# Fallback Attempt Chain Persistence

Date: 2026-06-13

Branch: `codex/p2-p3-scalability-hardening`

## Scope

- Added `ExecutionResult.attempt_chain` for structured fallback trace persistence.
- Recorded fallback attempt chains in workflow completion/result events.
- Projected fallback attempts into Textual work package detail data.
- Added fallback attempt count/details to deliberation reports.
- Updated analysis docs to mark the implemented P2 observability path.

## Behavior

- A single successful owner execution keeps `attempt_chain` empty.
- If the owner attempt fails or blocks and a fallback agent succeeds, the final result stores every attempt in order.
- If every fallback attempt fails or blocks, the aggregate failed result stores the full attempt chain.
- Each attempt entry includes `agent`, `status`, `summary`, `blockers`, and `raw_response_path`.
- Work Package detail modals can show the fallback reason and raw artifact path without loading the raw artifact body.
- Report markdown shows attempt count in the execution table and a detail section for packages with fallback attempts.

## Validation

```bash
PYTHONPATH=src python3 -m py_compile \
  src/trinity/workflow/models.py \
  src/trinity/workflow/execution.py \
  src/trinity/workflow/engine.py \
  src/trinity/textual_app/workflow_controller.py \
  src/trinity/tui/session.py \
  src/trinity/textual_app/snapshot.py \
  src/trinity/textual_app/widgets/work_package_detail_modal.py \
  src/trinity/tui/report.py \
  tests/test_execution_protocol.py \
  tests/test_report.py \
  tests/test_textual_snapshot.py
# passed

PYTHONPATH=src .venv/bin/python -m pytest \
  tests/test_execution_protocol.py \
  tests/test_report.py \
  tests/test_textual_snapshot.py -q
# 72 passed

PYTHONPATH=src .venv/bin/python -m pytest \
  tests/test_textual_workflow_controller.py \
  tests/test_tui_session.py \
  tests/test_textual_app.py -q
# 238 passed

PYTHONPATH=src .venv/bin/python -m pytest \
  tests/test_workflow_engine.py \
  tests/test_workflow_persistence.py -q
# 71 passed

PYTHONPATH=src .venv/bin/python -m pytest \
  tests/test_execution_protocol.py \
  tests/test_report.py \
  tests/test_textual_snapshot.py \
  tests/test_textual_workflow_controller.py \
  tests/test_tui_session.py \
  tests/test_textual_app.py -q
# 310 passed
```
