Claude Code Internals

Claude Code Internals Explorer

Procedures for analyzing Claude Code's standalone binary.

Quick Start

Note: All script paths are relative to this skill's directory (where SKILL.md resides).

Delegate all binary exploration to subagent:

Task tool (subagent_type: Explore)
Prompt: "Run scripts/find_installation.sh to get binary path.
        Then search for [keyword] using: strings $BINARY | grep -E '[pattern]' | head -50
        Return: version, matching lines with context (-B2 -A2)."

The subagent handles token-heavy strings output; main context receives only summarized findings.

Zero-Context Mode (Recommended)

Problem: Subagent output is recorded in session logs. Binary analysis can cause session file bloat → SIGTRAP crashes.

Solution: Write prompt to temp file, then execute via Headless CLI wrapper. Script internals are not logged; only final stdout is recorded.

Workflow

1. Write prompt to temp file (supports multiline)
2. Execute scripts/analyze-binary.sh <prompt_file> [allowed_tools]

Script Interface

The script injects BINARY_PATH automatically.

Example

# Use unique ID in filename for parallel independence
PROMPT_FILE="/tmp/internals_prompt_$$.txt"

# 1. Write prompt to temp file
cat > "$PROMPT_FILE" << 'EOF'
Search the binary for beta headers.

Instructions:
1. Use: strings "$BINARY_PATH" | grep -E "anthropic-beta|20[0-9]{2}-[0-9]{2}" | head -30
2. List all matching headers with their apparent status
3. Note any patterns suggesting feature flags
EOF

# 2. Execute with tool restriction
scripts/analyze-binary.sh "$PROMPT_FILE" "Bash,Read,Glob,Grep"

# 3. Cleanup (optional - /tmp clears on reboot)
rm -f "$PROMPT_FILE"

Dynamic Prompting

The agent constructs prompts dynamically based on investigation context.

File naming convention: /tmp/internals_prompt_<unique_id>.txt

• Use $$ (PID) or UUID for parallel execution independence
• Multiple concurrent investigations won't conflict

PROMPT_FILE="/tmp/internals_prompt_$(date +%s%N).txt"

cat > "$PROMPT_FILE" << 'EOF'
Investigate context management settings.
1. Search for contextWindow, warningThreshold, errorThreshold
2. Find related numeric constants (5-6 digit numbers)
3. Return: setting name, value, surrounding context
EOF

scripts/analyze-binary.sh "$PROMPT_FILE"

Tool Inheritance

Agent's tool restrictions are passed to Headless CLI via --allowedTools:

Why this works: Bash subagent executes the script as an external process. Only the script's stdout appears in session logs, not the intermediate 350K+ lines from strings.

Common Investigations

Resources

• scripts/find_installation.sh: Locate Claude Code binary
• references/search-patterns.md: Comprehensive search patterns by category
• references/known-features.md: Baseline of known features for comparison

Resource Map

Tips

1. Cache strings: strings $BINARY_PATH > /tmp/claude-strings.txt once, grep multiple times
2. Start narrow: Specific terms before broad exploration
3. Chain searches: Find one string, search nearby for related code
4. Clean up: Remove /tmp/claude-strings.txt after investigation