feat: vendor permission system source

pi-permission-system/src/tool-access-extractor-registry.ts

@@ -0,0 +1,68 @@
+/**
+ * Registry for custom tool access-intent extractors.
+ *
+ * Lets sibling extensions declare the filesystem path a tool will access when
+ * the tool's input shape is not the default `input.path` convention, so the
+ * cross-cutting `path` and `external_directory` gates can see it.
+ * One extractor per tool name; duplicate registration throws.
+ */
+
+/** Returns the filesystem path this tool will access, or `undefined` to decline. */
+export type ToolAccessExtractor = (
+  input: Record<string, unknown>,
+) => string | undefined;
+
+/**
+ * Read-only lookup used by the gate pipeline (ISP — exposes only the read
+ * side, not the registration surface).
+ */
+export interface ToolAccessExtractorLookup {
+  get(toolName: string): ToolAccessExtractor | undefined;
+}
+
+/**
+ * Registration side of the extractor registry (ISP — exposes only the write
+ * surface, mirroring the read-only {@link ToolAccessExtractorLookup}).
+ */
+export interface ToolAccessExtractorRegistrar {
+  register(toolName: string, extractor: ToolAccessExtractor): () => void;
+}
+
+/**
+ * Persistent registry mapping tool names to custom access-intent extractors.
+ *
+ * Owned by the extension factory (`index.ts`) so it survives across the
+ * per-tool-call gate evaluation cycle.
+ * Exposed to sibling extensions via `PermissionsService.registerToolAccessExtractor`.
+ */
+export class ToolAccessExtractorRegistry
+  implements ToolAccessExtractorLookup, ToolAccessExtractorRegistrar
+{
+  private readonly extractors = new Map<string, ToolAccessExtractor>();
+
+  /**
+   * Register an extractor for `toolName`.
+   *
+   * Throws if an extractor is already registered for that name — keeps
+   * resolution deterministic (a pi-permission-system package priority).
+   * Returns a disposer that removes the extractor; the disposer is
+   * identity-guarded so a stale call cannot evict a later registration.
+   */
+  register(toolName: string, extractor: ToolAccessExtractor): () => void {
+    if (this.extractors.has(toolName)) {
+      throw new Error(
+        `A tool access extractor is already registered for '${toolName}'.`,
+      );
+    }
+    this.extractors.set(toolName, extractor);
+    return () => {
+      if (this.extractors.get(toolName) === extractor) {
+        this.extractors.delete(toolName);
+      }
+    };
+  }
+
+  get(toolName: string): ToolAccessExtractor | undefined {
+    return this.extractors.get(toolName);
+  }
+}