Add Go worker agent prototype

scimesh/worker/task.py

@@ -0,0 +1,71 @@
+"""Per-task entry point executed by the Go worker agent.
+
+Reads a claimed task from JSON, runs the SDK-built workload with the same
+bridge the Python daemon uses (``SciMeshRunner``), and writes a result
+manifest consumed by the agent:
+
+- on success: ``{artifact_path, content_type, metrics}`` and exit 0;
+- on invalid input/validation failures: a sanitized message on stderr and
+  exit 3 (permanent, non-retryable);
+- on any other failure: exit 1 (retryable by the agent).
+
+The agent passes task parameters through unchanged; all scientific policy
+lives in the workload.
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import sys
+from pathlib import Path
+
+from .models import ClaimedTask
+from .runners import SciMeshRunner
+
+_EXIT_RETRYABLE = 1
+_EXIT_PERMANENT = 3
+
+
+def _load_task(path: Path) -> ClaimedTask:
+    try:
+        payload = json.loads(path.read_text(encoding="utf-8"))
+    except (OSError, ValueError) as error:
+        raise ValueError("task payload is unreadable") from error
+    return ClaimedTask.from_json(payload)
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(prog="scimesh.worker.task")
+    parser.add_argument("--task-json", required=True, type=Path)
+    parser.add_argument("--task-dir", required=True, type=Path)
+    parser.add_argument("--output", required=True, type=Path)
+    args = parser.parse_args(argv)
+    try:
+        task = _load_task(args.task_json)
+        task_dir = args.task_dir.resolve()
+        task_dir.mkdir(parents=True, exist_ok=True)
+        result = SciMeshRunner().run(task, task_dir)
+        if len(result.artifacts) != 1:
+            raise ValueError("runner must produce exactly one result artifact")
+        artifact = result.artifacts[0]
+        if not artifact.path.is_file():
+            raise ValueError("runner artifact is missing")
+        manifest = {
+            "artifact_path": str(artifact.path),
+            "content_type": artifact.content_type,
+            "metrics": dict(result.metrics),
+        }
+        args.output.parent.mkdir(parents=True, exist_ok=True)
+        args.output.write_text(json.dumps(manifest), encoding="utf-8")
+        return 0
+    except ValueError as error:
+        print(f"permanent: {error}", file=sys.stderr)
+        return _EXIT_PERMANENT
+    except Exception as error:  # noqa: BLE001 - exit code is the contract
+        print(f"retryable: {error}", file=sys.stderr)
+        return _EXIT_RETRYABLE
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())