docs: document kimi coding provider

Maintainer edit: add the provider reference row and a pasteable cookbook recipe so users know to select kimi_coding and set the required User-Agent header.

docs/provider-cookbook.md

@@ -18,6 +18,7 @@ Match the recipe to the credential or endpoint you already have:
 | An OpenCode Zen or Go key | [OpenCode Zen or Go](#recipe-opencode-zen-or-go) | `OPENCODE_API_KEY`, the Zen/Go provider key, and a model ID from the matching OpenCode endpoint |
 | An OpenAI platform API key and OpenAI model ID | [OpenAI Direct](#recipe-openai-direct) | `OPENAI_API_KEY`, `provider: "openai"`, and an OpenAI model available to that account |
 | An Anthropic API key and Anthropic model ID | [Anthropic Direct](#recipe-anthropic-direct) | `ANTHROPIC_API_KEY`, `provider: "anthropic"`, and a non-gateway model ID |
+| A Kimi Coding Plan key | [Kimi Coding Plan](#recipe-kimi-coding-plan) | `KIMI_CODING_API_KEY`, `provider: "kimi_coding"`, `model: "kimi-for-coding"`, and `extraHeaders.User-Agent` |
 | An OpenAI-compatible `/v1` endpoint that is not a named nanobot provider | [Custom OpenAI-Compatible Provider](#recipe-custom-openai-compatible-provider) | `apiBase`, optional API key, and the model ID served by that endpoint |
 | Ollama already running locally | [Ollama Local Model](#recipe-ollama-local-model) | Ollama `apiBase`, pulled model name, and local server availability |
 | vLLM, LM Studio, or another local OpenAI-compatible server | [vLLM or LM Studio](#recipe-vllm-or-lm-studio) | Local `/v1` base URL, any required key, and served model name |
@@ -272,6 +273,46 @@ If you use an Anthropic-compatible proxy, keep the preset provider as `anthropic
 
 Do not configure Anthropic-compatible endpoints as arbitrary custom provider names; named custom providers use the OpenAI-compatible request format.
 
+## Recipe: Kimi Coding Plan
+
+This recipe applies when your key comes from Kimi's Coding Plan endpoint. Nanobot uses a dedicated `kimi_coding` provider for this Anthropic Messages API endpoint; do not configure it as a generic `custom` provider.
+
+```json
+{
+  "providers": {
+    "kimiCoding": {
+      "apiKey": "${KIMI_CODING_API_KEY}",
+      "extraHeaders": {
+        "User-Agent": "claude-code/0.1.0"
+      }
+    }
+  },
+  "modelPresets": {
+    "kimiCoding": {
+      "label": "Kimi Coding",
+      "provider": "kimi_coding",
+      "model": "kimi-for-coding",
+      "maxTokens": 4096,
+      "temperature": 0.1
+    }
+  },
+  "agents": {
+    "defaults": {
+      "modelPreset": "kimiCoding"
+    }
+  }
+}
+```
+
+Verify:
+
+```bash
+nanobot status
+nanobot agent -m "Hello!"
+```
+
+The default base URL is `https://api.kimi.com/coding/v1`. This endpoint **requires** the `User-Agent` header; omitting it returns `403`. Keep the value above or use another Claude-compatible value accepted by your Kimi account.
+
 ## Recipe: Custom OpenAI-Compatible Provider
 
 This recipe applies to an OpenAI-compatible service that is not a named nanobot provider.