diff --git a/src/hooks/llm-slug-generator.test.ts b/src/hooks/llm-slug-generator.test.ts
new file mode 100644
index 000000000..ba65ee6c3
--- /dev/null
+++ b/src/hooks/llm-slug-generator.test.ts
@@ -0,0 +1,313 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { generateSlugViaLLM } from "./llm-slug-generator.js";
+import type { OpenClawConfig } from "../config/config.js";
+import type { EmbeddedPiRunResult } from "../agents/pi-embedded.js";
+
+const runEmbeddedPiAgentMock = vi.fn<
+  Parameters<typeof import("../agents/pi-embedded.js").runEmbeddedPiAgent>,
+  Promise<EmbeddedPiRunResult>
+>();
+
+vi.mock("../agents/pi-embedded.js", () => ({
+  runEmbeddedPiAgent: (...args: unknown[]) => runEmbeddedPiAgentMock(...args),
+}));
+
+describe("generateSlugViaLLM", () => {
+  beforeEach(() => {
+    runEmbeddedPiAgentMock.mockReset();
+  });
+
+  describe("model resolution", () => {
+    it("uses configured default model from agents.defaults.model.primary", async () => {
+      // Arrange: Config with custom default model (Sonnet instead of Opus)
+      const cfg: OpenClawConfig = {
+        agents: {
+          defaults: {
+            model: {
+              primary: "anthropic/claude-sonnet-4-5",
+            },
+          },
+        },
+      };
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "test-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      // Act
+      await generateSlugViaLLM({
+        sessionContent: "Some conversation about testing",
+        cfg,
+      });
+
+      // Assert: Should use Sonnet, not hardcoded Opus
+      expect(runEmbeddedPiAgentMock).toHaveBeenCalledTimes(1);
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+      expect(callArgs).toMatchObject({
+        provider: "anthropic",
+        model: "claude-sonnet-4-5",
+        config: cfg,
+      });
+    });
+
+    it("uses configured default model with custom provider", async () => {
+      // Arrange: Config with OpenRouter model
+      const cfg: OpenClawConfig = {
+        agents: {
+          defaults: {
+            model: {
+              primary: "openrouter/anthropic/claude-3.5-sonnet",
+            },
+          },
+        },
+      };
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "custom-provider-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      // Act
+      await generateSlugViaLLM({
+        sessionContent: "Testing custom provider",
+        cfg,
+      });
+
+      // Assert: Should use OpenRouter provider
+      expect(runEmbeddedPiAgentMock).toHaveBeenCalledTimes(1);
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+      expect(callArgs).toMatchObject({
+        provider: "openrouter",
+        model: "anthropic/claude-3.5-sonnet",
+        config: cfg,
+      });
+    });
+
+    it("falls back to DEFAULT_MODEL when no model.primary is configured", async () => {
+      // Arrange: Empty config (no custom model)
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "default-model-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      // Act
+      await generateSlugViaLLM({
+        sessionContent: "Testing default fallback",
+        cfg,
+      });
+
+      // Assert: Should fall back to DEFAULT_MODEL (claude-opus-4-5)
+      expect(runEmbeddedPiAgentMock).toHaveBeenCalledTimes(1);
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+      expect(callArgs).toMatchObject({
+        provider: "anthropic",
+        model: "claude-opus-4-5",
+        config: cfg,
+      });
+    });
+
+    it("uses Haiku when configured as default model", async () => {
+      // Arrange: Config with Haiku as default
+      const cfg: OpenClawConfig = {
+        agents: {
+          defaults: {
+            model: {
+              primary: "anthropic/claude-3-5-haiku-20241022",
+            },
+          },
+        },
+      };
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "haiku-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      // Act
+      await generateSlugViaLLM({
+        sessionContent: "Budget-friendly slug generation",
+        cfg,
+      });
+
+      // Assert: Should use Haiku
+      expect(runEmbeddedPiAgentMock).toHaveBeenCalledTimes(1);
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+      expect(callArgs).toMatchObject({
+        provider: "anthropic",
+        model: "claude-3-5-haiku-20241022",
+        config: cfg,
+      });
+    });
+  });
+
+  describe("slug generation", () => {
+    it("generates valid slug from LLM response", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "api-design" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Discussion about API design patterns",
+        cfg,
+      });
+
+      expect(slug).toBe("api-design");
+    });
+
+    it("cleans up LLM response with extra characters", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "  Bug Fix!  " }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Bug fix discussion",
+        cfg,
+      });
+
+      expect(slug).toBe("bug-fix");
+    });
+
+    it("truncates long slugs to 30 characters", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "this-is-a-very-long-slug-that-should-be-truncated-significantly" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Long discussion",
+        cfg,
+      });
+
+      // Verify length is enforced (implementation slices before final cleanup)
+      expect(slug?.length).toBeLessThanOrEqual(30);
+      expect(slug).toMatch(/^this-is-a-very-long-slug/);
+    });
+
+    it("returns null when LLM returns no payloads", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Test content",
+        cfg,
+      });
+
+      expect(slug).toBeNull();
+    });
+
+    it("returns null when LLM returns empty text", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Test content",
+        cfg,
+      });
+
+      expect(slug).toBeNull();
+    });
+
+    it("returns null when embedded agent throws error", async () => {
+      const cfg: OpenClawConfig = {};
+
+      runEmbeddedPiAgentMock.mockRejectedValue(new Error("LLM timeout"));
+
+      const slug = await generateSlugViaLLM({
+        sessionContent: "Test content",
+        cfg,
+      });
+
+      expect(slug).toBeNull();
+    });
+  });
+
+  describe("embedded agent parameters", () => {
+    it("passes correct parameters to runEmbeddedPiAgent", async () => {
+      const cfg: OpenClawConfig = {
+        agents: {
+          defaults: {
+            model: {
+              primary: "anthropic/claude-sonnet-4-5",
+            },
+          },
+        },
+      };
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "test-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      await generateSlugViaLLM({
+        sessionContent: "Testing parameters",
+        cfg,
+      });
+
+      expect(runEmbeddedPiAgentMock).toHaveBeenCalledTimes(1);
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+
+      // Verify all expected parameters are present
+      expect(callArgs).toMatchObject({
+        config: cfg,
+        provider: "anthropic",
+        model: "claude-sonnet-4-5",
+        timeoutMs: 15_000,
+      });
+
+      // Verify prompt includes session content
+      expect(callArgs?.prompt).toContain("Testing parameters");
+      expect(callArgs?.prompt).toContain("1-2 word filename slug");
+
+      // Verify session parameters
+      expect(callArgs?.sessionId).toMatch(/^slug-generator-\d+$/);
+      expect(callArgs?.sessionKey).toBe("temp:slug-generator");
+      expect(callArgs?.runId).toMatch(/^slug-gen-\d+$/);
+
+      // Verify temp session file path
+      expect(callArgs?.sessionFile).toContain("openclaw-slug-");
+      expect(callArgs?.sessionFile).toContain("session.jsonl");
+    });
+
+    it("truncates session content to 2000 characters in prompt", async () => {
+      const cfg: OpenClawConfig = {};
+      const longContent = "a".repeat(3000);
+
+      runEmbeddedPiAgentMock.mockResolvedValue({
+        payloads: [{ text: "truncated-slug" }],
+        meta: { runId: "test-run", sessionId: "test-session" },
+      });
+
+      await generateSlugViaLLM({
+        sessionContent: longContent,
+        cfg,
+      });
+
+      const callArgs = runEmbeddedPiAgentMock.mock.calls[0]?.[0];
+      const promptContentMatch = callArgs?.prompt.match(
+        /Conversation summary:\n([\s\S]+)\n\nReply/,
+      );
+      const extractedContent = promptContentMatch?.[1] ?? "";
+
+      expect(extractedContent.length).toBeLessThanOrEqual(2000);
+    });
+  });
+});