feat(plugins): discover packages and persist state

app-instance/backend/beaver/plugins/discovery.py

@@ -0,0 +1,74 @@
+"""Plugin package discovery."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Iterable
+
+from .manifest import load_plugin_manifest
+from .models import PluginDiscoveryError, PluginDiscoveryResult, PluginManifest
+
+
+def discover_plugins(
+    workspace: str | Path,
+    *,
+    search_paths: Iterable[str | Path] = (),
+) -> PluginDiscoveryResult:
+    workspace_root = Path(workspace).resolve()
+    candidates: list[Path] = []
+    candidates.extend(_candidate_manifest_paths(workspace_root / "plugins"))
+    for root in search_paths:
+        candidates.extend(_candidate_manifest_paths(Path(root).expanduser()))
+
+    manifests_by_id: dict[str, list[PluginManifest]] = {}
+    errors: list[PluginDiscoveryError] = []
+    for manifest_path in candidates:
+        try:
+            manifest = load_plugin_manifest(manifest_path, workspace=workspace_root)
+        except Exception as exc:  # noqa: BLE001 - discovery reports per-path errors.
+            errors.append(
+                PluginDiscoveryError(
+                    path=manifest_path,
+                    display_path=_display_path(manifest_path, workspace_root),
+                    message=str(exc),
+                    plugin_id=None,
+                )
+            )
+            continue
+        manifests_by_id.setdefault(manifest.plugin_id, []).append(manifest)
+
+    manifests: dict[str, PluginManifest] = {}
+    for plugin_id, matches in manifests_by_id.items():
+        if len(matches) == 1:
+            manifests[plugin_id] = matches[0]
+            continue
+        for manifest in matches:
+            errors.append(
+                PluginDiscoveryError(
+                    path=manifest.manifest_path,
+                    display_path=manifest.display_path,
+                    message=f"Duplicate plugin id: {plugin_id}",
+                    plugin_id=plugin_id,
+                )
+            )
+    return PluginDiscoveryResult(manifests=manifests, errors=errors)
+
+
+def _candidate_manifest_paths(root: Path) -> list[Path]:
+    if not root.exists() or not root.is_dir():
+        return []
+    results: list[Path] = []
+    for child in sorted(root.iterdir()):
+        if not child.is_dir():
+            continue
+        manifest = child / "beaver.plugin.json"
+        if manifest.is_file():
+            results.append(manifest)
+    return results
+
+
+def _display_path(path: Path, workspace: Path) -> str:
+    resolved = path.resolve()
+    if resolved.is_relative_to(workspace):
+        return resolved.relative_to(workspace).as_posix()
+    return f"<external>/{resolved.parent.name}/{resolved.name}"