Claude Code /compact costs $0.06 with warm cache, $0.53 cold

Tests on Claude Code 2.1.289 with Opus 5.5 found that compacting a 136k-token session costs $0.056–0.059 with a warm prompt cache, $0.53–0.54 after the cache expires, and $0.30–0.32 right after reading files. /clear sent no API request in 13 of 13 runs.

• Compacting 136k tokens with a warm cache: $0.056–0.059, about two normal turns
• Same compaction after cache expiry: $0.53–0.54, roughly 9x more
• Compaction right after reading files: $0.30–0.32 at 85k tokens
• /clear sent no requests in 13 of 13 runs; first request after it was 15,303 tokens