fix(vision-handoff): omit temperature on vision transcription call (Kimi rejects temperature: 0)

The vision handoff hardcoded temperature: 0 for the transcription sub-call,
but the Moonshot/Kimi vision model only allows temperature: 1 (or omitted),
causing an HTTP 400 "invalid temperature: only 1 is allowed for this model"
that blocked the entire image analysis for non-vision models like GLM 5.2.

Fix: omit temperature entirely so each vision provider uses its own default —
the truly universal, provider-agnostic approach (different providers have
different temperature constraints).

1 files changed, 5 insertions, 2 deletions

diff --git a/packages/vision-handoff/src/service.ts b/packages/vision-handoff/src/service.ts
index 5e6ad70..3f8462a 100644
--- a/packages/vision-handoff/src/service.ts
+++ b/packages/vision-handoff/src/service.ts
@@ -167,8 +167,11 @@ export function createVisionHandoffService(deps: VisionHandoffDeps): VisionHando
     };
     const providerOpts: ProviderStreamOptions = {
       model: vision.model,
-      // Low temperature for faithful transcription.
-      temperature: 0,
+      // NOTE: temperature is deliberately OMITTED. Different vision providers
+      // have different constraints (e.g. Moonshot/Kimi only allows temperature:
+      // 1; others allow 0–2). Hardcoding any value risks an HTTP 400 from a
+      // provider that rejects it. Omitting lets each provider use its own
+      // default — the truly universal, provider-agnostic choice.
       // A short system prompt keeps the vision model focused on describing.
       systemPrompt:
         "You are a vision assistant. Describe images faithfully and thoroughly for a developer who cannot see them.",