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>

src/commands/onboard-auth.models.ts

@@ -204,3 +204,26 @@ export function buildXaiModelDefinition(): ModelDefinitionConfig {
     maxTokens: XAI_DEFAULT_MAX_TOKENS,
   };
 }
+
+// Kilo Gateway model definitions
+export const KILOCODE_DEFAULT_MODEL_ID = "anthropic/claude-opus-4.6";
+export const KILOCODE_DEFAULT_CONTEXT_WINDOW = 200000;
+export const KILOCODE_DEFAULT_MAX_TOKENS = 8192;
+export const KILOCODE_DEFAULT_COST = {
+  input: 0,
+  output: 0,
+  cacheRead: 0,
+  cacheWrite: 0,
+};
+
+export function buildKilocodeModelDefinition(): ModelDefinitionConfig {
+  return {
+    id: KILOCODE_DEFAULT_MODEL_ID,
+    name: "Claude Opus 4.6",
+    reasoning: true,
+    input: ["text", "image"],
+    cost: KILOCODE_DEFAULT_COST,
+    contextWindow: KILOCODE_DEFAULT_CONTEXT_WINDOW,
+    maxTokens: KILOCODE_DEFAULT_MAX_TOKENS,
+  };
+}