Summary

Fixes #5318 - CLI writes file content twice when creating or editing files.

Problem

When the Kilo Code CLI creates or edits files, the content was being duplicated at the end of the file. This was visible in logs and caused issues where:

• New files had their content written twice
• When the LLM tried to fix the duplication, it added the code again, creating 3+ copies

Root Causes

1. Multi-line Edit Logic in applyEdit (Primary)

In packages/agent-runtime/src/host/VSCode.ts, the line-based edit logic had a bug:

const lastLine = lines[endLine] || ""
const newContent = firstLine.substring(0, startChar) + textEdit.newText + lastLine.substring(endChar)

When endChar = 0, lastLine.substring(0) returns the entire last line, causing duplication.

2. Multiple applyEdit Calls in CLI Mode (Secondary)

In src/integrations/editor/DiffViewProvider.ts, the update() method made up to 3 applyEdit calls when finalizing. In CLI mode, each call writes to disk, causing race conditions and potential duplication.

Solution

VSCode.ts Changes

• Replaced line-based editing with offset-based editing using slice() operations
• Added [...edits] spread to prevent mutation of the original edit array

DiffViewProvider.ts Changes

• Added CLI-specific code path that makes a single applyEdit call to replace the entire document content
• This eliminates the multiple-write issue in CLI mode

Testing

• Added new test file packages/agent-runtime/src/host/__tests__/VSCode.applyEdit.spec.ts
• Added CLI mode test in src/integrations/editor/__tests__/DiffViewProvider.spec.ts