Anthropic Bedrock request fails because SDK sends deprecated temperature parameter for Opus models

[mikhailmokhov]

When using Copilot SDK with Anthropic provider via Bedrock Mantle, Opus 4.7 and 4.8 inference fails with HTTP 400 because the upstream API rejects temperature for this model.

Error:
400 invalid_request_error: temperature is deprecated for this model.

Environment:

• @github/copilot-sdk: 1.0.0 (also seen previously on 1.0.0-beta.12)
• Runtime: Node.js on macOS
• Provider: Anthropic via Bedrock Mantle
• Model: anthropic.claude-opus-4-7/anthropic.claude-opus-4-8

Code to replicate:

import { CopilotClient, approveAll } from "@github/copilot-sdk";

const client = new CopilotClient();

await client.start();
const session = await client.createSession({
  onPermissionRequest: approveAll,
  provider: {
    type: "anthropic",
    baseUrl: `https://bedrock-mantle.${process.env.AWS_REGION}.api.aws/anthropic`,
    apiKey: process.env.BEDROCK_API_KEY,
    modelId: "anthropic.claude-opus-4-7", // Or "anthropic.claude-opus-4-8"
  },
});

const response = await session.sendAndWait({
  prompt: "List tools and skills.",
});

console.log(response);

await session.disconnect();

[github-actions]

Investigation Findings

Label applied: bug

What I investigated

• nodejs/src/types.ts — the ProviderConfig interface and how it's defined in the SDK
• nodejs/src/generated/rpc.ts — the JSON-RPC layer, specifically the provider field in session creation params (line ~8262)
• All source files for any temperature usage

What I found

The SDK itself does not set or send a temperature parameter — the SDK's ProviderConfig has no temperature field, and searching the entire codebase confirms temperature only appears in unrelated code comments/examples.

The provider config object is passed opaquely via JSON-RPC to the Copilot CLI runtime (the server-side component), which is responsible for constructing and sending the actual upstream API requests. The temperature value is injected by the runtime, not by the SDK client.

The bug is in the CLI runtime: it sends temperature in requests to Anthropic models claude-opus-4-7 and claude-opus-4-8 that have deprecated this parameter, causing the upstream API to return:

400 invalid_request_error: temperature is deprecated for this model.

Why it's a bug

The runtime should detect that the target model does not accept temperature and omit it. There is currently no workaround available at the SDK level — ProviderConfig exposes no way to suppress or override per-request inference parameters.

This needs to be fixed in the CLI runtime by adding model-specific logic to omit deprecated parameters when calling Anthropic Opus 4.7/4.8 (and any future models with similar constraints).

Generated by Bug Handler for issue #1557 · ● 3.2M · ◷

[roji]

Bedrock breaking change docs; though this isn't Bedrock-specific; from the Anthropic breaking changes docs:

Sampling parameters removed: Setting temperature, top_p, or top_k to any non-default value on Claude Opus 4.7 returns a 400 error. The safest migration path is to omit these parameters entirely from request payloads. Prompting is the recommended way to guide model behavior on Claude Opus 4.7. If you were using temperature = 0 for determinism, note that it never guaranteed identical outputs on prior models.