Claude Warmline — Security skill for Claude Code

claude-warmline

**English** | [日本語](README.ja.md) | [繁體中文](README.zh-TW.md) | [简体中文](README.zh-CN.md)

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**Warmline makes Claude Code's prompt-cache state visible.**

Claude Code can silently go cold

A working session carries tens or hundreds of thousands of tokens — system prompt, tools, every file it read, every reply — and Claude Code re-sends all of it on every turn. While the prompt cache holds, that context is *read back* at roughly **0.1×** the normal input price. When the cache goes cold, the same context is processed again at about **2×**. It goes cold after about an hour of inactivity, and instantly whenever the start of the conversation is rewritten — `/compact` and auto-compaction both do that. Come back to a big session after lunch and your next message pays the rebuild on all of it, at exactly the moment you wanted results, and nothing in the session tells you so.

**Warmline puts the cache state directly in your statusline, and gives you the tools to see what it has been doing historically.**

Opus 5 | claude-warmline | ctx 64% (127k) | cache HOT (127k, cold ~11:58) | 5h 78%

No guessing, and no timing-based inference. Since v2.1.251 Claude Code hands the statusline its own `prompt_cache` object — whether the prefix is warm, which TTL it is on, the second it expires — and warmline prints what that object says.

Then, for everything before this turn:

warmline audit

grades every recorded API turn of a session from the usage Claude Code wrote for it, and `--all` ranks every session on this machine.

![The warml