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Not every decision should be made by an LLM. Fabro provides several mechanisms for humans to participate in workflows — approving plans, choosing between options, providing free-form input, and steering agents while they run.

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Human gates

A human gate is a node with shape hexagon that pauses the workflow and presents the user with a choice. The options are derived from the outgoing edge labels: 
approve [shape=hexagon, label="Approve Plan"]

approve -> implement [label="[A] Approve"]
approve -> plan      [label="[R] Revise"]
approve -> skip      [label="[S] Skip"]
When execution reaches the gate, the user sees the node’s label (“Approve Plan”) and the available options. In the CLI, this appears as an interactive menu. In the web UI, it appears as a set of buttons.

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Keyboard accelerators

The prefixes [A], [R], [S] in edge labels serve as keyboard accelerators. Fabro supports three formats:
FormatExample
[K] Label[A] Approve
K) LabelA) Approve
K - LabelA - Approve
When matching the user’s selection to an edge, Fabro strips the accelerator prefix so typing A matches [A] Approve.

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Freeform input

In addition to fixed choices, a human gate can accept freeform text input. Add an edge with freeform=true: 
review [shape=hexagon, label="Review Changes"]

review -> implement [label="[A] Approve"]
review -> plan      [label="[R] Revise"]
review -> custom    [freeform=true]
If the user types something that doesn’t match any fixed option, their input routes to the freeform edge. The text is available to downstream nodes as human.gate.text in the run context.

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Default choice on timeout

If a human gate has a timeout configured, you can specify a default choice using the human.default_choice attribute: 
approve [shape=hexagon, label="Approve?", human.default_choice="approve"]
If the timeout elapses without a response, the workflow continues to the default target rather than failing.

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Auto-approve

For testing or fully automated runs, pass --auto-approve to skip all human gates: 
fabro run workflow.fabro --auto-approve
Auto-approve selects Yes for yes/no gates and the first option for multiple-choice gates.

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Where to place human gates

Human gates are most valuable at high-leverage decision points:
  • Before implementation — Approve a plan before the agent writes code
  • After review — Confirm that a code review’s findings are worth fixing
  • At branch points — Choose a strategy when multiple approaches are viable
  • Before external actions — Approve before deploying, merging, or sending notifications
A workflow can have multiple human gates. Place them where the cost of a wrong decision is high relative to the cost of a brief pause.

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Context set by human gates

When a user makes a selection, the human gate sets several context values for downstream use:
Context keyValue
human.gate.selectedThe accelerator key (e.g. "A") or "freeform"
human.gate.labelThe full label of the selected edge
human.gate.textThe user’s freeform text (if applicable)
These can be read in edge conditions or referenced by downstream agents.