Warn user when we overwrite a command due to conflict with extensions

packages/cli/src/config/extension-manager.ts

@@ -68,6 +68,10 @@ import {
   ExtensionSettingScope,
 } from './extensions/extensionSettings.js';
 import type { EventEmitter } from 'node:stream';
+import { glob } from 'glob';
+import { BuiltinCommandLoader } from '../services/BuiltinCommandLoader.js';
+import { McpPromptLoader } from '../services/McpPromptLoader.js';
+import { FileCommandLoader } from '../services/FileCommandLoader.js';
 
 interface ExtensionManagerParams {
   enabledExtensionOverrides?: string[];
@@ -236,6 +240,9 @@ Would you like to attempt to install via "git clone" instead?`,
         newExtensionConfig = await this.loadExtensionConfig(localSourcePath);
 
         const newExtensionName = newExtensionConfig.name;
+
+        await this.checkCommandConflicts(localSourcePath, newExtensionName);
+
         const previous = this.getExtensions().find(
           (installed) => installed.name === newExtensionName,
         );
@@ -899,6 +906,84 @@ Would you like to attempt to install via "git clone" instead?`,
     }
     await this.maybeStartExtension(extension);
   }
+
+  private async checkCommandConflicts(
+    localSourcePath: string,
+    extensionName: string,
+  ): Promise<void> {
+    const abortController = new AbortController();
+    const signal = abortController.signal;
+
+    // 1. Get current commands
+    const currentLoaders = [
+      new McpPromptLoader(this.config ?? null),
+      new BuiltinCommandLoader(this.config ?? null),
+      new FileCommandLoader(this.config ?? null),
+    ];
+
+    const currentCommandsResults = await Promise.allSettled(
+      currentLoaders.map((l) => l.loadCommands(signal)),
+    );
+    const currentCommandNames = new Set<string>();
+    for (const result of currentCommandsResults) {
+      if (result.status === 'fulfilled') {
+        result.value.forEach((cmd) => {
+          // If it's an update, don't count existing commands from the SAME extension as conflicts
+          if (cmd.extensionName !== extensionName) {
+            currentCommandNames.add(cmd.name);
+          }
+        });
+      }
+    }
+
+    // 2. Get commands from the new/updated extension
+    const extensionCommandsDir = path.join(localSourcePath, 'commands');
+    if (!fs.existsSync(extensionCommandsDir)) {
+      return;
+    }
+
+    const files = await glob('**/*.toml', {
+      cwd: extensionCommandsDir,
+      nodir: true,
+      dot: true,
+      follow: true,
+    });
+
+    const conflicts: Array<{
+      commandName: string;
+      renamedName: string;
+    }> = [];
+
+    for (const file of files) {
+      const relativePath = file.substring(0, file.length - 5); // length of '.toml'
+      const baseCommandName = relativePath
+        .split(path.sep)
+        .map((segment) => segment.replaceAll(':', '_'))
+        .join(':');
+
+      if (currentCommandNames.has(baseCommandName)) {
+        conflicts.push({
+          commandName: baseCommandName,
+          renamedName: `${extensionName}.${baseCommandName}`,
+        });
+      }
+    }
+
+    if (conflicts.length > 0) {
+      const conflictList = conflicts
+        .map(
+          (c) =>
+            ` - '/${c.commandName}' (will be renamed to '/${c.renamedName}')`,
+        )
+        .join('\n');
+
+      const warning = `WARNING: Installing extension '${extensionName}' will cause the following command conflicts:\n${conflictList}\n\nDo you want to continue installation?`;
+
+      if (!(await this.requestConsent(warning))) {
+        throw new Error('Installation cancelled due to command conflicts.');
+      }
+    }
+  }
 }
 
 function filterMcpConfig(original: MCPServerConfig): MCPServerConfig {

packages/cli/src/services/CommandService.test.ts

@@ -8,7 +8,7 @@ import { vi, describe, it, expect, beforeEach, afterEach } from 'vitest';
 import { CommandService } from './CommandService.js';
 import { type ICommandLoader } from './types.js';
 import { CommandKind, type SlashCommand } from '../ui/commands/types.js';
-import { debugLogger } from '@google/gemini-cli-core';
+import { debugLogger, coreEvents } from '@google/gemini-cli-core';
 
 const createMockCommand = (name: string, kind: CommandKind): SlashCommand => ({
   name,
@@ -37,6 +37,7 @@ class MockCommandLoader implements ICommandLoader {
 describe('CommandService', () => {
   beforeEach(() => {
     vi.spyOn(debugLogger, 'debug').mockImplementation(() => {});
+    CommandService.clearEmittedFeedbacksForTest();
   });
 
   afterEach(() => {
@@ -237,6 +238,32 @@ describe('CommandService', () => {
     expect(syncExtension?.extensionName).toBe('git-helper');
   });
 
+  it('should emit feedback when an extension command is renamed', async () => {
+    const builtinCommand = createMockCommand('deploy', CommandKind.BUILT_IN);
+    const extensionCommand = {
+      ...createMockCommand('deploy', CommandKind.FILE),
+      extensionName: 'firebase',
+      description: '[firebase] Deploy to Firebase',
+    };
+
+    const mockLoader1 = new MockCommandLoader([builtinCommand]);
+    const mockLoader2 = new MockCommandLoader([extensionCommand]);
+
+    const emitFeedbackSpy = vi.spyOn(coreEvents, 'emitFeedback');
+
+    await CommandService.create(
+      [mockLoader1, mockLoader2],
+      new AbortController().signal,
+    );
+
+    expect(emitFeedbackSpy).toHaveBeenCalledWith(
+      'info',
+      expect.stringContaining(
+        "Extension command '/deploy' from 'firebase' was renamed to '/firebase.deploy'",
+      ),
+    );
+  });
+
   it('should handle user/project command override correctly', async () => {
     const builtinCommand = createMockCommand('help', CommandKind.BUILT_IN);
     const userCommand = createMockCommand('help', CommandKind.FILE);

packages/cli/src/services/CommandService.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { debugLogger } from '@google/gemini-cli-core';
+import { debugLogger, coreEvents } from '@google/gemini-cli-core';
 import type { SlashCommand } from '../ui/commands/types.js';
 import type { ICommandLoader } from './types.js';
 
@@ -20,6 +20,16 @@ import type { ICommandLoader } from './types.js';
  * system to be extended with new sources without modifying the service itself.
  */
 export class CommandService {
+  private static emittedFeedbacks = new Set<string>();
+
+  /**
+   * Clears the set of emitted feedback messages.
+   * This should ONLY be used in tests to ensure isolation between test cases.
+   */
+  static clearEmittedFeedbacksForTest(): void {
+    CommandService.emittedFeedbacks.clear();
+  }
+
   /**
    * Private constructor to enforce the use of the async factory.
    * @param commands A readonly array of the fully loaded and de-duplicated commands.
@@ -77,6 +87,12 @@ export class CommandService {
           suffix++;
         }
 
+        const feedbackMsg = `Extension command '/${cmd.name}' from '${cmd.extensionName}' was renamed to '/${renamedName}' due to a conflict with an existing command.`;
+        if (!CommandService.emittedFeedbacks.has(feedbackMsg)) {
+          coreEvents.emitFeedback('info', feedbackMsg);
+          CommandService.emittedFeedbacks.add(feedbackMsg);
+        }
+
         finalName = renamedName;
       }
 

packages/cli/src/services/FileCommandLoader.ts

@@ -44,7 +44,7 @@ interface CommandDirectory {
  * Defines the Zod schema for a command definition file. This serves as the
  * single source of truth for both validation and type inference.
  */
-const TomlCommandDefSchema = z.object({
+export const TomlCommandDefSchema = z.object({
   prompt: z.string({
     required_error: "The 'prompt' field is required.",
     invalid_type_error: "The 'prompt' field must be a string.",

packages/cli/src/ui/components/SuggestionsDisplay.tsx

@@ -15,6 +15,7 @@ export interface Suggestion {
   description?: string;
   matchedIndex?: number;
   commandKind?: CommandKind;
+  extensionName?: string;
 }
 interface SuggestionsDisplayProps {
   suggestions: Suggestion[];
@@ -65,8 +66,13 @@ export function SuggestionsDisplay({
     [CommandKind.AGENT]: ' [Agent]',
   };
 
-  const getFullLabel = (s: Suggestion) =>
+  const getFullLabel = (s: Suggestion) => {
-    s.label + (s.commandKind ? (COMMAND_KIND_SUFFIX[s.commandKind] ?? '') : '');
+    let label = s.label;
+    if (s.commandKind && COMMAND_KIND_SUFFIX[s.commandKind]) {
+      label += COMMAND_KIND_SUFFIX[s.commandKind];
+    }
+    return label;
+  };
 
   const maxLabelLength = Math.max(
     ...suggestions.map((s) => getFullLabel(s).length),

packages/cli/src/ui/hooks/useSlashCompletion.ts

@@ -316,6 +316,7 @@ function useCommandSuggestions(
             value: cmd.name,
             description: cmd.description,
             commandKind: cmd.kind,
+            extensionName: cmd.extensionName,
           }));
 
           setSuggestions(finalSuggestions);