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DeepSeek prefix cache hit rate drop - CC Switch fix

Quick fix

Upgrade to cc-switch v3.16.3 to fix cache hit rate calculation errors caused by format conversion.

Symptom

Section titled “Symptom”
Error output
缓存命中率在低于 50%
English translation

Cache hit rate drops to below 50%

Cause

Section titled “Cause”

When using vendors like OpenCode Go, the CC Switch format conversion path (e.g., OpenAI→Anthropic) has a bug that causes cached tokens to be counted repeatedly in statistics, resulting in a significantly lower displayed cache hit rate (dropping from normal 90%+ to below 50%). This is a statistical false positive, not actual request failure.

Additionally, some users reported that when routing through CC Switch, request transformations such as Anthropic System Message Normalization and JSON Payload Canonicalization changed the request prefixes sent to DeepSeek, causing DeepSeek's automatic cache based on exact prefix matching to fail, actually decreasing hit rates. However, for this specific severe deviation issue of "hit rate displaying below 50%", it was confirmed as a statistical bug and fixed in v3.16.3.

Fix

Section titled “Fix”

  1. Update cc-switch to the latest version (at least v3.16.3), which has fixed the issue of duplicate counting of cached tokens.

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version3.16.2
PlatformsmacOSWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 2 real issues

FAQ

Section titled “FAQ”
Did the hit rate normalize after updating to v3.16.3?
Yes, according to feedback in issue #4243, the DeepSeek v4pro cache hit rate for OpenCode Go has returned to normal levels after updating to v3.16.3.
Why was the hit rate previously below 50%?
This was because cached tokens were counted repeatedly in the statistics on the format conversion path, halving the hit rate data. This is not an issue with the model service itself, but an internal statistical logic error in cc-switch.
Section titled “Related problems”
api failed deserialize json body intoDepending on the error: roll Claude Code back, upgrade cc-switch, turn the local proxy off, or stop sending unsupported fields.7 issues mergedRequest body format invalid error - Claude CodeUpgrade cc-switch and enable the Rectifier, or add MAX_THINKING_TOKENS=0, for compatibility with third-party API formats.4 issues mergedANTHROPIC_AUTH_TOKEN and ANTHROPIC_API_KEYOpen `~/.claude/settings.json`, delete the duplicate auth variable so only the one your provider needs remains, save, and restart Claude Code.4 issues merged

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