diff --git a/e2e/agent-token.drizzle.test.ts b/e2e/agent-token.drizzle.test.ts
index 1d75a4b..302a627 100644
--- a/e2e/agent-token.drizzle.test.ts
+++ b/e2e/agent-token.drizzle.test.ts
@@ -21,6 +21,10 @@ import {
 import { mountAgentTokens } from "../src/mount";
 import { mountRunScopedTokens } from "../src/mount-run-scoped";
 import { createAgentTokenVerifier, requireAgentToken } from "../src/middleware";
+import {
+  createRunBoundTokenVerifier,
+  requireRunBoundToken,
+} from "../src/run-bound";
 import type { WorkflowRunScopeEnv } from "../src/workflow-run-scope";
 
 const databaseUrl = process.env.DATABASE_URL;
@@ -539,4 +543,194 @@ describeIfDb("agent tokens", () => {
       await close();
     }
   });
+
+  test("requireRunBoundToken admits a run-bound bearer and sets workflowRunScope from the token", async () => {
+    const { db, close } = createDB({ ...target, schema: SCHEMA });
+    try {
+      const tenantId = `tnt_rb_${randomUUID().slice(0, 8)}`;
+      await seedTenant(db, tenantId);
+
+      const minted = await mintRunScopedToken(db, {
+        tenantId,
+        definitionId: "def_artifacts",
+        name: "workflow",
+        runId: "run_bound_1",
+      });
+
+      const scope = {
+        tenantId,
+        principalId: "principal_1",
+        runId: "run_bound_1",
+      };
+
+      const app = new Hono<TenantEnv>();
+      app.use(tenantFrom(db, tenantId));
+      app.get(
+        "/guarded",
+        requireRunBoundToken({
+          db,
+          resolveRunById: (runId) => (runId === "run_bound_1" ? scope : null),
+        }),
+        (c) =>
+          c.json({
+            tokenRunId: c.get("agentToken").runId,
+            scopeRunId: c.get("workflowRunScope").runId,
+            principalId: c.get("workflowRunScope").principalId,
+          }),
+      );
+
+      const ok = await app.request("/guarded", {
+        headers: { authorization: `Bearer ${minted.token}` },
+      });
+      expect(ok.status).toBe(200);
+      expect(await ok.json()).toEqual({
+        tokenRunId: "run_bound_1",
+        scopeRunId: "run_bound_1",
+        principalId: "principal_1",
+      });
+    } finally {
+      await close();
+    }
+  });
+
+  test("requireRunBoundToken returns identical 401 for every rejection case", async () => {
+    const { db, close } = createDB({ ...target, schema: SCHEMA });
+    try {
+      const tenantId = `tnt_rb401_${randomUUID().slice(0, 8)}`;
+      const otherTenantId = `tnt_rb401_o_${randomUUID().slice(0, 8)}`;
+      await seedTenant(db, tenantId);
+      await seedTenant(db, otherTenantId);
+
+      // A run-bound token.
+      const bound = await mintRunScopedToken(db, {
+        tenantId,
+        definitionId: "def_artifacts",
+        name: "workflow",
+        runId: "run_401",
+      });
+
+      // A definition-scoped token (no runId).
+      const unbound = await mintAgentToken(db, {
+        tenantId,
+        definitionId: "def_artifacts",
+        name: "artifacts",
+      });
+
+      // A token from a different tenant.
+      const foreign = await mintRunScopedToken(db, {
+        tenantId: otherTenantId,
+        definitionId: "def_artifacts",
+        name: "workflow",
+        runId: "run_foreign",
+      });
+
+      const app = new Hono<TenantEnv>();
+      app.use(tenantFrom(db, tenantId));
+      app.get(
+        "/guarded",
+        requireRunBoundToken({
+          db,
+          resolveRunById: (runId) =>
+            runId === "run_401" ? { tenantId, principalId: "p1", runId } : null,
+        }),
+        (c) => c.json({ ok: true }),
+      );
+
+      const expected = { error: "unauthorized" };
+
+      // No bearer.
+      const noBear = await app.request("/guarded");
+      expect(noBear.status).toBe(401);
+      expect(await noBear.json()).toEqual(expected);
+
+      // Fabricated bearer.
+      const fake = await app.request("/guarded", {
+        headers: { authorization: "Bearer invented" },
+      });
+      expect(fake.status).toBe(401);
+      expect(await fake.json()).toEqual(expected);
+
+      // Valid token but no runId (definition-scoped).
+      const noRun = await app.request("/guarded", {
+        headers: { authorization: `Bearer ${unbound.token}` },
+      });
+      expect(noRun.status).toBe(401);
+      expect(await noRun.json()).toEqual(expected);
+
+      // Valid token from another tenant.
+      const cross = await app.request("/guarded", {
+        headers: { authorization: `Bearer ${foreign.token}` },
+      });
+      expect(cross.status).toBe(401);
+      expect(await cross.json()).toEqual(expected);
+
+      // Valid run-bound token (positive control).
+      const ok = await app.request("/guarded", {
+        headers: { authorization: `Bearer ${bound.token}` },
+      });
+      expect(ok.status).toBe(200);
+    } finally {
+      await close();
+    }
+  });
+
+  test("createRunBoundTokenVerifier resolves run-bound tokens and rejects everything else", async () => {
+    const { db, close } = createDB({ ...target, schema: SCHEMA });
+    try {
+      const tenantId = `tnt_rbv_${randomUUID().slice(0, 8)}`;
+      await seedTenant(db, tenantId);
+
+      const bound = await mintRunScopedToken(db, {
+        tenantId,
+        definitionId: "def_artifacts",
+        name: "workflow",
+        runId: "run_verifier",
+      });
+
+      const unbound = await mintAgentToken(db, {
+        tenantId,
+        definitionId: "def_artifacts",
+        name: "artifacts",
+      });
+
+      const verify = createRunBoundTokenVerifier({
+        db,
+        resolveRunById: (runId) =>
+          runId === "run_verifier"
+            ? { tenantId, principalId: "p1", runId }
+            : null,
+      });
+
+      const app = new Hono<WorkflowRunScopeEnv>();
+      app.use("/:tenantId/*", async (c, next) =>
+        tenantFrom<WorkflowRunScopeEnv>(db, c.req.param("tenantId"))(c, next),
+      );
+      app.get("/:tenantId/check", async (c) => {
+        const result = await verify(c);
+        return c.json({ result: result ?? null });
+      });
+
+      const ok = await app.request(`/${tenantId}/check`, {
+        headers: { authorization: `Bearer ${bound.token}` },
+      });
+      expect(ok.status).toBe(200);
+      const body = (await ok.json()) as {
+        result: { workflowRunScope: { runId: string } } | null;
+      };
+      expect(body.result).not.toBeNull();
+      expect(body.result!.workflowRunScope.runId).toBe("run_verifier");
+
+      // Unbound token returns null.
+      const noRun = await app.request(`/${tenantId}/check`, {
+        headers: { authorization: `Bearer ${unbound.token}` },
+      });
+      expect(((await noRun.json()) as { result: unknown }).result).toBeNull();
+
+      // No bearer returns null.
+      const noBear = await app.request(`/${tenantId}/check`);
+      expect(((await noBear.json()) as { result: unknown }).result).toBeNull();
+    } finally {
+      await close();
+    }
+  });
 });
diff --git a/src/index.ts b/src/index.ts
index 5bd0ac8..642eb9f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -18,6 +18,14 @@ export {
   type ResolveRunForToken,
   type RunScopeForToken,
 } from "./mount-run-scoped.js";
+export {
+  createRunBoundTokenVerifier,
+  requireRunBoundToken,
+  type ResolveRunById,
+  type RequireRunBoundTokenOpts,
+  type RunBoundTokenVariables,
+  type RunBoundTokenVerifier,
+} from "./run-bound.js";
 export {
   createAgentTokenVerifier,
   requireAgentToken,
diff --git a/src/run-bound.ts b/src/run-bound.ts
new file mode 100644
index 0000000..235cdbe
--- /dev/null
+++ b/src/run-bound.ts
@@ -0,0 +1,104 @@
+// Middleware and verifier that bind an agent token to the specific run it
+// was issued for.  A token with a `runId` is only valid for requests to that
+// run; requests for any other run get the same 401 as an unknown bearer.
+// The run identity comes from the *token*, not from a request header, so
+// the consumer can trust it without a second header-based lookup.
+import type { TenantEnv } from "@intx/hub-api";
+import type { Context, MiddlewareHandler } from "hono";
+
+import {
+  type AgentTokenContext,
+  type AgentTokenVariables,
+  createAgentTokenVerifier,
+  type RequireAgentTokenOpts,
+} from "./middleware.js";
+import type {
+  ResolvedWorkflowRunScope,
+  WorkflowRunScopeEnv,
+} from "./workflow-run-scope.js";
+
+/** `(runId) => scope | null`: the host's lookup from a token's bound run ID
+ * to the full run scope it names, or `null` for unknown runs.  Unlike
+ * `resolveRun(runAddress)` in `AgentTokenAuth`, this resolves by the stored
+ * run ID, not by a user-supplied address. */
+export type ResolveRunById = (
+  runId: string,
+) => Promise<ResolvedWorkflowRunScope | null> | ResolvedWorkflowRunScope | null;
+
+export type RequireRunBoundTokenOpts<TSchema extends Record<string, unknown>> =
+  RequireAgentTokenOpts<TSchema> & {
+    resolveRunById: ResolveRunById;
+  };
+
+/** Context variables set by `requireRunBoundToken`: the verified token
+ * *and* the resolved workflow run scope. */
+export type RunBoundTokenVariables = AgentTokenVariables & {
+  workflowRunScope: ResolvedWorkflowRunScope;
+};
+
+/** Middleware that verifies a bearer, asserts it is bound to a run, resolves
+ * that run, and sets both `agentToken` and `workflowRunScope` on the
+ * context.  Every rejection — missing bearer, invalid token, unbound token,
+ * unknown run, wrong tenant — returns the same `401 { "error":
+ * "unauthorized" }` so a response never reveals whether a token is live.
+ *
+ * Must run behind the hub's tenant middleware. */
+export function requireRunBoundToken<TSchema extends Record<string, unknown>>(
+  opts: RequireRunBoundTokenOpts<TSchema>,
+): MiddlewareHandler<TenantEnv & { Variables: RunBoundTokenVariables }> {
+  const verify = createAgentTokenVerifier(opts);
+
+  return async (c, next) => {
+    const identity = await verify(c);
+
+    // Token missing, invalid, revoked or wrong tenant.
+    if (identity === undefined) {
+      return c.json({ error: "unauthorized" }, 401);
+    }
+
+    // Token not bound to a run (definition-scoped only).
+    if (identity.runId === null) {
+      return c.json({ error: "unauthorized" }, 401);
+    }
+
+    const scope = await opts.resolveRunById(identity.runId);
+
+    // Run unknown or belongs to a different tenant.
+    if (scope === null || scope.tenantId !== identity.tenantId) {
+      return c.json({ error: "unauthorized" }, 401);
+    }
+
+    c.set("agentToken", identity);
+    c.set("workflowRunScope", scope);
+    await next();
+    return undefined;
+  };
+}
+
+/** The same check as a function, for a route that falls back to its own
+ * authentication when no run-bound agent token is presented. */
+export type RunBoundTokenVerifier = <E extends WorkflowRunScopeEnv>(
+  c: Context<E>,
+) => Promise<
+  | {
+      agentToken: AgentTokenContext;
+      workflowRunScope: ResolvedWorkflowRunScope;
+    }
+  | undefined
+>;
+
+export function createRunBoundTokenVerifier<
+  TSchema extends Record<string, unknown>,
+>(opts: RequireRunBoundTokenOpts<TSchema>): RunBoundTokenVerifier {
+  const verify = createAgentTokenVerifier(opts);
+
+  return async (c) => {
+    const identity = await verify(c);
+    if (identity === undefined || identity.runId === null) return undefined;
+    const scope = await opts.resolveRunById(identity.runId);
+    if (scope === null || scope.tenantId !== identity.tenantId) {
+      return undefined;
+    }
+    return { agentToken: identity, workflowRunScope: scope };
+  };
+}