diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6babe5a..7ae4a72 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Add `--agent-model` and `DX_AGENT_MODEL` support. When set, the CLI sends the model name as the `X-DX-Agent-Model` header alongside existing agent provenance headers.
+
 ### Fixed
 
 - `dx -v` now prints the CLI version, matching the documented lowercase version flag. Version checks are also skipped for help/version output and global-option-only invocations, preventing update prompts from interfering with those commands.
diff --git a/src/cli.ts b/src/cli.ts
index dc611dc..91f3340 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -60,6 +60,12 @@ function createProgram(): Command {
     .addOption(
       new Option("--agent <name>", "Agent name to send as an HTTP header"),
     )
+    .addOption(
+      new Option(
+        "--agent-model <model>",
+        "Agent model name to send as an HTTP header",
+      ),
+    )
     .addOption(
       new Option(
         "--agent-session-id <id>",
diff --git a/src/commandHelpers.ts b/src/commandHelpers.ts
index 1a02289..5246e29 100644
--- a/src/commandHelpers.ts
+++ b/src/commandHelpers.ts
@@ -9,6 +9,7 @@ export function getContext(command: Command): CliContext {
   return {
     json: Boolean(root.json),
     agent: root.agent || process.env.DX_AGENT_NAME,
+    agentModel: root.agentModel || process.env.DX_AGENT_MODEL,
     agentSessionId: root.agentSessionId || process.env.DX_AGENT_SESSION_ID,
   };
 }
diff --git a/src/commands/catalog/entities.test.ts b/src/commands/catalog/entities.test.ts
index 8a6f98b..499df53 100644
--- a/src/commands/catalog/entities.test.ts
+++ b/src/commands/catalog/entities.test.ts
@@ -1059,6 +1059,7 @@ describe("catalog entities commands", () => {
     it("sends agent provenance from environment variables", async () => {
       process.env.DX_API_BASE_URL = "https://api.example.com";
       process.env.DX_AGENT_NAME = "codex";
+      process.env.DX_AGENT_MODEL = "gpt-5";
       process.env.DX_AGENT_SESSION_ID = "session-123";
       getToken.mockReturnValue("token-123");
 
@@ -1099,6 +1100,7 @@ describe("catalog entities commands", () => {
       const headers = (vi.mocked(fetch).mock.calls[0]?.[1] as RequestInit)
         .headers as Headers;
       expect(headers.get("X-DX-Agent-Name")).toBe("codex");
+      expect(headers.get("X-DX-Agent-Model")).toBe("gpt-5");
       expect(headers.get("X-DX-Agent-Session-Id")).toBe("session-123");
     });
 
diff --git a/src/commands/studio/query.ts b/src/commands/studio/query.ts
index 755d730..7fdc3dc 100644
--- a/src/commands/studio/query.ts
+++ b/src/commands/studio/query.ts
@@ -313,6 +313,10 @@ function buildHeaders(runtime: Runtime, accept: string): Headers {
     headers.set("X-DX-Agent-Name", runtime.context.agent);
   }
 
+  if (runtime.context.agentModel) {
+    headers.set("X-DX-Agent-Model", runtime.context.agentModel);
+  }
+
   if (runtime.context.agentSessionId) {
     headers.set("X-DX-Agent-Session-Id", runtime.context.agentSessionId);
   }
diff --git a/src/http.ts b/src/http.ts
index 50737c0..f92a521 100644
--- a/src/http.ts
+++ b/src/http.ts
@@ -29,6 +29,10 @@ export async function request<T extends Record<string, unknown>>(
     headers.set("X-DX-Agent-Name", runtime.context.agent);
   }
 
+  if (runtime.context.agentModel) {
+    headers.set("X-DX-Agent-Model", runtime.context.agentModel);
+  }
+
   if (runtime.context.agentSessionId) {
     headers.set("X-DX-Agent-Session-Id", runtime.context.agentSessionId);
   }
diff --git a/src/types.ts b/src/types.ts
index 378c5e1..f66ac8e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -12,6 +12,7 @@ export interface Runtime {
 export interface CliContext {
   json: boolean;
   agent?: string;
+  agentModel?: string;
   agentSessionId?: string;
 }
 
diff --git a/src/versionCheck.ts b/src/versionCheck.ts
index b158d38..451cbdf 100644
--- a/src/versionCheck.ts
+++ b/src/versionCheck.ts
@@ -129,6 +129,7 @@ export async function checkForNewVersion(
   const context = {
     json: argv.includes("--json"),
     agent: undefined,
+    agentModel: undefined,
     agentSessionId: undefined,
   };
   const runtime = await buildRuntimeSafe(context);