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Studio follows the platform rename: product branding F∆I -> Ch∆In in UI strings, command examples fai -> chain, and — critically — the spawned hub binary path ~/.fai/bin/fai -> ~/.fai/bin/chain so Studio launches the renamed binary. The fai_* Dart identifiers (FaiLog, widget files, the generated SDK) stay = vendor/internal namespace. flutter analyze: no issues. Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
90 lines
2.6 KiB
Markdown
90 lines
2.6 KiB
Markdown
# Flow composition
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A flow is a YAML file with three top-level keys: `inputs:`,
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`steps:`, `outputs:`. Read top to bottom, it tells the hub
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what kind of inputs to accept, which modules to call in what
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order, and what to surface as the final result.
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## Smallest possible flow
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```yaml
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name: hello
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description: Echo a name back as a greeting.
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inputs:
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name:
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type: text
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steps:
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- id: greet
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module: debug.echo
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inputs:
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payload: "Hello, {{ inputs.name }}"
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outputs:
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greeting: "{{ steps.greet.outputs.payload }}"
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```
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`chain run flows/hello.yaml --input name=World` produces:
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```json
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{ "greeting": "Hello, World" }
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```
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## Real-world example: extract → summarize
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The bundled `flows/extract-summarize.yaml` chains two modules:
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```yaml
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steps:
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- id: extract
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module: text.extract
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inputs:
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document: "{{ inputs.file }}"
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- id: summarize
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module: text.summarize
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inputs:
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text: "{{ steps.extract.outputs.text }}"
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style: "three bullet points"
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```
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The `{{ steps.extract.outputs.text }}` template plumbs the
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output of one step into the next. The flow engine type-coerces
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JSON / FileRef / Text per the destination module's manifest, so
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you don't need explicit conversion steps.
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## Templating reference (short)
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| Expression | Resolves to |
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|------------------------------------|----------------------------|
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| `{{ inputs.X }}` | input named X |
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| `{{ steps.Y.outputs.Z }}` | output Z of step Y |
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| `{{ env.OPENAI_API_KEY }}` | env var (must be declared) |
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| `{{ now }}` | ISO-8601 UTC timestamp |
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| `{{ flow.execution_id }}` | per-run id (audit-log key) |
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## Audit posture
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Every step emits four events:
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- `step.started` — module name, version, manifest hash
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- `step.completed` — duration, output size, well-known
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fields auto-elevated (`model_digest`, `engine`, …)
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- `step.failed` — error name + message
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- `flow.completed` — sum of step durations, total events
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All hash-chained into the same audit log. See the **Audit-log**
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explainer for the chain mechanics.
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## What you'll see in this app
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- **Flows page**: list of saved flows under `~/.fai/data/flows/`.
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Click `Run`, fill any required inputs, watch the result.
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- **Audit page**: per-step events appear within seconds of a
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flow finishing. Filter on `flow.` to see only flow-level
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rows.
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- **Store**: any installed module shows up as available for
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`module:` in a flow YAML. Synthetic federated entries
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(`mcp.<server>.<tool>`, `n8n.<endpoint>.<workflow>`) work
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the same way.
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