PostToolUse hook system-reminders include full file content, consuming excessive context

Problem

A single git commit message consumed ~18% of the session token budget. This is disproportionate — the actual work (writing code, running tests, taking screenshots) across 5 features in the same session used the other 82%.

Root Cause

The PostToolUse hook system-reminders now include the full content of every file modified by a formatter/linter. When lint-staged runs on a commit touching 10 files, the hook injects ~1,500+ lines of complete file contents as system-reminders into the conversation context in a single turn.

This did NOT happen before — previously the reminders only notified that the file was modified without dumping the content.

Token Impact

• 10 files committed → lint-staged reformats them → 10 system-reminders with full file contents
• Files ranged from 160 to 530 lines each
• Total injected: ~2,500+ lines of code as context in one turn
• Result: 18% of session budget consumed by a single commit operation

Reproduction

1. Have a project with lint-staged configured (prettier + eslint on pre-commit)
2. Stage and commit ~10 files via Claude Code
3. Observe the system-reminders after the commit — each reformatted file includes its full content with line numbers
4. Check session usage — single commit consumes disproportionate budget

Expected Behavior

1. System-reminders from formatter hooks should NOT include full file content — just notify the file was modified (as they did before)
2. A commit operation should not consume more than ~1-2% of session budget regardless of how many files lint-staged touches

Environment

• Claude Code VSCode Extension
• macOS Darwin 25.4.0
• Model: claude-opus-4-6 (1M context)
• lint-staged with prettier + eslint