Raise matching floor: boundary tokenizer, stemming/folding/stopwords, boosts, snippets, engine seam

AGENTS.md

@@ -5,7 +5,7 @@
 - `DESIGN.md` is the partner-facing architecture and decision log (with rationale for the spec cuts); keep it in sync when architecture decisions change.
 - `frxd` is the member node (init/add/index/serve/relay/query/status); `frx` is the thin client (search/query/status). Relay and node roles are separate subcommands.
 - `DEPLOY.md` documents the TLS/deployment story: members need no TLS (outbound HTTPS), relays terminate TLS with Caddy or a tunnel, `ca_cert` adds private CAs, `allow_insecure` opts into plain http on private networks, and non-loopback `http://` is refused by default.
-- Commands: `cargo build`, `cargo test` (99 tests: unit in `src/`; e2e `tests/phase1.rs`; conformance `tests/conformance.rs`; aggregates + member directory `tests/aggregates.rs`; registry `tests/registry.rs`; federation/isolation/admission `tests/federation.rs`; SSE `tests/streaming.rs`; encrypted unicast `tests/encryption.rs`; concurrency/restart `tests/concurrency.rs`; real subprocess CLI `tests/cli.rs`; 1000-doc `tests/scale.rs`; purge-log absence `tests/purges.rs`; shared fixtures `tests/common/mod.rs`). No CI/lint config.
+- Commands: `cargo build`, `cargo test` (100 tests: unit in `src/`; e2e `tests/phase1.rs`; conformance `tests/conformance.rs`; aggregates + member directory `tests/aggregates.rs`; registry `tests/registry.rs`; federation/isolation/admission `tests/federation.rs`; SSE `tests/streaming.rs`; encrypted unicast `tests/encryption.rs`; concurrency/restart `tests/concurrency.rs`; real subprocess CLI `tests/cli.rs`; 1000-doc `tests/scale.rs`; purge-log absence `tests/purges.rs`; shared fixtures `tests/common/mod.rs`). No CI/lint config. unit in `src/`; e2e `tests/phase1.rs`; conformance `tests/conformance.rs`; aggregates + member directory `tests/aggregates.rs`; registry `tests/registry.rs`; federation/isolation/admission `tests/federation.rs`; SSE `tests/streaming.rs`; encrypted unicast `tests/encryption.rs`; concurrency/restart `tests/concurrency.rs`; real subprocess CLI `tests/cli.rs`; 1000-doc `tests/scale.rs`; purge-log absence `tests/purges.rs`; shared fixtures `tests/common/mod.rs`). No CI/lint config.
 - E2E pattern: relay + nodes in-process on ephemeral ports with tempdir corpora; use `tests/common/mod.rs` helpers (`spawn_relay*`, `query_envelope`, `poll_messages`, `register`) for new coverage. Raw relay polls return envelopes (payload under `body`), not response bodies.
 
 ## Editing the spec
@@ -48,5 +48,7 @@
 - Language: Rust (settled, matches §7). Decided by the engine requirement, not preference: Tantivy gives in-process Lucene-class BM25 + incremental indexing; C/C++ embedded alternatives are worse (Xapian GPL-2+, CLucene unmaintained, SQLite FTS5 thin), plus single static musl binaries for the install story and memory safety on the untrusted network/crypto path. Don't re-litigate.
 - frxd modes (one binary, config toggles, no code required of publishers): querier (broadcast/local-first search), responder (match incoming queries against shared collections, sign), local index (watch dirs, extract text, explicit shared marking per I9). Use RFC terms querier/responder, not "subscriber/publisher".
 - Roles are not exclusive: a single node may issue queries and answer them concurrently (I5, §3 "any member"). Implement querier/responder as independent enable flags — never an exclusive mode enum or fixed deployment role.
-- Matching accuracy is a project-health concern: the cheap lexical gate is implemented (`[match] min_coverage`, default 0.4; queries of one or two terms require all of them, longer queries require a coverage fraction via OR-of-ANDs) after a demo false positive ("internal launch codes" matching "error codes"). Next stage is an optional local embedding rerank behind the gate; the model stays local and replaceable (I2/I5). Re-measure precision with a real corpus before tuning the threshold.
+- Matching floor: boundary tokenizer (`src/tokenizer.rs` — letter/digit splits so `5555` matches `DLEX5555`, lowercase, ASCII fold, English stopwords+stemmer) → coverage gate (`[match] min_coverage`, default 0.4; 1–2 term queries require all terms) → title boost 2.0 + phrase boost 3.0 + query-time snippets. Schema changes require a fresh index dir (`open_or_create` errors on mismatch).
+- Engine seam: `src/engine.rs` `SearchEngine` trait (`search` → `EngineOutput { hits, total: Option<u64> }`, `doc_count`); `respond()` in `src/node.rs` is the conformance wrapper (budget clamp, truncation from engine total — unknown total forces `truncated = true`). Power users can implement the trait (HTTP adapter or subprocess to an external engine).
+- Next matching steps: eval harness with a small golden set (precision@k + false-silence rate), then a dense recall leg (model2vec-rs 0.2.1 exists but needs `default-features = false, features = ["fancy-regex", "local-only"]` for musl/airgapped; verify crate + model licenses before bundling), then an optional cross-encoder reranker. Embeddings are for recall; reranking is the precision tier.
 - Identity/registry (RFC Draft 0.5 §4/§6): MA-hosted FQDN identifiers first (`<label>.frx.<ma-domain>`, no DNS needed by users), signed versioned registry snapshot with the MA key pinned; envelope `from` = identifier, `key` = pubkey; registry outage fails static. Member-hosted identities, MA anchor rollover, and unicast confidentiality are §10 open. Implementation phases: A (signed registry snapshot) and B (identifier + `key` + JCS on the wire) are built and tested. Prioritize frictionless onboarding (users may be department-level and cannot create DNS).