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Context Guard
Defense in depth for Claude Code context.
State preservation + security layer against prompt injection, leakage, and manipulation.
The Problem
When Claude Code hits ~95% context usage, it auto-compacts your conversation. You lose:
- Which files you were editing and why
- Your debugging trail, hypotheses, and decisions
- Build state, test results, error messages
- Uncommitted changes, stashes, and worktree state
- The overall narrative: "where were we?"
Context Guard captures your entire work environment — git state, actual code diffs, build health, worktrees, environment variables, and Claude's own memory — and automatically restores it after compaction.
Before: "Fix the auth bug in user-service.ts"
*edits 3 files, runs tests, debugging failing case*
--- COMPACTION ---
"I see we're working on a project. How can I help?"
After: --- COMPACTION ---
"Resuming: auth bug in user-service.ts, branch feat/auth-fix.
3 files modified (core:2, ui:1), tests failing on line 42.
Diff shows we added token validation but missed expiry check.
Continuing with the expiry logic..."
Quick Start
Plugin Install (recommended)
/plugin marketplace add jlceaser/context-guard
/plugin install context-guard@jlceaser
Restart Claude Code. That's it — hooks, skills, and agent are all active.
Manual Install
git clone https://github.com/jlceaser/context-guard.git
cd context-guard
bash install.sh # auto-configures settings.json via jq
bash test.sh # verify (31 tests)
One-liner
bash <(curl -sL https://raw.githubusercontent.com/jlceaser/context-guard/main/install.sh)
How It Works
Context at 80%
│
┌──────────▼──────────┐
│ PreCompact Hook │
│ ┌────────────────┐ │
│ │ Git state │ │
│ │ Code diffs │ │ ┌─────────────────┐
│ │ Build health │ │────▶│ Snapshot .md │
│ │ Worktrees │ │ │ + systemMessage │
│ │ Environment │ │ └────────┬────────┘
│ │ Claude memory │ │ │
│ └────────────────┘ │ │
└─────────────────────┘ │
▼
┌─────────────────────┐ ┌────────────────┐
│ --- COMPACTION --- │───▶│ systemMessage │
└─────────────────────┘ │ injected into │
│ compacted state │
┌─────────────────────┐ └────────┬───────┘
│ SessionStart Hook │◀────────────┘
│ Detects snapshot │
│ Injects recovery │──▶ Claude reads snapshot
└─────────────────────┘ and resumes work
Two-phase defense:
-
systemMessage — critical metadata (project, branch, dirty files) is injected directly into the compaction summary. This survives compaction and is immediately available.
-
Snapshot file — full state with code diffs is saved to disk. Claude reads this on the next turn to restore complete context.
Annotation Layer (v4.0.0):
- Persistent annotations — topic-based notes that survive everything. Save key findings with
/cg-annotate <topic> "note", retrieve with/cg-recall <topic>. Stored in~/.claude/annotations/<project>/<topic>.md. Inspired by context-hub.
Context Security
New in v0.5.0 — Context Guard now includes a security layer that protects against prompt injection, credential leakage, and context manipulation.
