Plugin cannot update FileTime after modifying files, causing "file modified since last read" errors #11249

Problem
When a plugin uses the tool.execute.after hook to modify files (e.g., running a formatter), subsequent write/edit operations on the same file fail with:

Error: File xxxxx has been modified since it was last read.
Last modification: 2026-01-30T03:53:46.637Z
Last read: 2026-01-30T03:53:35.616Z
Please read the file again before modifying it.

This happens even when the plugin has already read the file via the SDK client.

Root Cause

1. The plugin receives ctx.client which is an SDK client instance
2. The plugin can call ctx.client.read() to fetch file content after modifying it
3. However, calling ctx.client.read() does NOT update the FileTime tracking for the session
4. FileTime state is managed internally and only updated by the Read/Write/Edit tools themselves
5. Without a way for plugins to update FileTime, any external file modifications invalidate the timestamp tracking

Reproduction Steps

1. Create a plugin that modifies files in tool.execute.after:
2. Configure opencode to load this plugin
3. Open opencode and run: "Write a dummy file"
4. Plugin modifies the file after write completes
5. Error: "File has been modified since it was last read"

Current Workaround
Plugins can use the environment variable to disable FileTime checks:
export OPENCODE_DISABLE_FILETIME_CHECK=1
opencode
However, this:

• Disables ALL file modification safety checks
• Not plugin-specific (affects entire session)
• Reduces safety for concurrent edits