diff --git a/packages/blog/src/integrations/api/procedures.ts b/packages/blog/src/integrations/api/procedures.ts
index 50974e1..b8ee781 100644
--- a/packages/blog/src/integrations/api/procedures.ts
+++ b/packages/blog/src/integrations/api/procedures.ts
@@ -1,5 +1,6 @@
 import { t } from "@repo/core-shared/trpc/init";
 import { defineErrorMiddleware } from "@repo/core-shared/trpc/define-error-middleware";
+import { requireAuthenticated } from "@repo/core-shared/trpc/require-authenticated";
 
 import { ArticleNotFoundError } from "../../entities/errors/article";
 import { InputParseError } from "../../entities/errors/common";
@@ -10,3 +11,10 @@ export const blogProcedure = t.procedure.use(
     [ArticleNotFoundError, "NOT_FOUND"],
   ]),
 );
+
+/**
+ * Base procedure for MUTATING blog routes (audit finding B7): anonymous
+ * callers are rejected with UNAUTHORIZED before the controller runs.
+ * Read-only queries stay on `blogProcedure`.
+ */
+export const blogProtectedProcedure = blogProcedure.use(requireAuthenticated);
diff --git a/packages/blog/src/integrations/api/router.test.ts b/packages/blog/src/integrations/api/router.test.ts
index c791716..9eb63bc 100644
--- a/packages/blog/src/integrations/api/router.test.ts
+++ b/packages/blog/src/integrations/api/router.test.ts
@@ -30,7 +30,10 @@ describe("blogRouter", () => {
   });
 
   it("createArticle then articleBySlug returns the article", async () => {
-    const caller = blogRouter.createCaller({});
+    // Mutations are auth-gated (B7) — provide a server-resolved ctx.user.
+    const caller = blogRouter.createCaller({
+      user: { id: "u1", roles: [] },
+    });
 
     const created = await caller.createArticle({
       title: "Router Test Article",
@@ -45,6 +48,34 @@ describe("blogRouter", () => {
   });
 });
 
+describe("blogRouter authorization (B7)", () => {
+  beforeEach(() => {
+    blogContainer.unbindAll();
+    blogContainer.load(BlogModule);
+  });
+
+  afterEach(() => {
+    blogContainer.unbindAll();
+  });
+
+  it("createArticle rejects anonymous callers with UNAUTHORIZED", async () => {
+    const caller = blogRouter.createCaller({});
+    await expect(
+      caller.createArticle({
+        title: "Nope",
+        content: null,
+        authorId: "u1",
+        slug: "nope",
+      }),
+    ).rejects.toMatchObject({ code: "UNAUTHORIZED" });
+  });
+
+  it("read-only queries stay public", async () => {
+    const caller = blogRouter.createCaller({});
+    await expect(caller.listArticles({})).resolves.toEqual([]);
+  });
+});
+
 describe("blogRouter error mapping", () => {
   beforeEach(() => {
     blogContainer.unbindAll();
diff --git a/packages/blog/src/integrations/api/router.ts b/packages/blog/src/integrations/api/router.ts
index af74435..077017a 100644
--- a/packages/blog/src/integrations/api/router.ts
+++ b/packages/blog/src/integrations/api/router.ts
@@ -11,7 +11,7 @@ import type { IGetArticlesController } from "../../interface-adapters/controller
 import type { ICreateArticleController } from "../../interface-adapters/controllers/create-article.controller";
 import type { IGetArticleBySlugController } from "../../interface-adapters/controllers/get-article-by-slug.controller";
 
-import { blogProcedure } from "./procedures";
+import { blogProcedure, blogProtectedProcedure } from "./procedures";
 
 export const blogRouter = router({
   articleBySlug: blogProcedure
@@ -32,7 +32,8 @@ export const blogRouter = router({
       return ctrl(input);
     }),
 
-  createArticle: blogProcedure
+  // Mutations require an authenticated caller (B7).
+  createArticle: blogProtectedProcedure
     .input(createArticleInputSchema)
     .mutation(({ input }) => {
       const ctrl = blogContainer.get<ICreateArticleController>(
diff --git a/packages/core-shared/package.json b/packages/core-shared/package.json
index 81f39f3..9baf51d 100644
--- a/packages/core-shared/package.json
+++ b/packages/core-shared/package.json
@@ -16,6 +16,7 @@
     "./payload": "./src/payload/index.ts",
     "./trpc/init": "./src/trpc/init.ts",
     "./trpc/context": "./src/trpc/context.ts",
+    "./trpc/require-authenticated": "./src/trpc/require-authenticated.ts",
     "./trpc/define-error-middleware": "./src/trpc/define-error-middleware.ts",
     "./instrumentation": "./src/instrumentation/index.ts",
     "./instrumentation/otel": "./src/instrumentation/otel/index.ts",
diff --git a/packages/core-shared/src/trpc/require-authenticated.test.ts b/packages/core-shared/src/trpc/require-authenticated.test.ts
new file mode 100644
index 0000000..e7d3993
--- /dev/null
+++ b/packages/core-shared/src/trpc/require-authenticated.test.ts
@@ -0,0 +1,50 @@
+import { describe, it, expect } from "vitest";
+import { z } from "zod";
+import { t } from "@/trpc/init";
+import {
+  requireAuthenticated,
+  protectedProcedure,
+} from "@/trpc/require-authenticated";
+
+const echoRouter = t.router({
+  publicEcho: t.procedure
+    .input(z.object({ value: z.string() }).strict())
+    .query(({ input }) => input.value),
+  protectedEcho: protectedProcedure
+    .input(z.object({ value: z.string() }).strict())
+    .mutation(({ input, ctx }) => ({
+      value: input.value,
+      userId: (ctx as { user: { id: string } }).user.id,
+    })),
+  composedEcho: t.procedure
+    .use(requireAuthenticated)
+    .input(z.object({}).strict())
+    .mutation(() => "ok"),
+});
+
+describe("requireAuthenticated middleware (B7)", () => {
+  it("rejects anonymous callers with UNAUTHORIZED", async () => {
+    const caller = echoRouter.createCaller({});
+    await expect(caller.protectedEcho({ value: "x" })).rejects.toMatchObject({
+      code: "UNAUTHORIZED",
+    });
+    await expect(caller.composedEcho({})).rejects.toMatchObject({
+      code: "UNAUTHORIZED",
+    });
+  });
+
+  it("passes through authenticated callers and exposes ctx.user", async () => {
+    const caller = echoRouter.createCaller({
+      user: { id: "user-1", roles: [] },
+    });
+    await expect(caller.protectedEcho({ value: "x" })).resolves.toEqual({
+      value: "x",
+      userId: "user-1",
+    });
+  });
+
+  it("leaves public procedures untouched", async () => {
+    const caller = echoRouter.createCaller({});
+    await expect(caller.publicEcho({ value: "hi" })).resolves.toBe("hi");
+  });
+});
diff --git a/packages/core-shared/src/trpc/require-authenticated.ts b/packages/core-shared/src/trpc/require-authenticated.ts
new file mode 100644
index 0000000..c9fc888
--- /dev/null
+++ b/packages/core-shared/src/trpc/require-authenticated.ts
@@ -0,0 +1,32 @@
+import { TRPCError } from "@trpc/server";
+import { t } from "./init";
+import type { TrpcSessionUser } from "./context";
+
+/**
+ * Shared authentication guard for MUTATING tRPC procedures (audit finding
+ * B7). Reads the server-resolved `ctx.user` (attached by `createTrpcContext`
+ * via the app's `resolveUser`) and rejects anonymous callers with
+ * UNAUTHORIZED. Read-only queries stay public; each feature opts its
+ * mutations in by composing this middleware into its procedure chain:
+ *
+ * ```ts
+ * export const blogProtectedProcedure = blogProcedure.use(requireAuthenticated);
+ * ```
+ *
+ * The shared `t` is context-untyped, so the middleware narrows at runtime
+ * (same cast pattern as the dsr/audit routers) and re-publishes `user` into
+ * the downstream ctx with a non-optional type.
+ */
+export const requireAuthenticated = t.middleware(({ ctx, next }) => {
+  const user = (ctx as { user?: TrpcSessionUser }).user;
+  if (!user) {
+    throw new TRPCError({
+      code: "UNAUTHORIZED",
+      message: "Authentication required",
+    });
+  }
+  return next({ ctx: { ...ctx, user } });
+});
+
+/** Convenience base procedure for apps composing ad-hoc protected routes. */
+export const protectedProcedure = t.procedure.use(requireAuthenticated);
diff --git a/packages/media/src/integrations/api/procedures.ts b/packages/media/src/integrations/api/procedures.ts
index 98b3490..ea5244d 100644
--- a/packages/media/src/integrations/api/procedures.ts
+++ b/packages/media/src/integrations/api/procedures.ts
@@ -1,5 +1,6 @@
 import { t } from "@repo/core-shared/trpc/init";
 import { defineErrorMiddleware } from "@repo/core-shared/trpc/define-error-middleware";
+import { requireAuthenticated } from "@repo/core-shared/trpc/require-authenticated";
 
 import { MediaNotFoundError } from "../../entities/errors/media";
 import { InputParseError } from "../../entities/errors/common";
@@ -10,3 +11,10 @@ export const mediaProcedure = t.procedure.use(
     [MediaNotFoundError, "NOT_FOUND"],
   ]),
 );
+
+/**
+ * Base procedure for MUTATING media routes (audit finding B7): anonymous
+ * callers are rejected with UNAUTHORIZED before the controller runs.
+ * Read-only queries stay on `mediaProcedure`.
+ */
+export const mediaProtectedProcedure = mediaProcedure.use(requireAuthenticated);
diff --git a/packages/media/src/integrations/api/router.test.ts b/packages/media/src/integrations/api/router.test.ts
index 348258d..fc91b00 100644
--- a/packages/media/src/integrations/api/router.test.ts
+++ b/packages/media/src/integrations/api/router.test.ts
@@ -36,6 +36,29 @@ describe("mediaRouter", () => {
   });
 });
 
+describe("mediaRouter authorization (B7)", () => {
+  beforeEach(() => {
+    mediaContainer.unbindAll();
+    mediaContainer.load(MediaModule);
+  });
+
+  afterEach(() => {
+    mediaContainer.unbindAll();
+  });
+
+  it("deleteMedia rejects anonymous callers with UNAUTHORIZED", async () => {
+    const caller = mediaRouter.createCaller({});
+    await expect(caller.deleteMedia({ id: "some-id" })).rejects.toMatchObject({
+      code: "UNAUTHORIZED",
+    });
+  });
+
+  it("read-only queries stay public", async () => {
+    const caller = mediaRouter.createCaller({});
+    await expect(caller.listMedia({})).resolves.toEqual([]);
+  });
+});
+
 describe("mediaRouter error mapping", () => {
   beforeEach(() => {
     mediaContainer.unbindAll();
@@ -69,7 +92,8 @@ describe("mediaRouter error mapping", () => {
   });
 
   it("translates MediaNotFoundError → NOT_FOUND on deleteMedia with missing id", async () => {
-    const caller = mediaRouter.createCaller({});
+    // Mutations are auth-gated (B7) — provide a server-resolved ctx.user.
+    const caller = mediaRouter.createCaller({ user: { id: "u1", roles: [] } });
     try {
       await caller.deleteMedia({ id: "nonexistent-id" });
       throw new Error("expected throw");
diff --git a/packages/media/src/integrations/api/router.ts b/packages/media/src/integrations/api/router.ts
index c7a3608..0e1214a 100644
--- a/packages/media/src/integrations/api/router.ts
+++ b/packages/media/src/integrations/api/router.ts
@@ -11,21 +11,30 @@ import type { IGetMediaController } from "../../interface-adapters/controllers/g
 import type { IListMediaController } from "../../interface-adapters/controllers/list-media.controller";
 import type { IDeleteMediaController } from "../../interface-adapters/controllers/delete-media.controller";
 
-import { mediaProcedure } from "./procedures";
+import { mediaProcedure, mediaProtectedProcedure } from "./procedures";
 
 export const mediaRouter = router({
   getMedia: mediaProcedure.input(getMediaInputSchema).query(({ input }) => {
-    const ctrl = mediaContainer.get<IGetMediaController>(MEDIA_SYMBOLS.IGetMediaController);
+    const ctrl = mediaContainer.get<IGetMediaController>(
+      MEDIA_SYMBOLS.IGetMediaController,
+    );
     return ctrl(input);
   }),
   listMedia: mediaProcedure.input(listMediaInputSchema).query(({ input }) => {
-    const ctrl = mediaContainer.get<IListMediaController>(MEDIA_SYMBOLS.IListMediaController);
-    return ctrl(input);
-  }),
-  deleteMedia: mediaProcedure.input(deleteMediaInputSchema).mutation(({ input }) => {
-    const ctrl = mediaContainer.get<IDeleteMediaController>(MEDIA_SYMBOLS.IDeleteMediaController);
+    const ctrl = mediaContainer.get<IListMediaController>(
+      MEDIA_SYMBOLS.IListMediaController,
+    );
     return ctrl(input);
   }),
+  // Mutations require an authenticated caller (B7).
+  deleteMedia: mediaProtectedProcedure
+    .input(deleteMediaInputSchema)
+    .mutation(({ input }) => {
+      const ctrl = mediaContainer.get<IDeleteMediaController>(
+        MEDIA_SYMBOLS.IDeleteMediaController,
+      );
+      return ctrl(input);
+    }),
 });
 
 export type MediaRouter = typeof mediaRouter;