3 files changed, 183 insertions, 2 deletions

diff --git a/packages/core/src/core/coreToolScheduler.test.ts b/packages/core/src/core/coreToolScheduler.test.ts
index ec01a3af..d6030d6f 100644
--- a/packages/core/src/core/coreToolScheduler.test.ts
+++ b/packages/core/src/core/coreToolScheduler.test.ts
@@ -16,11 +16,14 @@ import {
   BaseTool,
   ToolCallConfirmationDetails,
   ToolConfirmationOutcome,
+  ToolConfirmationPayload,
   ToolResult,
   Config,
 } from '../index.js';
 import { Part, PartListUnion } from '@google/genai';
 
+import { ModifiableTool, ModifyContext } from '../tools/modifiable-tool.js';
+
 class MockTool extends BaseTool<Record<string, unknown>, ToolResult> {
   shouldConfirm = false;
   executeFn = vi.fn();
@@ -54,6 +57,47 @@ class MockTool extends BaseTool<Record<string, unknown>, ToolResult> {
   }
 }
 
+class MockModifiableTool
+  extends MockTool
+  implements ModifiableTool<Record<string, unknown>>
+{
+  constructor(name = 'mockModifiableTool') {
+    super(name);
+    this.shouldConfirm = true;
+  }
+
+  getModifyContext(
+    _abortSignal: AbortSignal,
+  ): ModifyContext<Record<string, unknown>> {
+    return {
+      getFilePath: () => 'test.txt',
+      getCurrentContent: async () => 'old content',
+      getProposedContent: async () => 'new content',
+      createUpdatedParams: (
+        _oldContent: string,
+        modifiedProposedContent: string,
+        _originalParams: Record<string, unknown>,
+      ) => ({ newContent: modifiedProposedContent }),
+    };
+  }
+
+  async shouldConfirmExecute(
+    _params: Record<string, unknown>,
+    _abortSignal: AbortSignal,
+  ): Promise<ToolCallConfirmationDetails | false> {
+    if (this.shouldConfirm) {
+      return {
+        type: 'edit',
+        title: 'Confirm Mock Tool',
+        fileName: 'test.txt',
+        fileDiff: 'diff',
+        onConfirm: async () => {},
+      };
+    }
+    return false;
+  }
+}
+
 describe('CoreToolScheduler', () => {
   it('should cancel a tool call if the signal is aborted before confirmation', async () => {
     const mockTool = new MockTool();
@@ -122,6 +166,76 @@ describe('CoreToolScheduler', () => {
   });
 });
 
+describe('CoreToolScheduler with payload', () => {
+  it('should update args and diff and execute tool when payload is provided', async () => {
+    const mockTool = new MockModifiableTool();
+    const toolRegistry = {
+      getTool: () => mockTool,
+      getFunctionDeclarations: () => [],
+      tools: new Map(),
+      discovery: {} as any,
+      registerTool: () => {},
+      getToolByName: () => mockTool,
+      getToolByDisplayName: () => mockTool,
+      getTools: () => [],
+      discoverTools: async () => {},
+      getAllTools: () => [],
+      getToolsByServer: () => [],
+    };
+
+    const onAllToolCallsComplete = vi.fn();
+    const onToolCallsUpdate = vi.fn();
+
+    const mockConfig = {
+      getSessionId: () => 'test-session-id',
+      getUsageStatisticsEnabled: () => true,
+      getDebugMode: () => false,
+    } as unknown as Config;
+
+    const scheduler = new CoreToolScheduler({
+      config: mockConfig,
+      toolRegistry: Promise.resolve(toolRegistry as any),
+      onAllToolCallsComplete,
+      onToolCallsUpdate,
+      getPreferredEditor: () => 'vscode',
+    });
+
+    const abortController = new AbortController();
+    const request = {
+      callId: '1',
+      name: 'mockModifiableTool',
+      args: {},
+      isClientInitiated: false,
+    };
+
+    await scheduler.schedule([request], abortController.signal);
+
+    const confirmationDetails = await mockTool.shouldConfirmExecute(
+      {},
+      abortController.signal,
+    );
+
+    if (confirmationDetails) {
+      const payload: ToolConfirmationPayload = { newContent: 'final version' };
+      await scheduler.handleConfirmationResponse(
+        '1',
+        confirmationDetails.onConfirm,
+        ToolConfirmationOutcome.ProceedOnce,
+        abortController.signal,
+        payload,
+      );
+    }
+
+    expect(onAllToolCallsComplete).toHaveBeenCalled();
+    const completedCalls = onAllToolCallsComplete.mock
+      .calls[0][0] as ToolCall[];
+    expect(completedCalls[0].status).toBe('success');
+    expect(mockTool.executeFn).toHaveBeenCalledWith({
+      newContent: 'final version',
+    });
+  });
+});
+
 describe('convertToFunctionResponse', () => {
   const toolName = 'testTool';
   const callId = 'call1';
diff --git a/packages/core/src/core/coreToolScheduler.ts b/packages/core/src/core/coreToolScheduler.ts
index 81fce558..53596941 100644
--- a/packages/core/src/core/coreToolScheduler.ts
+++ b/packages/core/src/core/coreToolScheduler.ts
@@ -17,6 +17,7 @@ import {
   Config,
   logToolCall,
   ToolCallEvent,
+  ToolConfirmationPayload,
 } from '../index.js';
 import { Part, PartListUnion } from '@google/genai';
 import { getResponseTextFromParts } from '../utils/generateContentResponseUtilities.js';
@@ -25,6 +26,7 @@ import {
   ModifyContext,
   modifyWithEditor,
 } from '../tools/modifiable-tool.js';
+import * as Diff from 'diff';
 
 export type ValidatingToolCall = {
   status: 'validating';
@@ -455,12 +457,16 @@ export class CoreToolScheduler {
             const originalOnConfirm = confirmationDetails.onConfirm;
             const wrappedConfirmationDetails: ToolCallConfirmationDetails = {
               ...confirmationDetails,
-              onConfirm: (outcome: ToolConfirmationOutcome) =>
+              onConfirm: (
+                outcome: ToolConfirmationOutcome,
+                payload?: ToolConfirmationPayload,
+              ) =>
                 this.handleConfirmationResponse(
                   reqInfo.callId,
                   originalOnConfirm,
                   outcome,
                   signal,
+                  payload,
                 ),
             };
             this.setStatusInternal(
@@ -492,6 +498,7 @@ export class CoreToolScheduler {
     originalOnConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>,
     outcome: ToolConfirmationOutcome,
     signal: AbortSignal,
+    payload?: ToolConfirmationPayload,
   ): Promise<void> {
     const toolCall = this.toolCalls.find(
       (c) => c.request.callId === callId && c.status === 'awaiting_approval',
@@ -545,11 +552,62 @@ export class CoreToolScheduler {
         } as ToolCallConfirmationDetails);
       }
     } else {
+      // If the client provided new content, apply it before scheduling.
+      if (payload?.newContent && toolCall) {
+        await this._applyInlineModify(
+          toolCall as WaitingToolCall,
+          payload,
+          signal,
+        );
+      }
       this.setStatusInternal(callId, 'scheduled');
     }
     this.attemptExecutionOfScheduledCalls(signal);
   }
 
+  /**
+   * Applies user-provided content changes to a tool call that is awaiting confirmation.
+   * This method updates the tool's arguments and refreshes the confirmation prompt with a new diff
+   * before the tool is scheduled for execution.
+   * @private
+   */
+  private async _applyInlineModify(
+    toolCall: WaitingToolCall,
+    payload: ToolConfirmationPayload,
+    signal: AbortSignal,
+  ): Promise<void> {
+    if (
+      toolCall.confirmationDetails.type !== 'edit' ||
+      !isModifiableTool(toolCall.tool)
+    ) {
+      return;
+    }
+
+    const modifyContext = toolCall.tool.getModifyContext(signal);
+    const currentContent = await modifyContext.getCurrentContent(
+      toolCall.request.args,
+    );
+
+    const updatedParams = modifyContext.createUpdatedParams(
+      currentContent,
+      payload.newContent,
+      toolCall.request.args,
+    );
+    const updatedDiff = Diff.createPatch(
+      modifyContext.getFilePath(toolCall.request.args),
+      currentContent,
+      payload.newContent,
+      'Current',
+      'Proposed',
+    );
+
+    this.setArgsInternal(toolCall.request.callId, updatedParams);
+    this.setStatusInternal(toolCall.request.callId, 'awaiting_approval', {
+      ...toolCall.confirmationDetails,
+      fileDiff: updatedDiff,
+    });
+  }
+
   private attemptExecutionOfScheduledCalls(signal: AbortSignal): void {
     const allCallsFinalOrScheduled = this.toolCalls.every(
       (call) =>
diff --git a/packages/core/src/tools/tools.ts b/packages/core/src/tools/tools.ts
index e9fc042b..cff969f8 100644
--- a/packages/core/src/tools/tools.ts
+++ b/packages/core/src/tools/tools.ts
@@ -199,12 +199,21 @@ export interface FileDiff {
 export interface ToolEditConfirmationDetails {
   type: 'edit';
   title: string;
-  onConfirm: (outcome: ToolConfirmationOutcome) => Promise<void>;
+  onConfirm: (
+    outcome: ToolConfirmationOutcome,
+    payload?: ToolConfirmationPayload,
+  ) => Promise<void>;
   fileName: string;
   fileDiff: string;
   isModifying?: boolean;
 }
 
+export interface ToolConfirmationPayload {
+  // used to override `modifiedProposedContent` for modifiable tools in the
+  // inline modify flow
+  newContent: string;
+}
+
 export interface ToolExecuteConfirmationDetails {
   type: 'exec';
   title: string;