- Plexer: always-active terminal multiplexing. NativePlexerController/ TmuxPlexerController share one interface, chosen by which env var is already set (TAI_PLEXER_SOCKET vs TMUX_PANE); NativePlexerBackend is the pty.fork()-based wrapper (raw mode, SIGWINCH resize forwarding, a Unix-socket control protocol, continuous session logging, a Ctrl+A prefix key distinct from tmux's own Ctrl+B). Auto-wraps new interactive shells via a .bashrc hook mirroring the existing command-not-found install pattern, gated on $TMUX/$TAI_PLEXER_ACTIVE/ a $HOME/.tai-no-plexer bypass. New plexer_send/read/type/status tools, env-gated on a detected controller. - tests/container.py + docker-compose.yml + tests/docker/Dockerfile: a disposable podman/docker image for the tests that must never touch a real machine (installing the plexer hook into a real ~/.bashrc, a live tmux session). Required suite (test_seal.py, test_tai.py, tests/plexer.py, tests/bashrc.py) gates the result; tests/rag.py runs as best-effort since its real-LLM dependency can't be satisfied inside a disposable container with no nested engine. - tests/bashrc.py: real end-to-end hook install + bash -i auto-wrap, anti-recursion, tmux-active skip, non-interactive skip, a live TmuxPlexerController test, and an install/uninstall round-trip. - tests/plexer.py: NativePlexerBackend under a real pty, plus a dedicated robustness pass (file permissions, >64KB payload framing, a malformed control request, a genuine self-deadlock fix in the write-to-child path). - tai_test.py: the shared async process-driving framework (pipe/pty transport, group-wide kill-and-reap, a StdinBridge for --interactive) both test files build on. - ChatClient last-resort backend: when there's no local opencode CLI but the sandbox box is already running, install opencode into it (official Node tarball, not apt -- apt's nodejs/npm pull in webpack/babel/jest as transitive deps) and route through it instead of giving up. Only reachable after the first retry round already failed everything else; never creates the box itself. TmuxPlexerController.status() fixed to use `list-panes` instead of `display-message -p`, which silently fell back to the default pane instead of erroring against a dead target. - Fix 4 pre-existing test_tai.py bugs surfaced by running it in a clean environment for the first time: two stale mock signatures (subprocess.run's stdout= kwarg, Chat.complete's deadline= kwarg), one $TMUX-dependent catalog assertion, one tty-dependent color assertion. - research/: a sourced research archive (Source Dossier/Citation Card/Conclusion tiers) backing the above design decisions, with its own audit.py consistency checker. - .gitignore: fix a blanket *.md rule that was about to silently drop the entire research/ archive from version control; add __pycache__/ and the one-off debug transcript this session started from. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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novel-rag: Hybrid BM25 + Dense Retrieval over SQLite FTS5 + sqlite-vec
Metadata
| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | sqlite-rag-hybrid-search |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | novel-rag: Hybrid BM25 + dense retrieval (RAG) over a fiction library -> SQLite FTS5 + sqlite-vec, fused with Reciprocal Rank Fusion, with a Hit@K/MRR eval harness |
| Source URL | https://github.com/Rohit-rockan/novel-rag |
| Source publisher / author | GitHub user Rohit-rockan |
| Source type | repository |
| Source date (published) | Unknown — not stated |
| Date researched | 2026-10-09 |
| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
| Research method | web search synthesis |
| Confidence | Medium |
| Status | Active |
Summary
A personal/hobby RAG project that retrieves passages from a fiction library using a hybrid pipeline: SQLite FTS5 for lexical (BM25) search, sqlite-vec for dense vector search, the two fused with Reciprocal Rank Fusion, evaluated with a Hit@K / MRR harness over the fiction corpus.
Key findings
- Demonstrates the "SQLite FTS5 + sqlite-vec + RRF" pattern as something an individual developer can assemble without a dedicated vector database service.
- Explicitly builds an evaluation harness (Hit@K, MRR) rather than shipping the hybrid design untested — a methodological point worth noting independent of the specific repo's code quality.
- Confirms RRF (not score-weighted fusion) is a viable, implementable choice for fusing a lexical and a dense ranking from the same SQLite file.
Pros / strengths
- Concrete, runnable existence proof that the FTS5+sqlite-vec+RRF combination works end-to-end in a single SQLite file, which is the architecture family this project's "tai" vault already resembles (FTS5 is already in use).
- Including an eval harness is a good practice signal — the repo isn't just claiming the hybrid approach works, it measures it.
Cons / limitations / caveats
- A single hobby/personal repository, not a peer-reviewed or widely-adopted reference implementation; no independent confirmation of the eval numbers was found during this research pass.
- No information was gathered on its actual Hit@K/MRR results, chunking strategy, or RRF constant (k) choice — only the high-level architecture description was available from the search result.
- "Fiction library" is a narrow, favorable domain for lexical search (named characters, specific phrases) and may not generalize to the kind of operational/log text
taineeds to search.
Relevance to tai
Served as the first concrete evidence, early in this research pass, that "SQLite FTS5 + vector extension + RRF" is a real, assembled pattern other developers use for local-first RAG — this grounded the initial (later superseded) proposal to give tai a hybrid BM25+vector search layer. See conclusions/no-vectors-bm25-chunked-rag.md for why that proposal was ultimately not adopted.
Changelog
| Date | Change |
|---|---|
| 2026-10-09 | Initial dossier created. |