[1/N] Polish deployment skills - Add a debug loop for unsupported models

.claude/skills/deployment/SKILL.md

@@ -222,6 +222,10 @@ For NEL-managed deployment (evaluation with self-deployment), use the evaluation
 | `Connection refused` on health check | Server still starting | Wait 30-60s for large models; check logs for errors |
 | `modelopt_fp4 not supported` | Framework doesn't support FP4 for this model | Check support matrix in `references/support-matrix.md` |
 
+## Unsupported Models
+
+If the model is not in the validated support matrix (`references/support-matrix.md`), deployment may fail due to weight key mismatches, missing architecture mappings, or quantized/unquantized layer confusion. Read `references/unsupported-models.md` for the iterative debug loop: **run → read error → diagnose → patch framework source → re-run**. For kernel-level issues, escalate to the framework team rather than attempting fixes.
+
 ## Success Criteria
 
 1. Server process is running and healthy (`/health` returns 200)

.claude/skills/deployment/references/unsupported-models.md

@@ -0,0 +1,63 @@
+# Deploying Unsupported Models
+
+When deploying a model not in the validated support matrix (`references/support-matrix.md`), expect failures. This guide covers the iterative debug loop for getting unsupported models running on vLLM, SGLang, or TRT-LLM.
+
+## Step 1 — Run and collect the error
+
+Submit the deployment job. When it fails, read the full log — focus on the **first** error traceback (not "See root cause above" wrappers). Identify the file and line number in the framework source.
+
+## Step 2 — Diagnose the root cause
+
+Fetch the framework source at the failing line (use `gh api` for the tagged version, or `find` inside the container). Common error categories:
+
+| Category | Symptoms | Examples |
+|----------|----------|----------|
+| **Weight key mismatch** | `KeyError`, `Unexpected key`, `Missing key` during weight loading | Checkpoint uses `model.language_model.layers.*` but framework expects `model.layers.*`. See [vllm#39406](https://github.com/vllm-project/vllm/pull/39406) |
+| **Quantized/unquantized layer confusion** | Wrong layer type loaded, dtype errors, shape mismatches | Framework tries to load unquantized layers with FP4 kernel due to overly broad `quantization_config.ignore` patterns or missing ignore entries. See [sglang#18937](https://github.com/sgl-project/sglang/pull/18937) |
+| **Missing architecture support** | `NoneType is not iterable`, `KeyError` on model type, unknown architecture | Framework's model handler doesn't recognize the text backbone type (e.g., `ministral3` not handled in vLLM's `mistral3.py` init). Fix: extend the model type mapping |
+| **Transformers version mismatch** | `ImportError`, `KeyError` on config fields | Framework ships with older transformers that doesn't know the model type. Fix: upgrade transformers after installing the framework |
+| **Kernel-level issues** | CUDA errors, `triton` import failures, unsupported ops | Framework lacks kernel support for this model + quantization combo |
+
+## Step 3 — Apply a targeted fix
+
+Focus on **small, targeted patches** to the framework source. Do not modify `config.json` or the checkpoint — fix the framework's handling instead.
+
+### Weight key mismatches and architecture mapping gaps
+
+Patch the framework source in the run script using `sed` or a Python one-liner. Keep patches minimal — change only what's needed to unblock the current error.
+
+```bash
+# Example: extend model type mapping in vLLM mistral3.py
+FRAMEWORK_FILE=$(find /usr/local/lib -path "*/vllm/model_executor/models/mistral3.py" 2>/dev/null | head -1)
+sed -i 's/old_pattern/new_pattern/' "${FRAMEWORK_FILE}"
+```
+
+> **Tip**: when locating framework source files inside containers, use `find` instead of Python import — some frameworks print log messages to stdout during import that can corrupt captured paths.
+
+### Quantized/unquantized layer confusion
+
+Check `hf_quant_config.json` ignore patterns against the framework's weight loading logic. The framework may try to load layers listed in `ignore` with quantized kernels, or vice versa. Fix by adjusting the framework's layer filtering logic.
+
+### Kernel-level issues
+
+These require framework kernel team involvement. Do NOT attempt to patch kernels. Instead:
+
+1. Document the exact error (model, format, framework version, GPU type)
+2. Inform the user: *"This model + quantization combination requires kernel support that isn't available in {framework} v{version}. I'd suggest reaching out to the {framework} kernel team or trying a different framework."*
+3. Suggest trying an alternative framework (vLLM → SGLang → TRT-LLM)
+
+## Step 4 — Re-run and iterate
+
+After applying a fix, resubmit the job. Each iteration may reveal a new error (e.g., fixing the init error exposes a weight loading error). Continue the loop: **run → read error → diagnose → patch → re-run**.
+
+Typical iteration count: 1-3 for straightforward fixes, 3-5 for models requiring multiple patches.
+
+## Step 5 — Know when to stop
+
+**Stop patching and escalate** when:
+
+- The error is in compiled CUDA kernels or triton ops (not Python-level)
+- The fix requires changes to core framework abstractions (not just model handlers)
+- You've done 5+ iterations without the server starting
+
+In these cases, inform the user and suggest: trying a different framework, checking for a newer framework version, or filing an issue with the framework team.