docs: clarify baseline deployment name must match pricing config key

.env.example

@@ -6,6 +6,9 @@ AZURE_MODEL_ROUTER_DEPLOYMENT=model-router
 # Azure OpenAI endpoint (for baseline model)
 AZURE_OPENAI_ENDPOINT=https://your-resource.openai.azure.com
 AZURE_OPENAI_KEY=your-azure-openai-api-key
+# Must match a key in the pricing section of your config file (e.g. gpt-4o, gpt-5).
+# If you use a custom deployment name, add a matching entry to configs/default.yaml
+# under pricing: using your exact deployment name. Otherwise baseline costs show as $0.00.
 AZURE_BASELINE_DEPLOYMENT=gpt-5
 
 # Judge model (defaults to same endpoint as baseline; override to use a different model)

QUICKSTART.md

@@ -139,6 +139,8 @@ copy .env.example .env     # Windows
 ```
 Open `.env` and set the four endpoint URLs and API keys (router, baseline, judge, optional Foundry project). The file is in `.gitignore`, so your secrets won't be committed.
 
+> **Note:** The value you set for `AZURE_BASELINE_DEPLOYMENT` must match a key in the `pricing` section of the config file you run (e.g. `configs/default.yaml`). If you use a custom deployment name such as `gpt-4o-baseline`, add a matching entry under `pricing:` in that same config with the same input/output rates; otherwise baseline costs will show as $0.00 and the cost comparison will be inaccurate.
+
 ### 2. Pick or edit a config
 - `configs/quick_test.yaml` — small, fast (~10 prompts) — good first run.
 - `configs/default.yaml` — full benchmark (100 prompts).