first extension execution path

src/guide_board/runners.py

@@ -0,0 +1,162 @@
+"""Runner bridge for extension-provided checks."""
+
+from __future__ import annotations
+
+import importlib.util
+from pathlib import Path
+from types import ModuleType
+from typing import Any, Callable
+
+from guide_board.errors import ValidationError
+from guide_board.io import load_json
+
+
+RunnerCallable = Callable[[dict[str, Any]], dict[str, Any]]
+
+
+def run_step(
+    root: Path,
+    run_dir: Path,
+    run_id: str,
+    plan: dict[str, Any],
+    step: dict[str, Any],
+) -> dict[str, Any]:
+    runner_ref = step.get("runner_ref")
+    if runner_ref is None:
+        return _no_runner_result(step)
+
+    extension = _extension_snapshot(plan, step["extension_id"])
+    extension_path = root / extension["path"]
+    manifest = load_json(extension_path / "extension.json")
+    entrypoint = _runner_entrypoint(manifest, runner_ref)
+    if entrypoint["kind"] == "python_module":
+        return _run_python_module(root, run_dir, run_id, plan, step, extension_path, entrypoint)
+    if entrypoint["kind"] == "external":
+        return {
+            "result": "blocked",
+            "observations": [
+                f"Runner {runner_ref!r} is declared as an external runner and is not implemented by the core."
+            ],
+            "facts": {
+                "runner_ref": runner_ref,
+                "runner_kind": "external",
+            },
+            "artifact_refs": [],
+        }
+    if entrypoint["kind"] == "command":
+        return {
+            "result": "blocked",
+            "observations": [
+                f"Runner {runner_ref!r} is declared as a command runner; command execution is not enabled yet."
+            ],
+            "facts": {
+                "runner_ref": runner_ref,
+                "runner_kind": "command",
+            },
+            "artifact_refs": [],
+        }
+    raise ValidationError(f"{runner_ref}: unsupported runner kind {entrypoint['kind']!r}")
+
+
+def _no_runner_result(step: dict[str, Any]) -> dict[str, Any]:
+    result = "manual" if step["kind"] == "check_group" else "skipped"
+    return {
+        "result": result,
+        "observations": [
+            "No runner is configured for this step in the baseline core."
+        ],
+        "facts": {
+            "runner_ref": None,
+            "runner_kind": None,
+        },
+        "artifact_refs": [],
+    }
+
+
+def _run_python_module(
+    root: Path,
+    run_dir: Path,
+    run_id: str,
+    plan: dict[str, Any],
+    step: dict[str, Any],
+    extension_path: Path,
+    entrypoint: dict[str, Any],
+) -> dict[str, Any]:
+    module_path = entrypoint.get("module_path")
+    callable_name = entrypoint.get("callable")
+    if not module_path or not callable_name:
+        raise ValidationError(f"{entrypoint['id']}: python_module runners need module_path and callable")
+
+    module_file = (extension_path / module_path).resolve()
+    try:
+        module_file.relative_to(extension_path.resolve())
+    except ValueError as exc:
+        raise ValidationError(
+            f"{entrypoint['id']}: module_path must stay inside the extension directory"
+        ) from exc
+
+    module = _load_module(module_file, entrypoint["id"])
+    runner = getattr(module, callable_name, None)
+    if not callable(runner):
+        raise ValidationError(f"{entrypoint['id']}: callable {callable_name!r} was not found")
+
+    context = {
+        "root": str(root),
+        "run_dir": str(run_dir),
+        "run_id": run_id,
+        "plan": plan,
+        "step": step,
+        "target_profile": plan["target_profile_snapshot"],
+        "assessment_profile": plan["assessment_profile_snapshot"],
+        "extension_path": str(extension_path),
+        "runner": entrypoint,
+    }
+    try:
+        result = runner(context)
+    except Exception as exc:  # noqa: BLE001 - extension failures become evidence.
+        return {
+            "result": "infrastructure_error",
+            "observations": [
+                f"Runner {entrypoint['id']!r} failed before producing evidence: {exc}"
+            ],
+            "facts": {
+                "runner_ref": entrypoint["id"],
+                "runner_kind": "python_module",
+                "error_type": type(exc).__name__,
+            },
+            "artifact_refs": [],
+        }
+    if not isinstance(result, dict):
+        raise ValidationError(f"{entrypoint['id']}: runner must return an object")
+    return {
+        "result": result.get("result", "unknown"),
+        "observations": result.get("observations", []),
+        "facts": result.get("facts", {}),
+        "artifact_refs": result.get("artifact_refs", []),
+    }
+
+
+def _load_module(path: Path, runner_id: str) -> ModuleType:
+    if not path.exists():
+        raise ValidationError(f"{runner_id}: module not found: {path}")
+    module_name = f"_guide_board_runner_{runner_id.replace('-', '_')}"
+    spec = importlib.util.spec_from_file_location(module_name, path)
+    if spec is None or spec.loader is None:
+        raise ValidationError(f"{runner_id}: unable to load module from {path}")
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def _extension_snapshot(plan: dict[str, Any], extension_id: str) -> dict[str, Any]:
+    for extension in plan["extension_snapshots"]:
+        if extension["id"] == extension_id:
+            return extension
+    raise ValidationError(f"step references unknown extension {extension_id!r}")
+
+
+def _runner_entrypoint(manifest: dict[str, Any], runner_ref: str) -> dict[str, Any]:
+    for entrypoint in manifest.get("runner_entrypoints", []):
+        if entrypoint["id"] == runner_ref:
+            return entrypoint
+    raise ValidationError(f"{manifest['id']}: runner {runner_ref!r} is not declared")