Mnemolis v3.55.0

[3.55.0]

Added — Grounded Answer Synthesis (opt-in, off by default)

Mnemolis retrieves; until now it never answered. Every response was source text — a truncated Kiwix article, a scored web-result list, a fused blob of [SOURCE — DESCRIPTION] sections — and turning that into an answer was the client's job. That's fine for Open WebUI and Claude Desktop; it's bad for the voice pipeline, where HA's TTS reads fused headers and headline excerpts aloud while the Beast's 4090 sits one hop away doing nothing but routing.

New synthesize=true on /search (and the MCP search tool) has the local LLM compose a short, grounded answer from the retrieved material only, returned in a separate answer field alongside the raw result — never instead of it. answer_style ∈ {voice, brief, detailed} controls length (voice ≈ ≤2 sentences for TTS). See the new Answer-Synthesis.md wiki page and Design Doc 4.

The whole feature is additive by contract. With SYNTHESIS_ENABLED false (the default for this release) or any request that doesn't opt in, the response is byte-identical to v3.54.2 and the three new fields (answer/answer_sources/synthesized) are null/[]/false. Any failure — timeout, empty reply, gate rejection, LLM unconfigured — yields answer: null plus a synthesis_skipped/synthesis_rejected explanation event, leaving the caller with exactly today's raw result.

Grounded or silent, enforced by gates, not hope. Synthesis runs in route_query() after retrieval, inside the same _ROUTE_STATS context so its events join the explanation chain. Pre-flight skips the LLM call entirely for empty/error results, sub-200-char results (a one-line "Front Door: locked" is already the ideal voice answer — this exempts most ha/uptime traffic), and changes output (already prose). The generation then passes a stack of gates: empty-reply rejection; the honest NOT_IN_SOURCES → "The retrieved sources don't answer this." success path; attribution parse (multi-source answers that can't say who said what are rejected); echo guard; a numeric-grounding check (every number in the answer must appear in the material after comma-normalization, the current year exempted — a miss rejects and logs the offending token at WARNING, the live-verification hook); and a sentence-boundary length backstop per style.

Details worth noting:

• Header parsing reuses fusion.HEADER_PATTERN/HEADER_SEPARATOR — exported from fusion.py, not re-derived — so a header-format change can't drift the synthesis parser away from the producer (the _looks_empty() cross-file-drift bug is the cautionary tale; a drift test pins the contract).
• New llm.generate() path, deliberately separate from complete(): complete()'s trailing-period stripping and last-line-of-thinking salvage are correct for one-token routing picks but actively wrong for a real answer, so generate() returns an empty response honestly as None (gate 1 rejects) rather than salvaging ungrounded chain-of-thought.
• Synthesized answers cache under a source-led key so they inherit the underlying source's TTL and can never outlive the retrieval they ground; the NOT_IN_SOURCES miss is never cached (the Cached Failure Bug found three times).
• /logs/stats gains a synthesis block from a new nullable synthesized status column (migration-safe guarded ALTER TABLE); Locust gains a dedicated [synthesize] bucket so the added generation cost shows honestly against [auto], not smeared into it.

Changed

• Version bumped to 3.55.0. Test suite: 1508 passing (from 1453 at v3.54.2), ruff clean. New config: SYNTHESIS_ENABLED, SYNTHESIS_TIMEOUT_SECONDS, SYNTHESIS_MODEL, SYNTHESIS_INPUT_BUDGET_CHARS, SYNTHESIS_MIN_INPUT_CHARS, SYNTHESIS_MAX_CHARS, SYNTHESIS_VOICE_MAX_CHARS.