feat: vendor permission system source

pi-permission-system/src/tool-input-formatter-registry.ts

@@ -0,0 +1,67 @@
+/**
+ * Registry for custom tool-input preview formatters.
+ *
+ * Allows extensions to register a formatter for a specific tool name so
+ * permission prompts can show a human-readable summary instead of raw JSON.
+ * One formatter per tool name; duplicate registration throws.
+ */
+
+/** A custom preview formatter for one tool's input. Returns `undefined` to decline. */
+export type ToolInputFormatter = (
+  input: Record<string, unknown>,
+) => string | undefined;
+
+/**
+ * Read-only lookup used by `ToolPreviewFormatter` (ISP — exposes only the
+ * read side, not the registration surface).
+ */
+export interface ToolInputFormatterLookup {
+  get(toolName: string): ToolInputFormatter | undefined;
+}
+
+/**
+ * Registration side of the formatter registry (ISP — exposes only the
+ * write surface, mirroring the read-only {@link ToolInputFormatterLookup}).
+ */
+export interface ToolInputFormatterRegistrar {
+  register(toolName: string, formatter: ToolInputFormatter): () => void;
+}
+
+/**
+ * Persistent registry mapping tool names to custom preview formatters.
+ *
+ * Owned by the extension factory (`index.ts`) so it survives across the
+ * per-tool-call `ToolPreviewFormatter` construction cycle.
+ * Exposed to sibling extensions via `PermissionsService.registerToolInputFormatter`.
+ */
+export class ToolInputFormatterRegistry
+  implements ToolInputFormatterLookup, ToolInputFormatterRegistrar
+{
+  private readonly formatters = new Map<string, ToolInputFormatter>();
+
+  /**
+   * Register a formatter for `toolName`.
+   *
+   * Throws if a formatter is already registered for that name — keeps
+   * resolution deterministic (a pi-permission-system package priority).
+   * Returns a disposer that removes the formatter; the disposer is
+   * identity-guarded so a stale call cannot evict a later registration.
+   */
+  register(toolName: string, formatter: ToolInputFormatter): () => void {
+    if (this.formatters.has(toolName)) {
+      throw new Error(
+        `A tool input formatter is already registered for '${toolName}'.`,
+      );
+    }
+    this.formatters.set(toolName, formatter);
+    return () => {
+      if (this.formatters.get(toolName) === formatter) {
+        this.formatters.delete(toolName);
+      }
+    };
+  }
+
+  get(toolName: string): ToolInputFormatter | undefined {
+    return this.formatters.get(toolName);
+  }
+}