feat(auth): add signIn rate-limit backfill with dual ip/account budgets

Wires the rate-limit primitive end-to-end through auth.signIn as the
canonical credential-stuffing defence example:

- manifest: rateLimit [ip 5/1m, account 10/1h] on signIn use case
- use case: rateLimit: IRateLimit dep; dual consume + TooManyRequestsError
- binders: ctx.rateLimit ?? new NoopRateLimit() in bind-production + bind-dev-seed
- tRPC: TooManyRequestsError → TOO_MANY_REQUESTS error code in authProcedure
- tests: RecordingRateLimit dual-consume assertion; InMemoryRateLimit
  budget-1 ip + account rejection; coverage 100% on use-cases layer
- ESLint: _manifest-ast.js extractRateLimitNames handles RateLimitBudget
  objects ({name,window,budget}) in addition to plain string literals,
  no-undeclared-rate-limit passes on both "ip" and "account" call sites

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

coverage/summary.json

@@ -1,33 +1,33 @@
 {
-  "generatedAt": "2026-05-20T08:59:30.996Z",
+  "generatedAt": "2026-05-20T09:21:52.321Z",
-  "commit": "24b2490",
+  "commit": "91d7a24",
   "repo": {
-    "statements": 97.43,
+    "statements": 97.38,
-    "branches": 92.35,
+    "branches": 92.39,
     "functions": 97.21,
-    "lines": 97.43,
+    "lines": 97.38,
     "counts": {
-      "lf": 5910,
+      "lf": 5948,
-      "lh": 5758,
+      "lh": 5792,
-      "brf": 1190,
+      "brf": 1196,
-      "brh": 1099,
+      "brh": 1105,
-      "fnf": 358,
+      "fnf": 359,
-      "fnh": 348
+      "fnh": 349
     }
   },
   "byPackage": {
     "@repo/auth": {
-      "statements": 94,
+      "statements": 93.81,
-      "branches": 92.11,
+      "branches": 92.5,
       "functions": 100,
-      "lines": 94,
+      "lines": 93.81,
       "counts": {
-        "lf": 834,
+        "lf": 872,
-        "lh": 784,
+        "lh": 818,
-        "brf": 114,
+        "brf": 120,
-        "brh": 105,
+        "brh": 111,
-        "fnf": 45,
+        "fnf": 46,
-        "fnh": 45
+        "fnh": 46
       }
     },
     "@repo/blog": {

packages/auth/src/application/use-cases/sign-in.use-case.test.ts

@@ -6,9 +6,14 @@ import {
 } from "@/application/use-cases/sign-in.use-case";
 import { MockUsersRepository } from "@/infrastructure/repositories/users.repository.mock";
 import { MockAuthenticationService } from "@/infrastructure/services/authentication.service.mock";
-import { AuthenticationError } from "@/entities/errors/auth";
+import {
+  AuthenticationError,
+  TooManyRequestsError,
+} from "@/entities/errors/auth";
 import type { IAuthenticationService } from "@/application/services/authentication.service.interface";
 import { userFactory } from "@/__factories__/user.factory";
+import { NoopRateLimit, InMemoryRateLimit } from "@repo/core-shared/rate-limit";
+import { RecordingRateLimit } from "@repo/core-testing/rate-limit";
 
 describe("signInUseCase", () => {
   it("returns a session + cookie on valid credentials", async () => {
@@ -20,7 +25,7 @@ describe("signInUseCase", () => {
     });
     await users.createUser(seedUser);
 
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     const result = await useCase({
       username: "alice",
       password: "testpassword",
@@ -33,7 +38,7 @@ describe("signInUseCase", () => {
   it("throws AuthenticationError when user does not exist", async () => {
     const users = new MockUsersRepository([]);
     const auth = new MockAuthenticationService(users);
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
 
     await expect(
       useCase({ username: "ghost", password: "anything" }),
@@ -50,11 +55,99 @@ describe("signInUseCase", () => {
       }),
     );
 
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     await expect(
       useCase({ username: "alice", password: "wrong" }),
     ).rejects.toBeInstanceOf(AuthenticationError);
   });
+
+  it("captures both ip and account consume calls via RecordingRateLimit", async () => {
+    const users = new MockUsersRepository([]);
+    const auth = new MockAuthenticationService(users);
+    const rl = new RecordingRateLimit();
+    const seedUser = userFactory.build({
+      username: "alice",
+      passwordHash: "hashed_testpassword",
+    });
+    await users.createUser(seedUser);
+
+    const useCase = signInUseCase(users, auth, rl);
+    await useCase({
+      username: "alice",
+      password: "testpassword",
+      clientIp: "1.2.3.4",
+    });
+
+    expect(rl.consumeCalls).toHaveLength(2);
+    expect(rl.consumeCalls[0]).toMatchObject({
+      budgetName: "ip",
+      key: "signIn:ip:1.2.3.4",
+    });
+    expect(rl.consumeCalls[1]).toMatchObject({
+      budgetName: "account",
+      key: "signIn:account:alice",
+    });
+  });
+
+  it("throws TooManyRequestsError when ip budget is exhausted", async () => {
+    const users = new MockUsersRepository([]);
+    const auth = new MockAuthenticationService(users);
+    const rl = new InMemoryRateLimit([
+      { name: "ip", window: "1m", budget: 1 },
+      { name: "account", window: "1h", budget: 10 },
+    ]);
+    const seedUser = userFactory.build({
+      username: "alice",
+      passwordHash: "hashed_testpassword",
+    });
+    await users.createUser(seedUser);
+
+    const useCase = signInUseCase(users, auth, rl);
+    await useCase({
+      username: "alice",
+      password: "testpassword",
+      clientIp: "1.2.3.4",
+    });
+
+    await expect(
+      useCase({
+        username: "alice",
+        password: "testpassword",
+        clientIp: "1.2.3.4",
+      }),
+    ).rejects.toBeInstanceOf(TooManyRequestsError);
+  });
+
+  it("throws TooManyRequestsError when account budget is exhausted", async () => {
+    const users = new MockUsersRepository([]);
+    const auth = new MockAuthenticationService(users);
+    const rl = new InMemoryRateLimit([
+      { name: "ip", window: "1m", budget: 100 },
+      { name: "account", window: "1h", budget: 1 },
+    ]);
+    const seedUser = userFactory.build({
+      username: "alice",
+      passwordHash: "hashed_testpassword",
+    });
+    await users.createUser(seedUser);
+
+    const useCase = signInUseCase(users, auth, rl);
+    // First call succeeds (ip allows, account allows, credentials ok)
+    await useCase({
+      username: "alice",
+      password: "testpassword",
+      clientIp: "1.2.3.4",
+    });
+
+    // Second call: ip still allows (high budget), account is exhausted
+    await expect(
+      useCase({
+        username: "alice",
+        password: "testpassword",
+        clientIp: "5.6.7.8",
+      }),
+    ).rejects.toBeInstanceOf(TooManyRequestsError);
+  });
 });
 
 describe("signInUseCase output validation", () => {
@@ -69,7 +162,7 @@ describe("signInUseCase output validation", () => {
       createSession: async () => ({ session: { id: 123 }, cookie: null }),
     } as unknown as IAuthenticationService;
 
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     await expect(
       useCase({ username: "alice", password: "x" }),
     ).rejects.toBeInstanceOf(ZodError);

packages/auth/src/application/use-cases/sign-in.use-case.ts

@@ -1,6 +1,10 @@
 import { z } from "zod";
 
-import { AuthenticationError } from "../../entities/errors/auth";
+import type { IRateLimit } from "@repo/core-shared/rate-limit";
+import {
+  AuthenticationError,
+  TooManyRequestsError,
+} from "../../entities/errors/auth";
 import { cookieSchema } from "../../entities/models/cookie";
 import { sessionSchema } from "../../entities/models/session";
 import type { IUsersRepository } from "../repositories/users.repository.interface";
@@ -11,6 +15,7 @@ export const signInInputSchema = z
   .object({
     username: z.string().min(3).max(31),
     password: z.string().min(6).max(255),
+    clientIp: z.string().optional(),
   })
   .strict();
 export type SignInInput = z.infer<typeof signInInputSchema>;
@@ -26,9 +31,28 @@ export type SignInOutput = z.infer<typeof signInOutputSchema>;
 export type ISignInUseCase = ReturnType<typeof signInUseCase>;
 
 export const signInUseCase =
-  (usersRepository: IUsersRepository, authenticationService: IAuthenticationService) =>
+  (
+    usersRepository: IUsersRepository,
+    authenticationService: IAuthenticationService,
+    rateLimit: IRateLimit,
+  ) =>
   async (input: SignInInput): Promise<SignInOutput> => {
-    const existingUser = await usersRepository.getUserByUsername(input.username);
+    const { allowed: ipAllowed } = await rateLimit.consume(
+      "ip",
+      `signIn:ip:${input.clientIp ?? ""}`,
+    );
+    if (!ipAllowed) throw new TooManyRequestsError("Too many sign-in attempts");
+
+    const { allowed: accountAllowed } = await rateLimit.consume(
+      "account",
+      `signIn:account:${input.username}`,
+    );
+    if (!accountAllowed)
+      throw new TooManyRequestsError("Too many sign-in attempts");
+
+    const existingUser = await usersRepository.getUserByUsername(
+      input.username,
+    );
     if (!existingUser) {
       throw new AuthenticationError("User does not exist");
     }

packages/auth/src/di/bind-dev-seed.ts

@@ -10,6 +10,7 @@ import {
   assertFeatureConformance,
   wireUseCase,
 } from "@repo/core-shared/conformance";
+import { NoopRateLimit } from "@repo/core-shared/rate-limit";
 import { authManifest } from "../feature.manifest.js";
 import { authContainer } from "./container.js";
 import { AUTH_SYMBOLS } from "./symbols.js";
@@ -85,12 +86,13 @@ export async function bindDevSeedAuth(ctx: BindContext): Promise<void> {
     container: authContainer,
     symbol: AUTH_SYMBOLS.ISignInUseCase,
     factory: signInUseCase,
-    deps: [repo, authService],
+    deps: [repo, authService, ctx.rateLimit ?? new NoopRateLimit()],
     feature: "auth",
     layer: "use-case",
     name: "signIn",
     tracer,
     logger,
+    rateLimit: ctx.rateLimit ?? new NoopRateLimit(),
   });
   const wrappedSignUp = wireUseCase({
     container: authContainer,

packages/auth/src/di/bind-production.ts

@@ -10,6 +10,7 @@ import {
   assertFeatureConformance,
   wireUseCase,
 } from "@repo/core-shared/conformance";
+import { NoopRateLimit } from "@repo/core-shared/rate-limit";
 import { authManifest } from "../feature.manifest";
 import { authContainer } from "./container";
 import { AUTH_SYMBOLS } from "./symbols";
@@ -77,12 +78,13 @@ export function bindProductionAuth(ctx: BindProductionContext): void {
     container: authContainer,
     symbol: AUTH_SYMBOLS.ISignInUseCase,
     factory: signInUseCase,
-    deps: [repo, authService],
+    deps: [repo, authService, ctx.rateLimit ?? new NoopRateLimit()],
     feature: "auth",
     layer: "use-case",
     name: "signIn",
     tracer,
     logger,
+    rateLimit: ctx.rateLimit ?? new NoopRateLimit(),
   });
   const wrappedSignUp = wireUseCase({
     container: authContainer,

packages/auth/src/di/bind-production.types.test.ts

@@ -19,7 +19,8 @@ describe("auth.signIn binding slot (type-level)", () => {
     // It returns a function with no brand attached — must not be assignable.
     const fakeRepo = {} as never;
     const fakeAuth = {} as never;
-    const unwrapped = signInUseCase(fakeRepo, fakeAuth);
+    const fakeRateLimit = {} as never;
+    const unwrapped = signInUseCase(fakeRepo, fakeAuth, fakeRateLimit);
 
     // @ts-expect-error — unwrapped factory has no __instrumented / __captured brand
     const _bad: Slot = unwrapped;

packages/auth/src/di/module.ts

@@ -1,5 +1,6 @@
 import { ContainerModule, type interfaces } from "inversify";
 
+import { NoopRateLimit } from "@repo/core-shared/rate-limit";
 import type { IUsersRepository } from "../application/repositories/users.repository.interface";
 import type { IAuthenticationService } from "../application/services/authentication.service.interface";
 import { MockUsersRepository } from "../infrastructure/repositories/users.repository.mock";
@@ -42,6 +43,7 @@ export const AuthModule = new ContainerModule((bind: interfaces.Bind) => {
       ctx.container.get<IAuthenticationService>(
         AUTH_SYMBOLS.IAuthenticationService,
       ),
+      new NoopRateLimit(),
     ),
   );
 

packages/auth/src/entities/errors/auth.ts

@@ -18,3 +18,10 @@ export class UnauthorizedError extends Error {
     this.name = "UnauthorizedError";
   }
 }
+
+export class TooManyRequestsError extends Error {
+  constructor(message: string, options?: ErrorOptions) {
+    super(message, options);
+    this.name = "TooManyRequestsError";
+  }
+}

packages/auth/src/entities/errors/errors.test.ts

@@ -3,6 +3,7 @@ import {
   AuthenticationError,
   UnauthenticatedError,
   UnauthorizedError,
+  TooManyRequestsError,
 } from "./auth";
 import { InputParseError } from "./common";
 
@@ -37,3 +38,12 @@ describe("InputParseError", () => {
     expect(err.message).toBe("invalid input");
   });
 });
+
+describe("TooManyRequestsError", () => {
+  it("is an instance of Error with the given message", () => {
+    const err = new TooManyRequestsError("too many attempts");
+    expect(err).toBeInstanceOf(Error);
+    expect(err.message).toBe("too many attempts");
+    expect(err.name).toBe("TooManyRequestsError");
+  });
+});

packages/auth/src/feature.manifest.ts

@@ -21,6 +21,10 @@ export const authManifest = defineFeature({
       audits: [],
       publishes: [],
       consumes: [],
+      rateLimit: [
+        { name: "ip", window: "1m", budget: 5 },
+        { name: "account", window: "1h", budget: 10 },
+      ],
     },
     signUp: {
       mutates: true,

packages/auth/src/index.ts

@@ -6,6 +6,7 @@ export {
   AuthenticationError,
   UnauthenticatedError,
   UnauthorizedError,
+  TooManyRequestsError,
 } from "./entities/errors/auth";
 export { InputParseError } from "./entities/errors/common";
 export { SESSION_COOKIE } from "./config";

packages/auth/src/integrations/api/procedures.ts

@@ -5,6 +5,7 @@ import {
   AuthenticationError,
   UnauthenticatedError,
   UnauthorizedError,
+  TooManyRequestsError,
 } from "../../entities/errors/auth";
 import { InputParseError } from "../../entities/errors/common";
 
@@ -14,5 +15,6 @@ export const authProcedure = t.procedure.use(
     [AuthenticationError, "UNAUTHORIZED"],
     [UnauthenticatedError, "UNAUTHORIZED"],
     [UnauthorizedError, "FORBIDDEN"],
+    [TooManyRequestsError, "TOO_MANY_REQUESTS"],
   ]),
 );

packages/auth/src/interface-adapters/controllers/sign-in.controller.test.ts

@@ -5,15 +5,19 @@ import { MockUsersRepository } from "@/infrastructure/repositories/users.reposit
 import { MockAuthenticationService } from "@/infrastructure/services/authentication.service.mock";
 import { InputParseError } from "@/entities/errors/common";
 import { userFactory } from "@/__factories__/user.factory";
+import { NoopRateLimit } from "@repo/core-shared/rate-limit";
 
 describe("signInController", () => {
   it("returns a cookie on successful sign-in", async () => {
     const users = new MockUsersRepository([]);
     const auth = new MockAuthenticationService(users);
-    const seedUser = userFactory.build({ username: "alice", passwordHash: "hashed_testpassword" });
+    const seedUser = userFactory.build({
+      username: "alice",
+      passwordHash: "hashed_testpassword",
+    });
     await users.createUser(seedUser);
 
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     const controller = signInController(useCase);
 
     const result = await controller({
@@ -27,18 +31,22 @@ describe("signInController", () => {
   it("throws InputParseError on invalid input", async () => {
     const users = new MockUsersRepository([]);
     const auth = new MockAuthenticationService(users);
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     const controller = signInController(useCase);
 
-    await expect(controller({ username: "ab" } as unknown)).rejects.toBeInstanceOf(InputParseError);
+    await expect(
+      controller({ username: "ab" } as unknown),
+    ).rejects.toBeInstanceOf(InputParseError);
   });
 
   it("throws InputParseError when input is not an object", async () => {
     const users = new MockUsersRepository([]);
     const auth = new MockAuthenticationService(users);
-    const useCase = signInUseCase(users, auth);
+    const useCase = signInUseCase(users, auth, new NoopRateLimit());
     const controller = signInController(useCase);
 
-    await expect(controller("garbage" as unknown)).rejects.toBeInstanceOf(InputParseError);
+    await expect(controller("garbage" as unknown)).rejects.toBeInstanceOf(
+      InputParseError,
+    );
   });
 });

packages/auth/tests/sign-in-flow.feature.test.ts

@@ -3,6 +3,7 @@
 
 import { describe, it, expect } from "vitest";
 import { RecordingEventBus } from "@repo/core-testing/instrumentation";
+import { NoopRateLimit } from "@repo/core-shared/rate-limit";
 import { MockUsersRepository } from "../src/infrastructure/repositories/users.repository.mock";
 import { MockAuthenticationService } from "../src/infrastructure/services/authentication.service.mock";
 import { signInUseCase } from "../src/application/use-cases/sign-in.use-case";
@@ -18,7 +19,9 @@ describe("auth feature: sign-up → sign-in → sign-out", () => {
     const users = new MockUsersRepository([]);
     const auth = new MockAuthenticationService(users);
 
-    const signIn = signInController(signInUseCase(users, auth));
+    const signIn = signInController(
+      signInUseCase(users, auth, new NoopRateLimit()),
+    );
     const signUp = signUpController(
       signUpUseCase(users, auth, new RecordingEventBus(), undefined),
     );

packages/core-eslint/rules/_manifest-ast.js

@@ -7,6 +7,31 @@ function extractStringLiterals(arrayExpr) {
     .map((el) => el.value);
 }
 
+/**
+ * Extract budget names from a rateLimit array that contains either string
+ * literals ("ip") or RateLimitBudget objects ({ name: "ip", window: "1m", budget: 5 }).
+ */
+function extractRateLimitNames(arrayExpr) {
+  const names = [];
+  for (const el of arrayExpr.elements) {
+    if (!el) continue;
+    if (el.type === "Literal" && typeof el.value === "string") {
+      names.push(el.value);
+    } else if (el.type === "ObjectExpression") {
+      const nameProp = el.properties.find(
+        (p) =>
+          p.type === "Property" &&
+          p.key.type === "Identifier" &&
+          p.key.name === "name" &&
+          p.value.type === "Literal" &&
+          typeof p.value.value === "string",
+      );
+      if (nameProp) names.push(nameProp.value.value);
+    }
+  }
+  return names;
+}
+
 /**
  * Parse a feature.manifest.ts file and extract per-use-case attributes.
  * Walks the AST to find the `defineFeature({...} as const)` call expression
@@ -98,11 +123,12 @@ function extractUseCaseEntry(objExpr) {
       (key === "audits" ||
         key === "publishes" ||
         key === "consumes" ||
-        key === "analyticsEvents" ||
+        key === "analyticsEvents") &&
-        key === "rateLimit") &&
       prop.value.type === "ArrayExpression"
     ) {
       entry[key] = extractStringLiterals(prop.value);
+    } else if (key === "rateLimit" && prop.value.type === "ArrayExpression") {
+      entry[key] = extractRateLimitNames(prop.value);
     }
   }
   return entry;
@@ -232,11 +258,12 @@ function extractUseCaseEntryFromObj(objExpr) {
       (key === "audits" ||
         key === "publishes" ||
         key === "consumes" ||
-        key === "analyticsEvents" ||
+        key === "analyticsEvents") &&
-        key === "rateLimit") &&
       prop.value.type === "ArrayExpression"
     ) {
       entry[key] = extractStringLiterals(prop.value);
+    } else if (key === "rateLimit" && prop.value.type === "ArrayExpression") {
+      entry[key] = extractRateLimitNames(prop.value);
     }
   }
   return entry;

packages/core-eslint/rules/no-undeclared-rate-limit.test.js

@@ -110,6 +110,50 @@ describe("no-undeclared-rate-limit", () => {
     });
   });
 
+  it("passes when rateLimit.consume budget matches a RateLimitBudget object in manifest rateLimit[]", () => {
+    const repoRoot = fs.mkdtempSync(path.join(os.tmpdir(), "nurl-obj-"));
+    const featureDir = path.join(repoRoot, "packages", "demo");
+    fs.mkdirSync(path.join(featureDir, "src", "application", "use-cases"), {
+      recursive: true,
+    });
+    fs.writeFileSync(
+      path.join(featureDir, "src", "feature.manifest.ts"),
+      `export const demoManifest = defineFeature({
+  name: "demo",
+  requiredCores: [],
+  useCases: {
+    signUp: { mutates: true, audits: [], publishes: [], consumes: [], rateLimit: [{ name: "ip", window: "1m", budget: 5 }, { name: "account", window: "1h", budget: 10 }] },
+  },
+  realtimeChannels: [],
+  jobs: [],
+} as const);`,
+    );
+    const useCaseFile = path.join(
+      featureDir,
+      "src",
+      "application",
+      "use-cases",
+      "sign-up.use-case.ts",
+    );
+    fs.writeFileSync(
+      useCaseFile,
+      `export const signUpUseCase = (rateLimit) => async (input) => {
+  await rateLimit.consume("ip", input.clientIp);
+  await rateLimit.consume("account", input.username);
+};`,
+    );
+    tester.run("no-undeclared-rate-limit", rule, {
+      valid: [
+        {
+          filename: useCaseFile,
+          code: fs.readFileSync(useCaseFile, "utf8"),
+          options: [{ repoRoot }],
+        },
+      ],
+      invalid: [],
+    });
+  });
+
   it("is a no-op for non-use-case files", () => {
     const { repoRoot } = makeFixture({
       manifestRateLimit: ["signUp.ip"],

packages/core-testing/package.json

@@ -15,6 +15,7 @@
     "./setup/node": "./src/setup/node.ts",
     "./setup/no-instrumentation": "./src/setup/no-instrumentation.ts",
     "./setup/no-sentry": "./src/setup/no-instrumentation.ts",
+    "./rate-limit": "./src/rate-limit/index.ts",
     "./stryker.base.json": "./stryker.base.json"
   },
   "scripts": {