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/concepts/model-providers.md

@@ -126,10 +126,22 @@ OpenClaw ships with the pi‑ai catalog. These providers require **no**
 - Example model: `vercel-ai-gateway/anthropic/claude-opus-4.6`
 - CLI: `openclaw onboard --auth-choice ai-gateway-api-key`
 
+### Kilo Gateway
+
+- Provider: `kilocode`
+- Auth: `KILOCODE_API_KEY`
+- Example model: `kilocode/anthropic/claude-opus-4.6`
+- CLI: `openclaw onboard --kilocode-api-key <key>`
+- Base URL: `https://api.kilo.ai/api/gateway/`
+
+See [/providers/kilocode](/providers/kilocode) for setup details.
+
 ### Other built-in providers
 
 - OpenRouter: `openrouter` (`OPENROUTER_API_KEY`)
 - Example model: `openrouter/anthropic/claude-sonnet-4-5`
+- Kilo Gateway: `kilocode` (`KILOCODE_API_KEY`)
+- Example model: `kilocode/anthropic/claude-opus-4.6`
 - xAI: `xai` (`XAI_API_KEY`)
 - Mistral: `mistral` (`MISTRAL_API_KEY`)
 - Example model: `mistral/mistral-large-latest`