fix(providers): apply Kimi Coding default headers

docs/configuration.md

@@ -230,7 +230,7 @@ Tracing covers the providers that go through nanobot's OpenAI-compatible client
 > - **MiniMax Coding Plan**: Exclusive discount links for the nanobot community: [Overseas](https://platform.minimax.io/subscribe/coding-plan?code=9txpdXw04g&source=link) · [Mainland China](https://platform.minimaxi.com/subscribe/token-plan?code=GILTJpMTqZ&source=link)
 > - **MiniMax (Mainland China)**: If your API key is from MiniMax's mainland China platform (minimaxi.com), set `"apiBase": "https://api.minimaxi.com/v1"` in your minimax provider config.
 > - **MiniMax thinking mode**: `providers.minimaxAnthropic` is the config block for `reasoningEffort` / thinking mode. MiniMax exposes that capability through its Anthropic-compatible endpoint, so nanobot keeps it as a separate provider instead of guessing MiniMax-specific thinking parameters on the generic OpenAI-compatible `minimax` endpoint. It uses the same `MINIMAX_API_KEY`. Default Anthropic-compatible base URL: `https://api.minimax.io/anthropic`; for mainland China use `https://api.minimaxi.com/anthropic`.
-> - **Kimi Coding Plan**: Use `providers.kimiCoding` with `provider: "kimi_coding"` for Kimi's dedicated Anthropic Messages API endpoint. The endpoint **requires** `extraHeaders.User-Agent` set to a Claude-compatible value such as `claude-code/0.1.0`; omitting it returns `403`.
+> - **Kimi Coding Plan**: Use `providers.kimiCoding` with `provider: "kimi_coding"` for Kimi's dedicated Anthropic Messages API endpoint. The endpoint requires a Claude-compatible `User-Agent`; nanobot sends `claude-code/0.1.0` by default, and you can override it with `extraHeaders.User-Agent` if your account requires a different value.
 > - **VolcEngine / BytePlus Coding Plan**: Subscription endpoints are configured through dedicated providers `volcengineCodingPlan` or `byteplusCodingPlan`, separate from the pay-per-use `volcengine` / `byteplus` providers.
 > - **OpenCode Zen / Go**: `providers.opencodeZen` and `providers.opencodeGo` use the same `OPENCODE_API_KEY`, but route to different OpenCode gateways. These providers use OpenCode's OpenAI-compatible `chat/completions` endpoints; choose model IDs from that endpoint family.
 > - **Zhipu Coding Plan**: If you're on Zhipu's coding plan, set `"apiBase": "https://open.bigmodel.cn/api/coding/paas/v4"` in your zhipu provider config.

docs/provider-cookbook.md

@@ -18,7 +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` |
+| A Kimi Coding Plan key | [Kimi Coding Plan](#recipe-kimi-coding-plan) | `KIMI_CODING_API_KEY`, `provider: "kimi_coding"`, and `model: "kimi-for-coding"` |
 | 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 |
@@ -281,10 +281,7 @@ This recipe applies when your key comes from Kimi's Coding Plan endpoint. Nanobo
 {
   "providers": {
     "kimiCoding": {
-      "apiKey": "${KIMI_CODING_API_KEY}",
-      "extraHeaders": {
-        "User-Agent": "claude-code/0.1.0"
-      }
+      "apiKey": "${KIMI_CODING_API_KEY}"
     }
   },
   "modelPresets": {
@@ -311,7 +308,7 @@ 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.
+The default base URL is `https://api.kimi.com/coding/v1`. This endpoint requires a Claude-compatible `User-Agent`; nanobot sends `claude-code/0.1.0` by default. If your account requires a different value, override it with `providers.kimiCoding.extraHeaders.User-Agent`.
 
 ## Recipe: Custom OpenAI-Compatible Provider