Long-Lived Session Hijacking

[borhen68]

If you starred TokenTamer waiting for the big feature — this is it.

What's New: Long-Lived Session Hijacking

We just shipped Anthropic prompt caching exploitation — the single most powerful cost-cutting feature in TokenTamer.

The Numbers

	Before	After
Cached input cost	—	$0.30 / Mtoken
Regular input cost	$3.00 / Mtoken	$3.00 / Mtoken
50-turn Claude Code session	~$5.00	~$0.50

Same model. Same reasoning. Same output. Just smarter billing.

How It Works

Claude Code (and most agents) re-send the entire conversation every turn. That means turn 50 sends messages 1-50 all over again. Expensive.

TokenTamer now injects cache_control breakpoints at three stable positions:

1. After the tools array (rarely changes)
2. After the system prompt (fixed for the session)
3. After the conversation prefix (everything except the last 2 turns)

Anthropic caches the prefix. You only pay for the new tail. On a long session, 80-90% of your input tokens become cached — and cached is 90% cheaper.

Verification

Run TokenTamer, use Claude Code, then check the response headers:

curl -I http://127.0.0.1:8000/v1/messages ...
# X-TokenTamer-Cache-Breakpoints: 3
# X-TokenTamer-Cache-Tokens: 12400