smriti ask: RAG over full work history

[ashu17706]

What

A question-answering command over the entire work history. Unlike smriti recall (keyword/semantic search returning snippets), smriti ask takes a natural language question and synthesizes a grounded answer from past sessions.

smriti ask "why do we use post-filtering for vector search?"
smriti ask "how do we handle rate limiting in our APIs?"
smriti ask "what's the best approach for smriti's team sharing?"
smriti ask "when did we last work on the ingest pipeline?"

Pipeline

question
  → expandQuery()               # generate retrieval queries
  → multi-angle recall          # FTS + vec per sub-query
  → rerank(question, results)   # score relevance to question
  → top-5 sessions              # with citations
  → Ollama synthesis            # grounded answer with session references

Output:

We use post-filtering for vector search because sqlite-vec's virtual
tables hang when combined with JOIN queries (discovered March 14, smriti
session abc123). The fix: run vectors_vec unfiltered (3x overfetch),
then filter results in a separate batch lookup.

Sources:
  [1] abc123 — Vector search with filters: post-filter approach (Mar 14)
  [2] def456 — Two-step vector query pattern (Feb 27)

Difference from smriti recall --synthesize

	recall --synthesize	ask
Input	Keyword/topic	Natural language question
Retrieval	Single search	Multi-angle via expandQuery
Ranking	RRF only	RRF + rerank
Output	Summary of what was found	Answer to question + citations

Why

recall is a lookup tool. ask is a reasoning tool. It closes the gap between "I know roughly what I'm looking for" and "I have a question and need an answer."

Prerequisite: #58 (Phase 3), #59 preferred (Phase 4 for best quality)

Acceptance Criteria

• smriti ask "question" command works end-to-end
• Answer includes session citations with IDs and dates
• --json flag returns structured output (answer + sources array)
• --no-synthesize returns ranked sources only (no Ollama call)
• Graceful fallback when Ollama unavailable (returns sources only)

[ashu17706]

Implemented and committed on the dev branch.