diff --git a/coverage/summary.json b/coverage/summary.json
index 8d9640e..1f7d879 100644
--- a/coverage/summary.json
+++ b/coverage/summary.json
@@ -1,18 +1,18 @@
 {
-  "generatedAt": "2026-05-19T21:51:40.371Z",
-  "commit": "5151454",
+  "generatedAt": "2026-05-20T08:21:18.294Z",
+  "commit": "a633561",
   "repo": {
     "statements": 97.38,
-    "branches": 92.19,
-    "functions": 97.1,
+    "branches": 92.2,
+    "functions": 97.11,
     "lines": 97.38,
     "counts": {
-      "lf": 5801,
-      "lh": 5649,
-      "brf": 1165,
-      "brh": 1074,
-      "fnf": 345,
-      "fnh": 335
+      "lf": 5807,
+      "lh": 5655,
+      "brf": 1166,
+      "brh": 1075,
+      "fnf": 346,
+      "fnh": 336
     }
   },
   "byPackage": {
@@ -101,17 +101,17 @@
       }
     },
     "@repo/core-shared": {
-      "statements": 98.03,
-      "branches": 95.89,
-      "functions": 92.08,
-      "lines": 98.03,
+      "statements": 98.04,
+      "branches": 95.9,
+      "functions": 92.16,
+      "lines": 98.04,
       "counts": {
-        "lf": 1067,
-        "lh": 1046,
-        "brf": 316,
-        "brh": 303,
-        "fnf": 101,
-        "fnh": 93
+        "lf": 1073,
+        "lh": 1052,
+        "brf": 317,
+        "brh": 304,
+        "fnf": 102,
+        "fnh": 94
       }
     },
     "@repo/core-ui": {
diff --git a/packages/core-shared/package.json b/packages/core-shared/package.json
index 14e5649..7630c7f 100644
--- a/packages/core-shared/package.json
+++ b/packages/core-shared/package.json
@@ -6,6 +6,7 @@
   "exports": {
     ".": "./src/index.ts",
     "./audit": "./src/audit/index.ts",
+    "./rate-limit": "./src/rate-limit/index.ts",
     "./conformance": "./src/conformance/index.ts",
     "./conformance/coverage": "./src/conformance/coverage.ts",
     "./di": "./src/di/index.ts",
diff --git a/packages/core-shared/src/conformance/brand-runtime.test.ts b/packages/core-shared/src/conformance/brand-runtime.test.ts
index 85bcb41..3c5e2fe 100644
--- a/packages/core-shared/src/conformance/brand-runtime.test.ts
+++ b/packages/core-shared/src/conformance/brand-runtime.test.ts
@@ -5,6 +5,7 @@ import {
   isCaptured,
   isAudited,
   isAnalyzed,
+  isRateLimited,
 } from "@/conformance/brand-runtime";
 
 describe("brand-runtime", () => {
@@ -23,6 +24,7 @@ describe("brand-runtime", () => {
     expect(isCaptured(fn)).toBe(false);
     expect(isAudited(fn)).toBe(false);
     expect(isAnalyzed(fn)).toBe(false);
+    expect(isRateLimited(fn)).toBe(false);
   });
 
   it("predicates discriminate between brands", () => {
@@ -45,6 +47,11 @@ describe("brand-runtime", () => {
     const analyzed = () => {};
     attachBrand(analyzed, "__analyzed");
     expect(isAnalyzed(analyzed)).toBe(true);
+
+    const rateLimited = () => {};
+    attachBrand(rateLimited, "__rateLimited");
+    expect(isRateLimited(rateLimited)).toBe(true);
+    expect(isInstrumented(rateLimited)).toBe(false);
   });
 
   it("composing brands stacks them on the same function", () => {
@@ -53,10 +60,12 @@ describe("brand-runtime", () => {
     attachBrand(fn, "__captured");
     attachBrand(fn, "__audited");
     attachBrand(fn, "__analyzed");
+    attachBrand(fn, "__rateLimited");
     expect(isInstrumented(fn)).toBe(true);
     expect(isCaptured(fn)).toBe(true);
     expect(isAudited(fn)).toBe(true);
     expect(isAnalyzed(fn)).toBe(true);
+    expect(isRateLimited(fn)).toBe(true);
   });
 
   it("attached brands are non-writable and non-configurable", () => {
diff --git a/packages/core-shared/src/conformance/brand-runtime.ts b/packages/core-shared/src/conformance/brand-runtime.ts
index c51998a..bb2b3e5 100644
--- a/packages/core-shared/src/conformance/brand-runtime.ts
+++ b/packages/core-shared/src/conformance/brand-runtime.ts
@@ -13,14 +13,15 @@
  * commitment, not a mutable flag.
  */
 
-import type { Analyzed, ConsentChecked } from "./brands";
+import type { Analyzed, ConsentChecked, RateLimited } from "./brands";
 
 type Brand =
   | "__instrumented"
   | "__captured"
   | "__audited"
   | "__analyzed"
-  | "__consentChecked";
+  | "__consentChecked"
+  | "__rateLimited";
 
 /**
  * Attaches the brand as a non-enumerable property on the given function.
@@ -68,3 +69,9 @@ export function isConsentChecked<F extends object>(
 ): fn is ConsentChecked<F> {
   return hasBrand(fn, "__consentChecked");
 }
+
+export function isRateLimited<F extends object>(
+  fn: unknown,
+): fn is RateLimited<F> {
+  return hasBrand(fn, "__rateLimited");
+}
diff --git a/packages/core-shared/src/conformance/brands.test.ts b/packages/core-shared/src/conformance/brands.test.ts
index 3e09bee..43a33f7 100644
--- a/packages/core-shared/src/conformance/brands.test.ts
+++ b/packages/core-shared/src/conformance/brands.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expectTypeOf } from "vitest";
-import type { Instrumented, Captured } from "@/conformance/brands";
+import type { Instrumented, Captured, RateLimited } from "@/conformance/brands";
 
 describe("brand types", () => {
   it("Instrumented<F> is structurally F plus a phantom flag", () => {
@@ -16,6 +16,12 @@ describe("brand types", () => {
     expectTypeOf<Captured<Fn>["__captured"]>().toEqualTypeOf<true>();
   });
 
+  it("RateLimited<F> is structurally F plus a phantom flag", () => {
+    type Fn = (n: number) => Promise<string>;
+    expectTypeOf<RateLimited<Fn>>().toBeCallableWith(1);
+    expectTypeOf<RateLimited<Fn>["__rateLimited"]>().toEqualTypeOf<true>();
+  });
+
   it("brands compose without conflict", () => {
     type Fn = (n: number) => Promise<string>;
     type Both = Instrumented<Fn> & Captured<Fn>;
diff --git a/packages/core-shared/src/conformance/brands.ts b/packages/core-shared/src/conformance/brands.ts
index ed8190a..76b5f8b 100644
--- a/packages/core-shared/src/conformance/brands.ts
+++ b/packages/core-shared/src/conformance/brands.ts
@@ -11,3 +11,4 @@ export type Instrumented<F> = F & { readonly __instrumented: true };
 export type Captured<F> = F & { readonly __captured: true };
 export type Analyzed<F> = F & { readonly __analyzed: true };
 export type ConsentChecked<F> = F & { readonly __consentChecked: true };
+export type RateLimited<F> = F & { readonly __rateLimited: true };
diff --git a/packages/core-shared/src/conformance/define-feature.test.ts b/packages/core-shared/src/conformance/define-feature.test.ts
index 0ea084a..1a97a03 100644
--- a/packages/core-shared/src/conformance/define-feature.test.ts
+++ b/packages/core-shared/src/conformance/define-feature.test.ts
@@ -2,7 +2,9 @@ import { describe, it, expect, expectTypeOf } from "vitest";
 import {
   defineFeature,
   type FeatureManifest,
+  type UseCaseManifest,
 } from "@/conformance/define-feature";
+import type { RateLimitBudget } from "@/rate-limit/rate-limit.interface";
 import {
   DEFAULT_COVERAGE_BANDS,
   DEFAULT_MUTATION_SCORE,
@@ -58,6 +60,41 @@ describe("defineFeature", () => {
     expectTypeOf(manifest).toMatchTypeOf<FeatureManifest>();
   });
 
+  it("accepts an optional rateLimit array on a use case", () => {
+    const manifest = defineFeature({
+      name: "auth",
+      requiredCores: [],
+      useCases: {
+        signIn: {
+          mutates: false,
+          audits: [],
+          publishes: [],
+          consumes: [],
+          rateLimit: [{ name: "login", window: "1m", budget: 5 }],
+        },
+      },
+      realtimeChannels: [],
+      jobs: [],
+    } as const);
+
+    expectTypeOf(manifest).toMatchTypeOf<FeatureManifest>();
+    expectTypeOf(manifest.useCases.signIn.rateLimit).toMatchTypeOf<
+      readonly RateLimitBudget[] | undefined
+    >();
+  });
+
+  it("use case without rateLimit satisfies UseCaseManifest", () => {
+    const uc: UseCaseManifest = {
+      mutates: false,
+      audits: [],
+      publishes: [],
+      consumes: [],
+    };
+    expectTypeOf(uc.rateLimit).toEqualTypeOf<
+      readonly RateLimitBudget[] | undefined
+    >();
+  });
+
   it("accepts an optional coverage section", () => {
     const manifest = defineFeature({
       name: "auth",
diff --git a/packages/core-shared/src/conformance/define-feature.ts b/packages/core-shared/src/conformance/define-feature.ts
index 04f330c..d3fcb06 100644
--- a/packages/core-shared/src/conformance/define-feature.ts
+++ b/packages/core-shared/src/conformance/define-feature.ts
@@ -1,4 +1,5 @@
 import type { CoverageManifest } from "./coverage";
+import type { RateLimitBudget } from "../rate-limit/rate-limit.interface";
 
 /**
  * Per-use-case manifest entry. Declares what the use case does at the contract
@@ -12,6 +13,7 @@ export type UseCaseManifest = {
   readonly publishes: readonly string[];
   readonly consumes: readonly string[];
   readonly analyticsEvents?: readonly string[];
+  readonly rateLimit?: readonly RateLimitBudget[];
 };
 
 /**
diff --git a/packages/core-shared/src/conformance/index.ts b/packages/core-shared/src/conformance/index.ts
index e68672e..3f38af3 100644
--- a/packages/core-shared/src/conformance/index.ts
+++ b/packages/core-shared/src/conformance/index.ts
@@ -3,6 +3,7 @@ export type {
   Captured,
   Analyzed,
   ConsentChecked,
+  RateLimited,
 } from "./brands";
 export type { FeatureManifest, UseCaseManifest } from "./define-feature";
 export { defineFeature } from "./define-feature";
@@ -29,6 +30,7 @@ export {
   isAudited,
   isAnalyzed,
   isConsentChecked,
+  isRateLimited,
 } from "./brand-runtime";
 export { ConformanceError } from "./conformance-error";
 export { assertFeatureConformance } from "./assert-bindings";
diff --git a/packages/core-shared/src/rate-limit/index.ts b/packages/core-shared/src/rate-limit/index.ts
new file mode 100644
index 0000000..290e9d9
--- /dev/null
+++ b/packages/core-shared/src/rate-limit/index.ts
@@ -0,0 +1,5 @@
+export type {
+  IRateLimit,
+  RateLimitBudget,
+  RateLimitDecision,
+} from "./rate-limit.interface";
diff --git a/packages/core-shared/src/rate-limit/rate-limit.interface.test.ts b/packages/core-shared/src/rate-limit/rate-limit.interface.test.ts
new file mode 100644
index 0000000..8d5b9be
--- /dev/null
+++ b/packages/core-shared/src/rate-limit/rate-limit.interface.test.ts
@@ -0,0 +1,41 @@
+import { describe, it, expectTypeOf } from "vitest";
+import type {
+  IRateLimit,
+  RateLimitBudget,
+  RateLimitDecision,
+} from "@/rate-limit/rate-limit.interface";
+
+describe("rate-limit types", () => {
+  it("RateLimitBudget has the expected shape", () => {
+    expectTypeOf<RateLimitBudget>().toMatchTypeOf<{
+      name: string;
+      window: string;
+      budget: number;
+    }>();
+  });
+
+  it("RateLimitDecision has the expected shape", () => {
+    expectTypeOf<RateLimitDecision>().toMatchTypeOf<{
+      allowed: boolean;
+      remaining: number;
+      resetAt: Date;
+    }>();
+  });
+
+  it("IRateLimit.consume returns Promise<RateLimitDecision>", () => {
+    expectTypeOf<
+      IRateLimit["consume"]
+    >().returns.resolves.toEqualTypeOf<RateLimitDecision>();
+  });
+
+  it("IRateLimit.consume accepts optional weight", () => {
+    type ConsumeParams = Parameters<IRateLimit["consume"]>;
+    expectTypeOf<ConsumeParams[0]>().toEqualTypeOf<string>();
+    expectTypeOf<ConsumeParams[1]>().toEqualTypeOf<string>();
+    expectTypeOf<ConsumeParams[2]>().toEqualTypeOf<number | undefined>();
+  });
+
+  it("IRateLimit.reset returns Promise<void>", () => {
+    expectTypeOf<IRateLimit["reset"]>().returns.resolves.toEqualTypeOf<void>();
+  });
+});
diff --git a/packages/core-shared/src/rate-limit/rate-limit.interface.ts b/packages/core-shared/src/rate-limit/rate-limit.interface.ts
new file mode 100644
index 0000000..1d36d4e
--- /dev/null
+++ b/packages/core-shared/src/rate-limit/rate-limit.interface.ts
@@ -0,0 +1,20 @@
+export type RateLimitBudget = {
+  name: string;
+  window: string;
+  budget: number;
+};
+
+export type RateLimitDecision = {
+  allowed: boolean;
+  remaining: number;
+  resetAt: Date;
+};
+
+export interface IRateLimit {
+  consume(
+    budgetName: string,
+    key: string,
+    weight?: number,
+  ): Promise<RateLimitDecision>;
+  reset(budgetName: string, key: string): Promise<void>;
+}