feat: add disposal evidence engine handling

progress.md

@@ -193,13 +193,47 @@
 | 2026-05-29 | Setup | Main Agent | Created Goal for `v1.2 轨迹识别` using `/Users/yoilun/Code/cold_display_guard` as the real project path | Active goal tracks lightweight trajectory detection plus YOLO-ready evidence contract |
 | 2026-05-29 | Setup | Main Agent | Read `/Users/yoilun/Code/goal-subagents-workflow-prompt.md` | Workflow requires task files, stage-based coding/testing agents, bug loop limit, and standard subagent context header |
 | 2026-05-29 | Setup | Main Agent | Read existing `task_plan.md`, `findings.md`, `progress.md`, and `docs/project.md` | v1.1 state is complete; v1.2 plan can start on branch `lightweight-trajectory-tracking` |
+| 2026-05-29 | Phase 1 | Main Agent | Marked Phase 1 as `in_progress` | Preparing coding agent for data contract and engine evidence handling |
+| 2026-05-29 | Phase 1 | Coding Agent | Implemented initial `disposal_evidence` contract and engine handling | Target engine tests and full Python tests passed in coding agent run, but testing agent found review issues |
+| 2026-05-29 | Phase 1 | Testing Agent | Reviewed phase 1 implementation | Verdict fail: evidence/count double consumption, missing target validation, null classifier fields coercion |
+| 2026-05-29 | Phase 1 | Coding Agent | Fixed testing-agent findings | Added target validation, nullable optional fields, and evidence/count double-consume guard |
+| 2026-05-29 | Phase 1 | Testing Agent | Re-tested phase 1 fixes | Verdict pass; no bugs found |
+| 2026-05-29 | Phase 1 | Main Agent | Ran local verification | `tests.test_engine` passed with 24 tests; full Python suite passed with 55 tests |
 
 ### Test Results
 
 | Time | Command | Result | Notes |
 | --- | --- | --- | --- |
+| 2026-05-29 | `PYTHONPATH=src python3 -m unittest tests.test_engine -v` | pass | 24 engine tests passed after phase 1 evidence fixes |
+| 2026-05-29 | `PYTHONPATH=src python3 -m unittest discover -s tests -v` | pass | 55 full Python tests passed after phase 1 |
 
 ### Bug Loop
 
 | Phase | Bug | Fix Attempt | Retest Result |
 | --- | --- | --- | --- |
+| Phase 1 | `disposal_evidence` and `trash_deposit_count` can double-consume the same disposal signal | Added regression test and suppress generic trash fallback when confirming source-specific evidence exists in the observation | Resolved; testing agent and local full Python suite passed |
+| Phase 1 | High-confidence evidence with non-trash target can close pending disposal | Added target whitelist for `trash` / `trash_bin` plus regression test | Resolved; testing agent and local full Python suite passed |
+| Phase 1 | `item_class: null` and `detector_score: null` lose null semantics | Changed optional evidence fields to preserve `None` plus regression test | Resolved; testing agent and local full Python suite passed |
+
+## 2026-05-29 Phase Completed: Phase 1 - Data Contract And Engine Evidence Handling
+
+Status: complete
+
+Files Changed:
+- `src/cold_display_guard/models.py`
+- `src/cold_display_guard/engine.py`
+- `tests/test_engine.py`
+- `task_plan.md`
+- `progress.md`
+
+Tests:
+- `PYTHONPATH=src python3 -m unittest tests.test_engine -v`: pass
+- `PYTHONPATH=src python3 -m unittest discover -s tests -v`: pass
+
+Notes:
+- `Observation` now supports `disposal_evidence`.
+- `BatchEngine` applies source-zone evidence before generic trash fallback and again after same-frame zone transitions.
+- Evidence must meet confidence threshold and target the trash.
+
+Risks:
+- Threshold is currently a phase-1 constant; later runtime config integration will make it configurable.