16 unit tests covering compose prompt XML structure, citation offset math, category filtering, and edge cases — all passing

> 16 unit tests covering compose prompt XML structure, citation offset math, category filtering, and edge cases — all passing

## What Happened
---
id: T03
parent: S02
milestone: M014
key_files:
  - backend/pipeline/test_harness_compose.py
  - .gsd/milestones/M014/slices/S02/tasks/T03-SUMMARY.md
key_decisions:
  - Used MockKeyMoment NamedTuple directly without extra ORM fields
duration: ""
verification_result: passed
completed_at: 2026-04-03T01:08:30.886Z
blocker_discovered: false
---

# T03: 16 unit tests covering compose prompt XML structure, citation offset math, category filtering, and edge cases — all passing

**16 unit tests covering compose prompt XML structure, citation offset math, category filtering, and edge cases — all passing**

## What Happened

Created backend/pipeline/test_harness_compose.py with 4 test classes (TestBuildComposePrompt, TestCitationReindexing, TestCategoryFiltering, TestEdgeCases) totaling 16 tests. Tests verify prompt XML tag structure, old/new moment index offsets, citation range validation, category filtering behavior, and edge cases (empty new moments, single moment, no subsections, large offsets). Fixed MockKeyMoment constructor mismatch — it's a 7-field NamedTuple without id/video_id/source_video.

## Verification

All 16 tests pass: cd backend && python -m pytest pipeline/test_harness_compose.py -v (0.41s). Compose subcommand accessible: python -m pipeline.test_harness compose --help exits 0.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd backend && python -m pytest pipeline/test_harness_compose.py -v` | 0 | ✅ pass | 3500ms |
| 2 | `cd backend && python -m pipeline.test_harness compose --help` | 0 | ✅ pass | 1500ms |


## Deviations

Removed id, video_id, source_video from _moment() helper — MockKeyMoment NamedTuple has only 7 fields.

## Known Issues

None.

## Files Created/Modified

- `backend/pipeline/test_harness_compose.py`
- `.gsd/milestones/M014/slices/S02/tasks/T03-SUMMARY.md`


## Deviations
Removed id, video_id, source_video from _moment() helper — MockKeyMoment NamedTuple has only 7 fields.

## Known Issues
None.
