Directory Watching

When started with --workflows-dir, the emulator watches a directory for workflow files and hot-reloads them on changes.

How it works

1. On startup, the emulator reads all .yaml and .json files in the directory
2. Each file is parsed and deployed as a workflow
3. The filename (without extension) becomes the workflow ID
4. The directory is watched for changes -- add, modify, or delete files and the emulator responds automatically

Workflow ID rules

The filename (minus extension) must be a valid workflow ID:

• Lowercase letters, digits, hyphens, and underscores only
• Must start with a letter
• Maximum 128 characters

Special cases

In-flight execution isolation

When a workflow file changes while an execution is running:

• The running execution continues using the workflow definition it started with
• Only new executions use the updated definition

This matches the real GCW behavior where each execution is pinned to a specific workflow revision.

Example

# Start with a workflows directory
gcw-emulator --workflows-dir=./workflows

# In another terminal, add a new workflow
cat > workflows/process-order.yaml << 'EOF'
main:
  params: [args]
  steps:
    - validate:
        call: http.post
        args:
          url: http://localhost:9090/validate
          body:
            order_id: ${args.order_id}
        result: validation
    - process:
        call: http.post
        args:
          url: http://localhost:9091/process
          body:
            order_id: ${args.order_id}
            validated: ${validation.body.valid}
        result: result
    - done:
        return: ${result.body}
EOF

# The emulator detects the new file and deploys it immediately
# Now you can execute it via the API