Fix codegen and build failures after @github/copilot update

Handle cross-schema $ref values (e.g. session-events.schema.json#/definitions/TypeName)
in the Java code generator. Previously the codegen emitted the raw $ref string as a Java
type name, causing compilation errors. Now cross-schema refs are resolved by loading the
referenced schema's definitions and recursing into schemaTypeToJava with the resolved schema.

Automated fix applied by codegen-agentic-fix workflow.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

scripts/codegen/java.ts

@@ -102,6 +102,11 @@ interface JavaTypeResult {
 let currentDefinitions: Record<string, JSONSchema7> = {};
 const pendingStandaloneTypes = new Map<string, JSONSchema7>();
 
+// Cross-schema definitions: keyed by schema filename (e.g. "session-events.schema.json"),
+// value is the definitions map from that schema. Populated by generateRpcTypes so that
+// cross-schema $ref values like "session-events.schema.json#/definitions/Foo" can be resolved.
+const crossSchemaDefinitions = new Map<string, Record<string, JSONSchema7>>();
+
 /**
  * Resolve a $ref in a JSON Schema against the current definitions.
  * Returns the resolved schema, or the original if no $ref is present.
@@ -131,6 +136,28 @@ function schemaTypeToJava(
 
     // Resolve $ref first — register standalone types for generation
     if (schema.$ref) {
+        // Handle cross-schema $ref (e.g. "session-events.schema.json#/definitions/Foo")
+        const crossSchemaMatch = schema.$ref.match(/^([^#]+)#\/definitions\/(.+)$/);
+        if (crossSchemaMatch) {
+            const [, schemaFile, typeName] = crossSchemaMatch;
+            const externalDefs = crossSchemaDefinitions.get(schemaFile);
+            if (externalDefs) {
+                const resolved = externalDefs[typeName];
+                if (resolved) {
+                    // Save and swap currentDefinitions so recursive calls resolve against
+                    // the external schema's definitions.
+                    const savedDefs = currentDefinitions;
+                    currentDefinitions = externalDefs;
+                    const result = schemaTypeToJava(resolved, required, context, propName, nestedTypes);
+                    currentDefinitions = savedDefs;
+                    return result;
+                }
+            }
+            // Fallback: extract just the type name and warn
+            console.warn(`[codegen] Unresolved cross-schema $ref: ${schema.$ref}`);
+            return { javaType: typeName, imports };
+        }
+
         const name = schema.$ref.replace(/^#\/definitions\//, "");
         const resolved = currentDefinitions[name];
         if (resolved) {
@@ -883,6 +910,19 @@ async function generateRpcTypes(schemaPath: string): Promise<void> {
     // Set module-level definitions for $ref resolution
     currentDefinitions = (schema.definitions ?? {}) as Record<string, JSONSchema7>;
     pendingStandaloneTypes.clear();
+    crossSchemaDefinitions.clear();
+
+    // Load cross-schema definitions (session-events) so that cross-schema $ref values
+    // like "session-events.schema.json#/definitions/Foo" can be resolved.
+    try {
+        const sessionEventsSchemaPath = await getSessionEventsSchemaPath();
+        const sessionEventsContent = await fs.readFile(sessionEventsSchemaPath, "utf-8");
+        const sessionEventsSchema = JSON.parse(sessionEventsContent) as JSONSchema7;
+        crossSchemaDefinitions.set("session-events.schema.json",
+            (sessionEventsSchema.definitions ?? {}) as Record<string, JSONSchema7>);
+    } catch (e) {
+        console.warn(`[codegen] Could not load session-events schema for cross-ref resolution: ${e}`);
+    }
 
     const packageName = "com.github.copilot.sdk.generated.rpc";
     const packageDir = `src/generated/java/com/github/copilot/sdk/generated/rpc`;