v0.33.2.0 feat(search-lite): token budget + semantic query cache + intent weighting

[garrytan-agents]

What

Three additive search features inspired by brain-kit. All backward-compatible: existing callers see identical behavior unless they opt in to the new options.

1. Token Budget Enforcement (src/core/search/token-budget.ts)

Cap the cumulative token cost of returned results so search payloads fit downstream context windows. Greedy top-down walk; preserves caller ordering; no re-rank. char/4 heuristic for token counting (no tokenizer dependency — keeps the bun --compile bundle small).

• SearchOpts.tokenBudget — numeric cap. Default undefined = no-op.
• HybridSearchMeta.token_budget = { budget, used, kept, dropped }
• HTTP query op: pass token_budget param.

2. Semantic Query Cache (src/core/search/query-cache.ts + migration v52)

Cache search results keyed by query embedding similarity. HNSW lookup: embedding <=> $1 < 0.08 (cosine similarity ≥ 0.92). Per-source isolation. Per-row TTL (default 3600s). Best-effort writes; all errors swallowed so the cache never breaks the search hot path.

• Migration v52 creates query_cache table. HALFVEC where pgvector ≥ 0.7; VECTOR otherwise. Embedding dim resolved from config.embedding_dimensions so non-OpenAI brains work.
• New gbrain cache CLI: stats / clear --yes / prune.
• Config keys: search.cache.enabled / search.cache.similarity_threshold / search.cache.ttl_seconds.
• HybridSearchMeta.cache = { status, similarity?, age_seconds? }
• Routed through new hybridSearchCached(engine, query, opts) wrapper. The query op in operations.ts now uses this wrapper so MCP/CLI calls benefit automatically. Skipped for two-pass walks + non-default embedding columns where cache semantics don't hold.

3. Zero-LLM Intent Weighting (src/core/search/intent-weights.ts)

Builds on the existing 4-intent classifier (src/core/search/query-intent.ts). New weight-adjustment layer applies subtle per-intent nudges:

Intent	Adjustment
entity	boost keyword RRF + exact slug/title match boost
temporal	default recency='on' when caller left it unset
event	boost keyword RRF (rare named entities) + soft recency
general	no-op (1.0 multipliers)

All adjustments are subtle (max 1.25×). Caller-explicit options always win — intent weighting never silently overrides explicit recency / salience. Default ON; opt out via opts.intentWeighting = false. The LLM query expansion path is still available and opt-in via opts.expansion = true — it just isn't the default anymore.

HybridSearchMeta.intent now surfaces classifier output for debugging.

Files changed (13)

 src/cli.ts                                |  +13 -1
 src/commands/cache.ts                     | +106 NEW
 src/core/migrate.ts                       | +104 NEW (migration v52)
 src/core/operations.ts                    |  +11 -2
 src/core/search/hybrid.ts                 | +281 -7
 src/core/search/intent-weights.ts         | +132 NEW
 src/core/search/query-cache.ts            | +321 NEW
 src/core/search/token-budget.ts           | +110 NEW
 src/core/types.ts                         |  +57 NEW
 test/hybrid-search-lite.serial.test.ts    | +163 NEW
 test/intent-weights.test.ts               | +123 NEW
 test/query-cache.test.ts                  | +247 NEW
 test/token-budget.test.ts                 | +125 NEW

Test results

• 44 new tests pass across the 4 new test files
  • test/token-budget.test.ts — 10 tests (pure module)
  • test/intent-weights.test.ts — 13 tests (pure module)
  • test/query-cache.test.ts — 12 tests (PGLite, including migration v52 schema verification + TTL expiration + source isolation)
  • test/hybrid-search-lite.serial.test.ts — 9 tests (PGLite e2e through hybridSearchCached)
• 105 existing search tests still pass (test/search.test.ts, test/query-intent*.test.ts, test/hybrid-meta.test.ts, test/search-limit.test.ts, test/search-lang-symbol-kind.test.ts, test/search-image-column.test.ts)
• 162 tests total pass when run together (no cross-file isolation issues)
• bun run verify clean (privacy + jsonb + progress + test-isolation + wasm + admin-build + admin-scope-drift + cli-exec + system-of-record + tsc --noEmit)
• bun run src/cli.ts doctor --fast runs successfully — pre-existing resolver_health / minions_migration failures on master are unrelated to this PR.

Design notes

• Backward compat is the contract. Token budget defaults to off. Cache defaults on but cache miss = normal search. Intent weighting defaults on but adjusts weights at most 1.25× and never overrides caller-explicit options.
• No new dependencies. Token counting uses char/4 (js-tiktoken would balloon the bun --compile bundle). Migration uses the same HALFVEC/VECTOR pgvector-version probe pattern as v45 (facts) and v40, so it works on both Postgres and PGLite without extra config.
• System-of-record clean. The query_cache table is a derived cache, not authoritative state. gbrain cache clear is the documented invalidation surface; the system-of-record check passes.

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