Token Optimization — Claude Code Recap Card T20

RTK: Upstream Filtering

RTK (Rust Token Killer) intercepts command outputs before they enter Claude’s context. It is not a post-hoc summary, it is a filter that eliminates structurally redundant noise.

# Installation
brew install rtk-ai/tap/rtk
# or: cargo install rtk

# Initialize in a project (sets up the hook automatically)
rtk init

Measured Savings

Command	Without RTK	With RTK	Reduction
`git log`	13,994 chars	1,076 chars	92%
`git status`	100 chars	24 chars	76%
`vitest run`	~50,000 chars	~5,000 chars	90%
`pnpm list`	~8,000 chars	~2,400 chars	70%

A 30-minute session with 10-15 git commands drops from ~150K to ~41K tokens, a 72% reduction on that item alone.

Essential RTK Commands

rtk git status        # Condensed git
rtk git log           # Clean log output
rtk cargo test        # Filtered Rust tests
rtk vitest run        # Condensed JS tests
rtk gh pr view 123    # Optimized GitHub PR
rtk gain              # Savings dashboard

Compact: Freeing Up Context

/compact summarizes the conversation history and frees roughly 40-50% of used context, without losing the thread of the session. Use it proactively at 70% usage, not as an emergency measure at 90%.

/compact              # Summarize the current session

The difference from /clear: compact preserves session continuity, clear starts from scratch.

`.claudeignore`: Excluding Noise

node_modules/
.next/
dist/
*.lock
coverage/

Without this file, Claude may read thousands of irrelevant files during a global search, consuming context unnecessarily.

Efficient Prompt Rules

Target, don’t load:

“Check the login function in auth.ts:45-60” rather than “Check auth.ts for issues”
Reference symbols (calculateTotal) rather than entire files
Avoid pasting large JSON blobs or raw logs into the prompt

What consumes the most:

Action	Estimated tokens
Reading a large file (2000 lines)	~5K+
MCP call (Serena, Context7)	~2K per call
Long conversation without /compact	Accumulation
Tests with full unfiltered output	3K-10K

Combined Strategy

RTK reduces the cost of bash commands (preventive). /compact frees up context mid-session (curative). .claudeignore avoids unnecessary reads (structural). These three levers are complementary and apply in parallel.