Fix Claude Code Conversation History Cache Invalidation (cch Sentinel Replacement) Causing 2-5x Token Burn in CLI, VS Code, and Standalone Binary — v2.1.69-v2.1.90

After applying the primary fix (CLAUDE_CODE_ATTRIBUTION_HEADER=false), add ENABLE_TOOL_SEARCH=false to prevent runtime tool injection from shifting the conversation context. Also use /compact before pauses > 5 minutes. These are supplementary safety measures — apply the primary fix FIRST.

1. Confirm Solution 1 is already applied: grep CLAUDE_CODE_ATTRIBUTION_HEADER ~/.claude/settings.json → should show 'false'
2. Add ENABLE_TOOL_SEARCH=false to the same env block in settings.json
3. Use /compact before any pause longer than 5 minutes during coding sessions
4. Keep sessions short: one major task per Claude Code session reduces cache impact
5. Front-load CLAUDE.md with the most critical project context

# Add ENABLE_TOOL_SEARCH=false alongside the attribution header fix:

python3 -c "import json; p='$HOME/.claude/settings.json'; d=json.load(open(p)); d.setdefault('env',{})['ENABLE_TOOL_SEARCH']='false'; json.dump(d,open(p,'w'),indent=2)"

# Verify both env vars are set:

grep -E 'CLAUDE_CODE_ATTRIBUTION_HEADER|ENABLE_TOOL_SEARCH' ~/.claude/settings.json

{
  "env": {
    "CLAUDE_CODE_ATTRIBUTION_HEADER": "false",
    "ENABLE_TOOL_SEARCH": "false"
  }
}

The community-developed /check-cache-bugs slash command (FlorianBruniaux) diagnoses all three known Claude Code cache bugs: Bug 1 (cch=00000 sentinel), Bug 2 (--resume deferred_tools_delta stripping), Bug 3 (attribution header absent on binary). Run this at the very START of a fresh session to get a clean diagnosis. If all three show CLEAN, your setup is safe.

1. mkdir -p ~/.claude/commands && curl -fsSL <URL> -o ~/.claude/commands/check-cache-bugs.md
2. Start a BRAND NEW Claude Code session — do NOT use --resume or --continue
3. As the VERY FIRST action: /check-cache-bugs
4. Review the three-line output for CLEAN/ACTIVE status
5. Safe alternative (no session pollution): claude -p "$(cat ~/.claude/commands/check-cache-bugs.md)"

mkdir -p ~/.claude/commands

curl -fsSL https://raw.githubusercontent.com/FlorianBruniaux/claude-code-ultimate-guide/main/examples/commands/check-cache-bugs.md -o ~/.claude/commands/check-cache-bugs.md

# START A NEW SESSION, then run: /check-cache-bugs

The cch sentinel replacement bug lives in the standalone binary's native Bun fork. v2.1.68 predates the bug entirely. If you need modern features, use the latest npm version (v2.1.173 as of June 2026) with the CLAUDE_CODE_ATTRIBUTION_HEADER workaround. This solution gives you two clear paths: safety (v2.1.68) or recency (latest + workaround).

1. PATH A (safest): npm install -g @anthropic-ai/claude-code@2.1.68
2. PATH B (latest): npm install -g @anthropic-ai/claude-code@latest, then apply Solution 1 from above
3. Verify version: claude --version should show your chosen version
4. CRITICAL: Confirm you are NOT running the standalone binary — run file $(which claude)

# PATH A: downgrade to last known-good (zero sentinel bug)

npm install -g @anthropic-ai/claude-code@2.1.68

claude --version

# PATH B: latest npm with workaround

npm install -g @anthropic-ai/claude-code@latest

npx @anthropic-ai/claude-code --version

# Confirm not using the standalone binary:

file $(which claude)

Add CLAUDE_CODE_ATTRIBUTION_HEADER=false to your Claude Code settings. This is a DEAD-SIMPLE fix requiring zero programming — just add one line to your settings file. This stops the cch=00000 sentinel from entering the conversation and prevents the native binary from rewriting tool results. This is a proper feature toggle in the Claude Code source and is used by multiple third-party projects. No version change needed.

1. Check if settings file exists: ls ~/.claude/settings.json 2>/dev/null || echo '{}' > ~/.claude/settings.json
2. Add the env block (use the config_example below — copy-paste it directly)
3. If you prefer a one-liner: python3 -c "exec(open('/dev/stdin').read())" and paste the short script OR manually edit the file
4. Restart Claude Code by closing ALL sessions and opening a fresh one
5. Run the ANTHROPIC_LOG=debug verification command to confirm the fix

# One-liner: create settings.json if missing, then set the env var

ls ~/.claude/settings.json 2>/dev/null || echo '{}' > ~/.claude/settings.json

# Python approach (requires python3):

python3 -c "import json; p='$HOME/.claude/settings.json'; d=json.load(open(p)); d.setdefault('env',{})['CLAUDE_CODE_ATTRIBUTION_HEADER']='false'; json.dump(d,open(p,'w'),indent=2)"

# OR manually: open ~/.claude/settings.json and add the env block from config_examples below

# Verify the setting took effect:

grep 'CLAUDE_CODE_ATTRIBUTION_HEADER' ~/.claude/settings.json

# Debug: check if sentinel is present in a quick one-shot session

ANTHROPIC_LOG=debug claude -p 'test' 2>&1 | grep -c 'cch=00000'

{
  "env": {
    "CLAUDE_CODE_ATTRIBUTION_HEADER": "false"
  }
}