Fabro Create Workflow

Turn requirements into a runnable Fabro workflow: a .fabro graph file defining the pipeline structure and an optional .toml run configuration.

Workflow

Step 1: Fetch Current Model Catalog

Run fabro model list to get available models and providers. Never guess model IDs or provider names -- they change frequently.

Step 2: Understand Requirements

Clarify what the workflow should accomplish:

• What is the end goal?
• What tools or languages are involved?
• Does it need human approval gates?
• Should multiple models or providers be used?
• Is parallelism needed (e.g., multi-perspective review, ensemble)?
• Does it need a verify/fix loop?
• What sandbox environment is appropriate (local, docker, daytona)?

Step 3: Choose Topology

Pick the simplest topology that satisfies the requirements. See references/example-workflows.md for complete examples of each pattern.

Combine patterns as needed. For example, a production pipeline might include a human gate after planning and a parallel fan-out for review.

Step 4: Write the DOT Graph

See references/dot-language.md for the full language reference.

Required elements:

1. digraph Name { ... } wrapper
2. graph [goal="..."] attribute
3. rankdir=LR (preferred for readability)
4. Exactly one start [shape=Mdiamond, label="Start"]
5. Exactly one exit [shape=Msquare, label="Exit"]

Choose node shapes by purpose:

• box (default) -- agent with tools (implement, fix, write code)
• tab -- single LLM call without tools (analyze, plan, review, synthesize)
• parallelogram -- shell command (build, test, lint)
• diamond -- conditional routing (no prompt, only conditions on edges)
• hexagon -- human decision gate
• component -- parallel fan-out
• tripleoctagon -- merge parallel results

Prompt guidelines:

• Be specific and actionable in prompts
• Tell the agent exactly what to do, what files to create/modify, what output to produce
• Use shape=tab for nodes that only need to think, not act
• Use prompt="@path/to/file.md" for long prompts (path relative to DOT file)
• Set reasoning_effort="low" on simple analysis or summary nodes

Edge routing:

• Use condition="outcome=success" and unconditional fallback for check gates
• Diamond nodes must have multiple outgoing edges with conditions
• Use max_visits on fix/retry nodes to prevent infinite loops (typically 3)
• Use goal_gate=true on verification nodes that must pass for the workflow to succeed
• Set retry_target on goal gates to specify where to jump on failure

Step 5: Assign Models via Stylesheet

Use model_stylesheet for model assignment rather than per-node attributes:

graph [model_stylesheet="
    *        { model: claude-sonnet-4-6;}
    .coding  { model: claude-opus-4-6;}
    .review  { model: gemini-3.1-pro-preview;}
"]

• Use * for the default model (usually a fast/cheap model)
• Use .class selectors for role-based assignment (.coding, .review, .verify)
• Use #nodeid selectors for specific node overrides
• Assign class="coding" etc. on nodes to match stylesheet rules
• Critical: Use semicolons between properties in stylesheet rules

Model selection heuristics:

• Fast/cheap models for simple analysis, summaries, routing: claude-haiku-4-5, gemini-3-flash-preview, gpt-5-mini
• Strong models for coding, complex reasoning: claude-opus-4-6, claude-sonnet-4-6, gpt-5.4
• Use reasoning_effort="high" for complex coding tasks
• For ensembles, pick models from different providers for diversity

Step 6: Write the TOML Run Configuration (if needed)

See references/run-configuration.md for the full reference.

A TOML file is optional for simple workflows (you can run fabro run workflow.fabro directly). Create one when you need:

• Sandbox configuration (provider, environment variables)
• Setup commands (install dependencies)
• Variable definitions
• LLM fallbacks
• Hooks
• Asset collection

Minimal TOML:

version = 1
graph = "workflow.fabro"

Common additions:

[sandbox]
provider = "local"

[sandbox.local]
worktree_mode = "always"

[sandbox.env]
NODE_ENV = "test"

Step 7: Validate

Run fabro run --preflight workflow.toml (or fabro run --preflight workflow.fabro) to validate without executing.

If validation fails, fix the reported errors and re-validate.

Guardrails

• Diamond nodes route only. Never put a prompt on a diamond node -- it only evaluates edge conditions.
• All nodes reachable from start. No orphan nodes.
• No edges into start or out of exit.
• LLM nodes need prompts. Every box and tab node must have a prompt attribute.
• Conditional nodes need multiple outgoing edges with condition attributes.
• Prevent infinite loops. Use max_visits on retry/fix nodes. Typical value: 3.
• Use goal_gate=true on critical verification steps that must succeed.
• Use outcome=success conditions on edges leaving command/conditional nodes.
• Model IDs must match the catalog. Always run fabro model list first.
• Semicolons in stylesheets. Properties must be separated by semicolons.

File Organization

Place workflow files together in a directory:

my-workflow/
  workflow.fabro        # the graph
  workflow.toml         # run configuration (optional)
  prompts/              # external prompt files (optional)
    implement.md
    review.md

Running Workflows

fabro run workflow.fabro                  # run graph directly
fabro run workflow.toml                   # run with TOML config
fabro run workflow.toml --dry-run         # simulated LLM backend
fabro run workflow.toml --no-retro        # skip retro (faster for testing)
fabro run workflow.toml --auto-approve    # auto-approve human gates
fabro run workflow.toml --model claude-opus-4-6  # override model
fabro run workflow.toml --sandbox local   # override sandbox
fabro validate workflow.fabro            # validate only

References

• references/dot-language.md -- Complete DOT language reference (node types, attributes, edges, conditions, stylesheets, fidelity, variables)
• references/run-configuration.md -- Complete TOML run configuration reference (sandbox, setup, hooks, LLM, vars, assets)
• references/example-workflows.md -- 9 complete example workflows from simple to production-grade

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