[BUG] prompt-caching-scope-2026-01-05 beta header sent even when enablePromptCaching and useAnthropicBetaHeaders are set to false
Preflight Checklist
- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code
What's Wrong?
Actual Behavior
The extension sends anthropic-beta: prompt-caching-scope-2026-01-05 header regardless of the user's settings, causing API failures with endpoints that do not support this beta feature.
What Should Happen?
Expected Behavior
When claudeCode.enablePromptCaching is set to false AND claudeCode.useAnthropicBetaHeaders is set to false, the extension should NOT send any anthropic-beta headers in API requests, including prompt-caching-scope-2026-01-05.
Error Messages/Logs
API Error: 400 {"error":{"message":"{"type":"error","error":{"type":"invalid_request_error","message":"Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header. Please consult our documentation at docs.anthropic.com or try again without the header."},"request_id":"req_vrtx_011CXbNF4WfFyNXrw5Cb2k4q"}. Received Model Group=claude-4.5-opus\nAvailable Model Group Fallbacks=None","type":"None","param":"None","code":"400"}}Steps to Reproduce
Steps to Reproduce
Install Claude Code extension v2.1.23 in VS Code
Configure settings.json with:
"claudeCode.enablePromptCaching": false
"claudeCode.useAnthropicBetaHeaders": false
Configure a custom API endpoint via ANTHROPIC_BASE_URL environment variable that does not support the prompt-caching-scope-2026-01-05 beta header
Select model claude-4.5-opus
Start a conversation with Claude Code
Result: API returns 400 error indicating unexpected beta header value
Claude Model
Opus
Is this a regression?
Yes, this worked in a previous version
Last Working Version
_No response_
Claude Code Version
2.1.23
Platform
Anthropic API
Operating System
macOS
Terminal/Shell
Other
Additional Information
<h2 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Bug Report: Prompt Caching Beta Header Sent Despite Settings Disabled</h2><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><strong>Title:</strong> <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">prompt-caching-scope-2026-01-05</code> beta header sent even when <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">enablePromptCaching</code> and <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">useAnthropicBetaHeaders</code> are set to false</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Environment</h3>
Component | Version
-- | --
OS | macOS 15.7.2 (Build 24G325)
Claude Code Extension | 2.1.23 (anthropic.claude-code-2.1.23-darwin-x64)
VS Code | (current stable)
Architecture | darwin-x64
<hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Description</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The Claude Code VS Code extension sends the <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">anthropic-beta: prompt-caching-scope-2026-01-05</code> header in API requests even when both prompt caching settings are explicitly disabled in user settings. This causes API errors when using proxy endpoints that do not support this beta header.</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Error Message</h3><div class="Z" style="position: relative; margin: 8px 0px; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><button class="Q Vo" title="Copy code" aria-label="Copy code to clipboard" style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; padding: 4px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(31, 31, 31); border-color: rgb(69, 69, 69); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; border-radius: 4px; cursor: pointer; opacity: 0; transition: opacity 0.15s, background 0.15s; display: flex; align-items: center; justify-content: center; position: absolute; top: 4px; right: 4px;"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" fill="currentColor" aria-hidden="true" data-slot="icon" class="hi"><path fill-rule="evenodd" d="M15.988 3.012A2.25 2.25 0 0 1 18 5.25v6.5A2.25 2.25 0 0 1 15.75 14H13.5v-3.379a3 3 0 0 0-.879-2.121l-3.12-3.121a3 3 0 0 0-1.402-.791 2.252 2.252 0 0 1 1.913-1.576A2.25 2.25 0 0 1 12.25 1h1.5a2.25 2.25 0 0 1 2.238 2.012ZM11.5 3.25a.75.75 0 0 1 .75-.75h1.5a.75.75 0 0 1 .75.75v.25h-3v-.25Z" clip-rule="evenodd"></path><path d="M3.5 6A1.5 1.5 0 0 0 2 7.5v9A1.5 1.5 0 0 0 3.5 18h7a1.5 1.5 0 0 0 1.5-1.5v-5.879a1.5 1.5 0 0 0-.44-1.06L8.44 6.439A1.5 1.5 0 0 0 7.378 6H3.5Z"></path></svg></button><pre style="overflow-x: auto; max-width: 100%; white-space: pre; padding: 8px; border-radius: 4px; margin: 0px; box-sizing: border-box;"><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 0px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">API Error: 400 {"error":{"message":"{"type":"error","error":{"type":"invalid_request_error","message":"Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header. Please consult our documentation at docs.anthropic.com or try again without the header."},"request_id":"req_vrtx_011CXbNF4WfFyNXrw5Cb2k4q"}. Received Model Group=claude-4.5-opus\nAvailable Model Group Fallbacks=None","type":"None","param":"None","code":"400"}}
</code></pre></div><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">User Settings (settings.json)</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The following settings are configured to explicitly disable prompt caching and beta headers:</p><div class="Z" style="position: relative; margin: 8px 0px; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><button class="Q Vo" title="Copy code" aria-label="Copy code to clipboard" style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; padding: 4px; background: none 0% 0% / auto repeat scroll padding-box border-box rgb(31, 31, 31); border-color: rgb(69, 69, 69); border-style: solid; border-width: 1px; border-image: none 100% / 1 / 0 stretch; border-radius: 4px; cursor: pointer; opacity: 0; transition: opacity 0.15s, background 0.15s; display: flex; align-items: center; justify-content: center; position: absolute; top: 4px; right: 4px;"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20" fill="currentColor" aria-hidden="true" data-slot="icon" class="hi"><path fill-rule="evenodd" d="M15.988 3.012A2.25 2.25 0 0 1 18 5.25v6.5A2.25 2.25 0 0 1 15.75 14H13.5v-3.379a3 3 0 0 0-.879-2.121l-3.12-3.121a3 3 0 0 0-1.402-.791 2.252 2.252 0 0 1 1.913-1.576A2.25 2.25 0 0 1 12.25 1h1.5a2.25 2.25 0 0 1 2.238 2.012ZM11.5 3.25a.75.75 0 0 1 .75-.75h1.5a.75.75 0 0 1 .75.75v.25h-3v-.25Z" clip-rule="evenodd"></path><path d="M3.5 6A1.5 1.5 0 0 0 2 7.5v9A1.5 1.5 0 0 0 3.5 18h7a1.5 1.5 0 0 0 1.5-1.5v-5.879a1.5 1.5 0 0 0-.44-1.06L8.44 6.439A1.5 1.5 0 0 0 7.378 6H3.5Z"></path></svg></button><pre style="overflow-x: auto; max-width: 100%; white-space: pre; padding: 8px; border-radius: 4px; margin: 0px; box-sizing: border-box;"><code class="language-json" style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 0px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">{
"claudeCode.selectedModel": "claude-4.5-opus",
"claudeCode.enablePromptCaching": false,
"claudeCode.useAnthropicBetaHeaders": false,
"claudeCode.preferredLocation": "panel",
"claudeCode.initialPermissionMode": "bypassPermissions",
"claudeCode.allowDangerouslySkipPermissions": true,
"claudeCode.environmentVariables": [
{
"name": "ANTHROPIC_BASE_URL",
"value": "xxxxx"
},
{
"name": "ANTHROPIC_AUTH_TOKEN",
"value": "<REDACTED>"
},
{
"name": "ANTHROPIC_MODEL",
"value": "claude-4.5-opus"
},
{
"name": "ANTHROPIC_SMALL_FAST_MODEL",
"value": "claude-4.5-haiku"
}
]
}
</code></pre></div><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Steps to Reproduce</h3><ol style="padding-inline-start: 1.5em; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li>Install Claude Code extension v2.1.23 in VS Code</li><li>Configure<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">settings.json</code><span> </span>with:<ul style="padding-inline-start: 1.5em;"><li><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">"claudeCode.enablePromptCaching": false</code></li><li><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">"claudeCode.useAnthropicBetaHeaders": false</code></li></ul></li><li>Configure a custom API endpoint via<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">ANTHROPIC_BASE_URL</code><span> </span>environment variable that does not support the<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">prompt-caching-scope-2026-01-05</code><span> </span>beta header</li><li>Select model<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">claude-4.5-opus</code></li><li>Start a conversation with Claude Code</li><li><strong>Result:</strong><span> </span>API returns 400 error indicating unexpected beta header value</li></ol><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Expected Behavior</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">When <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">claudeCode.enablePromptCaching</code> is set to <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">false</code> AND <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">claudeCode.useAnthropicBetaHeaders</code> is set to <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">false</code>, the extension should NOT send any <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">anthropic-beta</code> headers in API requests, including <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">prompt-caching-scope-2026-01-05</code>.</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Actual Behavior</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The extension sends <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">anthropic-beta: prompt-caching-scope-2026-01-05</code> header regardless of the user's settings, causing API failures with endpoints that do not support this beta feature.</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Investigation Performed</h3><ol style="padding-inline-start: 1.5em; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li><strong>Verified no workspace-level settings override:</strong><span> </span>No<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">.vscode/settings.json</code><span> </span>exists in the workspace</li><li><strong>Checked extension globalStorage:</strong><span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">/Users/joergpeetz/Library/Application Support/Code/User/globalStorage/anthropics.claude-code/settings.json</code><span> </span>contains only MCP server configuration, no cached prompt caching settings</li><li><strong>Confirmed settings are correctly set:</strong><span> </span>Both<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">enablePromptCaching</code><span> </span>and<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">useAnthropicBetaHeaders</code><span> </span>are explicitly set to<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">false</code><span> </span>in user settings</li></ol><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Suspected Root Cause</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">The extension appears to hardcode the <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">prompt-caching-scope-2026-01-05</code> beta header for <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">claude-4.5-opus</code> model requests, ignoring the user's <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">enablePromptCaching</code> and <code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">useAnthropicBetaHeaders</code> settings.</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Impact</h3><ul style="padding-inline-start: 1.5em; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li>Users cannot use Claude Code with API proxies or custom endpoints that do not support the prompt caching beta header</li><li>The settings<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">enablePromptCaching</code><span> </span>and<span> </span><code style="font-family: monospace; color: rgb(208, 208, 208); background-color: rgb(60, 60, 60); padding: 2px 4px; border-radius: 3px; font-size: 0.9em; word-break: break-word;">useAnthropicBetaHeaders</code><span> </span>appear to have no effect, creating confusion about their purpose</li></ul><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Workaround</h3><p style="margin-top: 0.1em; margin-bottom: 0.2em; white-space: pre-wrap; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">None available. The only option is to use an API endpoint that supports the beta header or wait for a fix.</p><hr style="font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><h3 style="color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">Additional Context</h3><ul style="padding-inline-start: 1.5em; color: rgb(204, 204, 204); font-family: -apple-system, "system-ui", "Segoe UI", Roboto, sans-serif; font-size: 13px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; background-color: rgb(24, 24, 24); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;"><li>Issue occurs when running multiple VS Code windows accessing the same Claude Code extension</li><li>The custom endpoint is an enterprise API proxy that forwards requests to Anthropic's API but does not support beta headers</li></ul>``