feat: vendor permission system source

pi-permission-system/src/extension-paths.ts

@@ -0,0 +1,66 @@
+import { join } from "node:path";
+import { getGlobalLogsDir } from "./config-paths";
+import { discoverGlobalNodeModulesRoot } from "./node-modules-discovery";
+
+/**
+ * Immutable path constants derived from `agentDir` at construction time.
+ *
+ * Computed once at startup in `computeExtensionPaths()` and embedded into
+ * `ExtensionRuntime`. Later refactorings (#129 PermissionSession, #130
+ * handler classes) consume this as a single dep instead of individual fields.
+ */
+export interface ExtensionPaths {
+  readonly agentDir: string;
+  readonly sessionsDir: string;
+  readonly subagentSessionsDir: string;
+  readonly forwardingDir: string;
+  readonly globalLogsDir: string;
+  /**
+   * Static Pi infrastructure directories used for external-directory
+   * read auto-allow. Computed once from `agentDir`,
+   * `discoverGlobalNodeModulesRoot()`, and (when provided) Pi's own
+   * install directory (`getPackageDir()`). Config-based extras
+   * (`piInfrastructureReadPaths`) are read from `runtime.config` at
+   * call time in the handler so they pick up config reloads.
+   */
+  readonly piInfrastructureDirs: readonly string[];
+}
+
+/**
+ * Compute all immutable path constants from `agentDir`.
+ *
+ * Calls `discoverGlobalNodeModulesRoot()` internally so the result is
+ * self-contained. Call this once at extension startup, not at module scope.
+ *
+ * `piPackageDir` is Pi's own install directory (from the coding-agent
+ * `getPackageDir()` API, resolved at the composition root). When provided it is
+ * auto-allowed for read-only tools so the agent can read Pi's bundled docs and
+ * examples regardless of install layout. It is strictly narrower than the
+ * discovered global `node_modules` root already included here.
+ */
+export function computeExtensionPaths(
+  agentDir: string,
+  piPackageDir?: string,
+): ExtensionPaths {
+  const sessionsDir = join(agentDir, "sessions");
+  const subagentSessionsDir = join(agentDir, "subagent-sessions");
+  const forwardingDir = join(sessionsDir, "permission-forwarding");
+  const globalLogsDir = getGlobalLogsDir(agentDir);
+
+  const globalNodeModulesRoot = discoverGlobalNodeModulesRoot();
+  const piInfrastructureDirs: string[] = [
+    agentDir,
+    join(agentDir, "git"),
+    ...(globalNodeModulesRoot ? [globalNodeModulesRoot] : []),
+    ...(piPackageDir ? [piPackageDir] : []),
+  ];
+
+  return {
+    agentDir,
+    sessionsDir,
+    subagentSessionsDir,
+    forwardingDir,
+    globalLogsDir,
+    piInfrastructureDirs,
+  };
+}