Follow Discord
Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeReleasesv2.1.237entry #7

Claude Code v2.1.237 ·

System prompt caching now requires a recognised endpoint

If you point Claude at a proxy or custom gateway, the system prompt is no longer cached.

You'll notice Notable Improvements
JSON All of v2.1.237
You'll noticeTier: how much it should matter to you
4Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Prompt CachingArea: what it touches
ImprovementsKind: in v2.1.237,
What probably matters to youSection of the release
What

The check deciding whether the system prompt block may be marked cacheable used to only require that experimental betas were not disabled. It now also requires a known provider and endpoint: Bedrock, Vertex and Mantle qualify only when ANTHROPIC_BEDROCK_BASE_URL, ANTHROPIC_VERTEX_BASE_URL and ANTHROPIC_BEDROCK_MANTLE_BASE_URL are unset, and Foundry only when ANTHROPIC_FOUNDRY_BASE_URL is unset or its hostname ends in .services.ai.azure.com. Behind a proxy or custom gateway, the system block stops being cached.

Details
  • First-party and Anthropic-on-AWS paths still have to pass the existing beta and base-URL checks.
  • No feature flag; the outcome is decided entirely by the provider and those environment variables, and it is live for everyone on this build.
Evidence

.services.ai.azure.com

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Names in the bundleANTHROPIC_BEDROCK_BASE_URLANTHROPIC_VERTEX_BASE_URLANTHROPIC_BEDROCK_MANTLE_BASE_URLANTHROPIC_FOUNDRY_BASE_URL
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up ANTHROPIC_VERTEX_BASE_URL, on Claude Code gateway compatibility guide. * **Amazon Bedrock or Agent Platform format**: the developer sets `CLAUDE_CODE_USE_BEDROCK=1` with `ANTHROPIC_BEDROCK_BASE_URL`, or `CLAUDE_CODE_USE_VERTEX=1` with `ANTHROPIC_VERTEX_BASE_URL`, pointing at your gateway. Claude Code uses tha… llm-gateway-protocol see the edit
Confirmed since Anthropic's documentation has since written up ANTHROPIC_BEDROCK_BASE_URL, on Claude Code gateway compatibility guide. * **Amazon Bedrock or Agent Platform format**: the developer sets `CLAUDE_CODE_USE_BEDROCK=1` with `ANTHROPIC_BEDROCK_BASE_URL`, or `CLAUDE_CODE_USE_VERTEX=1` with `ANTHROPIC_VERTEX_BASE_URL`, pointing at your gateway. Claude Code uses tha… llm-gateway-protocol see the edit
Confirmed since Anthropic's documentation has since written up ANTHROPIC_FOUNDRY_BASE_URL, on Deploy Claude Desktop on 3P with Microsoft Foundry. To send Microsoft Foundry traffic through a gateway or proxy you operate, such as Azure API Management in front of the resource, set `inferenceFoundryBaseUrl` (**Azure AI Foundry base URL**) to the gateway's base URL including any path, fo… third-party/claude-desktop/foundry see the edit
Confirmed since Anthropic's documentation has since written up ANTHROPIC_BEDROCK_MANTLE_BASE_URL, on Claude Code on Amazon Bedrock. Claude Code constructs the endpoint URL from the AWS region, resolved with the same precedence as [Amazon Bedrock above](#3-configure-claude-code). To override the URL for a custom endpoint or gateway, set `ANTHROPIC_BEDROCK_MANTLE_BASE_UR… amazon-bedrock see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up ANTHROPIC_BEDROCK_MANTLE_BASE_URL, on Claude Code on Amazon Bedrock.

See this entry in the whole of v2.1.237 →

Feedback