From 4c612127e0153b327e18fd367263485ede8a70b2 Mon Sep 17 00:00:00 2001
From: Roland Tannous <rolandtannous@gravityq.ai>
Date: Thu, 14 May 2026 11:18:44 +0400
Subject: [PATCH] studio/chat: force reasoningEnabled=true on local
 reasoning-effort models
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Followup to PR 5402 / 5412. The model-status refresh path in
use-chat-model-runtime carried reasoningEnabled forward verbatim for
every reasoning-capable model. That left one observable edge case:

  1. user picks an external model that supports Off (gpt-5.x, Claude
     4.x), clicks Off — store sets reasoningEnabled=false
  2. user switches back to a local reasoning-effort model
     (gpt-oss / Harmony-style) which does NOT support Off
  3. composer's effectiveReasoningEnabled override paints the UI as
     'Think: <level>' (on)
  4. chat-adapter sees reasoningEnabled=false on the local branch
     and sends '{}', so the backend's _request_reasoning_kwargs
     returns None and the Harmony template falls back to its own
     default effort instead of the displayed level

Mirror the composer's override in the store on load: for local
reasoning-effort models (where supportsReasoningOff is false), force
reasoningEnabled=true so the store and the UI agree on every send.
Other reasoning styles still inherit prior state — only the
reasoning-effort family changes.
---
 .../chat/hooks/use-chat-model-runtime.ts         | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts b/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
index 653d17d06e..3e0ead88d3 100644
--- a/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
+++ b/studio/frontend/src/features/chat/hooks/use-chat-model-runtime.ts
@@ -297,10 +297,20 @@ export function useChatModelRuntime() {
           reasoningEffort: clampedReasoningEffort,
           supportsPreserveThinking,
           supportsTools,
-          // Reset per-turn reasoning flag so models that do not support
-          // reasoning do not inherit a stale off state from a prior model.
+          // Reset per-turn reasoning flag so:
+          //   1. models that do not support reasoning do not inherit a stale
+          //      off state from a prior model, and
+          //   2. local reasoning-effort models (where the composer hides
+          //      the Off option via supportsReasoningOff=false) cannot end
+          //      up with reasoningEnabled=false carried over from an
+          //      external model where Off was selected — the composer would
+          //      keep showing "Think: <level>" via effectiveReasoningEnabled,
+          //      but the chat-adapter would omit the kwarg and the Harmony
+          //      template would fall back to its own default effort.
           reasoningEnabled: supportsReasoning
-            ? useChatRuntimeStore.getState().reasoningEnabled
+            ? reasoningStyle === "reasoning_effort"
+              ? true
+              : useChatRuntimeStore.getState().reasoningEnabled
             : true,
           ggufContextLength: currentGgufContextLength,
           ggufMaxContextLength,