workflow-chain

# Workflow Chain Orchestrate multi-step workflows by chaining skills and actions. ## Workflow Definition Workflows are YAML files in `~/.echo-agent/workflows/`: ```yaml name: morning-routine trigger: cron "0 8 * * *" steps: - id: get_weather skill: weather input: {location: "Beijing"} - id: get_todos skill: reminder action: due - id: compose skill: daily-briefing input: weather: "{{get_weather.output}}" todos: "{{get_todos.output}}" - id: deliver action: send channel: telegram content: "{{compose.output}}" ``` ## Security **Only run trusted workflow files.** The engine runs the commands listed in the JSON workflow definition. Never run workflow files from untrusted sources (downloads, user uploads, model-generated content) without manual review. Each `command` is parsed with `shlex` and executed as a single program with a fixed argument list — **shell syntax is not interpreted**. `;`, `&&`, `|`, `>` and `$(...)` are passed through as literal arguments, so one step cannot chain into another command. A step that genuinely needs a pipeline or redirection has to ask for a shell explicitly: ```json {"command": "sh -c 'grep ERROR app.log | wc -l > count.txt'"} ``` Writing it that way keeps the intent visible in the workflow file instead of every step carrying implicit shell power. ## Features - **Variable interpolation**: `{{step_id.output}}` references previous step results - **Conditional steps**: `when: "{{get_weather.temp}} < 5"` - **Error handling**: `on_error: skip | abort | retry(3)` - **Parallel steps**: `parallel: [step_a, step_b]` ## Built-in Templates ### Research Pipeline ```yaml name: research-pipeline steps: - {id: search, skill: web-search, input: {query: "{{topic}}"}} - {id: extract, skill: web-extract, input: {urls: "{{search.top_urls}}"}} - {id: report, skill: deep-research, input: {content: "{{extract.output}}"}} ``` ### Morning Routine ```yaml name: morning-routine trigger: cron "0 8 * * *" steps: - {id: weather, skill: weather, input: {location: "Beijing"}} - {id: briefing, skill: daily-briefing} - {id: send, action: send, channel: auto, content: "{{briefing.output}}"} ``` ## Script ```bash python3 scripts/workflow_engine.py run workflow.json # run a workflow from JSON file python3 scripts/workflow_engine.py inline "echo hello" "echo done" # chain commands inline python3 scripts/workflow_engine.py template --output my-workflow.json # generate a template ``` Workflow JSON format: ```json { "name": "my-workflow", "stages": [ {"name": "build", "mode": "sequential", "steps": [{"command": "echo build"}]}, {"name": "test", "mode": "parallel", "steps": [{"command": "echo t1"}, {"command": "echo t2"}]} ] } ``` ## Triggers | Type | Example | |------|---------| | Cron | `cron "0 8 * * *"` | | Keyword | `keyword "生成报告"` | | Manual | `manual` | | Event | `event "new_message"` |