File edits not applied - shows diff output only without modifying files

[falcon-head]

Description

Description

OpenCode initially works correctly and applies file edits as expected. However, after approximately 10-15 conversation summaries (when approaching context limit), it stops actually modifying files and instead only displays diff outputs in the terminal without applying any changes.

Expected Behavior

OpenCode should continue to apply file modifications even after multiple conversation summaries, maintaining its ability to write changes to files throughout extended coding sessions.

Actual Behavior

• First 10-15 operations: Works correctly, files are modified as requested
• After ~10-15 conversation summaries: Stops writing to files, only shows git-style diff output
• Files remain completely unchanged despite showing the intended modifications in diff format

Impact

This breaks long coding sessions, forcing users to restart OpenCode frequently or manually apply changes from diff outputs.

Additional Context

• Using GitHub provider with Claude Haiku 4.5
• OpenCode version 1.0.16 (recently upgraded to 1.0.20 still see this issue)
• Issue is reproducible after extended use

OpenCode version

1.0.20

Steps to reproduce

1. Start a new OpenCode session with GitHub Copilot provider (Claude Haiku 4.5)
2. Begin making file modifications (ask it to edit various files in your project)
3. Continue requesting changes until OpenCode summarizes the conversation approximately 10-15 times
4. After multiple summaries, request another file edit (e.g., "Add new menu items to header component")
5. Observe: OpenCode shows diff output in terminal instead of applying changes
6. Check the actual file - remains unchanged

Screenshot and/or share link

Operating System

macOS 26.0.1

Terminal

Kitty terminal

[rekram1-node]

It looks to me like the model isn't calling tools anymore at that stage