fix(kimi-coding): disable reasoning for Roo Code-based clients

[kilo-code-bot]

Summary

• The old Roo-based Kilo Code client does not preserve reasoning correctly, so for requests coming from that client we now force Kimi Code's `thinking.type` to `disabled`.
• Thread `originalHeaders` through `TransformRequestContext` so providers can key behavior off the originating client's headers.

Verification

• Inspected the kimi-coding transform output locally: `thinking.type` is `disabled` when the incoming user-agent begins with `Kilo-Code/`, and `enabled` otherwise (unless reasoning is explicitly disabled in the request).

Visual Changes

N/A

Reviewer Notes

• The new `originalHeaders` field on `TransformRequestContext` is non-optional; all call sites of `applyProviderSpecificLogic` and `provider.transformRequest` have been updated.
• Behavior for other BYOK providers (zai-coding, byteplus-coding, neurowatt) is unchanged.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• apps/web/src/app/api/openrouter/[...path]/route.ts
• apps/web/src/lib/ai-gateway/providers/direct-byok/kimi-coding.ts
• apps/web/src/lib/ai-gateway/providers/index.ts
• apps/web/src/lib/ai-gateway/providers/types.ts

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_{Reviewed by gpt-5.5-2026-04-23 · 609,024 tokens}