diff --git a/integration-tests/mcp-sampling.test.ts b/integration-tests/mcp-sampling.test.ts
new file mode 100644
index 00000000000..4edf852401a
--- /dev/null
+++ b/integration-tests/mcp-sampling.test.ts
@@ -0,0 +1,252 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * This test verifies MCP (Model Context Protocol) server integration.
+ * It uses a minimal MCP server implementation that doesn't require
+ * external dependencies, making it compatible with Docker sandbox mode.
+ */
+
+import { describe, it, beforeAll, expect } from 'vitest';
+import { TestRig, poll, validateModelOutput } from './test-helper.js';
+import { join } from 'node:path';
+import { writeFileSync } from 'node:fs';
+
+const serverScript = `#!/usr/bin/env node
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const readline = require('readline');
+const fs = require('fs');
+
+const debugEnabled = process.env['MCP_DEBUG'] === 'true' || process.env['VERBOSE'] === 'true';
+function debug(msg) {
+  if (debugEnabled) {
+    fs.writeSync(2, '[MCP-DEBUG] ' + msg + '\n');
+  }
+}
+
+debug('MCP sampling server starting...');
+
+class SimpleJSONRPC {
+  constructor() {
+    this.handlers = new Map();
+    this.rl = readline.createInterface({
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false
+    });
+    
+    this.rl.on('line', (line) => {
+      debug('Received line: ' + line);
+      try {
+        const message = JSON.parse(line);
+        debug('Parsed message: ' + JSON.stringify(message));
+        this.handleMessage(message);
+      } catch (e) {
+        debug('Parse error: ' + e.message);
+      }
+    });
+  }
+  
+  send(message) {
+    const msgStr = JSON.stringify(message);
+    debug('Sending message: ' + msgStr);
+    process.stdout.write(msgStr + '\n');
+  }
+
+  request(method, params) {
+    return new Promise((resolve, reject) => {
+      const id = Math.random().toString(36).substring(2);
+      this.handlers.set(id, (response) => {
+        if (response.error) {
+          reject(new Error(response.error.message));
+        }
+        else {
+          resolve(response.result);
+        }
+      });
+      this.send({
+        jsonrpc: '2.0',
+        id,
+        method,
+        params
+      });
+    });
+  }
+  
+  async handleMessage(message) {
+    if (message.id && this.handlers.has(message.id)) {
+      this.handlers.get(message.id)(message);
+      this.handlers.delete(message.id);
+      return;
+    }
+
+    if (message.method && this.handlers.has(message.method)) {
+      try {
+        const result = await this.handlers.get(message.method)(message.params || {});
+        if (message.id !== undefined) {
+          this.send({
+            jsonrpc: '2.0',
+            id: message.id,
+            result
+          });
+        }
+      }
+      catch (error) {
+        if (message.id !== undefined) {
+          this.send({
+            jsonrpc: '2.0',
+            id: message.id,
+            error: {
+              code: -32603,
+              message: error.message
+            }
+          });
+        }
+      }
+    }
+    else if (message.id !== undefined) {
+      this.send({
+        jsonrpc: '2.0',
+        id: message.id,
+        error: {
+          code: -32601,
+          message: 'Method not found'
+        }
+      });
+    }
+  }
+  
+  on(method, handler) {
+    this.handlers.set(method, handler);
+  }
+}
+
+const rpc = new SimpleJSONRPC();
+
+rpc.on('initialize', async (params) => {
+  debug('Handling initialize request');
+  return {
+    protocolVersion: '2024-11-05',
+    capabilities: {
+      sampling: true,
+    },
+    serverInfo: {
+      name: 'sampler-server',
+      version: '1.0.0'
+    }
+  };
+});
+
+rpc.on('tools/list', async () => {
+  debug('Handling tools/list request');
+  return {
+    tools: [{
+      name: 'sample',
+      description: 'Uses the LLM to sample a response to a prompt.',
+      inputSchema: {
+        type: 'object',
+        properties: {
+          prompt: { type: 'string', description: 'The prompt to sample' },
+        },
+        required: ['prompt']
+      }
+    }]
+  };
+});
+
+rpc.on('tools/call', async (params) => {
+  debug('Handling tools/call request for tool: ' + params.name);
+  if (params.name === 'sample') {
+    const { prompt } = params.arguments;
+    
+    debug('Requesting sampling from client...');
+    // MCP spec: messages at top level, content is a single object (not array)
+    const result = await rpc.request('sampling/createMessage', {
+      messages: [
+        {
+          role: 'user',
+          content: { type: 'text', text: prompt }
+        }
+      ]
+    });
+    debug('Received sampling result: ' + JSON.stringify(result));
+
+    return result;
+  }
+  throw new Error('Unknown tool: ' + params.name);
+});
+
+rpc.send({
+  jsonrpc: '2.0',
+  method: 'initialized'
+});
+`;
+
+describe('mcp-sampling', () => {
+  const rig = new TestRig();
+
+  beforeAll(async () => {
+    await rig.setup('mcp-sampling', {
+      settings: {
+        mcpServers: {
+          'sampler-server': {
+            command: 'node',
+            args: ['mcp-server.cjs'],
+          },
+        },
+      },
+    });
+
+    const testServerPath = join(rig.testDir!, 'mcp-server.cjs');
+    writeFileSync(testServerPath, serverScript);
+
+    if (process.platform !== 'win32') {
+      const { chmodSync } = await import('node:fs');
+      chmodSync(testServerPath, 0o755);
+    }
+
+    const { accessSync, constants } = await import('node:fs');
+    const isReady = await poll(
+      () => {
+        try {
+          accessSync(testServerPath, constants.F_OK);
+          return true;
+        } catch {
+          return false;
+        }
+      },
+      5000,
+      100,
+    );
+
+    if (!isReady) {
+      throw new Error('MCP server script was not ready in time.');
+    }
+  });
+
+  it('should use the sample tool and get a response', async () => {
+    const child = rig.run(
+      "Use the sample tool to ask 'what is the capital of France?'",
+      ['--auto-confirm-mcp-sampling'],
+    );
+
+    const foundToolCall = await rig.waitForToolCall('sample');
+    expect(foundToolCall, 'Expected to find a sample tool call').toBeTruthy();
+
+    const output = await child;
+
+    validateModelOutput(output, 'Paris', 'MCP sampling test');
+    expect(
+      output.includes('Paris'),
+      'Expected output to contain the capital of France (Paris)',
+    ).toBeTruthy();
+  });
+});
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index 8ef2b61688c..c4a5085a999 100644
--- a/package-lock.json
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         "node": ">=12"
       },
diff --git a/packages/cli/src/config/config.ts b/packages/cli/src/config/config.ts
index c5c61ce748d..7f2c22beffe 100755
--- a/packages/cli/src/config/config.ts
+++ b/packages/cli/src/config/config.ts
@@ -83,6 +83,7 @@ export interface CliArgs {
   outputFormat: string | undefined;
   fakeResponses: string | undefined;
   recordResponses: string | undefined;
+  autoConfirmMcpSampling: boolean | undefined;
 }
 
 export async function parseArguments(
@@ -248,6 +249,11 @@ export async function parseArguments(
           type: 'string',
           description: 'Path to a file to record model responses for testing.',
           hidden: true,
+        })
+        .option('auto-confirm-mcp-sampling', {
+          type: 'boolean',
+          description: 'Automatically confirm all MCP sampling requests.',
+          hidden: true,
         }),
     )
     // Register MCP subcommands
@@ -756,6 +762,7 @@ export async function loadCliConfig(
     ptyInfo: ptyInfo?.name,
     disableLLMCorrection: settings.tools?.disableLLMCorrection,
     modelConfigServiceConfig: settings.modelConfigs,
+    autoConfirmMcpSampling: argv.autoConfirmMcpSampling,
     // TODO: loading of hooks based on workspace trust
     enableHooks:
       (settings.tools?.enableHooks ?? true) &&
diff --git a/packages/cli/src/gemini.test.tsx b/packages/cli/src/gemini.test.tsx
index 896f89e3c82..7b0a93d8eb5 100644
--- a/packages/cli/src/gemini.test.tsx
+++ b/packages/cli/src/gemini.test.tsx
@@ -490,6 +490,7 @@ describe('gemini.tsx main function kitty protocol', () => {
       outputFormat: undefined,
       fakeResponses: undefined,
       recordResponses: undefined,
+      autoConfirmMcpSampling: undefined,
     });
 
     await act(async () => {
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index da6643349b5..33c9795a317 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -5,7 +5,7 @@
  */
 
 import React from 'react';
-import { render } from 'ink';
+import { render, type RenderOptions } from 'ink';
 import { AppContainer } from './ui/AppContainer.js';
 import { loadCliConfig, parseArguments } from './config/config.js';
 import * as cliConfig from './config/config.js';
@@ -265,7 +265,7 @@ export async function startInteractiveUI(
       alternateBuffer: useAlternateBuffer,
       incrementalRendering:
         settings.merged.ui.incrementalRendering !== false && useAlternateBuffer,
-    },
+    } as RenderOptions & { incrementalRendering?: boolean },
   );
 
   checkForUpdates(settings)
diff --git a/packages/cli/src/ui/AppContainer.tsx b/packages/cli/src/ui/AppContainer.tsx
index 72f74a76f0a..1ceedefd7f5 100644
--- a/packages/cli/src/ui/AppContainer.tsx
+++ b/packages/cli/src/ui/AppContainer.tsx
@@ -252,6 +252,13 @@ export const AppContainer = (props: AppContainerProps) => {
     setPermissionsDialogProps(null);
   }, []);
 
+  const [mcpSamplingRequest, setMcpSamplingRequest] = useState<{
+    serverName: string;
+    prompt: unknown;
+    resolve: () => void;
+    reject: (reason?: unknown) => void;
+  } | null>(null);
+
   const toggleDebugProfiler = useCallback(
     () => setShowDebugProfiler((prev) => !prev),
     [],
@@ -354,9 +361,33 @@ export const AppContainer = (props: AppContainerProps) => {
       setCurrentModel(config.getModel());
     };
 
+    const handleMcpSamplingRequest = (payload: {
+      serverName: string;
+      prompt: unknown;
+      resolve: () => void;
+      reject: (reason?: unknown) => void;
+    }) => {
+      // Wrap the resolve and reject to clear the state after calling them
+      const wrappedResolve = () => {
+        payload.resolve();
+        setMcpSamplingRequest(null);
+      };
+      const wrappedReject = (reason?: unknown) => {
+        payload.reject(reason);
+        setMcpSamplingRequest(null);
+      };
+      setMcpSamplingRequest({
+        ...payload,
+        resolve: wrappedResolve,
+        reject: wrappedReject,
+      });
+    };
+
     coreEvents.on(CoreEvent.ModelChanged, handleModelChanged);
+    coreEvents.on(CoreEvent.McpSamplingRequest, handleMcpSamplingRequest);
     return () => {
       coreEvents.off(CoreEvent.ModelChanged, handleModelChanged);
+      coreEvents.off(CoreEvent.McpSamplingRequest, handleMcpSamplingRequest);
     };
   }, [config]);
 
@@ -1473,6 +1504,7 @@ Logging in with Google... Restarting Gemini CLI to continue.
     !!proQuotaRequest ||
     isSessionBrowserOpen ||
     isAuthDialogOpen ||
+    !!mcpSamplingRequest ||
     authState === AuthState.AwaitingApiKeyInput;
 
   const pendingHistoryItems = useMemo(
@@ -1612,8 +1644,10 @@ Logging in with Google... Restarting Gemini CLI to continue.
       activePtyId,
       embeddedShellFocused,
       showDebugProfiler,
+      authState,
       customDialog,
       copyModeEnabled,
+      mcpSamplingRequest,
       warningMessage,
       bannerData,
       bannerVisible,
@@ -1708,6 +1742,7 @@ Logging in with Google... Restarting Gemini CLI to continue.
       apiKeyDefaultValue,
       authState,
       copyModeEnabled,
+      mcpSamplingRequest,
       warningMessage,
       bannerData,
       bannerVisible,
diff --git a/packages/cli/src/ui/components/ConsentPrompt.tsx b/packages/cli/src/ui/components/ConsentPrompt.tsx
index efa6b136a3e..6eb806d2f8e 100644
--- a/packages/cli/src/ui/components/ConsentPrompt.tsx
+++ b/packages/cli/src/ui/components/ConsentPrompt.tsx
@@ -9,30 +9,32 @@ import { type ReactNode } from 'react';
 import { theme } from '../semantic-colors.js';
 import { MarkdownDisplay } from '../utils/MarkdownDisplay.js';
 import { RadioButtonSelect } from './shared/RadioButtonSelect.js';
+import { Scrollable } from './shared/Scrollable.js';
 
 type ConsentPromptProps = {
   // If a simple string is given, it will render using markdown by default.
   prompt: ReactNode;
   onConfirm: (value: boolean) => void;
   terminalWidth: number;
+  availableTerminalHeight?: number;
 };
 
 export const ConsentPrompt = (props: ConsentPromptProps) => {
-  const { prompt, onConfirm, terminalWidth } = props;
+  const { prompt, onConfirm, terminalWidth, availableTerminalHeight } = props;
 
-  return (
-    <Box
-      borderStyle="round"
-      borderColor={theme.border.default}
-      flexDirection="column"
-      paddingY={1}
-      paddingX={2}
-    >
+  // Account for border (2) + paddingY (2) + marginTop (1) + RadioButtonSelect height (~3)
+  const scrollableHeight = availableTerminalHeight
+    ? availableTerminalHeight - 8
+    : undefined;
+
+  const content = (
+    <>
       {typeof prompt === 'string' ? (
         <MarkdownDisplay
           isPending={true}
           text={prompt}
-          terminalWidth={terminalWidth}
+          terminalWidth={terminalWidth - 6}
+          availableTerminalHeight={availableTerminalHeight}
         />
       ) : (
         prompt
@@ -46,6 +48,24 @@ export const ConsentPrompt = (props: ConsentPromptProps) => {
           onSelect={onConfirm}
         />
       </Box>
+    </>
+  );
+
+  return (
+    <Box
+      borderStyle="round"
+      borderColor={theme.border.default}
+      flexDirection="column"
+      paddingY={1}
+      paddingX={2}
+    >
+      {scrollableHeight ? (
+        <Scrollable height={scrollableHeight} hasFocus={true}>
+          {content}
+        </Scrollable>
+      ) : (
+        content
+      )}
     </Box>
   );
 };
diff --git a/packages/cli/src/ui/components/DialogManager.tsx b/packages/cli/src/ui/components/DialogManager.tsx
index f915bc78525..995cc4d248f 100644
--- a/packages/cli/src/ui/components/DialogManager.tsx
+++ b/packages/cli/src/ui/components/DialogManager.tsx
@@ -22,6 +22,7 @@ import { RELAUNCH_EXIT_CODE } from '../../utils/processUtils.js';
 import { SessionBrowser } from './SessionBrowser.js';
 import { PermissionsModifyTrustDialog } from './PermissionsModifyTrustDialog.js';
 import { ModelDialog } from './ModelDialog.js';
+import { McpSamplingDialog } from './McpSamplingDialog.js';
 import { theme } from '../semantic-colors.js';
 import { useUIState } from '../contexts/UIStateContext.js';
 import { useUIActions } from '../contexts/UIActionsContext.js';
@@ -31,6 +32,7 @@ import process from 'node:process';
 import { type UseHistoryManagerReturn } from '../hooks/useHistoryManager.js';
 import { AdminSettingsChangedDialog } from './AdminSettingsChangedDialog.js';
 import { IdeTrustChangeDialog } from './IdeTrustChangeDialog.js';
+import type { SamplingMessage } from '@modelcontextprotocol/sdk/types.js';
 
 interface DialogManagerProps {
   addItem: UseHistoryManagerReturn['addItem'];
@@ -97,6 +99,7 @@ export const DialogManager = ({
         prompt={uiState.confirmationRequest.prompt}
         onConfirm={uiState.confirmationRequest.onConfirm}
         terminalWidth={terminalWidth}
+        availableTerminalHeight={terminalHeight - staticExtraHeight}
       />
     );
   }
@@ -107,6 +110,7 @@ export const DialogManager = ({
         prompt={request.prompt}
         onConfirm={request.onConfirm}
         terminalWidth={terminalWidth}
+        availableTerminalHeight={terminalHeight - staticExtraHeight}
       />
     );
   }
@@ -231,5 +235,17 @@ export const DialogManager = ({
     );
   }
 
+  if (uiState.mcpSamplingRequest) {
+    return (
+      <McpSamplingDialog
+        serverName={uiState.mcpSamplingRequest.serverName}
+        prompt={uiState.mcpSamplingRequest.prompt as SamplingMessage[]}
+        onConfirm={uiState.mcpSamplingRequest.resolve}
+        onReject={uiState.mcpSamplingRequest.reject}
+        availableTerminalHeight={terminalHeight - staticExtraHeight}
+      />
+    );
+  }
+
   return null;
 };
diff --git a/packages/cli/src/ui/components/McpSamplingDialog.tsx b/packages/cli/src/ui/components/McpSamplingDialog.tsx
new file mode 100644
index 00000000000..791d6d8e51c
--- /dev/null
+++ b/packages/cli/src/ui/components/McpSamplingDialog.tsx
@@ -0,0 +1,96 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { Box, Text } from 'ink';
+import type { SamplingMessage } from '@modelcontextprotocol/sdk/types.js';
+import { RadioButtonSelect } from './shared/RadioButtonSelect.js';
+import { Scrollable } from './shared/Scrollable.js';
+import { theme } from '../semantic-colors.js';
+
+/**
+ * Extract text content from an MCP message content object.
+ */
+function getMessageText(content: SamplingMessage['content']): string {
+  if (typeof content === 'object' && content !== null) {
+    if ('text' in content && typeof content.text === 'string') {
+      return content.text;
+    }
+    if ('type' in content) {
+      // For non-text content types (image, audio), show the type
+      return `[${content.type} content]`;
+    }
+  }
+  return JSON.stringify(content);
+}
+
+export function McpSamplingDialog({
+  serverName,
+  prompt,
+  onConfirm,
+  onReject,
+  availableTerminalHeight,
+}: {
+  serverName: string;
+  prompt: SamplingMessage[];
+  onConfirm: () => void;
+  onReject: () => void;
+  availableTerminalHeight?: number;
+}) {
+  // Account for border (2) + padding (2) + title (1) + margin (1) +
+  // prompt border (2) + prompt padding (2) + margin (1) + buttons (2)
+  const scrollableHeight = availableTerminalHeight
+    ? availableTerminalHeight - 13
+    : undefined;
+
+  const content = (
+    <Box flexDirection="column" borderStyle="round" padding={1}>
+      {prompt.map((message, index) => (
+        <Box key={index} flexDirection="column" marginBottom={1}>
+          <Text bold color={theme.text.secondary}>
+            {message.role === 'user' ? 'User' : 'Assistant'}:
+          </Text>
+          <Text color={theme.text.primary}>
+            {getMessageText(message.content)}
+          </Text>
+        </Box>
+      ))}
+    </Box>
+  );
+
+  return (
+    <Box flexDirection="column" borderStyle="round" padding={1}>
+      <Box>
+        <Text>
+          MCP server <Text bold>{serverName}</Text> wants to run a prompt:
+        </Text>
+      </Box>
+      <Box marginTop={1}>
+        {scrollableHeight ? (
+          <Scrollable height={scrollableHeight} hasFocus={true}>
+            {content}
+          </Scrollable>
+        ) : (
+          content
+        )}
+      </Box>
+      <Box marginTop={1}>
+        <RadioButtonSelect
+          items={[
+            { label: 'Approve', value: true, key: 'Approve' },
+            { label: 'Reject', value: false, key: 'Reject' },
+          ]}
+          onSelect={(value) => {
+            if (value) {
+              onConfirm();
+            } else {
+              onReject();
+            }
+          }}
+        />
+      </Box>
+    </Box>
+  );
+}
diff --git a/packages/cli/src/ui/components/shared/Scrollable.test.tsx b/packages/cli/src/ui/components/shared/Scrollable.test.tsx
index 22c2055f49b..9c19c7303e0 100644
--- a/packages/cli/src/ui/components/shared/Scrollable.test.tsx
+++ b/packages/cli/src/ui/components/shared/Scrollable.test.tsx
@@ -101,20 +101,20 @@ describe('<Scrollable />', () => {
       throw new Error('capturedEntry is undefined');
     }
 
-    // Initial state (starts at bottom because of auto-scroll logic)
-    expect(capturedEntry.getScrollState().scrollTop).toBe(5);
+    // Initial state (starts at top on initial render)
+    expect(capturedEntry.getScrollState().scrollTop).toBe(0);
 
-    // Call scrollBy multiple times (upwards) in the same tick
+    // Call scrollBy multiple times (downwards) in the same tick
     act(() => {
-      capturedEntry!.scrollBy(-1);
-      capturedEntry!.scrollBy(-1);
+      capturedEntry!.scrollBy(1);
+      capturedEntry!.scrollBy(1);
     });
-    // Should have moved up by 2
-    expect(capturedEntry.getScrollState().scrollTop).toBe(3);
+    // Should have moved down by 2
+    expect(capturedEntry.getScrollState().scrollTop).toBe(2);
 
     act(() => {
-      capturedEntry!.scrollBy(-2);
+      capturedEntry!.scrollBy(2);
     });
-    expect(capturedEntry.getScrollState().scrollTop).toBe(1);
+    expect(capturedEntry.getScrollState().scrollTop).toBe(4);
   });
 });
diff --git a/packages/cli/src/ui/components/shared/Scrollable.tsx b/packages/cli/src/ui/components/shared/Scrollable.tsx
index 16436be7c6f..f77346fa030 100644
--- a/packages/cli/src/ui/components/shared/Scrollable.tsx
+++ b/packages/cli/src/ui/components/shared/Scrollable.tsx
@@ -51,6 +51,7 @@ export const Scrollable: React.FC<ScrollableProps> = ({
   }, [size]);
 
   const childrenCountRef = useRef(0);
+  const hasInitializedRef = useRef(false);
 
   // This effect needs to run on every render to correctly measure the container
   // and scroll to the bottom if new children are added. The if conditions
@@ -70,7 +71,9 @@ export const Scrollable: React.FC<ScrollableProps> = ({
       size.scrollHeight !== scrollHeight
     ) {
       setSize({ innerHeight, scrollHeight });
-      if (isAtBottom) {
+      // Only maintain scroll position at bottom after initial render.
+      // On initial render, start at top unless scrollToBottom is explicitly set.
+      if (isAtBottom && hasInitializedRef.current) {
         setScrollTop(Math.max(0, scrollHeight - innerHeight));
       }
     }
@@ -80,6 +83,7 @@ export const Scrollable: React.FC<ScrollableProps> = ({
       setScrollTop(Math.max(0, scrollHeight - innerHeight));
     }
     childrenCountRef.current = childCountCurrent;
+    hasInitializedRef.current = true;
   });
 
   const { getScrollTop, setPendingScrollTop } = useBatchedScroll(scrollTop);
diff --git a/packages/cli/src/ui/contexts/ScrollProvider.test.tsx b/packages/cli/src/ui/contexts/ScrollProvider.test.tsx
index 021e10e280a..41b96822da9 100644
--- a/packages/cli/src/ui/contexts/ScrollProvider.test.tsx
+++ b/packages/cli/src/ui/contexts/ScrollProvider.test.tsx
@@ -276,9 +276,9 @@ describe('ScrollProvider', () => {
     // Advance timers to trigger the batched update
     await vi.runAllTimersAsync();
 
-    // Should have called scrollBy once with accumulated delta (3)
+    // Should have called scrollBy once with accumulated delta (3 events * 3 lines = 9)
     expect(scrollBy).toHaveBeenCalledTimes(1);
-    expect(scrollBy).toHaveBeenCalledWith(3);
+    expect(scrollBy).toHaveBeenCalledWith(9);
   });
 
   it('handles mixed direction scroll events in batch', async () => {
@@ -335,7 +335,7 @@ describe('ScrollProvider', () => {
     await vi.runAllTimersAsync();
 
     expect(scrollBy).toHaveBeenCalledTimes(1);
-    expect(scrollBy).toHaveBeenCalledWith(1); // 1 + 1 - 1 = 1
+    expect(scrollBy).toHaveBeenCalledWith(3); // 3 + 3 - 3 = 3 (3 lines per scroll event)
   });
 
   it('respects scroll limits during batching', async () => {
@@ -390,13 +390,14 @@ describe('ScrollProvider', () => {
 
     await vi.runAllTimersAsync();
 
-    // Should have accumulated only 1, because subsequent scrolls would be blocked
-    // Actually, the logic in ScrollProvider uses effectiveScrollTop to check bounds.
-    // scrollTop=89, max=90.
-    // 1st scroll: pending=1, effective=90. Allowed.
-    // 2nd scroll: pending=1, effective=90. canScrollDown checks effective < 90. 90 < 90 is false. Blocked.
+    // Should have accumulated only 3 (one scroll event), because subsequent scrolls would be blocked
+    // The logic in ScrollProvider uses effectiveScrollTop to check bounds.
+    // scrollTop=89, max=90, scroll step=3.
+    // 1st scroll: pending=3, effective=92. canScrollDown checks 89 < 89.999. True, allowed.
+    // 2nd scroll: pending=6, effective=95. canScrollDown checks 92 < 89.999. False. Blocked.
+    // Note: The actual clamping to max happens in the Scrollable component's scrollBy.
     expect(scrollBy).toHaveBeenCalledTimes(1);
-    expect(scrollBy).toHaveBeenCalledWith(1);
+    expect(scrollBy).toHaveBeenCalledWith(3);
   });
 
   it('calls scrollTo when dragging scrollbar thumb if available', async () => {
diff --git a/packages/cli/src/ui/contexts/ScrollProvider.tsx b/packages/cli/src/ui/contexts/ScrollProvider.tsx
index b461622fb2f..041b5c5eeb4 100644
--- a/packages/cli/src/ui/contexts/ScrollProvider.tsx
+++ b/packages/cli/src/ui/contexts/ScrollProvider.tsx
@@ -80,7 +80,17 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
   );
 
   const register = useCallback((entry: ScrollableEntry) => {
-    setScrollables((prev) => new Map(prev).set(entry.id, entry));
+    setScrollables((prev) => {
+      // Check if entry already exists with same id - if so, just update the reference
+      // without creating a new Map to avoid unnecessary re-renders
+      const existing = prev.get(entry.id);
+      if (existing) {
+        // Update the existing entry in place to avoid Map recreation
+        prev.set(entry.id, entry);
+        return prev;
+      }
+      return new Map(prev).set(entry.id, entry);
+    });
   }, []);
 
   const unregister = useCallback((id: string) => {
@@ -125,40 +135,47 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
     }
   }, []);
 
-  const handleScroll = (direction: 'up' | 'down', mouseEvent: MouseEvent) => {
-    const delta = direction === 'up' ? -1 : 1;
-    const candidates = findScrollableCandidates(
-      mouseEvent,
-      scrollablesRef.current,
-    );
-
-    for (const candidate of candidates) {
-      const { scrollTop, scrollHeight, innerHeight } =
-        candidate.getScrollState();
-      const pendingDelta = pendingScrollsRef.current.get(candidate.id) || 0;
-      const effectiveScrollTop = scrollTop + pendingDelta;
-
-      // Epsilon to handle floating point inaccuracies.
-      const canScrollUp = effectiveScrollTop > 0.001;
-      const canScrollDown =
-        effectiveScrollTop < scrollHeight - innerHeight - 0.001;
-
-      if (direction === 'up' && canScrollUp) {
-        pendingScrollsRef.current.set(candidate.id, pendingDelta + delta);
-        scheduleFlush();
-        return true;
-      }
+  // Scroll 3 lines per scroll event for smoother trackpad/mouse wheel scrolling
+  const SCROLL_LINES_PER_EVENT = 3;
+
+  const handleScroll = useCallback(
+    (direction: 'up' | 'down', mouseEvent: MouseEvent) => {
+      const delta =
+        direction === 'up' ? -SCROLL_LINES_PER_EVENT : SCROLL_LINES_PER_EVENT;
+      const candidates = findScrollableCandidates(
+        mouseEvent,
+        scrollablesRef.current,
+      );
+
+      for (const candidate of candidates) {
+        const { scrollTop, scrollHeight, innerHeight } =
+          candidate.getScrollState();
+        const pendingDelta = pendingScrollsRef.current.get(candidate.id) || 0;
+        const effectiveScrollTop = scrollTop + pendingDelta;
+
+        // Epsilon to handle floating point inaccuracies.
+        const canScrollUp = effectiveScrollTop > 0.001;
+        const canScrollDown =
+          effectiveScrollTop < scrollHeight - innerHeight - 0.001;
+
+        if (direction === 'up' && canScrollUp) {
+          pendingScrollsRef.current.set(candidate.id, pendingDelta + delta);
+          scheduleFlush();
+          return true;
+        }
 
-      if (direction === 'down' && canScrollDown) {
-        pendingScrollsRef.current.set(candidate.id, pendingDelta + delta);
-        scheduleFlush();
-        return true;
+        if (direction === 'down' && canScrollDown) {
+          pendingScrollsRef.current.set(candidate.id, pendingDelta + delta);
+          scheduleFlush();
+          return true;
+        }
       }
-    }
-    return false;
-  };
+      return false;
+    },
+    [scheduleFlush],
+  );
 
-  const handleLeftPress = (mouseEvent: MouseEvent) => {
+  const handleLeftPress = useCallback((mouseEvent: MouseEvent) => {
     // Check for scrollbar interaction first
     for (const entry of scrollablesRef.current.values()) {
       if (!entry.ref.current || !entry.hasFocus()) {
@@ -258,9 +275,9 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
       return false;
     }
     return false;
-  };
+  }, []);
 
-  const handleMove = (mouseEvent: MouseEvent) => {
+  const handleMove = useCallback((mouseEvent: MouseEvent) => {
     const state = dragStateRef.current;
     if (!state.active || !state.id) return false;
 
@@ -303,9 +320,9 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
       entry.scrollBy(targetScrollTop - scrollTop);
     }
     return true;
-  };
+  }, []);
 
-  const handleLeftRelease = () => {
+  const handleLeftRelease = useCallback(() => {
     if (dragStateRef.current.active) {
       dragStateRef.current = {
         active: false,
@@ -315,9 +332,9 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
       return true;
     }
     return false;
-  };
+  }, []);
 
-  useMouse(
+  const mouseHandler = useCallback(
     (event: MouseEvent) => {
       if (event.name === 'scroll-up') {
         return handleScroll('up', event);
@@ -332,9 +349,11 @@ export const ScrollProvider: React.FC<{ children: React.ReactNode }> = ({
       }
       return false;
     },
-    { isActive: true },
+    [handleScroll, handleLeftPress, handleMove, handleLeftRelease],
   );
 
+  useMouse(mouseHandler, { isActive: true });
+
   const contextValue = useMemo(
     () => ({ register, unregister }),
     [register, unregister],
diff --git a/packages/cli/src/ui/contexts/UIStateContext.tsx b/packages/cli/src/ui/contexts/UIStateContext.tsx
index 80db5782ffe..9b9632af68d 100644
--- a/packages/cli/src/ui/contexts/UIStateContext.tsx
+++ b/packages/cli/src/ui/contexts/UIStateContext.tsx
@@ -13,6 +13,7 @@ import type {
   LoopDetectionConfirmationRequest,
   HistoryItemWithoutId,
   StreamingState,
+  AuthState,
   ActiveHook,
 } from '../types.js';
 import type { CommandContext, SlashCommand } from '../commands/types.js';
@@ -38,6 +39,13 @@ export interface ProQuotaDialogRequest {
   resolve: (intent: FallbackIntent) => void;
 }
 
+export interface McpSamplingRequest {
+  serverName: string;
+  prompt: unknown;
+  resolve: () => void;
+  reject: (reason?: unknown) => void;
+}
+
 import { type UseHistoryManagerReturn } from '../hooks/useHistoryManager.js';
 import { type RestartReason } from '../hooks/useIdeTrustListener.js';
 import type { TerminalBackgroundColor } from '../utils/terminalCapabilityManager.js';
@@ -130,6 +138,7 @@ export interface UIState {
   showDebugProfiler: boolean;
   showFullTodos: boolean;
   copyModeEnabled: boolean;
+  mcpSamplingRequest: McpSamplingRequest | null;
   warningMessage: string | null;
   bannerData: {
     defaultText: string;
@@ -137,6 +146,7 @@ export interface UIState {
   };
   bannerVisible: boolean;
   customDialog: React.ReactNode | null;
+  authState: AuthState;
   terminalBackgroundColor: TerminalBackgroundColor;
   settingsNonce: number;
   adminSettingsChanged: boolean;
diff --git a/packages/core/src/config/config.test.ts b/packages/core/src/config/config.test.ts
index c7d5f66a151..c3e7c910d8a 100644
--- a/packages/core/src/config/config.test.ts
+++ b/packages/core/src/config/config.test.ts
@@ -106,6 +106,7 @@ vi.mock('../core/contentGenerator.js');
 vi.mock('../core/client.js', () => ({
   GeminiClient: vi.fn().mockImplementation(() => ({
     initialize: vi.fn().mockResolvedValue(undefined),
+    setTools: vi.fn().mockResolvedValue(undefined),
     stripThoughtsFromHistory: vi.fn(),
     isInitialized: vi.fn().mockReturnValue(false),
   })),
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index 80b1dece501..1db1cf99d83 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -370,6 +370,7 @@ export interface ConfigParameters {
   ptyInfo?: string;
   disableYoloMode?: boolean;
   modelConfigServiceConfig?: ModelConfigServiceConfig;
+  autoConfirmMcpSampling?: boolean;
   enableHooks?: boolean;
   enableHooksUI?: boolean;
   experiments?: Experiments;
@@ -509,6 +510,7 @@ export class Config {
   readonly fakeResponses?: string;
   readonly recordResponses?: string;
   private readonly disableYoloMode: boolean;
+  private readonly autoConfirmMcpSampling: boolean;
   private pendingIncludeDirectories: string[];
   private readonly enableHooks: boolean;
   private readonly enableHooksUI: boolean;
@@ -709,6 +711,7 @@ export class Config {
     };
     this.retryFetchErrors = params.retryFetchErrors ?? false;
     this.disableYoloMode = params.disableYoloMode ?? false;
+    this.autoConfirmMcpSampling = params.autoConfirmMcpSampling ?? false;
 
     if (params.hooks) {
       const { disabled: _, ...restOfHooks } = params.hooks;
@@ -717,7 +720,6 @@ export class Config {
     if (params.projectHooks) {
       this.projectHooks = params.projectHooks;
     }
-
     this.experiments = params.experiments;
     this.onModelChange = params.onModelChange;
     this.onReload = params.onReload;
@@ -844,6 +846,11 @@ export class Config {
     }
 
     await this.geminiClient.initialize();
+    // Ensure any MCP tools discovered during async initialization are loaded.
+    // MCP servers start asynchronously above (not awaited), so tools may have
+    // been discovered before geminiClient.initialize() completed. This call
+    // ensures the LLM has access to all discovered tools.
+    await this.geminiClient.setTools();
   }
 
   getContentGenerator(): ContentGenerator {
@@ -1081,6 +1088,10 @@ export class Config {
     return this.sandbox;
   }
 
+  getAutoConfirmMcpSampling(): boolean {
+    return this.autoConfirmMcpSampling;
+  }
+
   isRestrictiveSandbox(): boolean {
     const sandboxConfig = this.getSandbox();
     const seatbeltProfile = process.env['SEATBELT_PROFILE'];
diff --git a/packages/core/src/mcp/oauth-provider.ts b/packages/core/src/mcp/oauth-provider.ts
index b79ec693a30..8e89e11cad3 100644
--- a/packages/core/src/mcp/oauth-provider.ts
+++ b/packages/core/src/mcp/oauth-provider.ts
@@ -463,17 +463,25 @@ export class MCPOAuthProvider {
 
     // Add resource parameter for MCP OAuth spec compliance
     // Only add if we have an MCP server URL (indicates MCP OAuth flow, not standard OAuth)
+    debugLogger.debug(
+      `buildAuthorizationUrl: mcpServerUrl=${mcpServerUrl}, adding resource parameter: ${!!mcpServerUrl}`,
+    );
     if (mcpServerUrl) {
       try {
-        params.append(
-          'resource',
-          OAuthUtils.buildResourceParameter(mcpServerUrl),
+        const resourceParam = OAuthUtils.buildResourceParameter(mcpServerUrl);
+        params.append('resource', resourceParam);
+        debugLogger.debug(
+          `Added resource parameter to authorization URL: ${resourceParam}`,
         );
       } catch (error) {
         debugLogger.warn(
           `Could not add resource parameter: ${getErrorMessage(error)}`,
         );
       }
+    } else {
+      debugLogger.debug(
+        'No mcpServerUrl provided, skipping resource parameter',
+      );
     }
 
     const url = new URL(config.authorizationUrl!);
@@ -521,18 +529,26 @@ export class MCPOAuthProvider {
 
     // Add resource parameter for MCP OAuth spec compliance
     // Only add if we have an MCP server URL (indicates MCP OAuth flow, not standard OAuth)
+    debugLogger.debug(
+      `exchangeCodeForToken: mcpServerUrl=${mcpServerUrl}, adding resource parameter: ${!!mcpServerUrl}`,
+    );
     if (mcpServerUrl) {
       const resourceUrl = mcpServerUrl;
       try {
-        params.append(
-          'resource',
-          OAuthUtils.buildResourceParameter(resourceUrl),
+        const resourceParam = OAuthUtils.buildResourceParameter(resourceUrl);
+        params.append('resource', resourceParam);
+        debugLogger.debug(
+          `Added resource parameter to token exchange: ${resourceParam}`,
         );
       } catch (error) {
         debugLogger.warn(
           `Could not add resource parameter: ${getErrorMessage(error)}`,
         );
       }
+    } else {
+      debugLogger.debug(
+        'No mcpServerUrl provided to token exchange, skipping resource parameter',
+      );
     }
 
     const response = await fetch(config.tokenUrl!, {
@@ -644,17 +660,25 @@ export class MCPOAuthProvider {
 
     // Add resource parameter for MCP OAuth spec compliance
     // Only add if we have an MCP server URL (indicates MCP OAuth flow, not standard OAuth)
+    debugLogger.debug(
+      `refreshAccessToken: mcpServerUrl=${mcpServerUrl}, adding resource parameter: ${!!mcpServerUrl}`,
+    );
     if (mcpServerUrl) {
       try {
-        params.append(
-          'resource',
-          OAuthUtils.buildResourceParameter(mcpServerUrl),
+        const resourceParam = OAuthUtils.buildResourceParameter(mcpServerUrl);
+        params.append('resource', resourceParam);
+        debugLogger.debug(
+          `Added resource parameter to refresh request: ${resourceParam}`,
         );
       } catch (error) {
         debugLogger.warn(
           `Could not add resource parameter: ${getErrorMessage(error)}`,
         );
       }
+    } else {
+      debugLogger.debug(
+        'No mcpServerUrl provided to refresh, skipping resource parameter',
+      );
     }
 
     const response = await fetch(tokenUrl, {
@@ -746,6 +770,10 @@ export class MCPOAuthProvider {
     mcpServerUrl?: string,
     events?: EventEmitter,
   ): Promise<OAuthToken> {
+    debugLogger.debug(
+      `authenticate called for server '${serverName}' with mcpServerUrl: ${mcpServerUrl}`,
+    );
+
     // Helper function to display messages through handler or fallback to console.log
     const displayMessage = (message: string) => {
       if (events) {
diff --git a/packages/core/src/tools/mcp-client.test.ts b/packages/core/src/tools/mcp-client.test.ts
index a448fd288b8..a407eab28d7 100644
--- a/packages/core/src/tools/mcp-client.test.ts
+++ b/packages/core/src/tools/mcp-client.test.ts
@@ -1608,6 +1608,14 @@ describe('connectToMcpServer with OAuth', () => {
   let testWorkspace: string;
   let mockAuthProvider: MCPOAuthProvider;
   let mockTokenStorage: MCPOAuthTokenStorage;
+  const mockConfig = {
+    getAutoConfirmMcpSampling: () => false,
+    getGeminiClient: () => ({
+      generateContent: vi.fn(),
+    }),
+    getModel: () => 'gemini-2.0-flash',
+    sanitizationConfig: EMPTY_CONFIG,
+  } as unknown as Config;
 
   beforeEach(() => {
     mockedClient = {
@@ -1679,7 +1687,7 @@ describe('connectToMcpServer with OAuth', () => {
       { httpUrl: serverUrl, oauth: { enabled: true } },
       false,
       workspaceContext,
-      EMPTY_CONFIG,
+      mockConfig,
     );
 
     expect(client).toBe(mockedClient);
@@ -1724,7 +1732,7 @@ describe('connectToMcpServer with OAuth', () => {
       { httpUrl: serverUrl, oauth: { enabled: true } },
       false,
       workspaceContext,
-      EMPTY_CONFIG,
+      mockConfig,
     );
 
     expect(client).toBe(mockedClient);
@@ -1742,6 +1750,14 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
   let mockedClient: ClientLib.Client;
   let workspaceContext: WorkspaceContext;
   let testWorkspace: string;
+  const mockConfig = {
+    getAutoConfirmMcpSampling: () => false,
+    getGeminiClient: () => ({
+      generateContent: vi.fn(),
+    }),
+    getModel: () => 'gemini-2.0-flash',
+    sanitizationConfig: EMPTY_CONFIG,
+  } as unknown as Config;
 
   beforeEach(() => {
     mockedClient = {
@@ -1779,7 +1795,7 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
         { url: 'http://test-server', type: 'http' },
         false,
         workspaceContext,
-        EMPTY_CONFIG,
+        mockConfig,
       ),
     ).rejects.toThrow('Connection failed');
 
@@ -1798,7 +1814,7 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
         { url: 'http://test-server', type: 'sse' },
         false,
         workspaceContext,
-        EMPTY_CONFIG,
+        mockConfig,
       ),
     ).rejects.toThrow('Connection failed');
 
@@ -1816,7 +1832,7 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
       { url: 'http://test-server' },
       false,
       workspaceContext,
-      EMPTY_CONFIG,
+      mockConfig,
     );
 
     expect(client).toBe(mockedClient);
@@ -1838,7 +1854,7 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
         { url: 'http://test-server' },
         false,
         workspaceContext,
-        EMPTY_CONFIG,
+        mockConfig,
       ),
     ).rejects.toThrow('Server error');
 
@@ -1855,7 +1871,7 @@ describe('connectToMcpServer - HTTP→SSE fallback', () => {
       { url: 'http://test-server' },
       false,
       workspaceContext,
-      EMPTY_CONFIG,
+      mockConfig,
     );
 
     expect(client).toBe(mockedClient);
@@ -1869,6 +1885,14 @@ describe('connectToMcpServer - OAuth with transport fallback', () => {
   let testWorkspace: string;
   let mockAuthProvider: MCPOAuthProvider;
   let mockTokenStorage: MCPOAuthTokenStorage;
+  const mockConfig = {
+    getAutoConfirmMcpSampling: () => false,
+    getGeminiClient: () => ({
+      generateContent: vi.fn(),
+    }),
+    getModel: () => 'gemini-2.0-flash',
+    sanitizationConfig: EMPTY_CONFIG,
+  } as unknown as Config;
 
   beforeEach(() => {
     mockedClient = {
@@ -1925,7 +1949,7 @@ describe('connectToMcpServer - OAuth with transport fallback', () => {
       { url: 'http://test-server', oauth: { enabled: true } },
       false,
       workspaceContext,
-      EMPTY_CONFIG,
+      mockConfig,
     );
 
     expect(client).toBe(mockedClient);
diff --git a/packages/core/src/tools/mcp-client.ts b/packages/core/src/tools/mcp-client.ts
index 1f96d34169a..250bbebc385 100644
--- a/packages/core/src/tools/mcp-client.ts
+++ b/packages/core/src/tools/mcp-client.ts
@@ -24,6 +24,7 @@ import type {
   Resource,
 } from '@modelcontextprotocol/sdk/types.js';
 import {
+  CreateMessageRequestSchema,
   ListResourcesResultSchema,
   ListRootsRequestSchema,
   ReadResourceResultSchema,
@@ -34,6 +35,10 @@ import {
 import { parse } from 'shell-quote';
 import type { Config, MCPServerConfig } from '../config/config.js';
 import { AuthProviderType } from '../config/config.js';
+import {
+  DEFAULT_GEMINI_FLASH_MODEL,
+  DEFAULT_GEMINI_MODEL_AUTO,
+} from '../config/models.js';
 import { GoogleCredentialProvider } from '../mcp/google-auth-provider.js';
 import { ServiceAccountImpersonationProvider } from '../mcp/sa-impersonation-provider.js';
 import { DiscoveredMCPTool } from './mcp-tool.js';
@@ -58,7 +63,7 @@ import type {
 import type { ToolRegistry } from './tool-registry.js';
 import { debugLogger } from '../utils/debugLogger.js';
 import { type MessageBus } from '../confirmation-bus/message-bus.js';
-import { coreEvents } from '../utils/events.js';
+import { coreEvents, CoreEvent } from '../utils/events.js';
 import type { ResourceRegistry } from '../resources/resource-registry.js';
 import {
   sanitizeEnvironment,
@@ -141,7 +146,7 @@ export class McpClient {
         this.serverConfig,
         this.debugMode,
         this.workspaceContext,
-        this.cliConfig.sanitizationConfig,
+        this.cliConfig,
       );
 
       this.registerNotificationHandlers();
@@ -825,7 +830,7 @@ export async function connectAndDiscover(
       mcpServerConfig,
       debugMode,
       workspaceContext,
-      cliConfig.sanitizationConfig,
+      cliConfig,
     );
 
     mcpClient.onerror = (error) => {
@@ -1327,7 +1332,7 @@ async function retryWithOAuth(
  *
  * @param mcpServerName The name of the MCP server, used for logging and identification.
  * @param mcpServerConfig The configuration specifying how to connect to the server.
- * @returns A promise that resolves to a connected MCP `Client` instance.
+ * @returns A promise that resolves to a connected MCP `Client` instance and its `Transport`.
  * @throws An error if the connection fails or the configuration is invalid.
  */
 export async function connectToMcpServer(
@@ -1335,7 +1340,7 @@ export async function connectToMcpServer(
   mcpServerConfig: MCPServerConfig,
   debugMode: boolean,
   workspaceContext: WorkspaceContext,
-  sanitizationConfig: EnvironmentSanitizationConfig,
+  cliConfig: Config,
 ): Promise<Client> {
   const mcpClient = new Client(
     {
@@ -1352,6 +1357,7 @@ export async function connectToMcpServer(
     roots: {
       listChanged: true,
     },
+    sampling: {},
   });
 
   mcpClient.setRequestHandler(ListRootsRequestSchema, async () => {
@@ -1367,6 +1373,170 @@ export async function connectToMcpServer(
     };
   });
 
+  // Timeout for sampling consent dialog (5 minutes)
+  const SAMPLING_CONSENT_TIMEOUT_MS = 5 * 60 * 1000;
+
+  mcpClient.setRequestHandler(CreateMessageRequestSchema, async (req) => {
+    const autoConfirm = cliConfig.getAutoConfirmMcpSampling();
+
+    let rejectSampling: ((reason?: unknown) => void) | undefined;
+
+    if (!autoConfirm) {
+      const consentPromise = new Promise<void>((resolve, reject) => {
+        const timeoutId = setTimeout(() => {
+          reject(new Error('Sampling consent request timed out'));
+        }, SAMPLING_CONSENT_TIMEOUT_MS);
+
+        rejectSampling = (reason) => {
+          clearTimeout(timeoutId);
+          reject(reason);
+        };
+
+        coreEvents.emit(CoreEvent.McpSamplingRequest, {
+          serverName: mcpServerName,
+          prompt: req.params.messages,
+          resolve: () => {
+            clearTimeout(timeoutId);
+            resolve();
+          },
+          reject: (_reason?: unknown) => {
+            clearTimeout(timeoutId);
+            reject(new Error('User rejected sampling request'));
+          },
+        });
+      });
+
+      await consentPromise;
+    }
+
+    try {
+      const geminiClient = cliConfig.getGeminiClient();
+      const contents = req.params.messages.map((message) => {
+        // MCP spec: message.content is a single object (not an array)
+        const content = message.content as {
+          type: string;
+          text?: string;
+          data?: string;
+          mimeType?: string;
+        };
+
+        let parts;
+        if (content.type === 'text' && content.text) {
+          parts = [{ text: content.text }];
+        } else if (
+          content.type === 'image' &&
+          content.data &&
+          content.mimeType
+        ) {
+          // For image content, convert to Gemini format
+          parts = [
+            {
+              inlineData: {
+                mimeType: content.mimeType,
+                data: content.data,
+              },
+            },
+          ];
+        } else if (
+          content.type === 'audio' &&
+          content.data &&
+          content.mimeType
+        ) {
+          // For audio content, convert to Gemini format
+          parts = [
+            {
+              inlineData: {
+                mimeType: content.mimeType,
+                data: content.data,
+              },
+            },
+          ];
+        } else {
+          throw new Error(
+            `Unsupported or invalid content type: ${content.type}`,
+          );
+        }
+
+        // Map MCP roles to Gemini roles
+        // MCP: 'user' | 'assistant'
+        // Gemini: 'user' | 'model'
+        const geminiRole =
+          message.role === 'assistant' ? 'model' : message.role;
+
+        return {
+          role: geminiRole,
+          parts,
+        };
+      });
+
+      // Resolve the model to use for sampling
+      // If the config model is "auto", use flash as it's faster and cheaper for sampling
+      let modelToUse = cliConfig.getModel();
+      if (modelToUse === DEFAULT_GEMINI_MODEL_AUTO) {
+        modelToUse = DEFAULT_GEMINI_FLASH_MODEL;
+      }
+
+      // TODO: Consider req.params.modelPreferences to select model based on server hints
+      // For now, we just use the resolved model from config
+
+      const result = await geminiClient.generateContent(
+        { model: modelToUse },
+        contents,
+        new AbortController().signal,
+      );
+
+      const firstCandidate = result.candidates?.[0];
+      if (
+        !firstCandidate ||
+        !firstCandidate.content ||
+        !firstCandidate.content.parts
+      ) {
+        throw new Error('No response from Gemini');
+      }
+
+      // MCP spec: response content should be a single object (not an array)
+      // Gemini can return multiple parts, so we'll concatenate text parts
+      const textParts: string[] = [];
+      for (const part of firstCandidate.content.parts) {
+        if ('text' in part && part.text) {
+          textParts.push(part.text);
+        } else {
+          throw new Error(
+            'Unsupported response part type - only text parts are supported',
+          );
+        }
+      }
+
+      const responseContent = {
+        type: 'text' as const,
+        text: textParts.join(''),
+      };
+
+      // Map Gemini's finish reason to MCP's stopReason
+      // Gemini: STOP, MAX_TOKENS, SAFETY, RECITATION, OTHER, BLOCKLIST, PROHIBITED_CONTENT, SPII
+      // MCP: endTurn, maxTokens, stopSequence (we'll map to endTurn or maxTokens)
+      let stopReason: 'endTurn' | 'maxTokens' | 'stopSequence' = 'endTurn';
+      if (firstCandidate.finishReason === 'MAX_TOKENS') {
+        stopReason = 'maxTokens';
+      }
+
+      // MCP spec: return role, content, model, and stopReason at top level (not wrapped in "message")
+      return {
+        role: 'assistant' as const,
+        content: responseContent,
+        model: modelToUse,
+        stopReason,
+      };
+    } catch (error) {
+      // Close the dialog with an error message if consent was required
+      if (rejectSampling) {
+        rejectSampling(error);
+      }
+      // Re-throw to propagate to MCP server
+      throw error;
+    }
+  });
+
   let unlistenDirectories: Unsubscribe | undefined =
     workspaceContext.onDirectoriesChanged(async () => {
       try {
@@ -1402,7 +1572,7 @@ export async function connectToMcpServer(
       mcpServerName,
       mcpServerConfig,
       debugMode,
-      sanitizationConfig,
+      cliConfig.sanitizationConfig,
     );
     try {
       await mcpClient.connect(transport, {
@@ -1772,7 +1942,20 @@ export async function createTransport(
         }
       }
       if (accessToken) {
-        headers['Authorization'] = `Bearer ${accessToken}`;
+        // Only use the stored token if no Authorization header is manually configured
+        // or if OAuth is explicitly enabled (which implies we should use the token)
+        const hasConfiguredAuth = Object.keys(
+          mcpServerConfig.headers || {},
+        ).some((k) => k.toLowerCase() === 'authorization');
+        const isOAuthEnabled = !!mcpServerConfig.oauth?.enabled;
+
+        if (!hasConfiguredAuth || isOAuthEnabled) {
+          headers['Authorization'] = `Bearer ${accessToken}`;
+        } else {
+          debugLogger.log(
+            `Ignoring stored OAuth token for server '${mcpServerName}' because an Authorization header is explicitly configured.`,
+          );
+        }
       }
     }
 
diff --git a/packages/core/src/utils/events.ts b/packages/core/src/utils/events.ts
index 79e440e9ad7..086124d1b86 100644
--- a/packages/core/src/utils/events.ts
+++ b/packages/core/src/utils/events.ts
@@ -108,12 +108,23 @@ export interface RetryAttemptPayload {
   model: string;
 }
 
+/**
+ * Payload for the 'mcp-sampling-request' event.
+ */
+export interface McpSamplingRequestPayload {
+  serverName: string;
+  prompt: unknown;
+  resolve: () => void;
+  reject: (reason?: unknown) => void;
+}
+
 export enum CoreEvent {
   UserFeedback = 'user-feedback',
   ModelChanged = 'model-changed',
   ConsoleLog = 'console-log',
   Output = 'output',
   MemoryChanged = 'memory-changed',
+  McpSamplingRequest = 'mcp-sampling-request',
   ExternalEditorClosed = 'external-editor-closed',
   SettingsChanged = 'settings-changed',
   HookStart = 'hook-start',
@@ -129,6 +140,7 @@ export interface CoreEvents {
   [CoreEvent.ConsoleLog]: [ConsoleLogPayload];
   [CoreEvent.Output]: [OutputPayload];
   [CoreEvent.MemoryChanged]: [MemoryChangedPayload];
+  [CoreEvent.McpSamplingRequest]: [McpSamplingRequestPayload];
   [CoreEvent.ExternalEditorClosed]: never[];
   [CoreEvent.SettingsChanged]: never[];
   [CoreEvent.HookStart]: [HookStartPayload];