---
phase: 01-foundation
plan: 01-02
subsystem: config
tags: [pydantic, toml, config, corpus.toml, validation]

# Dependency graph
requires: []
provides:
  - "CorpusConfig Pydantic model with embedding and sources"
  - "EmbeddingConfig with nomic-embed-text defaults"
  - "SourceConfig with include/exclude glob patterns"
  - "load_config() TOML reader with defaults for missing files"
  - "save_config() TOML writer with parent dir creation"
affects:
  - "01-foundation"  # CLI will use config
  - "02-ingest"      # Ingestion uses sources from config
  - "03-index"       # Indexing uses embedding config

tech-stack:
  added: []
  patterns:
    - "Pydantic BaseModel for configuration validation"
    - "TOML I/O with tomllib/tomli_w"
    - "Round-trip config serialization"
    - "Default config when file doesn't exist"

key-files:
  created:
    - "src/corpus_analyzer/config/__init__.py"
    - "src/corpus_analyzer/config/schema.py"
    - "src/corpus_analyzer/config/io.py"
    - "tests/config/__init__.py"
    - "tests/config/test_schema.py"
    - "tests/config/test_io.py"
  modified: []

key-decisions:
  - "Used Pydantic BaseModel (not pydantic-settings) for TOML file model"
  - "tomllib for reading (stdlib), tomli_w for writing (3rd party)"
  - "load_config returns defaults when file missing (no error)"
  - "save_config creates parent directories automatically"

patterns-established:
  - "TDD cycle: tests first, minimal implementation, verify all checks pass"
  - "Comprehensive docstrings on all classes and methods"
  - "Field default_factory for mutable defaults (lists)"

requirements-completed:
  - "CONF-01"
  - "CONF-02"
  - "CONF-03"
  - "CONF-04"

# Metrics
duration: ~12min
completed: 2026-02-23
---

# Phase 01-foundation: Plan 01-02 Summary

**Pydantic config models with TOML I/O for corpus.toml — embedding settings, source definitions, and round-trip serialization**

## Performance

- **Duration:** ~12 min
- **Started:** 2026-02-23T15:25:00Z
- **Completed:** 2026-02-23T15:37:00Z
- **Tasks:** 9
- **Files modified:** 6 created

## Accomplishments

- EmbeddingConfig with nomic-embed-text defaults (model, provider, host)
- SourceConfig with required name/path and optional include/exclude globs
- CorpusConfig root model with embedding defaults and sources list
- load_config() returning defaults when file missing, validating when present
- save_config() with automatic parent directory creation
- Full round-trip serialization preserving all data
- 18 tests covering defaults, validation errors, and I/O operations

## Task Commits

1. **RED: Schema tests** - Created tests/config/test_schema.py (6 tests)
2. **RED: I/O tests** - Created tests/config/test_io.py (8 tests)
3. **RED: Package init** - Created tests/config/__init__.py
4. **GREEN: Schema implementation** - Created src/corpus_analyzer/config/schema.py
5. **GREEN: I/O implementation** - Created src/corpus_analyzer/config/io.py
6. **GREEN: Package exports** - Created src/corpus_analyzer/config/__init__.py
7. **REFACTOR: Docstrings** - Comprehensive PEP 257 docstrings added
8. **VERIFY: Tests pass** - 18/18 tests passing
9. **VERIFY: Quality checks** - mypy clean, ruff clean

## Files Created

- `src/corpus_analyzer/config/__init__.py` - Package exports (CorpusConfig, load_config, save_config, etc.)
- `src/corpus_analyzer/config/schema.py` - Pydantic models (EmbeddingConfig, SourceConfig, CorpusConfig)
- `src/corpus_analyzer/config/io.py` - TOML load/save functions
- `tests/config/__init__.py` - Test package marker
- `tests/config/test_schema.py` - 10 schema validation tests
- `tests/config/test_io.py` - 8 I/O round-trip tests

## Decisions Made

- Used Pydantic BaseModel (not pydantic-settings) — this is a file config, not env-var config
- tomllib (stdlib) for reading, tomli_w for writing — Python 3.12+ pattern
- load_config returns defaults instead of raising — CLI can proceed without config file
- save_config creates parent directories — convenient for CLI init commands
- Field(default_factory=list) for mutable defaults — Pydantic best practice

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered

None - straightforward TDD implementation.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Config foundation complete, ready for CLI integration
- CorpusConfig can be loaded from corpus.toml or created with defaults
- Source definitions ready for file discovery and indexing

---

*Phase: 01-foundation*
*Completed: 2026-02-23*
