feat: add conversation history feature to AI assistant

- Add ConversationHistory dropdown component with list of past conversations - Add useConversations hook for fetching and managing conversations via React Query - Implement conversation switching with proper state management - Fix bug where reopening panel showed new greeting instead of resuming conversation - Fix bug where selecting from history caused conversation ID to revert - Add server-side history context loading for resumed conversations - Add Playwright E2E tests for conversation history feature - Add logging for debugging conversation flow Key changes: - AssistantPanel: manages conversation state with localStorage persistence - AssistantChat: header with [+] New Chat and [History] buttons - Server: skips greeting for resumed conversations, loads history context on first message - Fixed race condition in onConversationCreated callback
2026-01-29 22:02:05 +00:00 · 2026-01-16 21:47:58 +00:00
parent 91cc00a9d0
commit 7d761cb8d0
12 changed files with 1291 additions and 44 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -64,6 +64,7 @@ coverage.xml
 .hypothesis/
 .pytest_cache/
 nosetests.xml
+./ui/playwright-report

 # mypy
 .mypy_cache/
@@ -142,3 +143,4 @@ Pipfile.lock
 .tmp/
 .temp/
 tmpclaude-*-cwd
+./ui/test-results
--- a/server/routers/assistant_chat.py
+++ b/server/routers/assistant_chat.py
@@ -269,18 +269,23 @@ async def assistant_chat_websocket(websocket: WebSocket, project_name: str):
                elif msg_type == "start":
                    # Get optional conversation_id to resume
                    conversation_id = message.get("conversation_id")
+                    logger.info(f"Processing start message with conversation_id={conversation_id}")

                    try:
                        # Create a new session
+                        logger.info(f"Creating session for {project_name}")
                        session = await create_session(
                            project_name,
                            project_dir,
                            conversation_id=conversation_id,
                        )
+                        logger.info(f"Session created, starting...")

                        # Stream the initial greeting
                        async for chunk in session.start():
+                            logger.info(f"Sending chunk: {chunk.get('type')}")
                            await websocket.send_json(chunk)
+                        logger.info("Session start complete")
                    except Exception as e:
                        logger.exception(f"Error starting assistant session for {project_name}")
                        await websocket.send_json({
--- a/server/services/assistant_chat_session.py
+++ b/server/services/assistant_chat_session.py
@@ -23,6 +23,7 @@ from dotenv import load_dotenv
 from .assistant_database import (
    add_message,
    create_conversation,
+    get_messages,
 )

 # Load environment variables from .env file if present
@@ -178,6 +179,7 @@ class AssistantChatSession:
        self.client: Optional[ClaudeSDKClient] = None
        self._client_entered: bool = False
        self.created_at = datetime.now()
+        self._history_loaded: bool = False  # Track if we've loaded history for resumed conversations

    async def close(self) -> None:
        """Clean up resources and close the Claude client."""
@@ -195,10 +197,14 @@ class AssistantChatSession:
        Initialize session with the Claude client.

        Creates a new conversation if none exists, then sends an initial greeting.
+        For resumed conversations, skips the greeting since history is loaded from DB.
        Yields message chunks as they stream in.
        """
+        # Track if this is a new conversation (for greeting decision)
+        is_new_conversation = self.conversation_id is None
+
        # Create a new conversation if we don't have one
-        if self.conversation_id is None:
+        if is_new_conversation:
            conv = create_conversation(self.project_dir, self.project_name)
            self.conversation_id = conv.id
            yield {"type": "conversation_created", "conversation_id": self.conversation_id}
@@ -260,6 +266,7 @@ class AssistantChatSession:
        model = os.getenv("ANTHROPIC_DEFAULT_OPUS_MODEL", "claude-opus-4-5-20251101")

        try:
+            logger.info("Creating ClaudeSDKClient...")
            self.client = ClaudeSDKClient(
                options=ClaudeAgentOptions(
                    model=model,
@@ -276,25 +283,35 @@ class AssistantChatSession:
                    env=sdk_env,
                )
            )
+            logger.info("Entering Claude client context...")
            await self.client.__aenter__()
            self._client_entered = True
+            logger.info("Claude client ready")
        except Exception as e:
            logger.exception("Failed to create Claude client")
            yield {"type": "error", "content": f"Failed to initialize assistant: {str(e)}"}
            return

-        # Send initial greeting
-        try:
-            greeting = f"Hello! I'm your project assistant for **{self.project_name}**. I can help you understand the codebase, explain features, and answer questions about the project. What would you like to know?"
+        # Send initial greeting only for NEW conversations
+        # Resumed conversations already have history loaded from the database
+        if is_new_conversation:
+            # New conversations don't need history loading
+            self._history_loaded = True
+            try:
+                greeting = f"Hello! I'm your project assistant for **{self.project_name}**. I can help you understand the codebase, explain features, and answer questions about the project. What would you like to know?"

-            # Store the greeting in the database
-            add_message(self.project_dir, self.conversation_id, "assistant", greeting)
+                # Store the greeting in the database
+                add_message(self.project_dir, self.conversation_id, "assistant", greeting)

-            yield {"type": "text", "content": greeting}
+                yield {"type": "text", "content": greeting}
+                yield {"type": "response_done"}
+            except Exception as e:
+                logger.exception("Failed to send greeting")
+                yield {"type": "error", "content": f"Failed to start conversation: {str(e)}"}
+        else:
+            # For resumed conversations, history will be loaded on first message
+            # _history_loaded stays False so send_message() will include history
            yield {"type": "response_done"}
-        except Exception as e:
-            logger.exception("Failed to send greeting")
-            yield {"type": "error", "content": f"Failed to start conversation: {str(e)}"}

    async def send_message(self, user_message: str) -> AsyncGenerator[dict, None]:
        """
@@ -321,8 +338,30 @@ class AssistantChatSession:
        # Store user message in database
        add_message(self.project_dir, self.conversation_id, "user", user_message)

+        # For resumed conversations, include history context in first message
+        message_to_send = user_message
+        if not self._history_loaded:
+            self._history_loaded = True
+            history = get_messages(self.project_dir, self.conversation_id)
+            # Exclude the message we just added (last one)
+            history = history[:-1] if history else []
+            if history:
+                # Format history as context for Claude
+                history_lines = ["[Previous conversation history for context:]"]
+                for msg in history:
+                    role = "User" if msg["role"] == "user" else "Assistant"
+                    content = msg["content"]
+                    # Truncate very long messages
+                    if len(content) > 500:
+                        content = content[:500] + "..."
+                    history_lines.append(f"{role}: {content}")
+                history_lines.append("[End of history. Continue the conversation:]")
+                history_lines.append(f"User: {user_message}")
+                message_to_send = "\n".join(history_lines)
+                logger.info(f"Loaded {len(history)} messages from conversation history")
+
        try:
-            async for chunk in self._query_claude(user_message):
+            async for chunk in self._query_claude(message_to_send):
                yield chunk
            yield {"type": "response_done"}
        except Exception as e:
--- a/ui/e2e/conversation-history.spec.ts
+++ b/ui/e2e/conversation-history.spec.ts
@@ -0,0 +1,563 @@
+import { test, expect } from '@playwright/test'
+
+/**
+ * E2E tests for the Conversation History feature in the Assistant panel.
+ *
+ * Two test groups:
+ * 1. UI Tests - Only test UI elements, no API needed
+ * 2. Integration Tests - Test full flow with API (skipped if API unavailable)
+ *
+ * Run tests:
+ *   cd ui && npm run test:e2e
+ *   cd ui && npm run test:e2e:ui  (interactive mode)
+ */
+
+// =============================================================================
+// UI TESTS - No API required, just test UI elements
+// =============================================================================
+test.describe('Assistant Panel UI', () => {
+  test.setTimeout(30000)
+
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/')
+    await page.waitForSelector('button:has-text("Select Project")', { timeout: 10000 })
+  })
+
+  async function selectProject(page: import('@playwright/test').Page) {
+    const projectSelector = page.locator('button:has-text("Select Project")')
+    if (await projectSelector.isVisible()) {
+      await projectSelector.click()
+      const projectItem = page.locator('.neo-dropdown-item').first()
+      const hasProject = await projectItem.isVisible().catch(() => false)
+      if (!hasProject) {
+        return false
+      }
+      await projectItem.click()
+      await page.waitForTimeout(500)
+      return true
+    }
+    return false
+  }
+
+  async function waitForPanelOpen(page: import('@playwright/test').Page) {
+    await page.waitForFunction(() => {
+      const panel = document.querySelector('[aria-label="Project Assistant"]')
+      return panel && panel.getAttribute('aria-hidden') !== 'true'
+    }, { timeout: 5000 })
+  }
+
+  async function waitForPanelClosed(page: import('@playwright/test').Page) {
+    await page.waitForFunction(() => {
+      const panel = document.querySelector('[aria-label="Project Assistant"]')
+      return !panel || panel.getAttribute('aria-hidden') === 'true'
+    }, { timeout: 5000 })
+  }
+
+  // --------------------------------------------------------------------------
+  // Panel open/close tests
+  // --------------------------------------------------------------------------
+  test('Panel opens and closes with A key', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    const panel = page.locator('[aria-label="Project Assistant"]')
+
+    // Panel should be closed initially
+    await expect(panel).toHaveAttribute('aria-hidden', 'true')
+
+    // Press A to open
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+    await expect(panel).toHaveAttribute('aria-hidden', 'false')
+
+    // Press A again to close
+    await page.keyboard.press('a')
+    await waitForPanelClosed(page)
+    await expect(panel).toHaveAttribute('aria-hidden', 'true')
+  })
+
+  test('Panel closes when clicking backdrop', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    const panel = page.locator('[aria-label="Project Assistant"]')
+    await expect(panel).toHaveAttribute('aria-hidden', 'false')
+
+    // Click on the backdrop
+    const backdrop = page.locator('.fixed.inset-0.bg-black\\/20')
+    await backdrop.click()
+
+    // Panel should close
+    await waitForPanelClosed(page)
+    await expect(panel).toHaveAttribute('aria-hidden', 'true')
+  })
+
+  test('Panel closes with X button', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    const panel = page.locator('[aria-label="Project Assistant"]')
+    await expect(panel).toHaveAttribute('aria-hidden', 'false')
+
+    // Click X button (inside the panel dialog, not the floating button)
+    const closeButton = page.locator('[aria-label="Project Assistant"] button[title="Close Assistant (Press A)"]')
+    await closeButton.click()
+
+    // Panel should close
+    await waitForPanelClosed(page)
+    await expect(panel).toHaveAttribute('aria-hidden', 'true')
+  })
+
+  // --------------------------------------------------------------------------
+  // Header buttons tests
+  // --------------------------------------------------------------------------
+  test('New chat and history buttons are visible and clickable', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Verify New Chat button
+    const newChatButton = page.locator('button[title="New conversation"]')
+    await expect(newChatButton).toBeVisible()
+    await expect(newChatButton).toBeEnabled()
+
+    // Verify History button
+    const historyButton = page.locator('button[title="Conversation history"]')
+    await expect(historyButton).toBeVisible()
+    await expect(historyButton).toBeEnabled()
+  })
+
+  test('History dropdown opens and closes', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Click history button
+    const historyButton = page.locator('button[title="Conversation history"]')
+    await historyButton.click()
+
+    // Dropdown should be visible
+    const historyDropdown = page.locator('h3:has-text("Conversation History")')
+    await expect(historyDropdown).toBeVisible({ timeout: 5000 })
+
+    // Dropdown should be inside the panel (not hidden by edge)
+    const dropdownBox = await page.locator('.neo-dropdown:has-text("Conversation History")').boundingBox()
+    const panelBox = await page.locator('[aria-label="Project Assistant"]').boundingBox()
+
+    if (dropdownBox && panelBox) {
+      // Dropdown left edge should be >= panel left edge (not cut off)
+      expect(dropdownBox.x).toBeGreaterThanOrEqual(panelBox.x - 10) // small tolerance
+    }
+
+    // Close dropdown by pressing Escape (more reliable than clicking backdrop)
+    await page.keyboard.press('Escape')
+    await expect(historyDropdown).not.toBeVisible({ timeout: 5000 })
+  })
+
+  test('History dropdown shows empty state or conversations', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Click history button
+    const historyButton = page.locator('button[title="Conversation history"]')
+    await historyButton.click()
+
+    // Should show either "No conversations yet" or a list of conversations
+    const dropdown = page.locator('.neo-dropdown:has-text("Conversation History")')
+    await expect(dropdown).toBeVisible({ timeout: 5000 })
+
+    // Check content - either empty state or conversation items
+    const emptyState = dropdown.locator('text=No conversations yet')
+    const conversationItems = dropdown.locator('.neo-dropdown-item')
+
+    const hasEmpty = await emptyState.isVisible().catch(() => false)
+    const itemCount = await conversationItems.count()
+
+    // Should have either empty state or some items
+    expect(hasEmpty || itemCount > 0).toBe(true)
+    console.log(`History shows: ${hasEmpty ? 'empty state' : `${itemCount} conversations`}`)
+  })
+
+  // --------------------------------------------------------------------------
+  // Input area tests
+  // --------------------------------------------------------------------------
+  test('Input textarea exists and is focusable', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Input should exist
+    const inputArea = page.locator('textarea[placeholder="Ask about the codebase..."]')
+    await expect(inputArea).toBeVisible()
+
+    // Should be able to type in it (even if disabled, we can check it exists)
+    const placeholder = await inputArea.getAttribute('placeholder')
+    expect(placeholder).toBe('Ask about the codebase...')
+  })
+
+  test('Send button exists', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Send button should exist
+    const sendButton = page.locator('button[title="Send message"]')
+    await expect(sendButton).toBeVisible()
+  })
+
+  // --------------------------------------------------------------------------
+  // Connection status tests
+  // --------------------------------------------------------------------------
+  test('Connection status indicator exists', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Wait for any status to appear
+    await page.waitForFunction(() => {
+      const text = document.body.innerText
+      return text.includes('Connecting...') || text.includes('Connected') || text.includes('Disconnected')
+    }, { timeout: 10000 })
+
+    // One of the status indicators should be visible
+    const connecting = await page.locator('text=Connecting...').isVisible().catch(() => false)
+    const connected = await page.locator('text=Connected').isVisible().catch(() => false)
+    const disconnected = await page.locator('text=Disconnected').isVisible().catch(() => false)
+
+    expect(connecting || connected || disconnected).toBe(true)
+    console.log(`Connection status: ${connected ? 'Connected' : disconnected ? 'Disconnected' : 'Connecting'}`)
+  })
+
+  // --------------------------------------------------------------------------
+  // Panel header tests
+  // --------------------------------------------------------------------------
+  test('Panel header shows project name', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    // Open panel
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    // Header should show "Project Assistant"
+    const header = page.locator('h2:has-text("Project Assistant")')
+    await expect(header).toBeVisible()
+  })
+})
+
+// =============================================================================
+// INTEGRATION TESTS - Require API connection
+// =============================================================================
+test.describe('Conversation History Integration', () => {
+  test.setTimeout(120000)
+
+  test.beforeEach(async ({ page }) => {
+    await page.goto('/')
+    await page.waitForSelector('button:has-text("Select Project")', { timeout: 10000 })
+  })
+
+  async function selectProject(page: import('@playwright/test').Page) {
+    const projectSelector = page.locator('button:has-text("Select Project")')
+    if (await projectSelector.isVisible()) {
+      await projectSelector.click()
+      const projectItem = page.locator('.neo-dropdown-item').first()
+      const hasProject = await projectItem.isVisible().catch(() => false)
+      if (!hasProject) return false
+      await projectItem.click()
+      await page.waitForTimeout(500)
+      return true
+    }
+    return false
+  }
+
+  async function waitForPanelOpen(page: import('@playwright/test').Page) {
+    await page.waitForFunction(() => {
+      const panel = document.querySelector('[aria-label="Project Assistant"]')
+      return panel && panel.getAttribute('aria-hidden') !== 'true'
+    }, { timeout: 5000 })
+  }
+
+  async function waitForPanelClosed(page: import('@playwright/test').Page) {
+    await page.waitForFunction(() => {
+      const panel = document.querySelector('[aria-label="Project Assistant"]')
+      return !panel || panel.getAttribute('aria-hidden') === 'true'
+    }, { timeout: 5000 })
+  }
+
+  async function waitForAssistantReady(page: import('@playwright/test').Page): Promise<boolean> {
+    try {
+      await page.waitForSelector('text=Connected', { timeout: 15000 })
+      const inputArea = page.locator('textarea[placeholder="Ask about the codebase..."]')
+      await expect(inputArea).toBeEnabled({ timeout: 30000 })
+      return true
+    } catch {
+      console.log('Assistant not available - API may not be configured')
+      return false
+    }
+  }
+
+  async function sendMessageAndWaitForResponse(page: import('@playwright/test').Page, message: string) {
+    const inputArea = page.locator('textarea[placeholder="Ask about the codebase..."]')
+    await inputArea.fill(message)
+    await inputArea.press('Enter')
+    await expect(page.locator(`text=${message}`).first()).toBeVisible({ timeout: 5000 })
+    await page.waitForSelector('text=Thinking...', { timeout: 10000 }).catch(() => {})
+    await expect(inputArea).toBeEnabled({ timeout: 60000 })
+    await page.waitForTimeout(500)
+  }
+
+  // --------------------------------------------------------------------------
+  // Full flow test
+  // --------------------------------------------------------------------------
+  test('Full conversation flow: create, persist, switch conversations', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    if (!await waitForAssistantReady(page)) {
+      test.skip(true, 'Assistant API not available')
+      return
+    }
+
+    // STEP 1: Send first message
+    console.log('STEP 1: Ask 1+1')
+    await sendMessageAndWaitForResponse(page, 'how much is 1+1')
+    await expect(page.locator('.flex-1.overflow-y-auto')).toContainText('2', { timeout: 5000 })
+
+    // Count greeting messages before closing
+    const greetingSelector = 'text=Hello! I\'m your project assistant'
+    const greetingCountBefore = await page.locator(greetingSelector).count()
+    console.log(`Greeting count before close: ${greetingCountBefore}`)
+
+    // STEP 2: Close and reopen - should see same conversation WITHOUT new greeting
+    console.log('STEP 2: Close and reopen')
+    const closeButton = page.locator('[aria-label="Project Assistant"] button[title="Close Assistant (Press A)"]')
+    await closeButton.click()
+    await waitForPanelClosed(page)
+
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+    await page.waitForTimeout(2000)
+
+    // Verify our question is still visible (conversation resumed)
+    await expect(page.locator('text=how much is 1+1').first()).toBeVisible({ timeout: 10000 })
+
+    // CRITICAL: Verify NO new greeting was added (bug fix verification)
+    const greetingCountAfter = await page.locator(greetingSelector).count()
+    console.log(`Greeting count after reopen: ${greetingCountAfter}`)
+    expect(greetingCountAfter).toBe(greetingCountBefore)
+
+    // STEP 3: Start new chat
+    console.log('STEP 3: New chat')
+    const newChatButton = page.locator('button[title="New conversation"]')
+    await newChatButton.click()
+    await page.waitForTimeout(500)
+
+    if (!await waitForAssistantReady(page)) {
+      test.skip(true, 'Assistant API not available')
+      return
+    }
+
+    await expect(page.locator('text=how much is 1+1')).not.toBeVisible({ timeout: 5000 })
+
+    // STEP 4: Send second message in new chat
+    console.log('STEP 4: Ask 2+2')
+    await sendMessageAndWaitForResponse(page, 'how much is 2+2')
+    await expect(page.locator('.flex-1.overflow-y-auto')).toContainText('4', { timeout: 5000 })
+
+    // STEP 5: Check history has both conversations
+    console.log('STEP 5: Check history')
+    const historyButton = page.locator('button[title="Conversation history"]')
+    await historyButton.click()
+    await expect(page.locator('h3:has-text("Conversation History")')).toBeVisible()
+
+    const conversationItems = page.locator('.neo-dropdown:has-text("Conversation History") .neo-dropdown-item')
+    const count = await conversationItems.count()
+    console.log(`Found ${count} conversations`)
+    expect(count).toBeGreaterThanOrEqual(2)
+
+    // STEP 6: Switch to first conversation
+    console.log('STEP 6: Switch conversation')
+    await conversationItems.nth(1).click()
+    await page.waitForTimeout(2000)
+    await expect(page.locator('text=how much is 1+1').first()).toBeVisible({ timeout: 10000 })
+    await expect(page.locator('text=how much is 2+2')).not.toBeVisible()
+
+    console.log('All steps completed!')
+  })
+
+  // --------------------------------------------------------------------------
+  // Delete conversation test
+  // --------------------------------------------------------------------------
+  test('Delete conversation from history', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    if (!await waitForAssistantReady(page)) {
+      test.skip(true, 'Assistant API not available')
+      return
+    }
+
+    // Create a conversation
+    await sendMessageAndWaitForResponse(page, `test delete ${Date.now()}`)
+
+    // Open history and get count
+    const historyButton = page.locator('button[title="Conversation history"]')
+    await historyButton.click()
+    await expect(page.locator('h3:has-text("Conversation History")')).toBeVisible()
+
+    const conversationItems = page.locator('.neo-dropdown:has-text("Conversation History") .neo-dropdown-item')
+    const countBefore = await conversationItems.count()
+
+    // Delete first conversation
+    const deleteButton = page.locator('.neo-dropdown:has-text("Conversation History") button[title="Delete conversation"]').first()
+    await deleteButton.click()
+
+    // Confirm
+    const confirmButton = page.locator('button:has-text("Delete")').last()
+    await expect(confirmButton).toBeVisible()
+    await confirmButton.click()
+    await page.waitForTimeout(1000)
+
+    // Verify count decreased
+    await historyButton.click()
+    const countAfter = await conversationItems.count()
+    expect(countAfter).toBeLessThan(countBefore)
+  })
+
+  // --------------------------------------------------------------------------
+  // Send button state test
+  // --------------------------------------------------------------------------
+  test('Send button disabled when empty, enabled with text', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    if (!await waitForAssistantReady(page)) {
+      test.skip(true, 'Assistant API not available')
+      return
+    }
+
+    const inputArea = page.locator('textarea[placeholder="Ask about the codebase..."]')
+    const sendButton = page.locator('button[title="Send message"]')
+
+    // Empty = disabled
+    await inputArea.fill('')
+    await expect(sendButton).toBeDisabled()
+
+    // With text = enabled
+    await inputArea.fill('test')
+    await expect(sendButton).toBeEnabled()
+
+    // Empty again = disabled
+    await inputArea.fill('')
+    await expect(sendButton).toBeDisabled()
+  })
+
+  // --------------------------------------------------------------------------
+  // Shift+Enter test
+  // --------------------------------------------------------------------------
+  test('Shift+Enter adds newline, Enter sends', async ({ page }) => {
+    const hasProject = await selectProject(page)
+    if (!hasProject) {
+      test.skip(true, 'No projects available')
+      return
+    }
+
+    await page.keyboard.press('a')
+    await waitForPanelOpen(page)
+
+    if (!await waitForAssistantReady(page)) {
+      test.skip(true, 'Assistant API not available')
+      return
+    }
+
+    const inputArea = page.locator('textarea[placeholder="Ask about the codebase..."]')
+
+    // Type and add newline
+    await inputArea.fill('Line 1')
+    await inputArea.press('Shift+Enter')
+    await inputArea.pressSequentially('Line 2')
+
+    const value = await inputArea.inputValue()
+    expect(value).toContain('Line 1')
+    expect(value).toContain('Line 2')
+
+    // Enter sends
+    await inputArea.press('Enter')
+    await expect(page.locator('text=Line 1').first()).toBeVisible({ timeout: 5000 })
+  })
+})
--- a/ui/package-lock.json
+++ b/ui/package-lock.json
@@ -23,6 +23,7 @@
      },
      "devDependencies": {
        "@eslint/js": "^9.13.0",
+        "@playwright/test": "^1.57.0",
        "@tailwindcss/vite": "^4.0.0-beta.4",
        "@types/canvas-confetti": "^1.9.0",
        "@types/react": "^18.3.12",
@@ -1008,6 +1009,21 @@
        "@jridgewell/sourcemap-codec": "^1.4.14"
      }
    },
+    "node_modules/@playwright/test": {
+      "version": "1.57.0",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.57.0.tgz",
+      "integrity": "sha512-6TyEnHgd6SArQO8UO2OMTxshln3QMWBtPGrOCgs3wVEmQmwyuNtB10IZMfmYDE0riwNR1cu4q+pPcxMVtaG3TA==",
+      "dev": true,
+      "dependencies": {
+        "playwright": "1.57.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
    "node_modules/@radix-ui/primitive": {
      "version": "1.1.3",
      "resolved": "https://registry.npmjs.org/@radix-ui/primitive/-/primitive-1.1.3.tgz",
@@ -2172,6 +2188,66 @@
        "node": ">=14.0.0"
      }
    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/@emnapi/core": {
+      "version": "1.7.1",
+      "dev": true,
+      "inBundle": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "@emnapi/wasi-threads": "1.1.0",
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/@emnapi/runtime": {
+      "version": "1.7.1",
+      "dev": true,
+      "inBundle": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/@emnapi/wasi-threads": {
+      "version": "1.1.0",
+      "dev": true,
+      "inBundle": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/@napi-rs/wasm-runtime": {
+      "version": "1.1.0",
+      "dev": true,
+      "inBundle": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "@emnapi/core": "^1.7.1",
+        "@emnapi/runtime": "^1.7.1",
+        "@tybys/wasm-util": "^0.10.1"
+      }
+    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/@tybys/wasm-util": {
+      "version": "0.10.1",
+      "dev": true,
+      "inBundle": true,
+      "license": "MIT",
+      "optional": true,
+      "dependencies": {
+        "tslib": "^2.4.0"
+      }
+    },
+    "node_modules/@tailwindcss/oxide-wasm32-wasi/node_modules/tslib": {
+      "version": "2.8.1",
+      "dev": true,
+      "inBundle": true,
+      "license": "0BSD",
+      "optional": true
+    },
    "node_modules/@tailwindcss/oxide-win32-arm64-msvc": {
      "version": "4.1.18",
      "resolved": "https://registry.npmjs.org/@tailwindcss/oxide-win32-arm64-msvc/-/oxide-win32-arm64-msvc-4.1.18.tgz",
@@ -4028,6 +4104,50 @@
        "url": "https://github.com/sponsors/jonschlinkert"
      }
    },
+    "node_modules/playwright": {
+      "version": "1.57.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.57.0.tgz",
+      "integrity": "sha512-ilYQj1s8sr2ppEJ2YVadYBN0Mb3mdo9J0wQ+UuDhzYqURwSoW4n1Xs5vs7ORwgDGmyEh33tRMeS8KhdkMoLXQw==",
+      "dev": true,
+      "dependencies": {
+        "playwright-core": "1.57.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "optionalDependencies": {
+        "fsevents": "2.3.2"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.57.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.57.0.tgz",
+      "integrity": "sha512-agTcKlMw/mjBWOnD6kFZttAAGHgi/Nw0CZ2o6JqWSbMlI219lAFLZZCyqByTsvVAJq5XA5H8cA6PrvBRpBWEuQ==",
+      "dev": true,
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/playwright/node_modules/fsevents": {
+      "version": "2.3.2",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
+      "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
+      "hasInstallScript": true,
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
+      }
+    },
    "node_modules/postcss": {
      "version": "8.5.6",
      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.6.tgz",
--- a/ui/package.json
+++ b/ui/package.json
@@ -7,7 +7,9 @@
    "dev": "vite",
    "build": "tsc -b && vite build",
    "lint": "eslint .",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test:e2e": "playwright test",
+    "test:e2e:ui": "playwright test --ui"
  },
  "dependencies": {
    "@radix-ui/react-dialog": "^1.1.2",
@@ -25,6 +27,7 @@
  },
  "devDependencies": {
    "@eslint/js": "^9.13.0",
+    "@playwright/test": "^1.57.0",
    "@tailwindcss/vite": "^4.0.0-beta.4",
    "@types/canvas-confetti": "^1.9.0",
    "@types/react": "^18.3.12",
--- a/ui/playwright.config.ts
+++ b/ui/playwright.config.ts
@@ -0,0 +1,25 @@
+import { defineConfig, devices } from '@playwright/test'
+
+export default defineConfig({
+  testDir: './e2e',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: 'html',
+  use: {
+    baseURL: 'http://localhost:5173',
+    trace: 'on-first-retry',
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+  ],
+  webServer: {
+    command: 'npm run dev',
+    url: 'http://localhost:5173',
+    reuseExistingServer: !process.env.CI,
+  },
+})
--- a/ui/src/components/AssistantChat.tsx
+++ b/ui/src/components/AssistantChat.tsx
@@ -3,22 +3,41 @@
 *
 * Main chat interface for the project assistant.
 * Displays messages and handles user input.
+ * Supports conversation history with resume functionality.
 */

 import { useState, useRef, useEffect, useCallback } from 'react'
-import { Send, Loader2, Wifi, WifiOff } from 'lucide-react'
+import { Send, Loader2, Wifi, WifiOff, Plus, History } from 'lucide-react'
 import { useAssistantChat } from '../hooks/useAssistantChat'
-import { ChatMessage } from './ChatMessage'
+import { ChatMessage as ChatMessageComponent } from './ChatMessage'
+import { ConversationHistory } from './ConversationHistory'
+import type { ChatMessage } from '../lib/types'

 interface AssistantChatProps {
  projectName: string
+  conversationId?: number | null
+  initialMessages?: ChatMessage[]
+  isLoadingConversation?: boolean
+  onNewChat?: () => void
+  onSelectConversation?: (id: number) => void
+  onConversationCreated?: (id: number) => void
 }

-export function AssistantChat({ projectName }: AssistantChatProps) {
+export function AssistantChat({
+  projectName,
+  conversationId,
+  initialMessages,
+  isLoadingConversation,
+  onNewChat,
+  onSelectConversation,
+  onConversationCreated,
+}: AssistantChatProps) {
  const [inputValue, setInputValue] = useState('')
+  const [showHistory, setShowHistory] = useState(false)
  const messagesEndRef = useRef<HTMLDivElement>(null)
  const inputRef = useRef<HTMLTextAreaElement>(null)
  const hasStartedRef = useRef(false)
+  const lastConversationIdRef = useRef<number | null | undefined>(undefined)

  // Memoize the error handler to prevent infinite re-renders
  const handleError = useCallback((error: string) => {
@@ -29,25 +48,94 @@ export function AssistantChat({ projectName }: AssistantChatProps) {
    messages,
    isLoading,
    connectionStatus,
+    conversationId: activeConversationId,
    start,
    sendMessage,
+    clearMessages,
  } = useAssistantChat({
    projectName,
    onError: handleError,
  })

+  // Notify parent when a NEW conversation is created (not when switching to existing)
+  // This should only fire when conversationId was null/undefined and a new one was created
+  const previousConversationIdRef = useRef<number | null | undefined>(conversationId)
+  useEffect(() => {
+    // Only notify if we had NO conversation (null/undefined) and now we have one
+    // This prevents the bug where switching conversations would trigger this
+    const hadNoConversation = previousConversationIdRef.current === null || previousConversationIdRef.current === undefined
+    const nowHasConversation = activeConversationId !== null && activeConversationId !== undefined
+
+    if (hadNoConversation && nowHasConversation && onConversationCreated) {
+      console.log('[AssistantChat] New conversation created:', activeConversationId)
+      onConversationCreated(activeConversationId)
+    }
+
+    previousConversationIdRef.current = conversationId
+  }, [activeConversationId, conversationId, onConversationCreated])
+
  // Auto-scroll to bottom on new messages
  useEffect(() => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
  }, [messages])

-  // Start the chat session when component mounts (only once)
+  // Start or resume the chat session when component mounts or conversationId changes
  useEffect(() => {
-    if (!hasStartedRef.current) {
-      hasStartedRef.current = true
-      start()
+    console.log('[AssistantChat] useEffect running:', {
+      conversationId,
+      isLoadingConversation,
+      lastRef: lastConversationIdRef.current,
+      hasStarted: hasStartedRef.current
+    })
+
+    // Skip if we're loading conversation details
+    if (isLoadingConversation) {
+      console.log('[AssistantChat] Skipping - loading conversation')
+      return
    }
-  }, [start])
+
+    // Only start if conversationId has actually changed
+    if (lastConversationIdRef.current === conversationId && hasStartedRef.current) {
+      console.log('[AssistantChat] Skipping - same conversationId')
+      return
+    }
+
+    // Check if we're switching to a different conversation (not initial mount)
+    const isSwitching = lastConversationIdRef.current !== undefined &&
+                        lastConversationIdRef.current !== conversationId
+
+    console.log('[AssistantChat] Processing conversation change:', {
+      from: lastConversationIdRef.current,
+      to: conversationId,
+      isSwitching
+    })
+
+    lastConversationIdRef.current = conversationId
+    hasStartedRef.current = true
+
+    // Clear existing messages when switching conversations
+    if (isSwitching) {
+      console.log('[AssistantChat] Clearing messages for conversation switch')
+      clearMessages()
+    }
+
+    // Start the session with the conversation ID (or null for new)
+    console.log('[AssistantChat] Starting session with conversationId:', conversationId)
+    start(conversationId)
+  }, [conversationId, isLoadingConversation, start, clearMessages])
+
+  // Handle starting a new chat
+  const handleNewChat = useCallback(() => {
+    clearMessages()
+    onNewChat?.()
+  }, [clearMessages, onNewChat])
+
+  // Handle selecting a conversation from history
+  const handleSelectConversation = useCallback((id: number) => {
+    console.log('[AssistantChat] handleSelectConversation called with id:', id)
+    setShowHistory(false)
+    onSelectConversation?.(id)
+  }, [onSelectConversation])

  // Focus input when not loading
  useEffect(() => {
@@ -71,31 +159,92 @@ export function AssistantChat({ projectName }: AssistantChatProps) {
    }
  }

+  // Combine initial messages (from resumed conversation) with live messages
+  // Show initialMessages when:
+  // 1. We have initialMessages from the API
+  // 2. AND either messages is empty OR we haven't processed this conversation yet
+  // This prevents showing old conversation messages while switching
+  const isConversationSynced = lastConversationIdRef.current === conversationId && !isLoadingConversation
+  const displayMessages = initialMessages && (messages.length === 0 || !isConversationSynced)
+    ? initialMessages
+    : messages
+  console.log('[AssistantChat] displayMessages decision:', {
+    conversationId,
+    lastRef: lastConversationIdRef.current,
+    isConversationSynced,
+    initialMessagesCount: initialMessages?.length ?? 0,
+    messagesCount: messages.length,
+    displayMessagesCount: displayMessages.length,
+    showingInitial: displayMessages === initialMessages
+  })
+
  return (
    <div className="flex flex-col h-full">
-      {/* Connection status indicator */}
-      <div className="flex items-center gap-2 px-4 py-2 border-b-2 border-[var(--color-neo-border)] bg-[var(--color-neo-bg)]">
-        {connectionStatus === 'connected' ? (
-          <>
-            <Wifi size={14} className="text-[var(--color-neo-done)]" />
-            <span className="text-xs text-[var(--color-neo-text-secondary)]">Connected</span>
-          </>
-        ) : connectionStatus === 'connecting' ? (
-          <>
-            <Loader2 size={14} className="text-[var(--color-neo-progress)] animate-spin" />
-            <span className="text-xs text-[var(--color-neo-text-secondary)]">Connecting...</span>
-          </>
-        ) : (
-          <>
-            <WifiOff size={14} className="text-[var(--color-neo-danger)]" />
-            <span className="text-xs text-[var(--color-neo-text-secondary)]">Disconnected</span>
-          </>
-        )}
+      {/* Header with actions and connection status */}
+      <div className="flex items-center justify-between px-4 py-2 border-b-2 border-[var(--color-neo-border)] bg-[var(--color-neo-bg)]">
+        {/* Action buttons */}
+        <div className="flex items-center gap-1 relative">
+          <button
+            onClick={handleNewChat}
+            className="neo-btn neo-btn-ghost p-1.5 text-[var(--color-neo-text-secondary)] hover:text-[var(--color-neo-text)]"
+            title="New conversation"
+            disabled={isLoading}
+          >
+            <Plus size={16} />
+          </button>
+          <button
+            onClick={() => setShowHistory(!showHistory)}
+            className={`neo-btn neo-btn-ghost p-1.5 ${
+              showHistory
+                ? 'text-[var(--color-neo-text)] bg-[var(--color-neo-pending)]'
+                : 'text-[var(--color-neo-text-secondary)] hover:text-[var(--color-neo-text)]'
+            }`}
+            title="Conversation history"
+          >
+            <History size={16} />
+          </button>
+
+          {/* History dropdown */}
+          <ConversationHistory
+            projectName={projectName}
+            currentConversationId={conversationId ?? activeConversationId}
+            isOpen={showHistory}
+            onClose={() => setShowHistory(false)}
+            onSelectConversation={handleSelectConversation}
+          />
+        </div>
+
+        {/* Connection status */}
+        <div className="flex items-center gap-2">
+          {connectionStatus === 'connected' ? (
+            <>
+              <Wifi size={14} className="text-[var(--color-neo-done)]" />
+              <span className="text-xs text-[var(--color-neo-text-secondary)]">Connected</span>
+            </>
+          ) : connectionStatus === 'connecting' ? (
+            <>
+              <Loader2 size={14} className="text-[var(--color-neo-progress)] animate-spin" />
+              <span className="text-xs text-[var(--color-neo-text-secondary)]">Connecting...</span>
+            </>
+          ) : (
+            <>
+              <WifiOff size={14} className="text-[var(--color-neo-danger)]" />
+              <span className="text-xs text-[var(--color-neo-text-secondary)]">Disconnected</span>
+            </>
+          )}
+        </div>
      </div>

      {/* Messages area */}
      <div className="flex-1 overflow-y-auto bg-[var(--color-neo-bg)]">
-        {messages.length === 0 ? (
+        {isLoadingConversation ? (
+          <div className="flex items-center justify-center h-full text-[var(--color-neo-text-secondary)] text-sm">
+            <div className="flex items-center gap-2">
+              <Loader2 size={16} className="animate-spin" />
+              <span>Loading conversation...</span>
+            </div>
+          </div>
+        ) : displayMessages.length === 0 ? (
          <div className="flex items-center justify-center h-full text-[var(--color-neo-text-secondary)] text-sm">
            {isLoading ? (
              <div className="flex items-center gap-2">
@@ -108,8 +257,8 @@ export function AssistantChat({ projectName }: AssistantChatProps) {
          </div>
        ) : (
          <div className="py-4">
-            {messages.map((message) => (
-              <ChatMessage key={message.id} message={message} />
+            {displayMessages.map((message) => (
+              <ChatMessageComponent key={message.id} message={message} />
            ))}
            <div ref={messagesEndRef} />
          </div>
@@ -117,7 +266,7 @@ export function AssistantChat({ projectName }: AssistantChatProps) {
      </div>

      {/* Loading indicator */}
-      {isLoading && messages.length > 0 && (
+      {isLoading && displayMessages.length > 0 && (
        <div className="px-4 py-2 border-t-2 border-[var(--color-neo-border)] bg-[var(--color-neo-bg)]">
          <div className="flex items-center gap-2 text-[var(--color-neo-text-secondary)] text-sm">
            <div className="flex gap-1">
--- a/ui/src/components/AssistantPanel.tsx
+++ b/ui/src/components/AssistantPanel.tsx
@@ -3,10 +3,14 @@
 *
 * Slide-in panel container for the project assistant chat.
 * Slides in from the right side of the screen.
+ * Manages conversation state with localStorage persistence.
 */

+import { useState, useEffect, useCallback } from 'react'
 import { X, Bot } from 'lucide-react'
 import { AssistantChat } from './AssistantChat'
+import { useConversation } from '../hooks/useConversations'
+import type { ChatMessage } from '../lib/types'

 interface AssistantPanelProps {
  projectName: string
@@ -14,7 +18,83 @@ interface AssistantPanelProps {
  onClose: () => void
 }

+const STORAGE_KEY_PREFIX = 'assistant-conversation-'
+
+function getStoredConversationId(projectName: string): number | null {
+  try {
+    const stored = localStorage.getItem(`${STORAGE_KEY_PREFIX}${projectName}`)
+    if (stored) {
+      const data = JSON.parse(stored)
+      return data.conversationId || null
+    }
+  } catch {
+    // Invalid stored data, ignore
+  }
+  return null
+}
+
+function setStoredConversationId(projectName: string, conversationId: number | null) {
+  const key = `${STORAGE_KEY_PREFIX}${projectName}`
+  if (conversationId) {
+    localStorage.setItem(key, JSON.stringify({ conversationId }))
+  } else {
+    localStorage.removeItem(key)
+  }
+}
+
 export function AssistantPanel({ projectName, isOpen, onClose }: AssistantPanelProps) {
+  // Load initial conversation ID from localStorage
+  const [conversationId, setConversationId] = useState<number | null>(() =>
+    getStoredConversationId(projectName)
+  )
+
+  // Fetch conversation details when we have an ID
+  const { data: conversationDetail, isLoading: isLoadingConversation } = useConversation(
+    projectName,
+    conversationId
+  )
+
+  // Convert API messages to ChatMessage format for the chat component
+  const initialMessages: ChatMessage[] | undefined = conversationDetail?.messages.map((msg) => ({
+    id: `db-${msg.id}`,
+    role: msg.role,
+    content: msg.content,
+    timestamp: msg.timestamp ? new Date(msg.timestamp) : new Date(),
+  }))
+
+  console.log('[AssistantPanel] State:', {
+    conversationId,
+    isLoadingConversation,
+    conversationDetailId: conversationDetail?.id,
+    initialMessagesCount: initialMessages?.length ?? 0
+  })
+
+  // Persist conversation ID changes to localStorage
+  useEffect(() => {
+    setStoredConversationId(projectName, conversationId)
+  }, [projectName, conversationId])
+
+  // Reset conversation ID when project changes
+  useEffect(() => {
+    setConversationId(getStoredConversationId(projectName))
+  }, [projectName])
+
+  // Handle starting a new chat
+  const handleNewChat = useCallback(() => {
+    setConversationId(null)
+  }, [])
+
+  // Handle selecting a conversation from history
+  const handleSelectConversation = useCallback((id: number) => {
+    console.log('[AssistantPanel] handleSelectConversation called with id:', id)
+    setConversationId(id)
+  }, [])
+
+  // Handle when a new conversation is created (from WebSocket)
+  const handleConversationCreated = useCallback((id: number) => {
+    setConversationId(id)
+  }, [])
+
  return (
    <>
      {/* Backdrop - click to close */}
@@ -74,7 +154,17 @@ export function AssistantPanel({ projectName, isOpen, onClose }: AssistantPanelP

        {/* Chat area */}
        <div className="flex-1 overflow-hidden">
-          {isOpen && <AssistantChat projectName={projectName} />}
+          {isOpen && (
+            <AssistantChat
+              projectName={projectName}
+              conversationId={conversationId}
+              initialMessages={initialMessages}
+              isLoadingConversation={isLoadingConversation}
+              onNewChat={handleNewChat}
+              onSelectConversation={handleSelectConversation}
+              onConversationCreated={handleConversationCreated}
+            />
+          )}
        </div>
      </div>
    </>
--- a/ui/src/components/ConversationHistory.tsx
+++ b/ui/src/components/ConversationHistory.tsx
@@ -0,0 +1,202 @@
+/**
+ * Conversation History Dropdown Component
+ *
+ * Displays a list of past conversations for the assistant.
+ * Allows selecting a conversation to resume or deleting old conversations.
+ */
+
+import { useState, useEffect } from 'react'
+import { MessageSquare, Trash2, Loader2 } from 'lucide-react'
+import { useConversations, useDeleteConversation } from '../hooks/useConversations'
+import { ConfirmDialog } from './ConfirmDialog'
+import type { AssistantConversation } from '../lib/types'
+
+interface ConversationHistoryProps {
+  projectName: string
+  currentConversationId: number | null
+  isOpen: boolean
+  onClose: () => void
+  onSelectConversation: (conversationId: number) => void
+}
+
+/**
+ * Format a relative time string from an ISO date
+ */
+function formatRelativeTime(dateString: string | null): string {
+  if (!dateString) return ''
+
+  const date = new Date(dateString)
+  const now = new Date()
+  const diffMs = now.getTime() - date.getTime()
+  const diffSeconds = Math.floor(diffMs / 1000)
+  const diffMinutes = Math.floor(diffSeconds / 60)
+  const diffHours = Math.floor(diffMinutes / 60)
+  const diffDays = Math.floor(diffHours / 24)
+
+  if (diffSeconds < 60) return 'just now'
+  if (diffMinutes < 60) return `${diffMinutes}m ago`
+  if (diffHours < 24) return `${diffHours}h ago`
+  if (diffDays === 1) return 'yesterday'
+  if (diffDays < 7) return `${diffDays}d ago`
+
+  return date.toLocaleDateString()
+}
+
+export function ConversationHistory({
+  projectName,
+  currentConversationId,
+  isOpen,
+  onClose,
+  onSelectConversation,
+}: ConversationHistoryProps) {
+  const [conversationToDelete, setConversationToDelete] = useState<AssistantConversation | null>(null)
+
+  const { data: conversations, isLoading } = useConversations(projectName)
+  const deleteConversation = useDeleteConversation(projectName)
+
+  const handleDeleteClick = (e: React.MouseEvent, conversation: AssistantConversation) => {
+    e.stopPropagation()
+    setConversationToDelete(conversation)
+  }
+
+  const handleConfirmDelete = async () => {
+    if (!conversationToDelete) return
+
+    try {
+      await deleteConversation.mutateAsync(conversationToDelete.id)
+      setConversationToDelete(null)
+    } catch (error) {
+      console.error('Failed to delete conversation:', error)
+      setConversationToDelete(null)
+    }
+  }
+
+  const handleCancelDelete = () => {
+    setConversationToDelete(null)
+  }
+
+  const handleSelectConversation = (conversationId: number) => {
+    console.log('[ConversationHistory] handleSelectConversation called with id:', conversationId)
+    onSelectConversation(conversationId)
+    onClose()
+  }
+
+  // Handle Escape key to close dropdown
+  useEffect(() => {
+    if (!isOpen) return
+
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        e.preventDefault()
+        onClose()
+      }
+    }
+
+    document.addEventListener('keydown', handleKeyDown)
+    return () => document.removeEventListener('keydown', handleKeyDown)
+  }, [isOpen, onClose])
+
+  if (!isOpen) return null
+
+  return (
+    <>
+      {/* Backdrop */}
+      <div
+        className="fixed inset-0 z-40"
+        onClick={onClose}
+      />
+
+      {/* Dropdown */}
+      <div
+        className="absolute top-full left-0 mt-2 neo-dropdown z-50 w-[320px] max-w-[calc(100vw-2rem)]"
+        style={{ boxShadow: 'var(--shadow-neo)' }}
+      >
+        {/* Header */}
+        <div className="px-3 py-2 border-b-2 border-[var(--color-neo-border)] bg-[var(--color-neo-bg)]">
+          <h3 className="font-bold text-sm">Conversation History</h3>
+        </div>
+
+        {/* Content */}
+        {isLoading ? (
+          <div className="p-4 flex items-center justify-center">
+            <Loader2 size={20} className="animate-spin text-[var(--color-neo-text-secondary)]" />
+          </div>
+        ) : !conversations || conversations.length === 0 ? (
+          <div className="p-4 text-center text-[var(--color-neo-text-secondary)] text-sm">
+            No conversations yet
+          </div>
+        ) : (
+          <div className="max-h-[300px] overflow-auto">
+            {conversations.map((conversation) => {
+              const isCurrent = conversation.id === currentConversationId
+              console.log('[ConversationHistory] Rendering conversation:', {
+                id: conversation.id,
+                currentConversationId,
+                isCurrent
+              })
+
+              return (
+                <div
+                  key={conversation.id}
+                  className={`flex items-center group ${
+                    isCurrent
+                      ? 'bg-[var(--color-neo-pending)] text-[var(--color-neo-text-on-bright)]'
+                      : ''
+                  }`}
+                >
+                  <button
+                    onClick={() => handleSelectConversation(conversation.id)}
+                    className="flex-1 neo-dropdown-item text-left"
+                    disabled={isCurrent}
+                  >
+                    <div className="flex items-start gap-2">
+                      <MessageSquare size={16} className="mt-0.5 flex-shrink-0" />
+                      <div className="flex-1 min-w-0">
+                        <div className="font-medium truncate">
+                          {conversation.title || 'Untitled conversation'}
+                        </div>
+                        <div className={`text-xs flex items-center gap-2 ${
+                          isCurrent
+                            ? 'text-[var(--color-neo-text-on-bright)] opacity-80'
+                            : 'text-[var(--color-neo-text-secondary)]'
+                        }`}>
+                          <span>{conversation.message_count} messages</span>
+                          <span>|</span>
+                          <span>{formatRelativeTime(conversation.updated_at)}</span>
+                        </div>
+                      </div>
+                    </div>
+                  </button>
+                  <button
+                    onClick={(e) => handleDeleteClick(e, conversation)}
+                    className={`p-2 mr-2 transition-colors rounded ${
+                      isCurrent
+                        ? 'text-[var(--color-neo-text-on-bright)] opacity-60 hover:opacity-100 hover:bg-[var(--color-neo-danger)]/20'
+                        : 'text-[var(--color-neo-text-secondary)] opacity-0 group-hover:opacity-100 hover:text-[var(--color-neo-danger)] hover:bg-[var(--color-neo-danger)]/10'
+                    }`}
+                    title="Delete conversation"
+                  >
+                    <Trash2 size={14} />
+                  </button>
+                </div>
+              )
+            })}
+          </div>
+        )}
+      </div>
+
+      {/* Delete Confirmation Dialog */}
+      <ConfirmDialog
+        isOpen={conversationToDelete !== null}
+        title="Delete Conversation"
+        message={`Are you sure you want to delete "${conversationToDelete?.title || 'this conversation'}"? This action cannot be undone.`}
+        confirmLabel="Delete"
+        cancelLabel="Cancel"
+        variant="danger"
+        isLoading={deleteConversation.isPending}
+        onConfirm={handleConfirmDelete}
+        onCancel={handleCancelDelete}
+      />
+    </>
+  )
+}
--- a/ui/src/hooks/useAssistantChat.ts
+++ b/ui/src/hooks/useAssistantChat.ts
@@ -120,6 +120,7 @@ export function useAssistantChat({
    ws.onmessage = (event) => {
      try {
        const data = JSON.parse(event.data) as AssistantChatServerMessage;
+        console.log('[useAssistantChat] Received WebSocket message:', data.type, data);

        switch (data.type) {
          case "text": {
@@ -277,6 +278,7 @@ export function useAssistantChat({
            payload.conversation_id = existingConversationId;
            setConversationId(existingConversationId);
          }
+          console.log('[useAssistantChat] Sending start message:', payload);
          wsRef.current.send(JSON.stringify(payload));
        } else if (wsRef.current?.readyState === WebSocket.CONNECTING) {
          checkAndSendTimeoutRef.current = window.setTimeout(checkAndSend, 100);
@@ -336,7 +338,7 @@ export function useAssistantChat({

  const clearMessages = useCallback(() => {
    setMessages([]);
-    setConversationId(null);
+    // Don't reset conversationId here - it will be set by start() when switching
  }, []);

  return {
--- a/ui/src/hooks/useConversations.ts
+++ b/ui/src/hooks/useConversations.ts
@@ -0,0 +1,47 @@
+/**
+ * React Query hooks for assistant conversation management
+ */
+
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
+import * as api from '../lib/api'
+
+/**
+ * List all conversations for a project
+ */
+export function useConversations(projectName: string | null) {
+  return useQuery({
+    queryKey: ['conversations', projectName],
+    queryFn: () => api.listAssistantConversations(projectName!),
+    enabled: !!projectName,
+    staleTime: 30000, // Cache for 30 seconds
+  })
+}
+
+/**
+ * Get a single conversation with all its messages
+ */
+export function useConversation(projectName: string | null, conversationId: number | null) {
+  return useQuery({
+    queryKey: ['conversation', projectName, conversationId],
+    queryFn: () => api.getAssistantConversation(projectName!, conversationId!),
+    enabled: !!projectName && !!conversationId,
+  })
+}
+
+/**
+ * Delete a conversation
+ */
+export function useDeleteConversation(projectName: string) {
+  const queryClient = useQueryClient()
+
+  return useMutation({
+    mutationFn: (conversationId: number) =>
+      api.deleteAssistantConversation(projectName, conversationId),
+    onSuccess: (_, deletedId) => {
+      // Invalidate conversations list
+      queryClient.invalidateQueries({ queryKey: ['conversations', projectName] })
+      // Remove the specific conversation from cache
+      queryClient.removeQueries({ queryKey: ['conversation', projectName, deletedId] })
+    },
+  })
+}