diff --git a/docs/AGENTS.md b/docs/AGENTS.md
index 21f21e3a7b..b1a2667ed6 100644
--- a/docs/AGENTS.md
+++ b/docs/AGENTS.md
@@ -9,7 +9,15 @@ description: Agent instructions for AI assistants working on the mux codebase
 
 - `mux`: Electron + React desktop app for parallel agent workflows; UX must be fast, responsive, predictable.
 - Minor breaking changes are expected, but critical flows must allow upgrade↔downgrade without friction; skip migrations when breakage is tightly scoped.
-- Public work (issues/PRs/commits) must use 🤖 in the title and include "_Generated with `mux`_" in the body when applicable.
+- Public work (issues/PRs/commits) must use 🤖 in the title and include this footer in the body:
+
+  ```md
+  ---
+  _Generated with `mux` • Model: `<modelString>` • Thinking: `<thinkingLevel>`_
+  <!-- mux-attribution: model=<modelString> thinking=<thinkingLevel> -->
+  ```
+
+  Prefer sourcing values from `$MUX_MODEL_STRING` and `$MUX_THINKING_LEVEL` (bash tool env).
 
 ## PR + Release Workflow
 
diff --git a/src/node/runtime/initHook.test.ts b/src/node/runtime/initHook.test.ts
index d591678d45..bdd68ff592 100644
--- a/src/node/runtime/initHook.test.ts
+++ b/src/node/runtime/initHook.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect } from "bun:test";
-import { LineBuffer, createLineBufferedLoggers } from "./initHook";
+import { LineBuffer, createLineBufferedLoggers, getMuxEnv } from "./initHook";
 import type { InitLogger } from "./Runtime";
 
 describe("LineBuffer", () => {
@@ -53,6 +53,7 @@ describe("LineBuffer", () => {
   });
 });
 
+// getMuxEnv tests are placed here because initHook.ts owns the implementation.
 describe("createLineBufferedLoggers", () => {
   it("should create separate buffers for stdout and stderr", () => {
     const stdoutLines: string[] = [];
@@ -109,3 +110,35 @@ describe("createLineBufferedLoggers", () => {
     expect(stderrLines).toEqual(["also incomplete"]);
   });
 });
+
+describe("getMuxEnv", () => {
+  it("should include base MUX_ environment variables", () => {
+    const env = getMuxEnv("/path/to/project", "worktree", "feature-branch");
+
+    expect(env.MUX_PROJECT_PATH).toBe("/path/to/project");
+    expect(env.MUX_RUNTIME).toBe("worktree");
+    expect(env.MUX_WORKSPACE_NAME).toBe("feature-branch");
+    expect(env.MUX_MODEL_STRING).toBeUndefined();
+    expect(env.MUX_THINKING_LEVEL).toBeUndefined();
+  });
+
+  it("should include model + thinking env vars when provided", () => {
+    const env = getMuxEnv("/path/to/project", "worktree", "feature-branch", {
+      modelString: "openai:gpt-5.2-pro",
+      thinkingLevel: "medium",
+    });
+
+    expect(env.MUX_MODEL_STRING).toBe("openai:gpt-5.2-pro");
+    expect(env.MUX_THINKING_LEVEL).toBe("medium");
+  });
+
+  it("should allow explicit thinkingLevel=off", () => {
+    const env = getMuxEnv("/path/to/project", "local", "main", {
+      modelString: "anthropic:claude-3-5-sonnet",
+      thinkingLevel: "off",
+    });
+
+    expect(env.MUX_MODEL_STRING).toBe("anthropic:claude-3-5-sonnet");
+    expect(env.MUX_THINKING_LEVEL).toBe("off");
+  });
+});
diff --git a/src/node/runtime/initHook.ts b/src/node/runtime/initHook.ts
index f6bd9b6905..0ca80dace0 100644
--- a/src/node/runtime/initHook.ts
+++ b/src/node/runtime/initHook.ts
@@ -3,6 +3,7 @@ import * as fsPromises from "fs/promises";
 import * as path from "path";
 import type { InitLogger } from "./Runtime";
 import type { RuntimeConfig } from "@/common/types/runtime";
+import type { ThinkingLevel } from "@/common/types/thinking";
 import { isWorktreeRuntime, isSSHRuntime } from "@/common/types/runtime";
 
 /**
@@ -38,13 +39,34 @@ export function getInitHookPath(projectPath: string): string {
 export function getMuxEnv(
   projectPath: string,
   runtime: "local" | "worktree" | "ssh",
-  workspaceName: string
+  workspaceName: string,
+  options?: {
+    modelString?: string;
+    thinkingLevel?: ThinkingLevel;
+  }
 ): Record<string, string> {
-  return {
+  if (!projectPath) {
+    throw new Error("getMuxEnv: projectPath is required");
+  }
+  if (!workspaceName) {
+    throw new Error("getMuxEnv: workspaceName is required");
+  }
+
+  const env: Record<string, string> = {
     MUX_PROJECT_PATH: projectPath,
     MUX_RUNTIME: runtime,
     MUX_WORKSPACE_NAME: workspaceName,
   };
+
+  if (options?.modelString) {
+    env.MUX_MODEL_STRING = options.modelString;
+  }
+
+  if (options?.thinkingLevel !== undefined) {
+    env.MUX_THINKING_LEVEL = options.thinkingLevel;
+  }
+
+  return env;
 }
 
 /**
diff --git a/src/node/services/aiService.ts b/src/node/services/aiService.ts
index 373346c32c..cd7b94c642 100644
--- a/src/node/services/aiService.ts
+++ b/src/node/services/aiService.ts
@@ -1150,7 +1150,11 @@ export class AIService extends EventEmitter {
           muxEnv: getMuxEnv(
             metadata.projectPath,
             getRuntimeType(metadata.runtimeConfig),
-            metadata.name
+            metadata.name,
+            {
+              modelString,
+              thinkingLevel: thinkingLevel ?? "off",
+            }
           ),
           runtimeTempDir,
           backgroundProcessManager: this.backgroundProcessManager,