fix(bedrock): omit temperature for Claude Opus 4.7+ when thinking is off

[kimnamu]

Thank you 🙏

Thanks so much for Copilot and the Amazon Bedrock provider — it's been great to use with Claude on AWS. This is a small fix for the latest Opus models.

Fixes #2600

Problem

With the Bedrock provider, chatting with Claude Opus 4.7 / 4.8 fails for every message when the model's REASONING capability is off (the default):

Amazon Bedrock streaming request failed with status 400:
{"message":"`temperature` is deprecated for this model."}

Opus 4.6 and earlier, Sonnet (4 / 4.5 / 4.6), and Haiku 4.5 are unaffected.

Root cause

Opus 4.7+ no longer accepts the temperature parameter at all — Bedrock rejects any value, including the default. In BedrockChatModel.buildRequestBody(), the thinking-disabled branch always attached the resolved temperature:

} else {
  // Only set temperature if thinking is NOT enabled
  if (resolvedTemperature !== undefined) {
    payload.temperature = resolvedTemperature;
  }
}

The thinking-enabled path already special-cases Opus 4.7+ (adaptive thinking) and pins temperature: 1, which Opus 4.7+ accepts alongside adaptive thinking — so the model only worked when reasoning was turned on. With reasoning off, it always 400s.

Change

• Extract the existing Opus 4.7+ detection (previously inline in the thinking branch) into a small isOpus47OrNewer() helper, and reuse it.
• In the thinking-disabled path, omit temperature for Opus 4.7+. Every other model keeps its current behavior, and the thinking-enabled path is untouched.

The diff is intentionally minimal — no behavior change for any model other than Opus 4.7+ with thinking off.

Before / After (live Bedrock, Opus 4.8, reasoning off)

Same prompt (“What is the capital of France?”), same model (us.anthropic.claude-opus-4-8), reasoning off — built this branch and loaded it into Obsidian.

Before (current master)	After (this PR)
❌ 400 \temperature` is deprecated for this model.`	✅ The capital of France is Paris. (no console errors)

Behavior across the rest of the lineup is unchanged:

Model	Before	After
Opus 4.8 / 4.7	❌ 400	✅ replies normally
Sonnet 4.6 / Haiku 4.5	✅ works	✅ works (unchanged)
Opus 4.6 and earlier	✅ works	✅ works (unchanged)

I also confirmed the deprecation boundary directly against the Bedrock runtime API (only temperature differs between requests):

Request to us.anthropic.claude-opus-4-8	Result
temperature: 0.1	❌ 400 \temperature` is deprecated for this model.`
temperature omitted	✅ 200
temperature: 1 + thinking: adaptive	✅ 200

Tests

Added a temperature handling for Opus 4.7+ suite covering Opus 4.7/4.8 (bare + cross-region), Opus 4.6 and earlier, Sonnet/Haiku, the dated Opus 4.0 snapshot ID (claude-opus-4-20250514, which must not be treated as 4.7+), and the thinking-enabled case (still pins temperature: 1).

The new tests fail on master (they catch the bug) and pass with this fix:

Before (fix reverted, new tests run against current master logic):

✕ omits temperature for opus-4-7 when thinking is disabled
    expect(received).toBeUndefined()
    Received: 0.1
✕ omits temperature for opus-4-8 when thinking is disabled
    Received: 0.1
✕ omits temperature for opus-4-7 cross-region inference profiles
    Received: 0.7
✓ still sends temperature for opus-4-6 and earlier
✓ still sends temperature for sonnet-4-5 and haiku
✓ still sends temperature for dated Opus 4.0 snapshot IDs
Tests: 3 failed, 4 passed

After (this PR):

✓ omits temperature for opus-4-7 when thinking is disabled
✓ omits temperature for opus-4-8 when thinking is disabled
✓ omits temperature for opus-4-7 cross-region inference profiles
✓ still sends temperature for opus-4-6 and earlier
✓ still sends temperature for sonnet-4-5 and haiku
✓ still sends temperature for dated Opus 4.0 snapshot IDs
✓ forces temperature to 1 for opus-4-8 when thinking is enabled
Tests: 7 passed

• npm test → all suites pass (added 7 tests).
• npm run format / npm run lint → clean.
• npm run build → type-check + bundle succeed.

Checklist

• Code style consistent with the existing file (reuses the existing detection regex/comment style)
• Tested changes (unit tests + manual chat against live Bedrock)
• Linked to the issue (Bedrock: Claude Opus 4.7+ chat fails with 400 temperature is deprecated when reasoning is off #2600)
• Minimal, focused diff

[kimnamu]

Hi @logancyang, thank you again for maintaining Copilot and for taking the time to look at this. 🙏

I noticed the build (22.x) workflow hasn't run yet — I believe that's because this is my first contribution from a fork, so GitHub Actions needs a maintainer's approval to run. Whenever you have a moment, would you mind approving the workflow run? No rush at all, and I completely understand if you'd like to review the diff first.

For what it's worth, I ran the full checks locally and they pass:

• npm test → all suites pass (added 7 regression tests for the Opus 4.7+ temperature handling)
• npm run format and npm run lint → clean
• npm run build → type-check + bundle succeed

I also loaded the build into Obsidian and confirmed the fix end-to-end against live Bedrock: chatting with us.anthropic.claude-opus-4-8 (reasoning off) returned a normal reply, where it previously failed with 400 \temperature` is deprecated for this model.`

Happy to make any changes you'd like — thanks so much for your time and for considering this!