csf

One Go runtime. Agent work, typed tools, shared knowledge, observable experiments.

Developer preview. The first release makes no stability or compatibility promise.

Try the library · Workbench · Agent-native onboarding · Proofs · Add your code · Agent instructions · Examples · Terms · Glossary · Citation

1. Introduction

CSF — The Cerebrospinal Fluid — is the library and runtime at the centre of this repository: one Go process that composes agent sessions, typed tools, knowledge and experiment evidence around a brain and a spine. The repository front page is the overview; this page is the library's own technical guide.

CSF's current release, v0.2.3, is a developer preview. It makes no stability or compatibility promise beyond what this page states. This is a breaking integration baseline. Pin a reviewed snapshot and use the examples shipped with it. The public Go module is github.com/candacelabs/csf; this library is the package in its csf/ directory. This release does not introduce a /v2 module or claim backward compatibility for earlier experimental CSF interfaces. Human readers can find every term on this page explained in the plain-language glossary.

The brain proposes. The spine executes admitted behavior. CSF supplies the contracts and coordination that let each experiment inform the next decision.

2. Why Go: no IPC inside LITHE's CPU 0 (Housekeeping)

Figure 2 from Lim and Clites (2026) [1], arXiv:2603.07442. © the authors. Architecture inspiration: CSF coordinates the work, knowledge, and evidence around the brain and spine.

LITHE (Lim and Clites, 2026) names CPU 0 (Housekeeping) (LITHE §III-B) and treats inter-process communication (IPC) as an architectural concern (LITHE §III-C). CSF applies that framing to the coordination work inside the housekeeping layer: tools, sessions, schedules, knowledge and observation.

CSF prevents the avoidable IPC problem within this layer by composing those capabilities in one Go process. Services are Go libraries selected with functional options. They exchange typed values through function calls and coordinate concurrent work with goroutines and channels. An internal handoff needs no socket, wire serialization or separate daemon. Go's concurrency primitives let waiting on tools, storage and model calls coexist in the same runtime; contexts and explicit ownership give each operation a cancellation and cleanup path. The consumer example shows that composition.

PostgreSQL, OpenSearch, Langfuse and external model or simulator processes keep their protocol boundaries. LITHE's Brain–Spine shared-memory IPC remains a separate integration boundary. The CPU 0 mapping describes CSF's role; CPU affinity and isolation require deployment configuration.

The repository front page draws this as a CPU 0 mapping diagram, with the same boundaries.

3. Agent-native onboarding

CSF is intended to be agent-native. Alongside human-readable READMEs, it exposes an MCP server. The goal is a self-changeable MCP surface that an agent can learn, configure and extend for the consumer repository.

The intended first instruction to your agent is “Learn about CSF.” The LearnAboutCSF operation explains the pinned version's capabilities and extension points and submits the embedded guidance plus selected consumer files to the configured knowledge capability. Its first call needs no arguments. Set CSF_CONSUMER_ROOT to authorize a checkout, then select relative source paths in batches of up to 64. The response carries durable ingestion receipts with revisions and content hashes; queued receipts become searchable when the existing projection workers finish. Repeating the call is idempotent and retrieves matching indexed sources. Without knowledge configuration, the tool still explains CSF and reports that indexing is unavailable. See the configuration contract; library hosts use WithOnboarding for the same source authorization.

Copilot CLI history is an explicit opt-in source. Set CSF_COPILOT_HISTORY_SOURCE to a native history directory that the host is authorized to read; startup copies that directory into a disposable SDK home, and the live source is never opened by onboarding. Select at most 16 session IDs with copilot_session_ids in LearnAboutCSF. An empty first call does not read history. When the source is configured, the same MCP server exposes ListCopilotHistorySessions; list IDs there, then pass selected IDs to onboarding. Library hosts can call the bridge's typed ListHistorySessions method directly. Each retained document is a decoded SDK snapshot containing metadata and events. Its receipt is queued until projection workers index it, and only then can retrieval return it. The SDK transport fixture verifies resume, typed event reads and disconnect. Native acceptance with Copilot CLI 1.0.85 and SDK 1.0.11 also reads a persisted synthetic conversation without changing its source or making another model request. Real PostgreSQL/OpenSearch acceptance verifies retained history reaches the lexical search index. User history is not part of those fixtures. It guides the agent through this workflow:

1. Inspect the consumer repository and identify tooling CSF can take over.
2. Adopt CSF through its Bazel dependency, required environment settings and optional capabilities, keeping consumer integration code minimal.
3. Extend that same MCP server with the consumer's own tools: define their contracts, implement their behavior and expose them alongside CSF's tools.
4. Discover and call the resulting tools, run the consumer's checks and retain evidence that the integration works.

The aim is broad, mostly implicit dependence on CSF: it handles more underneath the consumer, and improvements arrive through CSF upgrades with minimal changes to consumer code. The agent can continue adapting its integration and adding tools as the repository's needs change.

Current status: the MCP server, agent configuration tools, typed consumer registration (WithMCPTool[In, Out]) and the onboarding operation exist. Consumer registration uses the pinned MCP SDK to derive and validate schemas, and rejects name collisions with CSF operations. The host still owns listener startup, authentication, repository authorization and consumer checks.

4. Proofs, not just hardware

LITHE bounds a model-written controller with hardware: its user-space real-time design "lacks the formal mathematical guarantees of a verified real-time operating system" (LITHE §V-A), and where control theory is unvalidated, "safety must be enforced via strict hardware-level limits on torque and velocity" (LITHE §V-C). CSF's direction is the complementary guarantee: a typed, bounded controller language whose compiled code is proved to compute what its source says, so a model chooses among checked options instead of emitting arbitrary code.

examples/proof/BrainSpine.lean models the arithmetic slice of brainspine.proto and machine-checks four theorems about that bounded model:

bash csf/examples/proof/check.sh runs the pinned Lean release with --trust=0 and admits only Lean's standard propext, Classical.choice and Quot.sound axioms. What is not proved: agreement between the Lean model and the canonical wire semantics (a reviewed translation boundary), any controller implementation (CSF ships none: the low-level spine is external and ROS-side, reached through ipc/ros), and csfc itself — its Lean verifier is a stub that returns notImplemented. The actuator clamp proves a numeric range only; timing, stability, collision avoidance, safe controller switching and physical safety remain outside every theorem.

5. System diagrams

These diagrams are generated, not hand-maintained. The shared architecture model also produces the human dictionary; its syntax is specified in EBNF. The OCaml documentation compiler checks identifiers, references and the declared graph before rendering. Separate architecture checks inspect selected Go ownership/process boundaries. These checks establish their stated source constraints, not runtime timing or physical safety.

Solid connections are existing components or configurable integrations. Dotted connections are planned. An integration shown here still needs its dependencies and configuration; it is not automatically running when you import CSF.

%% Generated from csf/compiler/language/architecture.csf; do not edit.
%% Documentation model only; status labels do not establish runtime verification.
flowchart TB
  classDef csf_existing fill:#0F766E,stroke:#115E59,stroke-width:2px,color:#FFFFFF;
  classDef csf_planned fill:#FEF3C7,stroke:#B45309,stroke-width:2px,color:#78350F;
  n_human["Human or agent client (existing)"]:::csf_existing
  n_brain["Brain (existing)"]:::csf_existing
  n_contracts["Shared typed contracts (existing)"]:::csf_existing
  n_stores["Store (existing)"]:::csf_existing
  n_jobs["Job ledger (existing)"]:::csf_existing
  n_views["Prometheus#44; Grafana and Langfuse (existing)"]:::csf_existing
  n_experiments["Training results and optional MLflow (existing)"]:::csf_existing
  n_vendor["Copilot brain provider (existing)"]:::csf_existing
  n_spine["Low#45;level spine controller (planned)"]:::csf_planned
  n_hardware["Consumer sensors and actuators (planned)"]:::csf_planned
  subgraph g_host["CSF#58; one Go application process"]
    n_bench["Workbench (existing)"]:::csf_existing
    n_api["Generated HTTP#44; CLI and MCP operations (existing)"]:::csf_existing
    n_knowledge["Knowledge and retrieval (existing)"]:::csf_existing
    n_ros["ROS spine capability (existing)"]:::csf_existing
    n_workers["Configured worker goroutines (existing)"]:::csf_existing
    n_inspect["Inspection (existing)"]:::csf_existing
    n_widgets["Widget SDK and gotth#45;live (existing)"]:::csf_existing
  end
  style g_host fill:#EEF2FF,stroke:#4338CA,stroke-width:2px,color:#1E1B4B
  n_human --> n_bench
  n_brain --> n_api
  n_contracts --> n_api
  n_bench --> n_api
  n_bench --> n_vendor
  n_api --> n_knowledge
  n_api -->|"spine status"| n_ros
  n_api --> n_workers
  n_api --> n_inspect
  n_knowledge --> n_stores
  n_workers --> n_jobs
  n_jobs --> n_stores
  n_inspect --> n_views
  n_brain --> n_experiments
  n_widgets -->|"keyed Kanban cards"| n_bench
  n_ros -.->|"planned ROS transport"| n_spine
  n_spine -.-> n_hardware
  linkStyle 0 stroke:#0F766E,stroke-width:2px
  linkStyle 1 stroke:#0F766E,stroke-width:2px
  linkStyle 2 stroke:#0F766E,stroke-width:2px
  linkStyle 3 stroke:#0F766E,stroke-width:2px
  linkStyle 4 stroke:#0F766E,stroke-width:2px
  linkStyle 5 stroke:#0F766E,stroke-width:2px
  linkStyle 6 stroke:#0F766E,stroke-width:2px
  linkStyle 7 stroke:#0F766E,stroke-width:2px
  linkStyle 8 stroke:#0F766E,stroke-width:2px
  linkStyle 9 stroke:#0F766E,stroke-width:2px
  linkStyle 10 stroke:#0F766E,stroke-width:2px
  linkStyle 11 stroke:#0F766E,stroke-width:2px
  linkStyle 12 stroke:#0F766E,stroke-width:2px
  linkStyle 13 stroke:#0F766E,stroke-width:2px
  linkStyle 14 stroke:#0F766E,stroke-width:2px
  linkStyle 15 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 16 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5

%% Generated from csf/compiler/language/architecture.csf; do not edit.
%% Documentation model only; status labels do not establish runtime verification.
flowchart LR
  classDef csf_existing fill:#0F766E,stroke:#115E59,stroke-width:2px,color:#FFFFFF;
  classDef csf_planned fill:#FEF3C7,stroke:#B45309,stroke-width:2px,color:#78350F;
  n_observe["Observe (existing)"]:::csf_existing
  n_retrieve["Retrieve (existing)"]:::csf_existing
  n_choose["Choose (planned)"]:::csf_planned
  n_check["Check (existing)"]:::csf_existing
  n_execute["Execute (existing)"]:::csf_existing
  n_evaluate["Evaluate (existing)"]:::csf_existing
  n_save_evidence["Save evidence (existing)"]:::csf_existing
  n_ouroboros["Ouroboros (planned)"]:::csf_planned
  n_select_controller["Select a controller between episodes (planned)"]:::csf_planned
  n_observe -.-> n_retrieve
  n_retrieve -.-> n_choose
  n_choose -.-> n_check
  n_check --> n_execute
  n_execute --> n_evaluate
  n_evaluate --> n_save_evidence
  n_evaluate -.-> n_select_controller
  n_select_controller -.->|"next agent iteration"| n_choose
  n_save_evidence -.-> n_ouroboros
  n_ouroboros -.->|"next iteration"| n_observe
  linkStyle 0 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 1 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 2 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 3 stroke:#0F766E,stroke-width:2px
  linkStyle 4 stroke:#0F766E,stroke-width:2px
  linkStyle 5 stroke:#0F766E,stroke-width:2px
  linkStyle 6 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 7 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 8 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5
  linkStyle 9 stroke:#B45309,stroke-width:2px,stroke-dasharray:5 5

%% Generated from csf/compiler/language/architecture.csf; do not edit.
%% Documentation model only; status labels do not establish runtime verification.
flowchart LR
  classDef csf_existing fill:#0F766E,stroke:#115E59,stroke-width:2px,color:#FFFFFF;
  classDef csf_planned fill:#FEF3C7,stroke:#B45309,stroke-width:2px,color:#78350F;
  n_submit["SubmitSimulation (existing)"]:::csf_existing
  n_admitted["Recorded simulation job (existing)"]:::csf_existing
  n_start_job["Start configured local profile (existing)"]:::csf_existing
  n_local_job["Simulator container (existing)"]:::csf_existing
  n_poll_job["Read simulator status#44; progress and logs (existing)"]:::csf_existing
  n_observations["Saved simulation observations (existing)"]:::csf_existing
  n_inspect_job["InspectSimulation (existing)"]:::csf_existing
  n_submit --> n_admitted
  n_admitted --> n_start_job
  n_start_job --> n_local_job
  n_local_job -->|"simulation steps and outputs"| n_poll_job
  n_poll_job --> n_observations
  n_poll_job -->|"continue while running"| n_local_job
  n_inspect_job -->|"read state and artifact references"| n_observations
  linkStyle 0 stroke:#0F766E,stroke-width:2px
  linkStyle 1 stroke:#0F766E,stroke-width:2px
  linkStyle 2 stroke:#0F766E,stroke-width:2px
  linkStyle 3 stroke:#0F766E,stroke-width:2px
  linkStyle 4 stroke:#0F766E,stroke-width:2px
  linkStyle 5 stroke:#0F766E,stroke-width:2px
  linkStyle 6 stroke:#0F766E,stroke-width:2px

6. The architecture for self-improving autonomy

The direction is a system that can inspect a result, propose a change, evaluate it against a fixed baseline, and retain the evidence for its next decision. Improvement is something to measure, not a consequence of adding an agent loop.

LITHE [1] separates best-effort reasoning, real-time control, transport, and housekeeping. Its CPU 0: Housekeeping box makes CSF's intended position concrete: coordinate tools, records, worker lifetimes and experiments around the brain and spine. That is our architectural mapping; CSF does not currently implement LITHE's loader, CPU isolation, or real-time controller hot swap.

Figure 1 from Lim and Clites (2026) [1], arXiv:2603.07442. © the authors.

Figures 2 and 1 are linked from the authors' paper, not copied. They illustrate LITHE, not measured CSF hardware behavior. Their authors retain ownership; CSF's source license does not relicense these externally hosted figures.

7. Try the library

Use Go 1.26. The smallest example needs no database, GPU, model account, or extra process. From the public repository root:

go run ./examples/csf-theme --listen 127.0.0.1:8089 --theme-dir ./examples/csf-theme

That mounts the generated HTTP API and MCP at http://127.0.0.1:8089/mcp. It is an integration example, not the complete Workbench UI. Its essential implementation is:

service, err := csf.New(csf.WithWorkbenchThemeDirectory(themeDirectory))
if err != nil {
    return err
}
router := httpserver.NewEngine("consumer")
service.Register(router)
router.Any("/mcp", gin.WrapH(service.MCPHandler()))
return httpserver.Serve(ctx, httpserver.NewStreamingServer(address, router))

The service registers its generated HTTP routes and provides the MCP handler; the caller owns the HTTP server, listener and cancellation. Place your CSS in workbench-theme.css inside the configured directory; ReloadWorkbenchTheme reloads that fixed file through the same generated API. A missing file restores the built-in appearance. No arbitrary file path is accepted from a tool caller.

For your own repository, start with the complete consumer example and extension guide. The example adds a custom Go endpoint beside CSF, uses its generated client, discovers MCP tools, reloads a theme, and tests shutdown. The archive acceptance script creates a fresh Git repository, vendors dependencies, then tests/builds with networking disabled.

bash examples/csf-consumer/test-archive.sh /path/to/csf-snapshot.tar.gz /tmp/csf-consumer-check

For Bazel consumers, use the public repository's archive instructions and depend on @csf//csf. Building that library does not start a host or database.

8. Run the Workbench

For native deployment, the optional dependency package builds selected PostgreSQL, OpenSearch, and Langfuse dependencies as independent systemd services. Langfuse uses ClickHouse and Redis; AWS S3 is its default object store. A credential or bucket-access failure offers an explicit MinIO opt-in that describes the local MinIO container, ports, and storage.

The supplied composition combines the CSF API, MCP, inspection, Workbench and configured workers in one Go application process. Application means a process-owning runnable composition; service means its owned lifecycle component. Widgets exist inside gotth-live, CSF's web layer. A widget is not a separate application.

Build the host and the Workbench browser assets from the public repository root:

go build -trimpath -o out/csf ./app/csf/cmd
npm --prefix services/copilot-adapter/ui ci
npm --prefix services/copilot-adapter/ui run build

The runtime image recipe packages the same host and UI with Git LFS and the pinned Copilot CLI. From the public repository root:

docker build -f app/csf/Dockerfile -t csf:local .
bash app/csf/test-image.sh csf:local

The image runs as the node user and contains /app/candace-runtime and /app/workbench-ui. Its acceptance check exercises a local Git LFS worktree checkout and HTTP startup without provider credentials. Bind-mount the private configuration, repository and writable worktree directory when configuring a Workbench deployment; the image does not provide a database or credentials.

The full Workbench uses your PostgreSQL database and a configured Copilot backend. Create a private JSON file with {"url":"postgres://..."} and configure an existing repository and worktree directory. Keep credentials out of Git.

./out/csf serve \
  --listen 127.0.0.1:14111 --origin http://127.0.0.1:14111 \
  --workbench-database-config /absolute/private/workbench-db.json \
  --workbench-repository /absolute/consumer-repository \
  --workbench-worktrees /absolute/consumer-worktrees \
  --workbench-ui ./services/copilot-adapter/ui/dist \
  --workbench-theme-dir /absolute/theme-directory

Open http://127.0.0.1:14111/ui/. The MCP endpoint is http://127.0.0.1:14111/mcp. The Workbench composition accepts a caller-supplied database and backend, and has an explicit Close. The Copilot bridge is a deliberate external backend boundary; it does not turn the model execution loop into an embedded Go implementation.

For your own composition, follow the runnable CSF host and Workbench lifecycle. After constructing the Workbench with its database, bridge, repository and worktree directory, call Register(router) and start the HTTP/MCP listener before calling Restore(ctx): restored sessions may connect to that MCP endpoint. Workbench API routes return 503 until restoration succeeds. Then run Adapter.RunSchedules(ctx) under the host's cancellation context. On shutdown, call Close(ctx) with a bounded context before closing the bridge and database.

Discover capabilities from MCP tools/list rather than copying operation names into a second schema. The optional JSON CLI uses the same generated contract:

printf '%s\n' '{}' | ./out/csf call --endpoint http://127.0.0.1:14111 GetSnapshot

9. Examples and boundaries

Neural training, ROS recording, perception, cross-simulator equivalence, and physical robot safety remain consumer work. See the simulator integration contract for required interfaces and evidence. A configured tool is not evidence that a job ran.

10. Contracts and release evidence

csfc is CSF's architecture compiler, with its own pinned OCaml build and executable under bin/. Its Lean verifier currently provides a compiling stub that returns notImplemented; it does not certify compiler output.

The architecture model generates the diagrams and human dictionary, using the declared grammar. The documentation compiler checks identifiers, references, and the graph; separate architecture checks inspect selected Go ownership/process boundaries. These establish source constraints, not runtime timing or physical safety.

brainspine.proto and the annotated API own the wire messages and operations. Generated Go, Python, OpenAPI, HTTP, CLI and MCP projections share those sources. Upstream generators keep their own filenames; Candace-generated output uses _cgen where it does not conflict with the upstream convention.

bash proto/generate.sh check
bash csf/tools/codegen/generate.sh check
go test ./csf/... ./services/copilot-adapter/... ./examples/csf-consumer

The public repository snapshot carries .candace-export.json; its downloadable source archive carries .candace-source.json with the source revision and tree. The public publisher proposes each snapshot in a ready PR against main. After that PR is merged, the publisher verifies the approved tree before tagging it and attaching its reproducible archive. An open snapshot PR is a release candidate, not a published release tag. Keep archive hashes, source revision, test receipts and any deployment receipt separate. Generated-code and generated-documentation percentages are separate measurements; neither is a proof coverage score.

11. Citation

[1] He Kai Lim and Tyler R. Clites. LITHE: Bridging Best-Effort Python and Real-Time C++ for Hot-Swapping Robotic Control Laws on Commodity Linux. arXiv:2603.07442 [cs.RO], 2026. Submitted to IROS 2026. https://doi.org/10.48550/arXiv.2603.07442

@misc{lim2026lithe,
  title         = {{LITHE}: Bridging Best-Effort {Python} and Real-Time {C++} for Hot-Swapping Robotic Control Laws on Commodity {Linux}},
  author        = {Lim, He Kai and Clites, Tyler R.},
  year          = {2026},
  eprint        = {2603.07442},
  archivePrefix = {arXiv},
  primaryClass  = {cs.RO},
  doi           = {10.48550/arXiv.2603.07442},
  url           = {https://arxiv.org/abs/2603.07442},
  note          = {Submitted to IROS 2026}
}

CSF's architecture is inspired by LITHE [1]. To cite CSF itself, name the exact release tag you used:

@software{csf2026,
  title   = {CSF — The Cerebrospinal Fluid},
  author  = {{Candace Labs}},
  version = {0.2.3},
  year    = {2026},
  url     = {https://github.com/candacelabs/csf}
}

The LITHE paper and its figures are distributed under arXiv's non-exclusive distribution license, not a Creative Commons license. © the authors; this repository's license does not cover them, and no figure file is copied into it.

License

Apache License 2.0. See LICENSE.