Session Guard

---
name: session-guard
description: >-
  Use when working on complex multi-step tasks, when a session is getting long
  (40+ tool calls), when the agent starts ignoring rules it followed earlier,
  when conventions drift, when output quality seems to degrade, or after any
  context compaction event. Prevents long-session corruption AND context
  compaction amnesia through behavioral self-enforcement.
---

# Session Guard

## Overview

Long sessions corrupt silently. Context compaction drops instructions unannounced. Hooks don't fix it (confirmed by multiple developers on GitHub issues #19471, #9796, #64171). This skill prevents both through behavioral self-enforcement: monitor health, anchor critical rules through compaction, split before damage occurs. No packages, no databases - pure behavioral enforcement that works in every harness.

## When to Use

- Session exceeds 40 tool calls
- Agent contradicts earlier decisions
- Style/naming conventions start drifting
- After any context compaction event
- Task scope growing unbounded

## Health Signals

| Signal | Threshold | Action |
|--------|-----------|--------|
| Tool call count | >40 | YELLOW: checkpoint + recite critical rules |
| Tool call count | >60 | RED: split or compact with anchor |
| Agent contradicts earlier decision | Any | VERIFY: re-read source of truth |
| Style/naming drift | Any | RECITE: state the active rules aloud |
| File read returns unexpected content | Any | RE-READ: don't trust cached state |
| Task scope growing unbounded | Continuous | SPLIT: one task per session |

## Protocol

### Green Zone (0-40 tool calls)
Normal operation. No intervention needed.

### Yellow Zone (40-60 tool calls)
1. CHECKPOINT - summarize progress in one paragraph
2. RECITE - state the 3-5 most critical active rules aloud: "Active rules: [naming convention], [file structure], [error handling pattern], [testing requirement]"
3. ASSESS - almost done? Push through. Not done? Prepare split.
4. REDUCE - no exploratory reads. Only targeted operations.

### Red Zone (60+ tool calls OR drift signal)
1. STOP - do not make more tool calls
2. VERIFY - re-read project rules (don't trust memory)
3. CHECKPOINT - write state to handoff document
4. SPLIT - create handoff, suggest fresh session

## Context Anchoring (anti-compaction)

When compaction has occurred (sudden loss of earlier context, or after /compact):

1. RE-READ the project's rules file immediately
2. RECITE the 3-5 critical rules aloud in your response
3. VERIFY your planned next action matches those rules before executing
4. If uncertain about ANY prior decision, RE-READ the source file - don't guess

### What survives compaction:
- Most recent user messages (high priority)
- Currently-invoked skill body (capped at 5K tokens, oldest dropped first)
- Git status and project structure
- File contents read AFTER compaction

### What gets LOST in compaction:
- Decisions made early in conversation
- Architectural rules stated only verbally (not in files)
- Context from tool outputs (file reads, command outputs)

### Compaction-Safe Pattern
Keep critical instructions in FILES (CLAUDE.md, CONTEXT.md), NOT in conversation. If a rule matters, it must live in a file the agent can re-read - not in something agreed on earlier.

## Common Mistakes

- Trusting that you remember the rules after 50+ tool calls (you don't - re-read)
- Re-reading EVERYTHING to be safe (wastes tool calls - be targeted)
- Feeling fine therefore assuming context is fine (compaction is SILENT)
- Splitting AFTER noticing problems (split BEFORE - prevention, not recovery)

## Why This Matters

Context compaction is the #1 unsolved platform problem in 2026. Hooks don't fix it (confirmed: the agent ignores post-compaction injections because the compaction summary creates narrative momentum). This skill is the lightweight behavioral countermeasure: no infrastructure, no packages - disciplined self-monitoring that works in every harness.

Run this skill on a real model without leaving the page. Every run is saved to your history for this skill.

How to use

1. 1Save the content below as SKILL.md in your agent's skills directory (e.g. .claude/skills/<name>/SKILL.md).
2. 2Or paste it directly into the conversation as context before asking the agent to do the task.
3. 3Adjust any project-specific paths or conventions mentioned in the skill to match your setup.