diff --git a/.changeset/gateway-eve-version-ua.md b/.changeset/gateway-eve-version-ua.md
new file mode 100644
index 000000000..83a936bb3
--- /dev/null
+++ b/.changeset/gateway-eve-version-ua.md
@@ -0,0 +1,9 @@
+---
+"eve": patch
+---
+
+Send a versioned `User-Agent` on AI Gateway model calls. eve now sets a leading
+`eve/<version> (<agent name>)` product token, and the AI SDK appends its own
+`ai/<version> ai-sdk/provider-utils/<version> runtime/node.js/<version>` tokens
+after it, so gateway traffic is attributable to both the eve and SDK versions
+alongside the existing `x-title` and `http-referer` attribution headers.
diff --git a/packages/eve/src/harness/tool-loop.test.ts b/packages/eve/src/harness/tool-loop.test.ts
index 9396dbb2f..b725c99f2 100644
--- a/packages/eve/src/harness/tool-loop.test.ts
+++ b/packages/eve/src/harness/tool-loop.test.ts
@@ -8019,6 +8019,7 @@ describe("createToolLoopHarness", () => {
 
         const agentCall = vi.mocked(ToolLoopAgent).mock.calls[0]?.[0];
         expect(agentCall?.headers).toEqual({
+          "user-agent": "eve/0.0.0 (Weather Agent)",
           "x-title": "Weather Agent",
           "http-referer": "https://my-agent.vercel.app",
         });
@@ -8031,6 +8032,39 @@ describe("createToolLoopHarness", () => {
       }
     });
 
+    it("sets a versioned user-agent suffixed with the agent name", async () => {
+      setupStopResultForAttribution();
+      const originalProductionUrl = process.env.VERCEL_PROJECT_PRODUCTION_URL;
+      delete process.env.VERCEL_PROJECT_PRODUCTION_URL;
+      const originalUrl = process.env.VERCEL_URL;
+      delete process.env.VERCEL_URL;
+      try {
+        const config: ToolLoopHarnessConfig = {
+          mode: "conversation",
+          resolveModel: vi.fn().mockResolvedValue("anthropic/claude-sonnet-4-5"),
+          runtimeIdentity: {
+            agentId: "weather-agent",
+            agentName: "Weather Agent",
+            eveVersion: "9.9.9",
+            modelId: "anthropic/claude-sonnet-4-5",
+          },
+          tools: new Map(),
+        };
+        const runStep = createToolLoopHarness(config);
+        await runStep(createTestSession(), { message: "hi" });
+
+        const agentCall = vi.mocked(ToolLoopAgent).mock.calls[0]?.[0];
+        expect(agentCall?.headers?.["user-agent"]).toBe("eve/9.9.9 (Weather Agent)");
+      } finally {
+        if (originalProductionUrl !== undefined) {
+          process.env.VERCEL_PROJECT_PRODUCTION_URL = originalProductionUrl;
+        }
+        if (originalUrl !== undefined) {
+          process.env.VERCEL_URL = originalUrl;
+        }
+      }
+    });
+
     it("falls back to agentId when agentName is not set", async () => {
       setupStopResultForAttribution();
       const originalProductionUrl = process.env.VERCEL_PROJECT_PRODUCTION_URL;
@@ -8053,6 +8087,7 @@ describe("createToolLoopHarness", () => {
 
         const agentCall = vi.mocked(ToolLoopAgent).mock.calls[0]?.[0];
         expect(agentCall?.headers).toEqual({
+          "user-agent": "eve/0.0.0 (weather-agent)",
           "x-title": "weather-agent",
         });
       } finally {
@@ -8088,6 +8123,7 @@ describe("createToolLoopHarness", () => {
 
         const agentCall = vi.mocked(ToolLoopAgent).mock.calls[0]?.[0];
         expect(agentCall?.headers).toEqual({
+          "user-agent": "eve/0.0.0 (My Agent)",
           "x-title": "My Agent",
           "http-referer": "https://preview-123.vercel.app",
         });
@@ -8183,6 +8219,7 @@ describe("createToolLoopHarness", () => {
 
         const compactCall = vi.mocked(compactMessages).mock.calls[0];
         expect(compactCall?.[5]).toEqual({
+          "user-agent": "eve/0.0.0 (Weather Agent)",
           "x-title": "Weather Agent",
           "http-referer": "https://my-agent.vercel.app",
         });
diff --git a/packages/eve/src/harness/tool-loop.ts b/packages/eve/src/harness/tool-loop.ts
index 0b4e30606..17ab1cf9f 100644
--- a/packages/eve/src/harness/tool-loop.ts
+++ b/packages/eve/src/harness/tool-loop.ts
@@ -19,6 +19,7 @@ import {
 } from "ai";
 import { isScheduleAppAuth } from "#channel/schedule-auth.js";
 import { resolveInstalledPackageInfo } from "#internal/application/package.js";
+import { EVE_PACKAGE_NAME } from "#internal/package-name.js";
 import {
   createErrorId,
   createLogger,
@@ -263,8 +264,15 @@ function enrichTelemetry(
  * Builds AI Gateway app attribution headers when the model is gateway-routed.
  *
  * Gateway routing is detected by `typeof model === "string"` — the same
- * condition used for the `gateway-auto` cache path. Returns `undefined`
- * for non-gateway models or when no meaningful attribution is available.
+ * condition used for the `gateway-auto` cache path. Sets a leading
+ * `user-agent` product token (`eve/<version> (<agent>)`); the AI SDK then
+ * appends its own `ai/<v> ai-sdk/provider-utils/<v> runtime/node.js/<v>`
+ * tokens after it (via `withUserAgentSuffix`), so the gateway sees both the
+ * eve and SDK versions without eve reconstructing the SDK's. The agent name
+ * rides in a UA comment so a spaced display name stays a valid User-Agent.
+ * Also sets the OpenRouter-style `x-title` (agent name) and `http-referer`
+ * (deployment host). Returns `undefined` for non-gateway models or when no
+ * meaningful attribution is available.
  */
 function buildGatewayAttributionHeaders(
   model: LanguageModel,
@@ -274,18 +282,20 @@ function buildGatewayAttributionHeaders(
     return undefined;
   }
 
+  const version = runtimeIdentity?.eveVersion;
   const title = runtimeIdentity?.agentName ?? runtimeIdentity?.agentId;
   const deploymentHost = process.env.VERCEL_PROJECT_PRODUCTION_URL || process.env.VERCEL_URL;
   const referer = deploymentHost ? `https://${deploymentHost}` : undefined;
 
-  if (!title && !referer) {
-    return undefined;
-  }
-
   const headers: Record<string, string> = {};
+  if (version) {
+    headers["user-agent"] = title
+      ? `${EVE_PACKAGE_NAME}/${version} (${title})`
+      : `${EVE_PACKAGE_NAME}/${version}`;
+  }
   if (title) headers["x-title"] = title;
   if (referer) headers["http-referer"] = referer;
-  return headers;
+  return Object.keys(headers).length > 0 ? headers : undefined;
 }
 
 async function resolveActiveRuntimeModel(input: {