feat: improve UI/UX with volume meter and refine input area styling

- Add VolumeMeter component for realtime audio visualization
- Refactor input area to show volume meter in realtime mode
- Update button styling and layout for cleaner interface
- Improve text input integration with better visual hierarchy
- Add volume state tracking to Speechmatics audio hook
- Add agent working directory validation on creation
- Update agent prompt with better orchestration guidelines

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

packages/server/src/server/acp/agent-manager.test.ts

@@ -166,6 +166,16 @@ describe("AgentManager", () => {
   // ==========================================================================
 
   describe("Agent Creation and Directory Control", () => {
+    it("should reject creation when working directory does not exist", async () => {
+      const nonExistentDir = join(tmpDir, "does-not-exist");
+
+      await expect(
+        manager.createAgent({
+          cwd: nonExistentDir,
+        })
+      ).rejects.toThrow(/Working directory does not exist or is not accessible/);
+    });
+
     it(
       "should create agent and run in specified directory",
       async () => {

packages/server/src/server/acp/agent-manager.ts

@@ -1,5 +1,6 @@
 import { spawn, ChildProcess } from "child_process";
 import { Writable, Readable } from "stream";
+import { access, constants } from "fs/promises";
 import {
   ClientSideConnection,
   ndJsonStream,
@@ -102,6 +103,15 @@ export class AgentManager {
     const agentId = uuidv4();
     const cwd = options.cwd;
 
+    // Validate that the working directory exists
+    try {
+      await access(cwd, constants.R_OK | constants.X_OK);
+    } catch (error) {
+      throw new Error(
+        `Working directory does not exist or is not accessible: ${cwd}`
+      );
+    }
+
     // Spawn the ACP process
     const agentProcess = spawn("npx", ["@zed-industries/claude-code-acp"], {
       stdio: ["pipe", "pipe", "pipe"],