fix(opencode): use api.npm to detect Anthropic SDK for cache control

[llc1123]

Issue for this PR

Closes#14642

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The applyCaching function incorrectly used model.providerID === "anthropic" to detect Anthropic SDK models. This fails for non-Claude models (e.g. kimi-k2.5) that use @ai-sdk/anthropic but have a different providerID.

Changed detection to use model.api.npm:

constisAnthropicSdk=model.api.npm==="@ai-sdk/anthropic"||model.api.npm==="@ai-sdk/google-vertex/anthropic"constuseMessageLevelOptions=isAnthropicSdk||model.providerID.includes("bedrock")

How did you verify your code works?

• Typecheck passes (bun turbo typecheck)
• 104 tests pass (including new test for kimi-k2.5 scenario)

Screenshots / recordings

N/A — no UI changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[Copilot]

Pull request overview

This PR fixes a bug in cache control detection for models using the Anthropic SDK. The applyCaching function previously used model.providerID === "anthropic" to determine whether to apply message-level cache control, which failed for non-Claude models (like kimi-k2.5) that use @ai-sdk/anthropic but have a different providerID. The fix changes the detection to use model.api.npm instead, correctly identifying Anthropic SDK usage regardless of the model's providerID.

Changes:

• Updated applyCaching to detect Anthropic SDK via model.api.npm (checking for @ai-sdk/anthropic or @ai-sdk/google-vertex/anthropic)
• Added test case validating that non-Claude models using @ai-sdk/anthropic correctly receive message-level cache control

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/opencode/src/provider/transform.ts	Fixed Anthropic SDK detection in applyCaching function to use model.api.npm instead of model.providerID
packages/opencode/test/provider/transform.test.ts	Added test case for kimi-k2.5 model using Anthropic SDK to verify message-level cache control

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.