workflow-chain

# Workflow Chain Orchestrate multi-step workflows by chaining skills and actions. ## Execution boundary The bundled `workflow_engine.py` reads JSON files with `stages` and command `steps`. It does not scan `~/.echo-agent/workflows/`, parse YAML skill recipes, substitute `{{variables}}`, evaluate `when`, retry failed steps, or register cron/keyword/event triggers. A command must name an actual executable and its arguments; this is separate from the core Agent-task DAG `workflow` tool. To combine skills, the Agent reads their instructions and invokes supported tools explicitly. Use the core `cronjob` tool with human approval for periodic execution; a JSON workflow file alone schedules nothing. ## 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. ## Supported command stages - `mode: "sequential"` runs steps in order; `"parallel"` uses a bounded thread pool. - Each step has a `command`, optional `timeout` and `ignore_error`. - `ignore_error` permits continuation after that step's failure; it is not rollback or automatic retry. - Outputs are collected for reporting, not interpolated into later commands. ## 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"}]} ] } ```