diff --git a/.opencode/plans/1773330460043-shiny-wolf.md b/.opencode/plans/archive/1773330460043-shiny-wolf.md
similarity index 100%
rename from .opencode/plans/1773330460043-shiny-wolf.md
rename to .opencode/plans/archive/1773330460043-shiny-wolf.md
diff --git a/.opencode/tools/multi-model.test.ts b/.opencode/tools/multi-model.test.ts
new file mode 100644
index 0000000..7d58d99
--- /dev/null
+++ b/.opencode/tools/multi-model.test.ts
@@ -0,0 +1,181 @@
+import { expect, test, mock, spyOn, beforeEach, afterEach, describe } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import multiModelTool from "./multi-model";
+
+let originalBun$: typeof Bun.$;
+let mockCommandResponses: Record<string, { ok: boolean; stdout: string; stderr: string }> = {};
+
+function setupMockBun$() {
+  const mockFn = mock((strings: TemplateStringsArray, ...values: any[]) => {
+    const parts = values[0] as string[];
+    const commandSignature = parts.join(" ");
+
+    return {
+      quiet: () => ({
+        nothrow: async () => {
+          const response = mockCommandResponses[commandSignature] ?? { ok: true, stdout: "", stderr: "" };
+          return {
+            exitCode: response.ok ? 0 : 1,
+            stdout: { toString: () => response.stdout },
+            stderr: { toString: () => response.stderr },
+          };
+        },
+      }),
+    };
+  });
+
+  (globalThis as any).Bun.$ = mockFn;
+  return mockFn;
+}
+
+function restoreOriginalBun$() {
+  (globalThis as any).Bun.$ = originalBun$;
+}
+
+describe("multi-model tool", () => {
+  let existsSyncMock: ReturnType<typeof spyOn>;
+  let bunMock: ReturnType<typeof setupMockBun$>;
+
+  beforeEach(() => {
+    spyOn(os, "homedir").mockReturnValue("/mock/home");
+    existsSyncMock = spyOn(fs, "existsSync").mockReturnValue(false);
+    bunMock = setupMockBun$();
+
+    mockCommandResponses = {
+      "git rev-parse --is-inside-work-tree": { ok: true, stdout: "true", stderr: "" },
+      "command -v tmux": { ok: true, stdout: "/usr/bin/tmux", stderr: "" },
+      "command -v opencode": { ok: true, stdout: "/usr/bin/opencode", stderr: "" },
+      "opencode models": { ok: true, stdout: "openai/gpt-4o\nanthropic/claude-3-5-sonnet", stderr: "" },
+      "tmux has-session -t test-session": { ok: false, stdout: "", stderr: "session not found" },
+      "git show-ref --verify --quiet refs/heads/opencode/test-session/gpt-4o": { ok: false, stdout: "", stderr: "" },
+    };
+  });
+
+  afterEach(() => {
+    restoreOriginalBun$();
+  });
+
+  test("fails if session name is empty", async () => {
+    const result = await multiModelTool.execute(
+      { sessionName: "", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: `sessionName` must not be empty.");
+  });
+
+  test("fails if no models are provided", async () => {
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: [] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: Model names must not be empty.");
+  });
+
+  test("fails if duplicate models are provided", async () => {
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o", "openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Duplicate model names are not allowed");
+  });
+
+  test("fails if not inside a git repository", async () => {
+    mockCommandResponses["git rev-parse --is-inside-work-tree"] = { ok: false, stdout: "", stderr: "not a git repo" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: `multi-model` requires a git repository.");
+  });
+
+  test("fails if tmux is not installed", async () => {
+    mockCommandResponses["command -v tmux"] = { ok: false, stdout: "", stderr: "" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: `tmux` is not installed or not on `PATH`.");
+  });
+
+  test("fails if opencode is not installed", async () => {
+    mockCommandResponses["command -v opencode"] = { ok: false, stdout: "", stderr: "" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: `opencode` is not installed or not on `PATH`.");
+  });
+
+  test("fails if model name is not in allowlist", async () => {
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["invalid/model"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: Model name 'invalid/model' not found");
+  });
+
+  test("fails if session already exists", async () => {
+    mockCommandResponses["tmux has-session -t test-session"] = { ok: true, stdout: "", stderr: "" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Error: Session already exists");
+  });
+
+  test("successfully plans and executes tmux launch with single model", async () => {
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Use `tmux attach -t test-session` to join session");
+  });
+
+  test("successfully launches multiple models", async () => {
+    mockCommandResponses["git show-ref --verify --quiet refs/heads/opencode/test-session/claude-3-5-sonnet"] = { ok: false, stdout: "", stderr: "" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test-session", models: ["openai/gpt-4o", "anthropic/claude-3-5-sonnet"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Use `tmux attach -t test-session` to join session");
+  });
+
+  test("sanitizes session name", async () => {
+    mockCommandResponses["tmux has-session -t test session!"] = { ok: false, stdout: "", stderr: "" };
+
+    const result = await multiModelTool.execute(
+      { sessionName: "test session!", models: ["openai/gpt-4o"] },
+      { metadata: mock() } as any
+    );
+
+    expect(result).toContain("Use `tmux attach -t test session!` to join session");
+  });
+});
+
+describe("unit functions", () => {
+  test("shellQuote escapes single quotes", () => {
+    const value = "test'value";
+    const quoted = "'" + value.replace(/'/g, `'"'"'`) + "'";
+    expect(quoted).toBe("'test'\"'\"'value'");
+  });
+
+  test("normalizeModels trims and filters empty", () => {
+    expect([" openai/gpt-4o ", ""].map(m => m.trim()).filter(Boolean)).toEqual(["openai/gpt-4o"]);
+  });
+});