feat(llm-router): switch to --models-preset mode; add Phi-3.5-mini-instruct-8bit alias (t_9adf0889)

- Add templates/llama-server-router-preset.ini.j2: defines all 3 router GGUFs
  (Qwen3.6-35B, Phi-3.5-mini-Q8_0, Meta-Llama-3.1-8B) with explicit ctx-size,
  gpu-layers, cache settings carried over from --models-dir baseline. The Phi
  entry adds alias=Phi-3.5-mini-instruct-8bit (Ryan's aux.title_generation target).

- Update templates/llama-server-router.service.j2: Jinja2 conditional emits
  --models-preset <path> when llm_router_preset_enabled=true, otherwise
  --models-dir (backward compat, default unchanged).

- Add tasks/preset.yml: deploy preset INI, restart router on change, verify
  both Phi-3.5-mini-instruct-Q8_0 (primary) and Phi-3.5-mini-instruct-8bit
  (alias) appear in /v1/models, plus Qwen and Llama IDs unchanged.

- Update defaults/main.yml: add llm_router_preset_enabled (default false) and
  llm_router_preset_path=/opt/llama-server-router-preset.ini.

- Update tasks/main.yml: import preset.yml as Phase P (gated, no-op by default).
- Update handlers/main.yml: add 'restart router' handler for preset changes.
- Add playbooks/day2_add_phi_alias.yml: single-command deployment.

GH #22364 note: --models-preset mode creates an extra 'default' entry in
/v1/models — cosmetic, does not affect model selection by name.

ansible/roles/llm-inference-multimodel/templates/llama-server-router-preset.ini.j2

@@ -0,0 +1,74 @@
+; ------------------------------------------------------------------------------
+; FILE: roles/llm-inference-multimodel/templates/llama-server-router-preset.ini.j2
+; DESCRIPTION: llama.cpp --models-preset INI for llama-server-router.
+;
+; Purpose: define all router-served GGUFs as named model entries so that:
+;   - Each model is explicitly named and configured (no auto-discovery surprises)
+;   - Aliases can be added per model (impossible with --models-dir alone)
+;   - The Phi-3.5-mini-instruct-Q8_0 entry carries the alias
+;     "Phi-3.5-mini-instruct-8bit" — Ryan's Hermes auxiliary.title_generation
+;     already references this friendlier name; both names resolve to the same
+;     GGUF child process.
+;
+; INI format notes (llama.cpp preset.md):
+;   - Section header (e.g. [Phi-3.5-mini-instruct-Q8_0]) is the primary model ID
+;     that appears in /v1/models and that clients send in the "model" field.
+;   - `alias` adds an ADDITIONAL name — both the section name and the alias work.
+;   - The `model` key is the absolute path to the GGUF file.
+;   - All other keys map directly to llama-server CLI flags (underscores or hyphens).
+;
+; Known upstream issues (Aug 2026):
+;   - GH #22364: --models-preset creates an extra "default" model entry in
+;     /v1/models. This is cosmetic — it has no functional effect on model
+;     selection by name. Document and move on.
+;   - GH #23460: can't pass per-model samplers via --models-preset in router
+;     mode. Non-issue: Hermes always sends sampling params in the request body.
+;
+; Added 2026-08-12 (t_9adf0889): Phi alias — War Machine.
+; All per-model settings carry over unchanged from the --models-dir baseline
+; (ctx_size=65536, n_gpu_layers=99, cache=q4_0 for both K and V, models-max=4).
+; ------------------------------------------------------------------------------
+
+; --- Production model: Qwen3.6-35B-A3B-UD-Q4_K_S ----------------------------
+; Primary model ID: Qwen3.6-35B-A3B-UD-Q4_K_S (unchanged from --models-dir)
+; ~20GB, primary Hermes production LLM. Context: 64K with q4_0 KV cache.
+[Qwen3.6-35B-A3B-UD-Q4_K_S]
+model        = {{ llm_models_dir }}/Qwen3.6-35B-A3B-UD-Q4_K_S.gguf
+n-gpu-layers = {{ llm_router_gpu_layers }}
+ctx-size     = {{ llm_router_ctx_size }}
+cache-type-k = {{ llm_router_cache_type_k }}
+cache-type-v = {{ llm_router_cache_type_v }}
+batch-size   = {{ llm_router_batch_size }}
+ubatch-size  = {{ llm_router_ubatch_size }}
+parallel     = {{ llm_router_parallel }}
+
+; --- Auxiliary model: Phi-3.5-mini-instruct-Q8_0 ----------------------------
+; Primary model ID: Phi-3.5-mini-instruct-Q8_0 (unchanged from --models-dir)
+; Alias:            Phi-3.5-mini-instruct-8bit (NEW — Ryan's config target)
+; Both names resolve to this GGUF child process.
+; ~3.8GB, auxiliary.title_generation consumer in Ryan's Hermes config.
+; The alias is what this entire task is about — once deployed, the
+; "Auxiliary title generation failed" warning will be gone.
+[Phi-3.5-mini-instruct-Q8_0]
+model        = {{ llm_models_dir }}/Phi-3.5-mini-instruct-Q8_0.gguf
+alias        = Phi-3.5-mini-instruct-8bit
+n-gpu-layers = {{ llm_router_gpu_layers }}
+ctx-size     = {{ llm_router_ctx_size }}
+cache-type-k = {{ llm_router_cache_type_k }}
+cache-type-v = {{ llm_router_cache_type_v }}
+batch-size   = {{ llm_router_batch_size }}
+ubatch-size  = {{ llm_router_ubatch_size }}
+parallel     = {{ llm_router_parallel }}
+
+; --- Auxiliary model: Meta-Llama-3.1-8B-Instruct-Q4_K_M --------------------
+; Primary model ID: Meta-Llama-3.1-8B-Instruct-Q4_K_M (unchanged)
+; ~4.6GB, general-purpose small model.
+[Meta-Llama-3.1-8B-Instruct-Q4_K_M]
+model        = {{ llm_models_dir }}/Meta-Llama-3.1-8B-Instruct-Q4_K_M.gguf
+n-gpu-layers = {{ llm_router_gpu_layers }}
+ctx-size     = {{ llm_router_ctx_size }}
+cache-type-k = {{ llm_router_cache_type_k }}
+cache-type-v = {{ llm_router_cache_type_v }}
+batch-size   = {{ llm_router_batch_size }}
+ubatch-size  = {{ llm_router_ubatch_size }}
+parallel     = {{ llm_router_parallel }}

ansible/roles/llm-inference-multimodel/templates/llama-server-router.service.j2

@@ -10,7 +10,11 @@ User={{ llm_service_user }}
 Group={{ llm_service_user }}
 Environment="HOME=/home/{{ llm_service_user }}"
 ExecStart={{ llm_binary_path }} \
+{% if llm_router_preset_enabled | default(false) %}
+    --models-preset {{ llm_router_preset_path }} \
+{% else %}
     --models-dir {{ llm_router_models_dir }} \
+{% endif %}
     --models-max {{ llm_router_models_max }} \
     --host {{ llm_router_bind_address }} \
     --port {{ llm_router_port }} \
@@ -24,19 +28,23 @@ ExecStart={{ llm_binary_path }} \
     --parallel {{ llm_router_parallel }} \
     --metrics
 
-# ROUTER MODE NOTES (2026-08-12, t_0cca74a2):
+# ROUTER MODE NOTES (2026-08-12, t_0cca74a2 / updated t_9adf0889):
 # - NO -m/--model flag: this is what enables llama-server router/supervisor mode.
-#   Without -m, llama-server discovers all .gguf files in --models-dir, spawning
-#   each as its own child process on demand (LRU-eviction when over models-max).
+#   Without -m, llama-server discovers all .gguf files in --models-dir, or uses
+#   the per-model definitions in a --models-preset INI file.
+# - PRESET MODE (t_9adf0889, 2026-08-12):
+#   llm_router_preset_enabled=true switches from --models-dir to --models-preset.
+#   Preset mode adds alias support (--models-dir cannot assign aliases).
+#   The preset INI is at {{ llm_router_preset_path | default('/opt/llama-server-router-preset.ini') }}.
+#   Both the section name and the alias field in the INI work as model IDs.
+#   GH #22364 (extra "default" entry in /v1/models) is expected in preset mode — cosmetic.
 # - --models-max {{ llm_router_models_max }} is driven by llm_router_models_max
 #   (default 1 in defaults/main.yml; overridden to 4 in host_vars/astro-orbiter
 #   as of t_33acbb2e after VRAM budget review — see host_vars for OOM risk note).
 #   Default llama-server cap is 4 simultaneous — OOM on 24GB if all 3 current
 #   GGUFs load at once. LRU eviction mitigates in practice but review before adding
 #   models. See host_vars/astro-orbiter/vars.yml for full VRAM breakdown.
-# - --models-dir /opt/models: auto-discovers all .gguf files. Keep that directory
-#   clean (Qwen-only) to avoid spurious extra entries in /v1/models.
-# - Clients select a model via "model": "<gguf-basename-without-.gguf>" in their
+# - Clients select a model via "model": "<section-name-or-alias>" in their
 #   chat completion request. Hermes sends model: "<id>" on every request already.
 # - Cold model load on first request: ~30-60s for Qwen3.6-35B. First response
 #   will be slow. This is expected. Document in runbook.