---
id: T02
parent: S01
milestone: M001
provides:
  - LLM output models (TrafficAnalysis, SecurityAssessment, PolicyProposal, RuleDecision) for pipeline stages
  - PipelineState TypedDict for LangGraph state management
  - Complete exception hierarchy (9 classes) for structured error handling
requires: []
affects: []
key_files: []
key_decisions: []
patterns_established: []
observability_surfaces: []
drill_down_paths: []
duration: 4min
verification_result: passed
completed_at: 2026-03-08
blocker_discovered: false
---
# T02: 01-project-foundation 02

**# Phase 1 Plan 2: Pipeline Models and Exception Hierarchy Summary**

## What Happened

# Phase 1 Plan 2: Pipeline Models and Exception Hierarchy Summary

**LLM output models (TrafficAnalysis, SecurityAssessment, PolicyProposal, RuleDecision), PipelineState TypedDict for LangGraph, and 9-class exception hierarchy with structured error context**

## Performance

- **Duration:** 4 min
- **Started:** 2026-03-08T15:50:19Z
- **Completed:** 2026-03-08T15:54:18Z
- **Tasks:** 3
- **Files modified:** 7

## Accomplishments
- Implemented 4 LLM output models with Pydantic validation (non-negative counts, confidence 0.0-1.0, RiskLevel enum)
- PolicyProposal nests UniversalRule from adapters module proving cross-module import chain works
- PipelineState TypedDict with total=False stores flow log references as strings (not raw data) for LangGraph checkpoint compatibility
- 9-class exception hierarchy with PolicyFoundryError base carrying optional error_code and details dict
- 48 total tests passing, Pyright strict clean, Ruff clean

## Task Commits

Each task was committed atomically:

1. **Task 1: Pipeline LLM output models with tests** - `22ad56c` (feat)
2. **Task 2: PipelineState TypedDict with tests** - `970a7a8` (feat)
3. **Task 3: Exception hierarchy with tests** - `1939085` (feat)

_Note: TDD tasks combined RED+GREEN into single commits for atomicity_

## Files Created/Modified
- `src/policyfoundry/pipeline/schema.py` - TrafficAnalysis, SecurityAssessment, PolicyProposal, RuleDecision Pydantic models
- `src/policyfoundry/pipeline/state.py` - PipelineState TypedDict for LangGraph state management
- `src/policyfoundry/exceptions.py` - 9-class exception hierarchy with structured error context
- `tests/test_models/test_pipeline_schema.py` - 10 tests for LLM output model validation
- `tests/test_models/test_pipeline_state.py` - 6 tests for PipelineState TypedDict behavior
- `tests/test_exceptions/__init__.py` - Test package init
- `tests/test_exceptions/test_exceptions.py` - 10 tests for exception hierarchy, defaults, and catch-by-parent

## Decisions Made
- Used `list[dict]` with `# type: ignore[type-arg]` for flexible LLM output fields -- Pyright strict requires type args on dict but LLM outputs are unstructured JSON
- PipelineState uses `typing.TypedDict` (not typing_extensions) with `total=False` so partial state construction is valid during pipeline execution
- Exception `details` defaults to `{}` (not None) so callers can safely access `.details` without None checks

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Ruff lint violations in test files**
- **Found during:** Task 3 (overall verification)
- **Issue:** Line too long in docstrings (E501), unsorted imports (I001), runtime import in type-only context (TC001)
- **Fix:** Shortened docstrings, auto-fixed import sorting with ruff, moved PipelineState import to TYPE_CHECKING block with `from __future__ import annotations`
- **Files modified:** tests/test_exceptions/test_exceptions.py, tests/test_models/test_pipeline_schema.py, tests/test_models/test_pipeline_state.py
- **Verification:** `uv run ruff check src/ tests/` passes with "All checks passed!"
- **Committed in:** 1939085 (part of Task 3 commit)

---

**Total deviations:** 1 auto-fixed (lint cleanup)
**Impact on plan:** Necessary for passing verification. No scope creep.

## Issues Encountered
None - all tasks executed smoothly after auto-fixes.

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- All Phase 1 foundation models complete: NormalizedFlowLog, UniversalRule, TrafficAnalysis, SecurityAssessment, PolicyProposal, RuleDecision
- PipelineState TypedDict ready for LangGraph integration in Phases 6-7
- Exception hierarchy ready for structured error handling across all phases
- 48 tests green, Pyright strict clean, Ruff clean
- Phase 2 (Configuration System) can proceed

## Self-Check: PASSED

All 7 key files verified present. All 3 commits verified in git log.

---
*Phase: 01-project-foundation*
*Completed: 2026-03-08*
