feat(ai): add Hugging Face provider support

- Add huggingface to KnownProvider type
- Add HF_TOKEN env var mapping
- Process huggingface models from models.dev (14 models)
- Use openai-completions API with compat settings
- Add tests for all provider test suites
- Update documentation

fixes #994

packages/coding-agent/README.md

@@ -93,6 +93,7 @@ For each built-in provider, pi maintains a list of tool-capable models, updated
 - Vercel AI Gateway
 - ZAI
 - OpenCode Zen
+- Hugging Face
 - MiniMax
 
 See [docs/providers.md](docs/providers.md) for detailed setup instructions.

packages/coding-agent/docs/providers.md

@@ -62,6 +62,7 @@ pi
 | Vercel AI Gateway | `AI_GATEWAY_API_KEY` |
 | ZAI | `ZAI_API_KEY` |
 | OpenCode Zen | `OPENCODE_API_KEY` |
+| Hugging Face | `HF_TOKEN` |
 | MiniMax | `MINIMAX_API_KEY` |
 | MiniMax (China) | `MINIMAX_CN_API_KEY` |
 

packages/coding-agent/src/core/model-resolver.ts

@@ -31,6 +31,7 @@ export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	mistral: "devstral-medium-latest",
 	minimax: "MiniMax-M2.1",
 	"minimax-cn": "MiniMax-M2.1",
+	huggingface: "moonshotai/Kimi-K2.5",
 	opencode: "claude-opus-4-5",
 };