VSCode Extension: File modification reminders consume excessive context

Problem

When using the Claude Code VSCode extension, file modification tracking injects system reminders about every file modified during the session into every subsequent message. This rapidly consumes context, especially when multiple files are edited.

Example

After editing 5 files, each message includes ~300+ lines of repeated reminders:

<system-reminder>
Note: file1.cs was modified...
[50 lines of diff]
</system-reminder>
<system-reminder>
Note: file2.cs was modified...
[50 lines of diff]
</system-reminder>
... (repeated for all 5 files, every message)

Impact

• Context burns ~5x faster than necessary
• Users must /compact or start new conversations frequently
• The same information is sent repeatedly even when those files aren't being touched

Proposed Solution

Store modification tracking in a session file, load on-demand:

.claude/session/modified-files.json

{
  "ASConstants.cs": {
    "modified": "2026-01-28T07:54:19Z",
    "by": "claude",
    "summary": "Added BuildInfo class"
  }
}

Behavior change:

• Current: Inject all file diffs into every message "just in case"
• Proposed: Only inject relevant file info when Claude is about to edit that specific file

This would:

1. Reduce context usage dramatically
2. Still prevent accidental reverts (check before editing)
3. Scale better with longer sessions / more file edits

Alternative

At minimum, only send a one-line summary per file instead of full diffs every message:

Modified files this session: ASConstants.cs, ASPreferences.cs, AS101000.aspx (use Read tool before editing)

Environment

• VSCode Extension
• Windows 11
• Claude Opus 4.5