Task 002: add shared domain contracts

apps/runner/src/application/job_output_validation.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+import importlib.util
+import os
+import sys
+from functools import lru_cache
+from pathlib import Path
+from typing import Any, Mapping
+
+
+@lru_cache(maxsize=1)
+def _backend_contracts_module() -> Any:
+    contracts_dir = _backend_contracts_dir()
+    init_file = contracts_dir / "__init__.py"
+    module_name = "_pipeline_backend_domain_contracts"
+
+    existing = sys.modules.get(module_name)
+    if existing is not None and Path(str(existing.__file__)).resolve() == init_file.resolve():
+        return existing
+    sys.modules.pop(module_name, None)
+
+    spec = importlib.util.spec_from_file_location(
+        module_name,
+        init_file,
+        submodule_search_locations=[str(contracts_dir)],
+    )
+    if spec is None or spec.loader is None:
+        raise RuntimeError(f"Cannot load backend contract module from {init_file}")
+
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[module_name] = module
+    spec.loader.exec_module(module)
+    return module
+
+
+def _backend_contracts_dir() -> Path:
+    for candidate in _backend_contract_candidates():
+        init_file = candidate / "__init__.py"
+        if init_file.is_file():
+            return candidate
+
+    candidates = ", ".join(str(path) for path in _backend_contract_candidates())
+    raise RuntimeError(f"Cannot find backend contract package. Checked: {candidates}")
+
+
+def _backend_contract_candidates() -> tuple[Path, ...]:
+    configured = os.environ.get("PIPELINE_BACKEND_CONTRACTS_DIR")
+    candidates: list[Path] = []
+    if configured:
+        candidates.append(Path(configured))
+
+    current_file = Path(__file__).resolve()
+    candidates.append(Path("/app/backend_contracts/contracts"))
+
+    for parent in current_file.parents:
+        candidates.append(parent / "apps" / "backend" / "src" / "domain" / "contracts")
+
+    return tuple(dict.fromkeys(candidates))
+
+
+def validate_agent_job_output(payload: Mapping[str, Any]) -> Any:
+    contracts = _backend_contracts_module()
+    return contracts.AgentJobOutput.model_validate(payload)