SurfSense/docs/adr

Architecture decision records

Each file here records one decision and the reasons for it: the why behind what architecture/ describes. An accepted ADR is not rewritten. When a decision changes, a new ADR supersedes the old one, and the only edits an accepted ADR takes are its Status line, which becomes "Superseded by" with a link to the new record (or, when only part is superseded, names that part and the record that supersedes it), and fixes to its links.

Adding one

Take the next free number. Add the record in the same pull request as the change it decides, or with the proposal that makes it. Use this shape and keep it short:

# ADR NNNN: <the decision, stated as a sentence>

- **Status:** Accepted
- **Date:** YYYY-MM-DD
- **Supersedes:** <only if it does>
- **Source:** [<short name> L<a>–<b>](<permalink>)

## Context
<the problem and the constraints that forced a choice>

## Decision
<the choice, precisely; bullets are fine>

## Consequences
<what it makes true, what it costs, what it rules out>

## Where the code stands
<only when the code does not fully hold the decision; state the gap plainly, citing file paths>

The Date is the day the decision was first written down. Source links are permalinks to a fixed commit, so they keep working after the file they point at moves or is deleted.

Numbering

0001 and 0002 were hosted-era records about the git-native knowledge base. They were deleted on 17 Sep 2026 in commit 35c83caa8, and their numbers are retired. 0003 was written for the hosted stack and restored for the desktop app.

Index

Number	Title	Status
0003	Generated deliverables are a document type, not a second corpus	Accepted
0004	The desktop app is its own tree on FastAPI, SQLite and Huey, with no accounts	Accepted, in part superseded by 0035
0005	Schema changes are hand-written Alembic revisions that the API applies at startup	Accepted
0006	Retrieval widens recall with FTS5 and sqlite-vec, then orders the union by cosine similarity	Accepted, the ordering decision superseded by 0031
0007	Embeddings come from a bundled bge-small model run in process on the CPU	Accepted, amended by 0036
0008	Ingest and Studio jobs run on separate Huey queues, each drained by its own worker	Accepted
0009	The UI stays fresh by invalidating queries on server-sent events, with no sync engine	Accepted
0010	Studio models emit structured content and trusted builders render it, so no model-written code runs	Accepted, in part superseded by 0028
0011	llama-server in router mode is the one local model runtime	Accepted, in part superseded by 0026 and the model catalog proposal
0012	The GPU backend is Vulkan everywhere off Apple Silicon, with no CUDA payload	Accepted, for Docker images superseded by 0035
0013	Model fit comes from the allocator's view of one device, and only physics refuses an install	Accepted
0014	The model catalog is a curated offline manifest plus Hugging Face search, and SurfSense downloads the files itself	Accepted, in part superseded by 0026, 0027 and the model catalog proposal
0015	Remote models come through named OpenAI-compatible connections, discovered live	Accepted, in part revised by the model catalog proposal, in part superseded by 0038
0016	The app sends no telemetry or crash reports	Accepted
0017	Every outbound destination is off until the user allows it	Accepted, in part superseded by 0027
0018	Provider keys are encrypted with a per-install secret kept in the OS keychain	Accepted
0019	Licenses are signed files verified offline, and they gate only plugins and priority support	Accepted
0020	The new app and the legacy app share one release feed and are kept apart by update channel	Accepted
0021	There is no Intel Mac build	Accepted
0022	Hosted accounts move to the app as a markdown-only export that is re-embedded locally	Accepted
0023	Every hosted sunset behaviour sits behind a runtime flag, and nothing is deleted or redirected unconditionally	Accepted
0024	The license portal has no accounts and no license tables; Stripe and Keygen are the system of record	Accepted
0025	The hosted scraper API client ships as a paid plugin whose source lives in this repo	Accepted, in part superseded by 0047
0026	Curated models are ordered by their position in the manifest, with no score	Accepted, in part revised by the model catalog proposal
0027	Egress consent is per host, so model search and downloads share one	Accepted
0028	Model-written code may run on the user's machine without a sandbox, and the agent asks before each shell command	Accepted, in part superseded by 0039
0029	Interface text lives in ICU MessageFormat catalogs, one flat JSON file per language	Accepted
0030	FormatJS renders interface text from precompiled, bundled catalogs, with no network at build or run time	Accepted
0031	Ranking blends the two legs on absolute scales, keyword strength being term coverage rather than BM25	Accepted, amended by 0032 and 0033
0032	The index and the question are split by one tokenizer, FTS5's own, and it keeps a word's combining marks	Accepted
0033	Every candidate is scored on its own cosine, because a chunk the vector leg did not reach is unmeasured rather than unrelated	Accepted
0034	Whether a chat model reads images is llama.cpp's own answer for a local model and the catalog's for a remote one, and it is stored nowhere	Accepted
0035	The desktop app's stack also ships as one Docker container, with Caddy as its only listener	Accepted
0036	The index records which embedder built it, and the embedder is fixed once per install	Accepted
0037	Curated embedders are a fourth engine in the local catalog, and embedding is a type, never a slot	Accepted
0038	A ChatGPT plan is a connection signed in through OpenAI's open-source flow, not the Codex CLI's client	Accepted, its request body superseded by 0050
0039	Model-written document scripts run without approval in SurfSense's script runner, and the agent's general shell is off	Accepted
0047	SurfSense's paid plugins are source-available under the Business Source License and unlocked by the SurfSense license	Accepted, in part to be superseded by 0054
0048	The API is the only path to a text model, so one gate can count everything that generates	Accepted
0049	A prompt changes only at its end, so the cached start of it is never read again	Accepted
0050	A remote text model answers on the route its manifest entry records, with its connection's credential, and SurfSense owns a ChatGPT plan's sign-in for both engines	Accepted
0051	A plugin is an MCP server, and SurfSense decides which of its tools each caller gets, remote servers first	Proposed
0052	The chat engine's model never calls tools; SurfSense chooses a plugin tool through structured output and calls it	Proposed, deferred
0053	First-party plugins are listed in the app, third-party plugins in a registry in this repository, and third-party plugins start off	Proposed
0054	SurfSense's own plugins, free and paid, run on one plugin host, with the registry served beside it	Proposed