diff --git a/src/permissions/index.test.ts b/src/permissions/index.test.ts
new file mode 100644
index 0000000..c18965c
--- /dev/null
+++ b/src/permissions/index.test.ts
@@ -0,0 +1,102 @@
+import { describe, expect, test } from "bun:test";
+import {
+  checkPermission,
+  summarizeTool,
+  truncateToolResult,
+  SAFE_TOOLS,
+  type PermissionsFile,
+} from "./index";
+import type { ToolCall } from "../api/client.js";
+
+function tc(name: string, args: Record<string, unknown>): ToolCall {
+  return {
+    id: "call_test",
+    type: "function",
+    function: { name, arguments: JSON.stringify(args) },
+  };
+}
+
+const emptyPerms: PermissionsFile = {
+  trusted_tools: [],
+  allowed_commands: [],
+  denied_commands: [],
+};
+
+describe("summarizeTool", () => {
+  test("read_file / write_file / edit_file", () => {
+    expect(summarizeTool(tc("read_file", { path: "src/foo.ts" }))).toBe("read   src/foo.ts");
+    expect(summarizeTool(tc("read_file", { path: "a.ts", offset: 10, limit: 5 }))).toBe("read   a.ts:10–14");
+    expect(summarizeTool(tc("write_file", { path: "out.txt" }))).toBe("write  out.txt");
+    expect(summarizeTool(tc("edit_file", { path: "x.ts" }))).toBe("edit   x.ts");
+  });
+
+  test("run_command truncates long commands", () => {
+    expect(summarizeTool(tc("run_command", { command: "npm test" }))).toBe("$  npm test");
+    const long = "x".repeat(80);
+    const s = summarizeTool(tc("run_command", { command: long }));
+    expect(s.startsWith("$  ")).toBe(true);
+    expect(s.length).toBeLessThanOrEqual(3 + 60);
+    expect(s.endsWith("…")).toBe(true);
+  });
+
+  test("apply_patch counts files", () => {
+    const patch = "*** Add File: a.ts\n+1\n*** Update File: b.ts\n@@\n";
+    expect(summarizeTool(tc("apply_patch", { patch }))).toBe("patch  2 files");
+  });
+
+  test("glob / grep / list_dir", () => {
+    expect(summarizeTool(tc("glob", { pattern: "**/*.ts" }))).toBe("glob   **/*.ts");
+    expect(summarizeTool(tc("grep", { pattern: "TODO", path: "src" }))).toBe('grep   "TODO" in src');
+    expect(summarizeTool(tc("list_dir", { path: "src" }))).toBe("ls     src");
+  });
+});
+
+describe("checkPermission pattern matching", () => {
+  test("SAFE_TOOLS always allow", () => {
+    for (const name of ["read_file", "glob", "grep", "todo_read"]) {
+      expect(SAFE_TOOLS.has(name)).toBe(true);
+      expect(checkPermission(tc(name, {}), emptyPerms)).toBe("allow");
+    }
+  });
+
+  test("denied_commands match wins over allowed", () => {
+    const perms: PermissionsFile = {
+      trusted_tools: [],
+      allowed_commands: ["rm *"],
+      denied_commands: ["rm -rf /"],
+    };
+    expect(checkPermission(tc("run_command", { command: "rm -rf /" }), perms)).toBe("deny");
+  });
+
+  test("allowed_commands glob match vs non-match", () => {
+    const perms: PermissionsFile = {
+      trusted_tools: [],
+      allowed_commands: ["git status", "git diff *"],
+      denied_commands: [],
+    };
+    expect(checkPermission(tc("run_command", { command: "git status" }), perms)).toBe("allow");
+    expect(checkPermission(tc("run_command", { command: "git diff HEAD" }), perms)).toBe("allow");
+    expect(checkPermission(tc("run_command", { command: "npm install" }), perms)).toBe("ask");
+  });
+
+  test("trusted write tools allow; untrusted ask", () => {
+    expect(checkPermission(tc("write_file", { path: "a" }), emptyPerms)).toBe("ask");
+    expect(checkPermission(tc("write_file", { path: "a" }), {
+      ...emptyPerms,
+      trusted_tools: ["write_file"],
+    })).toBe("allow");
+  });
+});
+
+describe("truncateToolResult", () => {
+  test("leaves short results alone", () => {
+    expect(truncateToolResult("hello")).toBe("hello");
+  });
+
+  test("truncates oversized results with a note", () => {
+    const big = "a".repeat(50_000);
+    const out = truncateToolResult(big);
+    expect(out.length).toBeLessThan(big.length);
+    expect(out).toContain("truncated");
+  });
+});