feat: vendor permission system source

pi-permission-system/src/session-approval.ts

@@ -0,0 +1,54 @@
+import type { ForwardedSessionApproval } from "#src/authority/permission-forwarding";
+
+/**
+ * Value object for a session-scoped approval: one surface, one-or-more patterns.
+ *
+ * Owned by gate descriptors and passed to the session store — the runner never
+ * needs to know whether there is one pattern or many.
+ */
+export class SessionApproval {
+  private constructor(
+    readonly surface: string,
+    readonly patterns: readonly string[],
+  ) {}
+
+  /** Create an approval for a single pattern (the common case). */
+  static single(surface: string, pattern: string): SessionApproval {
+    return new SessionApproval(surface, [pattern]);
+  }
+
+  /**
+   * Create an approval for multiple patterns (e.g. bash external-directory
+   * gates that cover several uncovered paths in one prompt).
+   */
+  static multiple(
+    surface: string,
+    patterns: readonly string[],
+  ): SessionApproval {
+    return new SessionApproval(surface, [...patterns]);
+  }
+
+  /** Representative pattern for the interactive prompt — the first, if any. */
+  get representativePattern(): string | undefined {
+    return this.patterns[0];
+  }
+
+  /**
+   * Single-pattern shape `applyPermissionGate` echoes back to the caller.
+   * Returns `undefined` when patterns is empty (degenerate case).
+   */
+  toGateApproval(): { surface: string; pattern: string } | undefined {
+    const pattern = this.representativePattern;
+    if (pattern === undefined) return undefined;
+    return { surface: this.surface, pattern };
+  }
+
+  /**
+   * Plain data shape for relaying this approval on a forwarded request, so the
+   * serving node can record the same pattern(s) as a whole-session grant.
+   * Returns a defensive copy of the patterns.
+   */
+  toForwardedData(): ForwardedSessionApproval {
+    return { surface: this.surface, patterns: [...this.patterns] };
+  }
+}