feat(qwen36-vl): split thinking — non-thinking default + qwen3.6-35b-a3b-thinking variant

The qwen3.6-35b-a3b VL checkpoint is a single hybrid model with a per-
request enable_thinking switch (Qwen3-style), defaulting thinking ON.
Make the default non-thinking and add an opt-in reasoning variant,
mirroring the existing glm-5.1 / glm-5.1-reasoning gateway split.

- qwen36-vl compose: add --reasoning-parser qwen3 (model-matched) so the
  single :8007 endpoint splits <think> into reasoning_content when on and
  routes all output to content when off — serving both modes cleanly.
- litellm gateway: base qwen3.6-35b-a3b pins chat_template_kwargs
  enable_thinking=false (non-thinking default); new qwen3.6-35b-a3b-thinking
  pins enable_thinking=true (opt-in reasoning). Same upstream checkpoint,
  no extra VRAM/container.

Deployed + verified on ana-ml2 (vLLM recreated, healthy) and ana-docker
(litellm reloaded): default returns a direct answer with no reasoning_content;
-thinking returns cleanly-separated reasoning_content, no raw tag leak.

stacks/litellm/conf/config.yaml

@@ -33,12 +33,37 @@ model_list:
   # --- Qwen3.6-35B-A3B vision-language MoE (official FP8) — vision + chat. vLLM
   #     on ana-ml2 GPU 1, :8007. Explicit entry shadows the "*" wildcard llama-swap
   #     route. REPLACED qwen3.5-9b-fp8 2026-06-14 (the 9B is retired; this is a
-  #     35B-A3B MoE — served under its TRUE name, never aliased under the old one). ---
+  #     35B-A3B MoE — served under its TRUE name, never aliased under the old one).
+  #
+  #     THINKING SPLIT (2026-06-15, operator call — mirrors the glm-5.1 pattern
+  #     above). One hybrid checkpoint; the per-request `enable_thinking` switch
+  #     picks the mode. LiteLLM forwards extra_body verbatim to vLLM, where
+  #     chat_template_kwargs lands in the chat template. vLLM runs
+  #     --reasoning-parser qwen3 so reasoning surfaces as reasoning_content. ---
+  # qwen3.6-35b-a3b: thinking DISABLED by default. The checkpoint defaults
+  #   thinking ON; enable_thinking=false forces the empty <think></think> block.
+  #   Reasoning is opt-in via qwen3.6-35b-a3b-thinking below.
   - model_name: qwen3.6-35b-a3b
     litellm_params:
       model: hosted_vllm/qwen3.6-35b-a3b
       api_base: http://10.250.50.54:8007/v1
       api_key: os.environ/VLLM_API_KEY
+      extra_body:
+        chat_template_kwargs:
+          enable_thinking: false
+    model_info:
+      mode: chat
+  # qwen3.6-35b-a3b-thinking: identical upstream checkpoint, thinking ENABLED
+  #   (opt-in reasoning). The qwen3 reasoning-parser splits <think>…</think> into
+  #   reasoning_content; content holds just the answer.
+  - model_name: qwen3.6-35b-a3b-thinking
+    litellm_params:
+      model: hosted_vllm/qwen3.6-35b-a3b
+      api_base: http://10.250.50.54:8007/v1
+      api_key: os.environ/VLLM_API_KEY
+      extra_body:
+        chat_template_kwargs:
+          enable_thinking: true
     model_info:
       mode: chat
 

stacks/qwen36-vl/compose.yaml

@@ -27,6 +27,18 @@
 # cost. 0.42 (~40 GB) = weights + graph + generous KV. Granite drops to 0.25/64K
 # to make room (the FP8-vs-maxed-granite tradeoff, operator-approved 2026-06-14).
 #
+# THINKING TOGGLE: this is ONE hybrid checkpoint (not separate Instruct/Thinking
+# downloads) with a Qwen3-style per-request `enable_thinking` switch. The chat
+# template defaults thinking ON (`<think>\n`); passing
+# `chat_template_kwargs={"enable_thinking":false}` emits the empty
+# `<think>\n\n</think>\n\n` block (no reasoning). We run --reasoning-parser qwen3
+# (model-matched — its vLLM docstring describes THIS checkpoint) so ONE endpoint
+# serves BOTH modes cleanly: thinking-ON splits <think>…</think> into
+# reasoning_content; thinking-OFF routes everything to content. The gateway
+# selects the mode per model_name (stacks/litellm/conf/config.yaml):
+#   qwen3.6-35b-a3b          → enable_thinking:false  (non-thinking DEFAULT)
+#   qwen3.6-35b-a3b-thinking → enable_thinking:true   (opt-in reasoning)
+#
 # All tunables live in .env — edit that, not this file.
 
 name: qwen36-vl
@@ -72,6 +84,13 @@ services:
       - --dtype
       - auto
       - --enable-prefix-caching
+      # Model-matched reasoning parser for the hybrid thinking toggle (see header).
+      # Splits <think>…</think> into reasoning_content when thinking is ON; routes
+      # all output to content when the empty think-block signals thinking OFF — so
+      # this single :8007 endpoint serves both the non-thinking default and the
+      # qwen3.6-35b-a3b-thinking gateway variant.
+      - --reasoning-parser
+      - qwen3
     deploy:
       resources:
         reservations: