tuvl 2026.2.6

YAML-driven workflow orchestration engine — compose pipelines of functional nodes, LLM calls, API integrations, and MCP tools, served as a REST API with Postgres persistence and Redis-backed state

  tuvl
_{/ˈtuːvəl/  ·  തൂവൽ  ·  feather}

YAML-driven workflow orchestration engine — compose pipelines of functional nodes,
LLM calls, API integrations, and MCP tools, served as a REST API
with Postgres persistence and Redis-backed state.

Website  ·  Docs  ·  GitHub

⚠️ Beta release. tuvl 2026.2.6 is a beta intended for evaluation and development — not yet recommended for production deployments. APIs and YAML schemas may still change before the stable release, which is coming soon.

tuvl lets you define, run, and manage multi-step AI workflows using plain YAML files. No boilerplate. No complex overhead. No lock-in.

Install tuvl[standard] during development to get Tuvl Insight — a full browser-based developer portal for designing models, configuring datasources, managing LLM providers, building workflows visually, controlling access, and testing execution — all without leaving your local environment.

• Website: tuvl.io
• GitHub: tuvl-io/tuvl

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🏛️ Architecture & Data Flow

flowchart TD
    subgraph Configuration
        YAML[YAML Definitions] -->|load_all_configs| Reg[In-Memory Registries]
    end

    subgraph Transport Layer
        Reg -->|Mount Endpoints| REST[FastAPI REST Server]
        Reg -->|Mount Services| GRPC[gRPC Server]
    end

    Client([Clients]) -->|HTTP/JSON| REST
    Client -->|HTTP/2 Protobuf| GRPC

    subgraph Security: Authentication & Authorization
        REST --> Auth[Biscuit Token Auth<br>Verify Crypto Signature]
        GRPC --> Auth
        Auth -->|Extract Identity| AuthZ[IAM Scope Guard<br>Enforce Model/Route Scopes]
    end

    AuthZ -->|Workflow Route| Engine{WorkflowEngine.run}
    AuthZ -->|Auto-Generated CRUD| UoW[Workflow Unit of Work<br>Pydantic-Validated CRUD]

    subgraph Execution & Integrations
        Engine -->|ModelOp| UoW
        UoW -->|SQLModel Object Mapper| PG[(PostgreSQL)]
        Engine -->|Agent| LLM[LiteLLM Any Provider]
        Engine -->|DataSearch| RAG[(pgvector RAG)]
        Engine -->|Functional| Nodes[Custom Python Nodes]
        Engine -->|MCP| MCP[MCP Tools]
        Engine -->|APICall| ExtAPI[External APIs]
    end

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📦 Installation

Core (production server)

pip install tuvl
# or
uv add tuvl

Installs the full workflow engine and REST API server. Sufficient for all production deployments.

With Tuvl Insight (developer portal)

pip install "tuvl[standard]"
# or
uv add "tuvl[standard]"

Adds Tuvl Insight — a full browser-based developer portal, active only when TUVL_DEV_MODE=true. See the Tuvl Insight section for the full feature list.

CLI (global tool)

uv tool install tuvl

SDKs

Coming soon — SDKs are being prepared for release alongside the source code.

SDK	Package	Status
Python	pip install tuvl-sdk / uv add tuvl-sdk	Coming soon
JavaScript / TypeScript	npm install @tuvl/client	Beta — @tuvl/client

The SDKs provide typed clients for triggering workflows, subscribing to execution events via SSE, and managing workflow instances from your own applications.

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🚀 Quick Start

1. Scaffold a new project:

# Create a new folder named 'my-project' in the current directory
tuvl init my-project

# Create it inside a specific parent directory
tuvl init my-project --project-dir /path/to/workspace

# Initialise an already-named path (project name inferred from last component)
tuvl init --project-dir /path/to/workspace/my-project

tuvl init always creates the target directory (it will not overwrite an existing one). Prompts for Postgres and LLM provider credentials and writes a pyproject.toml + .env.

2. Install dependencies:

uv sync

Installs tuvl and any project-level packages into a local .venv. Add extra packages with uv add <package> — useful when your nodes use libraries like pandas or httpx.

3. Start the development server:

uv run tuvl dev

Starts the engine with hot reload on http://localhost:8000. If tuvl[standard] is installed, the Insight dashboard is available at http://localhost:8000/insight.

4. Run in production:

tuvl run --project-dir /path/to/project --workers 4

Starts the production uvicorn server without hot reload.

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🗂️ Project Structure

A tuvl project directory contains:

my-project/
├── pyproject.toml        # Project deps — add extras with: uv add <pkg>
├── .env                  # LLM API keys and database config (git-ignored)
├── .env.example          # Safe-to-commit template
├── config.yaml           # Directory layout (customisable)
├── models/               # Data model definitions (YAML)
├── datasources/          # Datasource definitions (YAML)
├── llms/                 # LLM / AgentModel configs (YAML)
├── nodes/                # Custom Python node implementations
└── workflows/            # Workflow definitions (YAML)

Share a project by committing everything except .env — collaborators run uv sync to reproduce the exact environment.

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⚙️ CLI Reference

Command	Description
tuvl init <name>	Create <name>/ in the current directory and scaffold inside it
tuvl init <name> --project-dir <parent>	Create <parent>/<name>/ and scaffold inside it
tuvl init --project-dir <path>	Scaffold into <path>/ (project name inferred from last component)
tuvl init <name> --sample	Same as above, plus sample recruitment pipeline covering every step kind
tuvl init <name> --multi-tenant	Scaffold in multi-tenant mode — locks deployment_mode: multi_tenant in .tuvl/system.yaml, injects tenant_id columns into every model, and enables Postgres Row-Level Security tooling
tuvl dev	Start the engine in dev mode with hot reload. The dev key is written to .tuvl/.dev-session (mode 0600); pass --show-key to print it, and --auto-login to automatically bypass the Insight security screen
tuvl run	Start the production server. Requires a persistent TUVL_BISCUIT_PRIVATE_KEY in .env (generate one with tuvl keys generate) — unlike tuvl dev, it will not fall back to an ephemeral signing key
tuvl test	Run LLM-as-a-Judge tests against workflow definitions. In multi-tenant projects, automatically injects a synthetic tenant so the data-layer guard doesn't reject test runs
tuvl validate	Validate workflow and model YAML files
tuvl keys generate	Print a fresh Ed25519 Biscuit signing key (64-hex) plus the .env line; add --write to write it into the project .env (owner-only perms, --force to overwrite)
tuvl db generate-rls	Emit ALTER TABLE … ENABLE ROW LEVEL SECURITY + tenant-scoped policy SQL for every tenant-aware model (multi-tenant only)
tuvl db check-rls	Verify that RLS is enabled and policies are present on every tenant-aware table
tuvl stream-watch	Tail workflow execution events from the engine's SSE stream
tuvl help	Show all commands

Common options

tuvl dev --port 9000 --project-dir ./my-project
tuvl dev --show-key                  # print the dev API key (off by default)
tuvl dev --auto-login                # automatically bypass the Tuvl Insight security screen
tuvl run --host 0.0.0.0 --port 8000 --workers 2
tuvl run --allow-host 10.0.0.0/8     # IP allowlist
tuvl keys generate                   # print a production Biscuit key + the .env line
tuvl keys generate --write           # write TUVL_BISCUIT_PRIVATE_KEY into .env (needed by `tuvl run`)
tuvl validate --project-dir ./my-project

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🔩 Workflow Step Kinds

Workflows are YAML files defining a sequence of steps. Each step has a kind:

Kind	Description
Functional	Execute a registered Python node function
Agent	Call an LLM (via litellm) with a prompt template, read context keys, write output back to context
AutonomousAgent	Run a bounded tool-calling loop — the model calls declared tools (other steps) until it emits an outcome.enum, capped by max_iterations / token_budget. Guided by agent.steering + per-agent scoped steering_files/skills; optionally watched by a spec.supervisor
APICall	Make an outbound HTTP request and map the response into context
MCP	Call a tool via the Model Context Protocol (stdio or SSE)
Router	Evaluate a condition and branch to a named route
ModelOp	Perform CRUD operations on a registered data model
Response	Shape and return the final HTTP response from context keys
HumanInTheLoop	Pause for a human approve/reject decision, then resume where it left off

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🧰 Makefile Targets

For development within the monorepo:

make setup        # Install core dependencies
make setup-all    # Install core + Tuvl Insight + dev tools
make dev-ui       # Run server + Insight dashboard (TUVL_DEV_MODE=true)
make dev-core     # Run server in dev mode without UI
make build-ui     # Compile React SPA into tuvl-insight wheel
make build        # Build both tuvl and tuvl-insight wheels → dist/
make publish      # build → publish both wheels to PyPI (set UV_PUBLISH_TOKEN)
make lint         # Run ruff check
make fmt          # Run ruff check --fix + ruff format
make check        # CI gate: ruff check + ruff format --check
make typecheck    # Run mypy (advisory)
make clean        # Remove build artifacts

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🔬 Tuvl Insight (Developer Portal)

Installed via pip install "tuvl[standard]". Active only when TUVL_DEV_MODE=true.

Tuvl Insight is not just an observability tool — it is a complete local developer portal that covers the full development lifecycle of a tuvl project.

Design & Configuration

Section	Description
Workflows	Visual YAML editor with a live graph view of step connections, routes, and node types. Create, edit, and save workflow definitions without touching files directly.
Models	Form-driven model designer — define fields, types (PostgreSQL-native and extended), primary keys, relationships, and constraints. Generates YAML automatically.
Datasources	Configure Postgres datasource connections (host, port, database, credentials) with a structured form.
LLM Models	Manage AgentModel definitions — select from preset providers (OpenAI, Anthropic, Ollama, Groq, Gemini, LiteLLM proxy) or configure custom endpoints and API keys.

Access Control

Section	Description
IAM	Create and manage users and roles. Assign and revoke role scopes. The role editor shows a live scope-suggestion palette — click any scope pill to add it to the role without typing. Scope strings are served by GET /admin/scopes and cover every CRUD model, workflow, and system scope registered in the engine. Full CRUD for the built-in identity and access management layer.
Federation	Configure OAuth2/OIDC federation providers (Google, GitHub, Microsoft, and custom). Manage client credentials and scopes.

Infrastructure & Reference

Section	Description
Settings	Configure infrastructure components — Redis connection and other runtime settings.
API Docs	Embedded Swagger UI and ReDoc viewer for the live tuvl REST API, including all dynamically-generated workflow and model endpoints.

Execution Testing

Feature	Where	Description
Tuvl Lens	Spectrum page (/insight)	Execute a single workflow node in isolation with mock state — unit-test individual steps without running a full workflow
Tuvl Spectrum	Spectrum page (/insight)	Run a complete workflow and capture a deep-copy state snapshot after every step — full execution trace with per-step timing
Workflow Canvas Test Mode	Workflow editor toolbar	Run any workflow directly from the canvas with a custom JSON input. Results stream live: nodes light up with status badges, the right-hand Test Out panel shows a step-by-step context diff, and a bottom status bar tracks overall progress
Agents dashboard	Agents page (/insight)	Live view of in-flight AutonomousAgent runs — iteration/token progress, an expandable per-run trace timeline, and pause / resume / abort / steer controls (operator API: /api/agents/runs)
Agent Supervisor	spec.supervisor (workflow YAML) — or the off-spine Supervisor node in the Insight canvas	A per-workflow watcher that observes each AutonomousAgent run and pauses/aborts/steers it via deterministic rules and/or an LLM judge (criteria, or a scoped criteria_file .md policy) — breaking a runaway loop mid-flight. Author it visually: drop the Supervisor node, pick a model + policy, and it serializes to spec.supervisor. Emits OTel agent metrics (agent.iterations/tool_calls/aborts/…)
Portal UI	GET /insight	Browser interface to the full developer portal

Workflow Canvas Test Mode — at a glance

1. Open a workflow in the editor and click ▶ Test in the toolbar.
2. Fill the input JSON — required fields are auto-scaffolded from the workflow's input_schema.
3. Click ▶ Run. The canvas switches automatically to test mode:
   • Each node shows a live status badge (⏳ running, ✓ success, ✗ error).
   • The Test Out panel opens on the right, streaming step results as they arrive.
   • Click any step to inspect the before/after context diff with Logs and Error sub-tabs.
   • The Final State entry shows every key in the terminal context.
4. A status bar at the bottom of the canvas shows overall result and a one-click View Output shortcut.

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🔒 Security & Multi-Tenancy

tuvl ships single-tenant by default and multi-tenant by opt-in. Both modes share the same auth, observability, and hardening primitives.

Authentication & Identity

• Biscuit tokens — cryptographically attenuable bearer tokens with offline verification. The engine fails closed in production if no signing key is configured.
• Dev sentinel — a fixed sentinel keypair is used only when TUVL_DEV_MODE=true; production startup refuses to boot with the sentinel active.
• User identity propagation — current_user_id is bound from the verified Biscuit principal() fact and attached to every log line and OpenTelemetry span.
• Token revocation — a Redis-backed blacklist supports immediate revocation; the UI revokes any prior session token before storing a new one on login.

Multi-Tenant Mode (tuvl init --multi-tenant)

Layer	Guarantee
Tenant binding	tenant() fact extracted from the Biscuit at verification time → pushed into current_tenant_id contextvar (sync + async + gRPC)
Fail-closed boundary	MissingTenantContextError raised at the data-access layer when the contextvar is unset — never silently leaks across tenants
Postgres RLS	tuvl db generate-rls emits per-model policies keyed on app.current_tenant_id; a SQLAlchemy after_begin hook issues SET LOCAL app.current_tenant_id for every session
Defence in depth	Raw-SQL paths (RAG, search) guard the tenant filter at the query builder; tuvl db check-rls is a CI-friendly verifier
Cross-version safety	Versioned model tables use a composite key including tenant_id to prevent cross-tenant collisions on shared sequences

Embed the engine in your own host application via the public tuvl.tenancy module:

from tuvl.tenancy import tenant_scope

# Set the tenant before invoking any tuvl handler. Every DB session opened
# inside the scope binds `SET LOCAL app.current_tenant_id`, so RLS isolates
# the tenant automatically. Use `async_tenant_scope` from async code.
with tenant_scope("acme-corp"):
    ...  # call your mounted tuvl workflow endpoints / handlers here

Hardening Defaults

• CRUD endpoint scope enforcement — every auto-generated model route (/models/{model}/…) enforces a Biscuit scope() fact. Default names are {modelname.lower()}:read, {modelname.lower()}:write, {modelname.lower()}:delete; override per model with spec.access in the ModelDefinition YAML. Tokens carrying iam:admin satisfy every scope check.
• Secrets file modes — .tuvl/.dev-session and .env are created with mode 0600 so other accounts on shared hosts can't read them.
• Dev key handling — never echoed to the terminal by default (tuvl dev --show-key opts in); always persisted owner-only.
• UI session storage — the dev portal stores the bearer key in sessionStorage (tab-scoped) with a 15-minute idle expiry watchdog.
• Markdown rendering — rehype-sanitize is applied to every ReactMarkdown mount to neutralise XSS in user-controlled prompt output.
• Env-driven UI config — REST and gRPC base URLs come from VITE_API_BASE / VITE_GRPC_BASE; the Vite dev proxy honours VITE_API_TARGET for remote engine connections.
• Verbose error logging — gated behind import.meta.env.DEV so production bundles don't leak structured RPC errors to the console.
• Allowlists — tuvl run --allow-host accepts IP and CIDR ranges; localhost is always permitted.
• Pooling & limits — connection pool sizing is configurable; a shared HTTP client is reused across API-call steps.

Observability

• Structured JSON logs via structlog with tenant_id, user_id, workflow, step_id, and run_id on every record.
• OpenTelemetry spans cover HTTP requests, workflow executions, individual steps, LLM calls, and database transactions — see docs/observability.md.
• HITL (human-in-the-loop) state machine emits dedicated events for pause, resume, and timeout transitions.

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MIT — see LICENSE.