fix(auth): tighten bridge claim protocol

backend/src/auth/session-store.ts

@@ -609,6 +609,9 @@ function claimOidcState(directory: string, filename: string): OidcStateClaim | u
     before = fileIdentity(lstatSync(statePath) as Stats);
   } catch (error) {
     if (isNotFound(error)) return undefined;
+    // A winner can install its hard-link after the first claim check and before this state
+    // identity check. That process owns the state; this contender must fail closed as used.
+    if (oidcClaimExists(directory, filename)) return undefined;
     throw invalid();
   }
   try {

backend/src/auth/windows-auth-storage.ts

@@ -70,6 +70,8 @@ export interface WindowsAuthStorageBridgeOptions {
   thtExecutable?: string;
   /** Test-only child-launch seam; production uses the fixed no-shell Node child-process launcher. */
   spawnChild?: WindowsAuthStorageSpawn;
+  /** Test-only input scheduling seam for real child-process lifecycle tests. */
+  beforeInputForTest?: () => Promise<void>;
 }
 
 const responseSchema = z.strictObject({
@@ -117,8 +119,8 @@ function validateRoot(root: string): void {
     || !win32.isAbsolute(root) || win32.normalize(root) !== root) throw invalid();
 }
 
-function validateFilename(filename: string, claim = false): void {
-  if (typeof filename !== "string" || !(claim ? CLAIM_FILENAME : DIGEST_FILENAME).test(filename)) throw invalid();
+function validateFilename(filename: string, allowClaim = false): void {
+  if (typeof filename !== "string" || (!DIGEST_FILENAME.test(filename) && !(allowClaim && CLAIM_FILENAME.test(filename)))) throw invalid();
 }
 
 function safeThtExecutable(value: string | undefined): string {
@@ -144,7 +146,16 @@ function parseResponse(result: WindowsAuthStorageInvocationResult): BridgeRespon
 
 function encodedRequest(request: BridgeRequest): Buffer {
   validateRoot(request.root);
-  if (request.filename !== undefined) validateFilename(request.filename);
+  if (request.operation === "list") {
+    if (request.filename !== undefined || request.contentBase64 !== undefined) throw invalid();
+  } else {
+    if (request.filename === undefined) throw invalid();
+    const allowClaim = request.operation === "remove" && request.directory === "oidc";
+    validateFilename(request.filename, allowClaim);
+    if (request.contentBase64 !== undefined && request.operation !== "create" && request.operation !== "replace") throw invalid();
+  }
+  if ((request.operation === "claim-consume" || request.operation === "read-claim" || request.operation === "remove-claim")
+    && request.directory !== "oidc") throw invalid();
   if (request.contentBase64 !== undefined) canonicalBase64(request.contentBase64, directoryMaximum(request.directory));
   const encoded = Buffer.from(JSON.stringify(request), "utf8");
   if (encoded.length === 0 || encoded.length > MAX_PROTOCOL_BYTES) throw invalid();
@@ -165,6 +176,7 @@ const spawnTht: WindowsAuthStorageSpawn = (executable, args, options) => spawn(e
 async function invokeTht(
   invocation: WindowsAuthStorageInvocation,
   spawnChild: WindowsAuthStorageSpawn = spawnTht,
+  beforeInputForTest?: () => Promise<void>,
 ): Promise<WindowsAuthStorageInvocationResult> {
   return new Promise((resolve, reject) => {
     let settled = false;
@@ -260,10 +272,18 @@ async function invokeTht(
       stderr.push(Buffer.from(chunk));
     });
     stdin.once("error", abort);
-    try {
-      stdin.end(invocation.input);
-    } catch {
-      abort();
+    const writeInput = (): void => {
+      if (aborted || settled) return;
+      try {
+        stdin.end(invocation.input);
+      } catch {
+        abort();
+      }
+    };
+    if (beforeInputForTest === undefined) {
+      writeInput();
+    } else {
+      void Promise.resolve().then(beforeInputForTest).then(writeInput, abort);
     }
   });
 }
@@ -279,7 +299,11 @@ function contentFrom(response: BridgeResponse, maximum: number): Buffer | undefi
 
 export function createWindowsAuthStorageBridge(options: WindowsAuthStorageBridgeOptions = {}): WindowsAuthStorageBridge {
   const executable = safeThtExecutable(options.thtExecutable);
-  const invoke = options.invoke ?? ((invocation: WindowsAuthStorageInvocation) => invokeTht(invocation, options.spawnChild));
+  const invoke = options.invoke ?? ((invocation: WindowsAuthStorageInvocation) => invokeTht(
+    invocation,
+    options.spawnChild,
+    options.beforeInputForTest,
+  ));
   const request = async (value: BridgeRequest): Promise<BridgeResponse> => {
     try {
       const response = await invoke({
@@ -325,7 +349,7 @@ export function createWindowsAuthStorageBridge(options: WindowsAuthStorageBridge
       const response = await request({ version: PROTOCOL_VERSION, operation: "list", root, directory });
       if (response.entries === undefined) throw invalid();
       for (const entry of response.entries) {
-        if (!DIGEST_FILENAME.test(entry.name) && !CLAIM_FILENAME.test(entry.name)) throw invalid();
+        if (!DIGEST_FILENAME.test(entry.name) && !(directory === "oidc" && CLAIM_FILENAME.test(entry.name))) throw invalid();
       }
       return response.entries.map((entry) => ({ name: entry.name, modifiedUnixMs: entry.modifiedUnixMs }));
     },

backend/test/auth-session-store.test.ts

@@ -22,6 +22,7 @@ import { afterEach, describe, expect, test, vi } from "vitest";
 const fsHooks = vi.hoisted(() => ({
   afterRead: undefined as undefined | (() => void),
   afterWrite: undefined as undefined | (() => void),
+  beforeLstat: undefined as undefined | ((path: string) => boolean),
   afterLstat: undefined as undefined | ((path: string) => boolean),
   transformLstat: undefined as undefined | ((path: string, info: import("node:fs").Stats) => import("node:fs").Stats),
 }));
@@ -45,6 +46,8 @@ vi.mock("node:fs", async (importOriginal) => {
       return result;
     },
     lstatSync: (...args: Parameters<typeof actual.lstatSync>) => {
+      const before = fsHooks.beforeLstat;
+      if (before?.(String(args[0]))) fsHooks.beforeLstat = undefined;
       const original = actual.lstatSync(...args);
       const result = fsHooks.transformLstat?.(String(args[0]), original) ?? original;
       const callback = fsHooks.afterLstat;
@@ -69,6 +72,7 @@ const validLocalUser = { enabled: true, authRevision: 7, roles: ["admin"] as con
 afterEach(() => {
   fsHooks.afterRead = undefined;
   fsHooks.afterWrite = undefined;
+  fsHooks.beforeLstat = undefined;
   fsHooks.afterLstat = undefined;
   fsHooks.transformLstat = undefined;
   for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true });
@@ -297,6 +301,23 @@ describe("file-backed auth session store", () => {
     expect(existsSync(statePath)).toBe(true);
   });
 
+  test("treats a competing OIDC claim installed between availability and state checks as unavailable", async () => {
+    const storageRoot = root();
+    const store = validStore(storageRoot);
+    const created = await store.createOidcState({ nonce: "n".repeat(43), codeVerifier: "v".repeat(43), returnTo: "/" }, base);
+    const statePath = digestPath(storageRoot, "oidc", created.state);
+    const stateClaimPath = claimPath(storageRoot, created.state);
+    fsHooks.beforeLstat = (observed) => {
+      if (observed !== statePath) return false;
+      linkSync(statePath, stateClaimPath);
+      return true;
+    };
+
+    await expect(store.consumeOidcState(created.state)).resolves.toBeUndefined();
+    expect(existsSync(statePath)).toBe(true);
+    expect(existsSync(stateClaimPath)).toBe(true);
+  });
+
   test("prunes an expired OIDC state abandoned after an atomic claim", async () => {
     const storageRoot = root();
     const store = validStore(storageRoot);
@@ -639,6 +660,72 @@ describe("file-backed auth session store", () => {
     }
   });
 
+  test("prunes empty Windows directories through the required Go entries array", async () => {
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async () => ({
+        code: 0,
+        stdout: Buffer.from('{"version":1,"ok":true,"entries":[]}\n'),
+        stderr: Buffer.alloc(0),
+      }),
+    });
+    const originalPlatform = Object.getOwnPropertyDescriptor(process, "platform");
+    if (!originalPlatform) throw new Error("platform descriptor unavailable");
+    Object.defineProperty(process, "platform", { configurable: true, value: "win32" });
+    try {
+      const store = createFileAuthSessionStore("C:\\ProgramData\\ThothII\\auth", {
+        currentAuthConfigRevision: () => revision,
+        findLocalUser: async () => validLocalUser,
+      }, { windowsStorageBridge: bridge });
+
+      await expect(store.prune(base)).resolves.toBe(0);
+    } finally {
+      Object.defineProperty(process, "platform", originalPlatform);
+    }
+  });
+
+  test("prunes a stale Windows OIDC orphan claim through the Go DTO path", async () => {
+    const claim = `${"d".repeat(64)}.claim`;
+    let removed = false;
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async ({ input }) => {
+        const request = JSON.parse(input.toString("utf8")) as { operation: string; directory: string; filename?: string };
+        const response = (value: Record<string, unknown>) => ({
+          code: 0,
+          stdout: Buffer.from(`${JSON.stringify({ version: 1, ok: true, ...value })}\n`),
+          stderr: Buffer.alloc(0),
+        });
+        if (request.operation === "list") {
+          return response({
+            entries: request.directory === "oidc"
+              ? [{ name: claim, modifiedUnixMs: base.getTime() }]
+              : [],
+          });
+        }
+        if (request.operation === "remove" && request.directory === "oidc" && request.filename === claim) {
+          removed = true;
+          return response({ removed: true });
+        }
+        throw new Error("unexpected bridge request");
+      },
+    });
+    const originalPlatform = Object.getOwnPropertyDescriptor(process, "platform");
+    if (!originalPlatform) throw new Error("platform descriptor unavailable");
+    Object.defineProperty(process, "platform", { configurable: true, value: "win32" });
+    try {
+      const store = createFileAuthSessionStore("C:\\ProgramData\\ThothII\\auth", {
+        currentAuthConfigRevision: () => revision,
+        findLocalUser: async () => validLocalUser,
+      }, { windowsStorageBridge: bridge });
+
+      await expect(store.prune(new Date(base.getTime() + 11 * 60_000))).resolves.toBe(1);
+      expect(removed).toBe(true);
+    } finally {
+      Object.defineProperty(process, "platform", originalPlatform);
+    }
+  });
+
   test("revokes on config, local-user, revision, enabled, or role mismatch before returning", async () => {
     const storageRoot = root();
     let currentRevision = revision;

backend/test/fixtures/windows-auth-storage-real-child.mjs

@@ -0,0 +1,21 @@
+import { appendFileSync, closeSync, writeFileSync } from "node:fs";
+
+const [, , mode, marker] = process.argv;
+
+writeFileSync(marker, `started:${process.pid}\n`);
+process.on("exit", () => appendFileSync(marker, "exited\n"));
+process.on("SIGTERM", () => {
+  appendFileSync(marker, "terminated\n");
+  process.exit(0);
+});
+
+if (mode === "stdin") {
+  closeSync(0);
+  appendFileSync(marker, "stdin-closed\n");
+} else if (mode === "stdout") {
+  process.stdout.write(Buffer.alloc(64 * 1024 + 1));
+} else if (mode === "stderr") {
+  process.stderr.write(Buffer.alloc(64 * 1024 + 1));
+}
+
+setInterval(() => {}, 1_000);

backend/test/windows-auth-storage.test.ts

@@ -1,10 +1,63 @@
+import { appendFileSync, chmodSync, existsSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { spawn } from "node:child_process";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { fileURLToPath } from "node:url";
 import { EventEmitter } from "node:events";
 import { PassThrough } from "node:stream";
-import { describe, expect, test, vi } from "vitest";
+import { afterEach, describe, expect, test, vi } from "vitest";
 import { createWindowsAuthStorageBridge } from "../src/auth/windows-auth-storage.js";
 
 const root = "C:\\ProgramData\\ThothII\\auth";
 const filename = "a".repeat(64) + ".json";
+const realChildFixture = fileURLToPath(new URL("./fixtures/windows-auth-storage-real-child.mjs", import.meta.url));
+const fixtureRoots: string[] = [];
+
+function shellQuote(value: string): string {
+  return `'${value.replaceAll("'", `'\\''`)}'`;
+}
+
+async function waitForMarker(marker: string, expected: string): Promise<void> {
+  const deadline = Date.now() + 3_000;
+  while (Date.now() < deadline) {
+    if (existsSync(marker) && readFileSync(marker, "utf8").includes(expected)) return;
+    await new Promise<void>((resolve) => setTimeout(resolve, 10));
+  }
+  throw new Error(`real helper marker did not contain ${expected}`);
+}
+
+function realChildBridge(mode: "timeout" | "stdout" | "stderr" | "stdin") {
+  const directory = mkdtempSync(join(tmpdir(), "thothii-auth-bridge-child-"));
+  fixtureRoots.push(directory);
+  const marker = join(directory, "marker.txt");
+  const launcher = join(directory, "tht.exe");
+  writeFileSync(launcher, `#!/bin/sh\nexec ${shellQuote(process.execPath)} ${shellQuote(realChildFixture)} ${shellQuote(mode)} ${shellQuote(marker)} "$@"\n`, { mode: 0o700 });
+  chmodSync(launcher, 0o700);
+  return {
+    marker,
+    bridge: createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      spawnChild: (_executable, args, options) => spawn(launcher, [...args], options),
+      ...(mode === "stdin" ? {
+        beforeInputForTest: async () => {
+          await waitForMarker(marker, "stdin-closed");
+          appendFileSync(marker, "before-input\n");
+        },
+      } : {}),
+    } as never),
+  };
+}
+
+afterEach(() => {
+  for (const directory of fixtureRoots.splice(0)) {
+    const marker = join(directory, "marker.txt");
+    try {
+      const pid = Number(/^started:(\d+)$/m.exec(readFileSync(marker, "utf8"))?.[1]);
+      if (Number.isSafeInteger(pid) && pid > 0) process.kill(pid, "SIGKILL");
+    } catch { /* the test-owned child already exited or did not start */ }
+    rmSync(directory, { recursive: true, force: true });
+  }
+});
 
 class FakeBridgeChild extends EventEmitter {
   readonly stdin = new PassThrough();
@@ -110,6 +163,52 @@ describe("Windows auth-storage bridge", () => {
     ]);
   });
 
+  test("parses the Go helper's required empty entries array", async () => {
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async () => ({
+        code: 0,
+        stdout: Buffer.from('{"version":1,"ok":true,"entries":[]}\n'),
+        stderr: Buffer.alloc(0),
+      }),
+    });
+
+    await expect(bridge.list(root, "sessions")).resolves.toEqual([]);
+  });
+
+  test("allows only canonical OIDC claim removal and rejects claims elsewhere", async () => {
+    const claim = `${"b".repeat(64)}.claim`;
+    const invoke = vi.fn(async () => ({
+      code: 0,
+      stdout: Buffer.from('{"version":1,"ok":true,"removed":true}\n'),
+      stderr: Buffer.alloc(0),
+    }));
+    const bridge = createWindowsAuthStorageBridge({ thtExecutable: "C:\\tht.exe", invoke });
+
+    await expect(bridge.remove(root, "oidc", claim)).resolves.toBe(true);
+    await expect(bridge.remove(root, "sessions", claim)).rejects.toThrow("auth_session_store_invalid");
+    await expect(bridge.read(root, "oidc", claim)).rejects.toThrow("auth_session_store_invalid");
+    await expect(bridge.create(root, "oidc", claim, Buffer.from("record"))).rejects.toThrow("auth_session_store_invalid");
+    await expect(bridge.replace(root, "oidc", claim, Buffer.from("record"))).rejects.toThrow("auth_session_store_invalid");
+    await expect(bridge.remove(root, "oidc", `../${claim}`)).rejects.toThrow("auth_session_store_invalid");
+    await expect(bridge.remove(root, "oidc", `${claim}.bak`)).rejects.toThrow("auth_session_store_invalid");
+    expect(invoke).toHaveBeenCalledTimes(1);
+  });
+
+  test("rejects OIDC claim entries returned for a sessions list", async () => {
+    const claim = `${"c".repeat(64)}.claim`;
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async () => ({
+        code: 0,
+        stdout: Buffer.from(`{"version":1,"ok":true,"entries":[{"name":"${claim}","modifiedUnixMs":1}]}\n`),
+        stderr: Buffer.alloc(0),
+      }),
+    });
+
+    await expect(bridge.list(root, "sessions")).rejects.toThrow("auth_session_store_invalid");
+  });
+
   test("aborts a stdin-closed looping helper on timeout and waits for close", async () => {
     vi.useFakeTimers();
     const child = new FakeBridgeChild();
@@ -189,4 +288,17 @@ describe("Windows auth-storage bridge", () => {
 
     await expect(bridge.list(root, "sessions")).rejects.toThrow("auth_session_store_invalid");
   });
+
+  test.each(["timeout", "stdout", "stderr", "stdin"] as const)("kills a real %s helper process through the production spawn path", async (mode) => {
+    const { bridge, marker } = realChildBridge(mode);
+    const startedAt = Date.now();
+    const pending = bridge.list(root, "sessions");
+    const outcome = pending.then(() => undefined, (error: unknown) => error);
+    await waitForMarker(marker, "started");
+    if (mode === "stdin") await waitForMarker(marker, "before-input");
+
+    await expect(outcome).resolves.toMatchObject({ message: "auth_session_store_invalid" });
+    await waitForMarker(marker, "terminated");
+    if (mode === "stdin") expect(Date.now() - startedAt).toBeLessThan(2_000);
+  }, 10_000);
 });