# cairn-rs
**Self-hostable Rust control plane for production AI agent deployments.**
---
## What is cairn-rs
cairn-rs is a source-available operator control plane that sits between your AI agents and your infrastructure. It handles the operational concerns โ event sourcing, task orchestration, approval gates, provider routing, cost metering, and real-time observability โ so your agent code stays focused on product logic.
The architecture is fully event-sourced: every agent action, LLM call, approval decision, and checkpoint is appended to an immutable log. The current state of any entity is derived by replaying its events. This gives you a complete audit trail, deterministic replay, and idempotent command handling out of the box.
cairn-rs is designed for teams that want the reliability of purpose-built infrastructure without the complexity of a hosted platform. It runs as a single binary, stores events in Postgres (or SQLite for local dev), and ships a React operator dashboard that works without additional configuration.
<!-- TODO: add screenshot -->
---
## Key features
### Core Runtime
- **Event-sourced runtime** โ 120+ domain event types; append-only log with monotonically increasing positions; idempotent command dispatch via causation-id deduplication
- **Real-time SSE streaming** โ live event feed at `GET /v1/stream`; reconnecting clients replay via `Last-Event-ID`; no polling required
- **Multi-tenant isolation** โ tenant / workspace / project hierarchy; RBAC per workspace; every query scoped by `ProjectKey`
- **Durable recovery** โ dual checkpoint (Intent/Result) per orchestrator iteration; deterministic `ToolCallId` with call_index for parallel dispatch; `RetrySafety` three-tier classification (IdempotentSafe / DangerousPause / AuthorResponsible); parallel-where-independent startup dependency graph with per-branch readiness at `/health/ready`
### Plugin Marketplace
- **One-click plugin activation** โ discover, install, credential wizard, enable per project; no code changes to cairn-rs core
- **Per-project scoping** โ plugins enabled per project; tool visibility and signal routing filtered by `VisibilityContext`; agents only see what their project has turned on
- **Signal Knowledge Capture** โ plugin signals auto-projected into cairn-graph (default on) and optionally ingested into cairn-memory (opt-in per signal type)
- **External binary model** โ plugins are independent executables speaking JSON-RPC over stdio; not bundled, not embedded, not arg0
### Sandbox Workspace
- **Per-run isolated environments** โ `cairn-workspace` crate with OverlayFS (Linux) and reflink-copy (macOS/Windows) providers
- **Immutable repo cache** โ `RepoCloneCache` (tenant-scoped) + `ProjectRepoAccessService` (project-scoped access allowlist); disk-efficient sharing with per-project isolation
- **Resource limits** โ disk, memory, wall-clock caps with three exhaustion modes (Destroy / PauseAwaitOperator / ReportOnly)
- **Drift detection** โ overlay sandboxes check base_revision on recovery; reflink sandboxes are physically independent
### Agent Loop
- **Plan / Execute / Direct modes** โ Plan mode restricts agents to Observational + Internal tools; produces a markdown plan artifact for human review before any external action
- **Guardian resolver** โ LLM-based approval resolver with structured output, risk ceiling, fail-closed timeout; configurable per project with tenant inheritance
- **Inline context compaction** โ automatic history summarization when context exceeds threshold; preserves recent steps, compresses older ones
- **30+ built-in tools** โ all classified by ToolEffect (Observational/Internal/External) and RetrySafety; wired into the orchestrate registry with `tool_search` for deferred-tier discovery
### Unified Decision Layer
- **One truth per decision** โ single `DecisionRecorded` event for both Allowed and Denied; 8-step evaluation (scope โ visibility โ guardrail โ budget โ cache โ resolver โ write โ return)
- **Learned rules** โ singleflight cache with Miss/Pending/Resolved states; operator-approved decisions auto-apply to future equivalent requests within TTL
- **Selective invalidation** โ policy-rule reference index; editing a guardrail rule invalidates only decisions that referenced it
### Triggers
- **Signal-to-run binding** โ declarative `Trigger` entity with condition DSL (Equals/Contains/Exists/Not) and `RunTemplate` for reusable run configuration
- **Durable fire ledger** โ prevents duplicate runs on webhook retry or signal replay; separate from ingress dedup
- **Loop prevention** โ `source_run_id` on signal envelope; chain-depth tracking with configurable cap
- **Runaway protection** โ per-trigger rate limits + per-project trigger budgets, both backed by durable projections
### Protocols & Observability
- **SQ/EQ protocol** โ versioned REST + SSE for external clients (IDE extensions, scripts, alternate dashboards); scope-bound transport sessions with `correlation_id` threading
- **A2A Agent Card** โ `GET /.well-known/agent.json` per A2A v0.3; task submission at `POST /v1/a2a/tasks`
- **OTLP GenAI export** โ every LLM call, tool invocation, and run exported as OTel spans with 2025 GenAI semantic conventions; works with Langfuse, Phoenix, Grafana Tempo, Jaeger, Datadog
- **Dynamic provider discovery** โ `PluginCapability::GenerationProvider` lets plugins register as LLM providers at runtime
### Foundation (Phase 1)
- **LLM provider abstraction** โ unified generation interface over OpenAI, Anthropic, Bedrock, OpenRouter, Azure, and any OpenAI-compatible endpoint; priority-ranked fallback chains
- **Approval workflows** โ human-in-the-loop gates that block run or task progression until an operator resolves; full decision audit trail
- **Built-in eval framework** โ eval runs, scoring rubrics, locked baselines, regression detection, multi-armed bandit for live traffic steering
- **Operator dashboard** โ embedded React + TypeScript UI; sessions, runs, tasks, approvals, traces, costs, memory, and playground views
- **Cost tracking** โ per-call token counts and USD micros; run-level and session-level aggregation
- **Knowledge and memory** โ document ingestion pipeline with chunking, deduplication, and multi-factor scoring
---
## Quick start
### Cargo (local dev)
```bash
git clone https://github.com/avifenesh/cairn-rs
cd cairn-rs
cargo run -p cairn-app
# Health check
curl http://localhost:3000/health
# {"status":"healthy","version":"...","uptime_secs":3,"store_ok":true,"plugin_registry_count":0,"checks":[...]}
# With Ollama for local LLM support
OLLAMA_HOST=http://localhost:11434 cargo run -p cairn-app
# With the agntic.garden split inference API (brain + worker tiers)
CAIRN_BRAIN_URL=https://agntic.garden/inference/brain/v1 \
CAIRN_WORKER_URL=https://agntic.garden/inference/worker/v1 \
OPENAI_COMPAT_API_KEY=Cairn-Inference-2026! \
cargo run -p cairn-app
# With any other OpenAI-compatible provider (legacy single-endpoint)
OPENAI_COMPAT_BASE_URL=https://your-server/v1 \
OPENAI_COMPAT_API_KEY=your-key \
cargo run -p cairn-app
# With OpenRouter (free models available โ great for testing)
CAIRN_BRAIN_URL=https://openrouter.ai/api/v1 \
OPENROUTER_API_KEY=sk-or-your-key-here \
cargo run -p cairn-app
```
Default bearer token: `dev-admin-token`. Set `CAIRN_ADMIN_TOKEN` to override.
**Inference providers:** cairn-rs supports a split-tier inference API:
- **Brain** (`CAIRN_BRAIN_URL`): heavy generation โ default model `cyankiwi/gemma-4-31B-it-AWQ-4bit`
- **Worker** (`CAIRN_WORKER_URL`): everyday generation + embeddings โ default model `qwen3.5:9b`
- Both read `OPENAI_COMPAT_API_KEY` for auth; `CAIRN_BRAIN_KEY` / `CAIRN_WORKER_KEY` take precedence when set.
- Legacy `OPENAI_COMPAT_BASE_URL` still works and maps to the worker path.
- **[OpenRouter](https://openrouter.ai)** โ set `OPENROUTER_API_KEY` (preferred) or any of the above key vars.
Free-tier models include `qwen/qwen3-coder:free` (262K context), `deepseek/deepseek-chat:free`, and more.
OpenRouter exposes a standard OpenAI-compatible endpoint so no code changes are required.
All model names are hot-reloadable via `PUT /v1/settings/defaults/system/<key>` โ no restart required.
### Docker
```bash
# One command โ starts cairn-app + Postgres
docker compose up --build
# Background
docker compose up -d --build
# Override the admin token
echo 'CAIRN_ADMIN_TOKEN=my-secret-token' > .env
docker compose up -d
```
Schema migrations run automatically on first boot. Connect an LLM provider
by setting `CAIRN_BRAIN_URL` + `OPENAI_COMPAT_API_KEY`, `OPENROUTER_API_KEY`,
or `OLLAMA_HOST` in a `.env` file, or register at runtime via
`POST /v1/providers/connections`.
### After startup
| URL | Description |
|-----|-------------|
| `http://localhost:3000` | Operator dashboard |
| `http://localhost:3000/v1/docs` | Interactive API explorer (Swagger UI) |
| `http://localhost:3000/v1/openapi.json` | OpenAPI 3.0 spec |
| `http://localhost:3000/health` | Liveness probe |
---
## Architecture
cairn-rs currently spans a 20-crate workspace plus `cairn-providers` as a
repo-local path crate consumed by the app/runtime surface. Each crate owns
one bounded context with no circular dependencies.
```
cairn-domain pure domain types, events, lifecycle rules, RFC contracts
cairn-store append-only event log + synchronous projections (InMemory / Postgres / SQLite)
cairn-runtime service implementations: sessions, runs, tasks, approvals, routing, evals
cairn-fabric bridge to FlowFabric: atomic leases, 6-dim state vectors, Valkey-native execution
cairn-providers unified chat/completion/embedding provider abstraction
cairn-api HTTP types, SSE payloads, auth, bootstrap config, API error shapes
cairn-app axum HTTP server, startup wiring, all route handlers, embedded React UI
cairn-memory knowledge pipeline: ingest, chunking, retrieval, graph-backed expansion
cairn-graph entity relationship graph: nodes, edges, traversal, proximity scoring
cairn-evals eval runs, rubrics, baselines, scorecard matrices, bandit experiments
cairn-tools tool invocation, plugin host (stdio JSON-RPC), capability verification
cairn-tools-derive proc-macro helpers for built-in and plugin-exposed tools
cairn-agent agent orchestration loop, reflection, hook pipeline
cairn-orchestrator gather/decide/execute loop runner over the runtime spine
cairn-signal signal ingestion and routing between agents
cairn-channels async message channels between agents
cairn-plugin-catalog bundled marketplace catalog descriptors for RFC 015
cairn-plugin-proto plugin wire protocol types and capability declarations
cairn-workspace repo clone cache and sandbox lifecycle primitives
cairn-github standalone GitHub App auth, webhook, and REST client SDK
cairn-integrations integration registry and per-service plugin surfaces
```
`cairn-fabric` sits between `cairn-runtime` and FlowFabric's Valkey-native
execution engine. It adapts cairn's run and task service traits onto FF's
FCALL surface (`ff_issue_claim_grant`, `ff_claim_execution`,
`ff_suspend_execution`, etc.), giving the runtime atomic lease semantics
and multi-dimensional execution state without owning that state itself.
FF remains the source of truth for lease, lifecycle, and eligibility;
cairn-fabric is the thin adapter.
### Data flow
```
HTTP request
โโโบ Command handler
โโโบ append(events) โโโบ InMemoryStore projections โโโบ read models
โ โโโบ Postgres event log (when --db postgres://...)
โ โโโบ broadcast channel โโโบ SSE subscribers
โโโบ HTTP response (returns latest projected state)
```
State is always derived from the log. Postgres stores events for durability and cursor-based replay; the in-memory store drives read models and the SSE broadcast. There is no separate synchronization step.
---
## Configuration
| Variable | Default | Description |
|----------|---------|-------------|
| `CAIRN_ADMIN_TOKEN` | `dev-admin-token` | Bearer token for the admin account. Required in team mode. |
| `OLLAMA_HOST` | _(unset)_ | Ollama base URL, e.g. `http://localhost:11434`. Enables local LLM endpoints. |
| `CAIRN_BRAIN_URL` | _(unset)_ | Heavy/generate provider base URL (e.g. `https://โฆ/brain/v1`). Used for generation. |
| `CAIRN_BRAIN_KEY` | _(unset)_ | API key for the brain provider. |
| `CAIRN_WORKER_URL` | _(unset)_ | Light/embed provider base URL (e.g. `https://โฆ/worker/v1`). Used for embedding. |
| `CAIRN_WORKER_KEY` | _(unset)_ | API key for the worker provider. |
| `OPENAI_COMPAT_BASE_URL` | _(unset)_ | Legacy: maps to both BRAIN and WORKER when set. Superseded by the split vars above. |
| `OPENAI_COMPAT_API_KEY` | _(unset)_ | Legacy: API key for the legacy single-endpoint provider. |
| `OPENROUTER_API_KEY` | _(unset)_ | API key for [OpenRouter](https://openrouter.ai). When set, `CAIRN_BRAIN_URL` can be pointed at `https://openrouter.ai/api/v1`. Free-tier models (e.g. `qwen/qwen3-coder:free`) work without a paid account. |
| `CAIRN_FABRIC_WAITPOINT_HMAC_SECRET` | _(required when Fabric enabled)_ | 32-byte hex secret seeded into every FlowFabric execution partition at boot. Rotate at runtime via `POST /v1/admin/rotate-waitpoint-hmac`. See [SECURITY.md](./SECURITY.md). |
| `CAIRN_FABRIC_INSTANCE_ID` | _(auto UUID)_ | Per-process instance id used to filter lease-history frames when multiple cairn-app instances share a Valkey. See [docs/operations/cross-instance-isolation.md](./docs/operations/cross-instance-isolation.md). |
> **FlowFabric / Valkey.** Cairn's execution engine (`cairn-fabric`) persists
> lease, lifecycle, and eligibility state in Valkey 7.0+. A Valkey instance is
> required unless you are running purely against the in-memory store
> (`--db memory`, dev only).
### CLI flags
```
cairn-app [OPTIONS]
--addr <addr> Bind address (default: 127.0.0.1)
--port <port> Listen port (default: 3000)
--mode team Bind 0.0.0.0, require token, enable team features
--db <url> postgres://... or sqlite:path.db or memory
Also reads DATABASE_URL env var (Postgres default)
```
### Persistence backends
| Backend | Config | Notes |
|---------|--------|-------|
| Postgres | `DATABASE_URL=postgres://...` _(default)_ | Full durability. Concurrent writers. Schema migrations run on startup. |
| SQLite | `--db sqlite:cairn.db` | Durable single-file store. Single-writer. |
| In-memory | `--db memory` | Resets on restart. Local development only. Startup warning emitted. |
---
## API overview
All `/v1/` routes require `Authorization: Bearer <token>`. `/health` and `/v1/stream` are public.
| Group | Endpoints |
|-------|-----------|
| **Health** | `GET /health`, `GET /v1/status`, `GET /v1/dashboard`, `GET /v1/overview` |
| **Sessions** | `GET/POST /v1/sessions`, `GET /v1/sessions/:id`, `GET /v1/sessions/:id/runs` |
| **Runs** | `GET/POST /v1/runs`, `GET /v1/runs/:id`, `POST /v1/runs/:id/claim`, `POST /v1/runs/:id/pause`, `POST /v1/runs/:id/resume`, `GET /v1/runs/:id/events`, `GET /v1/runs/:id/cost` |
| **Tasks** | `GET /v1/tasks`, `POST /v1/tasks/:id/claim`, `POST /v1/tasks/:id/complete`, `POST /v1/tasks/:id/cancel`, `POST /v1/tasks/:id/release-lease` |
| **Approvals** | `POST /v1/approvals` (create gate), `GET /v1/approvals/pending`, `POST /v1/approvals/:id/approve`, `POST /v1/approvals/:id/reject`, `POST /v1/approvals/:id/resolve` |
| **Prompts** | `GET /v1/prompts/assets`, `GET /v1/prompts/releases`, `POST /v1/prompts/releases/:id/transition`, `POST /v1/prompts/releases/:id/activate` |
| **Events** | `GET /v1/events` (cursor replay), `POST /v1/events/append` (idempotent write), `GET /v1/stream` (SSE live feed) |
| **Providers** | `GET /v1/providers`, `GET /v1/providers/health`, `POST /v1/providers/connections`, `POST /v1/providers/bindings` |
| **Ollama** | `GET /v1/providers/ollama/models`, `POST /v1/providers/ollama/generate`, `POST /v1/providers/ollama/stream` |
| **Memory** | `POST /v1/memory/ingest`, `GET /v1/memory/search`, `GET /v1/memory/documents/:id`, `GET /v1/memory/diagnostics`, `POST /v1/memory/feedback` |
| **Sources** | `GET /v1/sources`, `GET /v1/sources/:id`, `POST /v1/sources` |
| **Bundles** | `POST /v1/bundles/import`, `POST /v1/bundles/export` |
| **Evals** | `POST /v1/evals/runs`, `POST /v1/evals/runs/:id/start`, `POST /v1/evals/runs/:id/complete`, `GET /v1/evals/scorecard/:asset_id` |
| **Costs** | `GET /v1/costs`, `GET /v1/traces`, `GET /v1/sessions/:id/llm-traces` |
| **Admin** | `POST /v1/admin/tenants`, `GET /v1/settings`, `GET /v1/db/status` |
---
## Development
### Prerequisites
- Rust 1.95 (pinned via `rust-toolchain.toml` โ `rustup` will install it automatically on first build)
- Node.js 20+ (for the UI only)
### Build and test
```bash
# Full workspace build
cargo build --workspace
# Run the server (Postgres via DATABASE_URL, or in-memory fallback)
cargo run -p cairn-app
# Run all 3,300+ tests
cargo test --workspace
# Run the end-to-end integration suite (6 full-workflow tests)
cargo test -p cairn-app --test full_workspace_suite
# Run the 81-check smoke test against a running server
CAIRN_ADMIN_TOKEN=cairn-demo-token cargo run -p cairn-app &
CAIRN_TOKEN=cairn-demo-token ./scripts/smoke-test.sh
# UI development server (proxies /v1/* to localhost:3000)
cd ui && npm install && npm run dev
# Opens at http://localhost:5173
# Rebuild UI and embed it in the binary
cd ui && npm run build
cargo build -p cairn-app # picks up ui/dist/ via rust-embed
```
### Project structure
```
crates/
cairn-app/ HTTP server binary + embedded React UI (ui/dist/)
cairn-domain/ Domain types, events, RFC contracts
cairn-store/ Event log, projections, Postgres/SQLite adapters
cairn-runtime/ Service layer (sessions, runs, tasks, approvals, routing)
cairn-api/ HTTP API types, SSE, auth, bootstrap
cairn-memory/ Knowledge retrieval pipeline
cairn-graph/ Entity graph (nodes, edges, traversal)
cairn-evals/ Eval framework, rubrics, bandit experiments
cairn-tools/ Tool invocation, plugin host
cairn-tools-derive/ Proc-macro helpers for tools
cairn-agent/ Agent orchestration loop
cairn-orchestrator/ Gather/decide/execute loop runner
cairn-signal/ Signal routing
cairn-channels/ Agent message channels
cairn-plugin-proto/ Plugin wire protocol
cairn-plugin-catalog/ Marketplace catalog descriptors
cairn-workspace/ Repo clone cache and sandbox lifecycle
cairn-github/ GitHub App auth, webhook, REST client
cairn-integrations/ Integration registry and plugin surfaces
cairn-fabric/ Bridge from cairn-runtime to FlowFabric (Valkey-native lease + lifecycle)
ui/ React + TypeScript operator dashboard
docs/
design/rfcs/ RFC specifications (001โ023)
api/ Per-subject HTTP API reference (start here)
api-reference.md Redirect stub โ docs/api/
deployment.md Docker, Postgres, TLS, production hardening
operations/
rfc020-recovery.md Readiness endpoints and crash-recovery behaviour
```
### RFC compliance
Cairn's behaviour is specified by RFCs in `docs/design/rfcs/`. Each RFC has a corresponding integration test that serves as the compliance proof.
| RFC | Scope |
|-----|-------|
| 002 | Event-log durability, idempotency, SSE replay |
| 003 | Memory retrieval pipeline |
| 004 | Checkpoints, eval system, baselines |
| 005 | Approval blocking |
| 006 | Prompt release lifecycle |
| 007 | Provider connection health |
| 008 | Multi-tenant isolation, RBAC |
| 009 | Provider routing and cost tracking |
| 013 | Bundle import/export, eval rubrics |
| 014 | Commercial tiers and feature gating |
| 015 | Plugin marketplace and per-project scoping |
| 016 | Sandbox workspace primitive (OverlayFS / reflink) |
| 017 | GitHub reference plugin |
| 018 | Agent loop enhancements (plan mode, guardian, compaction) |
| 019 | Unified decision layer |
| 020 | Durable recovery (readiness gate, dual checkpoint, tool-call idempotency) |
| 021 | Control-plane protocols (SQ/EQ, A2A) |
| 022 | Triggers and signal routing |
| 023 | Business model and cloud architecture |
---
## Contributing
See [CONTRIBUTING.md](./CONTRIBUTING.md) for prerequisites, development
workflow, testing instructions, code style requirements, and the pull-request
process.
---
## License
BSL-1.1 โ see [LICENSE](./LICENSE).