@file autocomplete dialog not appearing since 1.0.6 (regression)

Bug Report

Environment

• Claude Code Version: 1.0.16 (current)
• Platform: macOS Darwin 24.5.0
• Project Size: 98,183 files
• Version Control: jj (Jujutsu) + Git

Issue Description

The @file autocomplete/search dialog stopped appearing starting from version 1.0.6. This is a regression as the dialog worked correctly in version 1.0.4.

Regression Details

• Working Version: 1.0.4 - @file shows autocomplete dialog
• Broken Since: 1.0.6 - @file dialog does not appear
• Current Version Tested: 1.0.16

Expected Behavior

When typing @file, an autocomplete dialog should appear showing available files to select from (as it did in 1.0.4).

Actual Behavior

• Typing @file does not trigger the autocomplete dialog (broken since 1.0.6)
• Workaround: Manually typing the full filename (e.g., @README.md) still works and reads the file correctly

Project Context

• Very large codebase with 98,183 files including:
• vendor dependencies
• .git directory (legacy)
• .jj directory (current VCS)
• Project has proper CLAUDE.md file in root directory

Reproduction Steps

1. Open Claude Code in large project (98k+ files with jj+git VCS)
2. Type @file in the input field
3. Expected: Autocomplete dialog appears with file list
4. Actual: No dialog appears
5. Workaround: Type @README.md directly - this works and reads the file

Hypothesis

The autocomplete dialog regression might be related to:

• File count thresholds introduced in 1.0.6 to prevent UI lag in large projects
• Performance optimizations that disabled file indexing for autocomplete
• VCS directory scanning changes affecting file discovery

Impact

• Users cannot discover available files through autocomplete
• Workflow disruption for users who relied on file browsing
• Manual typing still works, so file reading functionality is intact

System Information

Working directory: /Users/gerald/Projects/omni-pilot
Version Control: jj (Jujutsu) + Git
File count: 98,183 files
Platform: macOS Darwin 24.5.0

Suggested Investigation

1. Check if file count limits for autocomplete dialog were introduced in 1.0.6
2. Verify if there's a configurable threshold to re-enable autocomplete in large projects
3. Test autocomplete behavior with smaller projects to confirm size-related threshold