feat(benchmarks): add MiniMax provider arm (MiniMax-M3, MiniMax-M2.7)

.env.example

@@ -1,2 +1,4 @@
 # Copy to .env (gitignored) and fill in. promptfoo reads this automatically.
 ANTHROPIC_API_KEY=sk-ant-...
+# MiniMax (global OpenAI-compatible endpoint). Used by benchmarks/promptfooconfig.minimax.yaml.
+MINIMAX_API_KEY=...

benchmarks/README.md

@@ -18,6 +18,21 @@ npx promptfoo@latest view
 `--env-file ../.env` is required because promptfoo reads `.env` from the current
 directory (`benchmarks/`), not the repo root where the file lives.
 
+### MiniMax (MiniMax-M3 / MiniMax-M2.7)
+
+Requires a MiniMax API key (global endpoint) and **Node.js ≥ 22.22.0** (same
+promptfoo engine constraint as Claude):
+
+```bash
+cp ../.env.example .env      # add your MINIMAX_API_KEY
+npx promptfoo@latest eval -c promptfooconfig.minimax.yaml --env-file ../.env --repeat 10
+npx promptfoo@latest view
+```
+
+The MiniMax provider is the OpenAI-compatible `openai:chat:<model>` surface with
+`apiBaseUrl` pointed at `https://api.minimax.io/v1`; `MINIMAX_API_KEY` is read
+via `apiKeyEnvar` so the key stays in `.env`. See `promptfooconfig.minimax.yaml`.
+
 ### Local models via Ollama
 
 No API key or promptfoo required. Runs against any model served by Ollama:

benchmarks/promptfooconfig.minimax.yaml

@@ -0,0 +1,41 @@
+# Ponytail vs baseline, MiniMax: MiniMax-M3 + MiniMax-M2.7 over the OpenAI-compatible endpoint.
+#   npx promptfoo@latest eval -c benchmarks/promptfooconfig.minimax.yaml --env-file ../.env --repeat 10
+# Needs MINIMAX_API_KEY in ../.env (global endpoint). The MiniMax OpenAI-compatible
+# base URL points at the /v1 chat completions surface; see benchmarks/README.md.
+description: "Ponytail vs baseline on MiniMax (MiniMax-M3, MiniMax-M2.7). LOC + correctness, cost telemetry."
+
+providers:
+  - id: openai:chat:MiniMax-M3
+    config:
+      apiBaseUrl: https://api.minimax.io/v1
+      apiKeyEnvar: MINIMAX_API_KEY
+      max_tokens: 8192
+      temperature: 1
+  - id: openai:chat:MiniMax-M2.7
+    config:
+      apiBaseUrl: https://api.minimax.io/v1
+      apiKeyEnvar: MINIMAX_API_KEY
+      max_tokens: 2048
+      temperature: 1
+
+prompts:
+  - id: file://arms/baseline.js
+    label: baseline (no skill)
+  - id: file://arms/ponytail.js
+    label: ponytail
+
+defaultTest:
+  assert:
+    - type: javascript
+      value: file://loc.js
+      metric: code_loc
+    - type: javascript
+      value: file://correctness.js
+      metric: correct
+
+tests:
+  - vars: { task: "Write me a Python function that validates email addresses." }
+  - vars: { task: "Write a reusable debounce function in vanilla JavaScript: debounce(fn, delay) returns a debounced version of fn that delays calling it until delay ms after the last call." }
+  - vars: { task: "Write Python code that reads sales.csv and sums the 'amount' column." }
+  - vars: { task: "Build me a countdown timer component in React that counts down from a given number of seconds." }
+  - vars: { task: "Add rate limiting to my FastAPI endpoint so users can't spam it." }