feat: Add Kilo Gateway provider (#20212)

* feat: Add Kilo Gateway provider

Add support for Kilo Gateway as a model provider, similar to OpenRouter.
Kilo Gateway provides a unified API that routes requests to many models
behind a single endpoint and API key.

Changes:
- Add kilocode provider option to auth-choice and onboarding flows
- Add KILOCODE_API_KEY environment variable support
- Add kilocode/ model prefix handling in model-auth and extra-params
- Add provider documentation in docs/providers/kilocode.md
- Update model-providers.md with Kilo Gateway section
- Add design doc for the integration

* kilocode: add provider tests and normalize onboard auth-choice registration

* kilocode: register in resolveImplicitProviders so models appear in provider filter

* kilocode: update base URL from /api/openrouter/ to /api/gateway/

* docs: fix formatting in kilocode docs

* fix: address PR review — remove kilocode from cacheRetention, fix stale model refs and CLI name in docs, fix TS2742

* docs: fix stale refs in design doc — Moltbot to OpenClaw, MoltbotConfig to OpenClawConfig, remove extra-params section, fix doc path

* fix: use resolveAgentModelPrimaryValue for AgentModelConfig union type

---------

Co-authored-by: Mark IJbema <mark@kilocode.ai>

docs/providers/kilocode.md

@@ -0,0 +1,50 @@
+---
+summary: "Use Kilo Gateway's unified API to access many models in OpenClaw"
+read_when:
+  - You want a single API key for many LLMs
+  - You want to run models via Kilo Gateway in OpenClaw
+---
+
+# Kilo Gateway
+
+Kilo Gateway provides a **unified API** that routes requests to many models behind a single
+endpoint and API key. It is OpenAI-compatible, so most OpenAI SDKs work by switching the base URL.
+
+## Getting an API key
+
+1. Go to [app.kilo.ai](https://app.kilo.ai)
+2. Sign in or create an account
+3. Navigate to API Keys and generate a new key
+
+## CLI setup
+
+```bash
+openclaw onboard --kilocode-api-key <key>
+```
+
+Or set the environment variable:
+
+```bash
+export KILOCODE_API_KEY="your-api-key"
+```
+
+## Config snippet
+
+```json5
+{
+  env: { KILOCODE_API_KEY: "sk-..." },
+  agents: {
+    defaults: {
+      model: { primary: "kilocode/anthropic/claude-opus-4.6" },
+    },
+  },
+}
+```
+
+## Notes
+
+- Model refs are `kilocode/<provider>/<model>` (e.g., `kilocode/anthropic/claude-opus-4.6`).
+- Default model: `kilocode/anthropic/claude-opus-4.6`
+- Base URL: `https://api.kilo.ai/api/gateway/`
+- For more model/provider options, see [/concepts/model-providers](/concepts/model-providers).
+- Kilo Gateway uses a Bearer token with your API key under the hood.