---
phase: 01-foundation
plan: 01-01
subsystem: database
tags: [lancedb, pydantic, vector-db, embeddings, schema]

# Dependency graph
requires: []
provides:
  - "ChunkRecord LanceModel schema for vector storage"
  - "make_chunk_id() deterministic hash helper"
  - "768-dim vector support for nomic-embed-text"
  - "Idempotent upsert via merge_insert key"
affects:
  - "01-foundation"  # Future tasks in this phase will use the schema
  - "02-ingest"      # Ingestion will create ChunkRecords
  - "03-query"       # Query will read from chunks table

tech-stack:
  added:
    - "lancedb - Vector database with LanceModel pydantic integration"
  patterns:
    - "LanceModel pydantic schema for type-safe vector records"
    - "Deterministic ID generation via sha256 for idempotent operations"
    - "Schema-driven test design (vector dim from schema, not hardcoded)"

key-files:
  created:
    - "src/corpus_analyzer/store/schema.py"
    - "tests/store/test_schema.py"
  modified:
    - "src/corpus_analyzer/store/__init__.py"
    - "tests/store/__init__.py"

key-decisions:
  - "Vector dimension 768 fixed for nomic-embed-text (changing requires table rebuild)"
  - "chunk_id as sha256 of source_name + file_path + start_line + text for idempotent upserts"
  - "indexed_at stored as ISO8601 string (not datetime) to avoid pyarrow coercion issues"
  - "embedding_model stored per-chunk for model mismatch detection at query time"

patterns-established:
  - "TDD cycle: RED (tests first) → GREEN (implementation) → REFACTOR (docs/cleanup)"
  - "LanceModel with comprehensive field annotations and docstrings"
  - "Type: ignore for lancedb (untyped library) with specific error codes"

requirements-completed:
  - "CONF-02"
  - "INGEST-04"
  - "INGEST-06"

# Metrics
duration: ~15min
completed: 2026-02-23
---

# Phase 01-foundation: Plan 01-01 Summary

**LanceDB ChunkRecord schema with 768-dim vector support and deterministic sha256 chunk_id for idempotent upserts**

## Performance

- **Duration:** ~15 min (verification pass)
- **Started:** 2026-02-23T15:09:00Z
- **Completed:** 2026-02-23T15:24:00Z
- **Tasks:** 6
- **Files modified:** 2

## Accomplishments

- ChunkRecord LanceModel with 11 fields (chunk_id, file_path, source_name, text, vector, start_line, end_line, file_type, content_hash, embedding_model, indexed_at)
- Vector(768) dimension fixed for nomic-embed-text embeddings
- make_chunk_id() helper generating deterministic sha256 from source_name + file_path + start_line + text
- Complete test coverage (17 tests) for determinism, uniqueness, field validation, and vector dimension checks
- Full type annotations and comprehensive docstrings

## Task Commits

Files were already implemented and verified:

1. **Tests verification** - All 17 tests passing (pytest)
2. **Type checking** - mypy passes with type: ignore for lancedb
3. **Linting** - ruff passes with no issues

## Files Created/Modified

- `src/corpus_analyzer/store/schema.py` - ChunkRecord LanceModel + make_chunk_id() helper
- `tests/store/test_schema.py` - 17 comprehensive TDD tests
- `src/corpus_analyzer/store/__init__.py` - Package marker (empty)
- `tests/store/__init__.py` - Package marker (empty)

## Decisions Made

- Added `type: ignore[import-untyped]` for lancedb.pydantic import (library lacks stubs)
- Added `type: ignore[misc]` for LanceModel subclass (has type Any)
- Followed schema-driven test design: tests reference Vector(768) from schema, not hardcoded number

## Deviations from Plan

None - plan executed exactly as written. Files were already implemented per the plan specification.

## Issues Encountered

- mypy initially failed on lancedb imports (missing stubs) - fixed with targeted type: ignore comments

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Schema foundation complete, ready for table creation and data ingestion
- ChunkRecord can be instantiated and validated
- make_chunk_id() ready for generating merge keys during indexing

---

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