session-guard

# 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.