diff --git a/opencode.json b/opencode.json
index e20209c6..a7d952b7 100644
--- a/opencode.json
+++ b/opencode.json
@@ -1,5 +1,13 @@
 {
   "$schema": "https://opencode.ai/config.json",
   "mcp": {},
-  "provider": {}
+  "provider": {
+    "openrouter": {
+      "npm": "@openrouter/ai-sdk-provider",
+      "name": "OpenRouter",
+      "models": {
+        "anthropic/claude-sonnet-4": {}
+      }
+    }
+  }
 }
diff --git a/packages/opencode/src/session/index.ts b/packages/opencode/src/session/index.ts
index 8baf7da0..0dd4e4e6 100644
--- a/packages/opencode/src/session/index.ts
+++ b/packages/opencode/src/session/index.ts
@@ -210,8 +210,9 @@ export namespace Session {
         previous.metadata.assistant.tokens.cache.write +
         previous.metadata.assistant.tokens.output
       if (
+        model.info.limit.context &&
         tokens >
-        (model.info.limit.context - (model.info.limit.output ?? 0)) * 0.9
+          (model.info.limit.context - (model.info.limit.output ?? 0)) * 0.9
       ) {
         await summarize({
           sessionID: input.sessionID,