Chapter 11: Graph Conditions — Dynamic Routing

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Graph edges can have conditions — Python functions that decide at runtime whether an edge should fire. This unlocks feedback loops and branching pipelines.

orchestrations:
  pipeline:
    mode: graph
    entry_name: writer
    reset_on_revisit: true
    max_node_executions: 6
    edges:
      - from: writer
        to: reviewer
      - from: reviewer
        to: writer
        condition: ./conditions.py:needs_revision
      - from: reviewer
        to: publisher
        condition: ./conditions.py:is_approved

Writing Condition Functions

Condition functions receive the graph execution context and return True or False:

# conditions.py

def needs_revision(context: dict) -> bool:
    """Route back to writer if reviewer says REVISE."""
    last_output = str(context.get("last_output", ""))
    return "REVISE" in last_output.upper()

def is_approved(context: dict) -> bool:
    """Route to publisher if reviewer approves."""
    last_output = str(context.get("last_output", ""))
    return "APPROVED" in last_output.upper()

The condition spec format is the same as tools and hooks: ./file.py:function_name or module.path:function_name.

Loops and Revisits

When an edge condition creates a loop (reviewer → writer → reviewer), you need two settings:

• reset_on_revisit: true — Resets the agent's conversation state when it's visited again. Without this, the agent accumulates context from all previous visits.
• max_node_executions: N — Safety cap on how many times any node can execute. Prevents infinite loops.

How Conditions Are Evaluated

For a given node, all outgoing edges are checked. Edges without conditions always fire. Edges with conditions fire only if the function returns True. If no outgoing edge fires, the pipeline stops.

Tips & Tricks

• Make your reviewer agent's output deterministic by instructing it to start with keywords like "REVISE:" or "APPROVED:" — this makes condition functions simple and reliable.
• Always set max_node_executions when you have loops — it's your safety net against infinite cycles.
• reset_on_revisit is usually what you want for revision loops — the writer should get fresh context each time, not accumulate all previous attempts.
• Condition functions must be callable. If you accidentally point to a non-callable (like a string or class), kaboo-workflows will raise a clear error.

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Next: Chapter 12 — Nested Orchestrations →