llama-server sends thinking/reasoning tokens as "reasoning_content"
in the SSE delta (separate from "content"). The studio was only
reading delta.content, so all reasoning tokens from models like
Qwen3.5, Qwen3-Thinking, DeepSeek-R1, etc. were silently dropped.
This caused "replies with nothing" for thinking models: the model
would spend its entire token budget on reasoning, produce zero
content tokens, and the user would see an empty response.
Fix: read reasoning_content from the delta and wrap it in
<think>...</think> tags. The frontend already has full support
for these tags (parse-assistant-content.ts splits them into
reasoning parts, reasoning.tsx renders a collapsible "Thinking..."
indicator).
Verified with Qwen3.5-27B-GGUF (UD-Q4_K_XL):
- Before: "What is 2+2?" -> empty response (all tokens in reasoning)
- After: shows collapsible thinking + answer "4"
961720c1b1