EPIC: Search and retrieval (VS-4)

[kmosoti]

Outcome

The app can retrieve source-grounded context through lexical, vector, graph, and learner-state channels.

Scope

• SQLite FTS5
• Lexical search service
• Vector backend adapter and first implementation
• NetworkX graph traversal
• Hybrid retriever
• Context packer

Source Docs

• docs/01-requirements.md: Retrieval
• docs/02-architecture-mermaid.md: Retrieval Flow

Done When

• Lexical search returns source spans.
• Vector search works behind an adapter.
• Graph expansion is bounded by depth and node count.
• RetrievedContext includes source spans, concepts, outcomes, and learner flags.