feat(astro-orbiter): bump Qwen3.8-27B ctx-size 32768->131072 (128K) [t_441470b9]

ansible/host_vars/astro-orbiter/vars.yml

@@ -34,14 +34,14 @@ common_root_lv: ubuntu-lv
 # (t_33acbb2e) so the router can keep more than one GGUF resident on-demand
 # and LRU-evict when needed.
 #
-# VRAM NOTE (t_33acbb2e, updated t_55c164f5, updated t_34b96e83, updated t_f5f7e9ad):
+# VRAM NOTE (t_33acbb2e, updated t_55c164f5, updated t_34b96e83, updated t_f5f7e9ad, updated t_441470b9):
 # With models-max=4 and all 5 GGUFs registered, worst case is all 5 loaded simultaneously:
-#   Qwen3.8-27B Q4_K_M:               ~23.1GB (weights ~17.1GB + KV ~6GB @ 64K ctx, q4_0)
+#   Qwen3.8-27B Q4_K_M:               ~23.3GB (weights ~17.1GB + KV ~6.2GB @ 128K ctx, q4_0) ← UPDATED
 #   Phi-3.5-mini-instruct Q8_0:       ~4.3GB  (weights ~3.8GB + KV ~0.5GB @ 32K ctx)
 #   Meta-Llama-3.1-8B Q4_K_M:        ~5.6GB  (weights ~4.6GB + KV ~0.2GB @ 8K ctx)
 #   Qwen2.5-Coder-14B Q4_K_M:        ~9.0GB  (weights ~8.4GB + KV ~0.6GB @ 16K ctx)
 #   nomic-embed-text-v1.5 Q4_K_M:    ~0.09GB (~84MB, embedding only — no KV cache)
-#   Total worst-case:                 ~42.1GB  >>  24GB RTX 3090
+#   Total worst-case:                 ~42.3GB  >>  24GB RTX 3090
 #
 # OOM RISK: Full co-residency is impossible on 24GB. LRU eviction prevents this
 # in practice: models-max=4 means the router can REGISTER 5 models but only keeps
@@ -65,6 +65,9 @@ common_root_lv: ubuntu-lv
 # auxiliary models evict it on demand, and vice versa).
 # NOTE: Qwen3.8 does NOT have load-on-startup — it loads on first request.
 # This avoids an LRU eviction race with nomic-embed at startup.
+# UPDATED (t_441470b9, 2026-08-16): ctx bumped to 131072 (128K). Measured
+# VRAM: 20,282 MiB at 131072 ctx. nomic-embed 558 MiB always resident ->
+# ~20.8GB total, ~3.2GB headroom. models-max=2 unchanged (same constraint).
 llm_router_models_max: 2
 
 llm_staged_models: