On branch copilot/add-classical-code-gen-workflow-ready-for-review

modified:   scripts/codegen/java.ts

- Put `visible = true` on `SessionEventEvent`.
- Add `type` property. on `UnknownSessionEvent`.

modified:   src/generated/java/com/github/copilot/sdk/generated/SessionEvent.java
modified:   src/generated/java/com/github/copilot/sdk/generated/UnknownSessionEvent.java

- Regenerated.

modified:   src/main/java/com/github/copilot/sdk/CopilotSession.java

- Use Double Check Locked to fix Big Risk #2 2. Lazy `SessionRpc` initialization is not thread-safe (HIGH)

modified:   src/test/java/com/github/copilot/sdk/ForwardCompatibilityTest.java
modified:   src/test/java/com/github/copilot/sdk/SessionEventDeserializationTest.java

- Refine tests based on changes.

Signed-off-by: Ed Burns <edburns@microsoft.com>

Author: edburns

scripts/codegen/java.ts

@@ -302,7 +302,7 @@ async function generateSessionEventBaseClass(
     lines.push(` */`);
     lines.push(`@JsonIgnoreProperties(ignoreUnknown = true)`);
     lines.push(`@JsonInclude(JsonInclude.Include.NON_NULL)`);
-    lines.push(`@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type", defaultImpl = UnknownSessionEvent.class)`);
+    lines.push(`@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type", visible = true, defaultImpl = UnknownSessionEvent.class)`);
     lines.push(`@JsonSubTypes({`);
     for (let i = 0; i < variants.length; i++) {
         const v = variants[i];
@@ -373,19 +373,26 @@ async function generateUnknownEventClass(packageName: string, packageDir: string
     lines.push(`package ${packageName};`);
     lines.push("");
     lines.push(`import com.fasterxml.jackson.annotation.JsonIgnoreProperties;`);
+    lines.push(`import com.fasterxml.jackson.annotation.JsonProperty;`);
     lines.push(`import javax.annotation.processing.Generated;`);
     lines.push("");
     lines.push(`/**`);
     lines.push(` * Fallback for event types not yet known to this SDK version.`);
+    lines.push(` * <p>`);
+    lines.push(` * {@link #getType()} returns the original type string from the JSON payload,`);
+    lines.push(` * preserving forward compatibility with event types introduced by newer CLI versions.`);
     lines.push(` *`);
     lines.push(` * @since 1.0.0`);
     lines.push(` */`);
     lines.push(`@JsonIgnoreProperties(ignoreUnknown = true)`);
     lines.push(GENERATED_ANNOTATION);
     lines.push(`public final class UnknownSessionEvent extends SessionEvent {`);
     lines.push("");
+    lines.push(`    @JsonProperty("type")`);
+    lines.push(`    private String type = "unknown";`);
+    lines.push("");
     lines.push(`    @Override`);
-    lines.push(`    public String getType() { return "unknown"; }`);
+    lines.push(`    public String getType() { return type; }`);
     lines.push(`}`);
     lines.push("");
 

src/generated/java/com/github/copilot/sdk/generated/SessionEvent.java

@@ -294,16 +294,23 @@ public SessionUiApi getUi() {
      * var agents = session.getRpc().agent.list().get();
      * }</pre>
      *
-     * @return the session-scoped typed RPC client
+     * @return the session-scoped typed RPC client (never {@code null})
+     * @throws IllegalStateException
+     *             if the session is not connected
      * @since 1.0.0
      */
     public SessionRpc getRpc() {
         if (rpc == null) {
-            return null;
+            throw new IllegalStateException("Session is not connected — RPC client is unavailable");
         }
         SessionRpc current = sessionRpc;
         if (current == null) {
-            sessionRpc = current = new SessionRpc(rpc::invoke, sessionId);
+            synchronized (this) {
+                current = sessionRpc;
+                if (current == null) {
+                    sessionRpc = current = new SessionRpc(rpc::invoke, sessionId);
+                }
+            }
         }
         return current;
     }

src/generated/java/com/github/copilot/sdk/generated/UnknownSessionEvent.java

@@ -53,7 +53,7 @@ void parse_unknownEventType_returnsUnknownSessionEvent() throws Exception {
         SessionEvent result = MAPPER.readValue(json, SessionEvent.class);
 
         assertInstanceOf(UnknownSessionEvent.class, result);
-        assertEquals("unknown", result.getType());
+        assertEquals("future.feature_from_server", result.getType());
     }
 
     @Test
@@ -69,7 +69,7 @@ void parse_unknownEventType_preservesOriginalType() throws Exception {
         SessionEvent result = MAPPER.readValue(json, SessionEvent.class);
 
         assertInstanceOf(UnknownSessionEvent.class, result);
-        assertEquals("unknown", result.getType());
+        assertEquals("future.feature_from_server", result.getType());
     }
 
     @Test

src/main/java/com/github/copilot/sdk/CopilotSession.java

@@ -844,7 +844,8 @@ void testParseUnknownEventType() throws Exception {
         assertNotNull(event, "Unknown event types should return an UnknownSessionEvent");
         assertInstanceOf(com.github.copilot.sdk.generated.UnknownSessionEvent.class, event,
                 "Unknown event types should return UnknownSessionEvent for forward compatibility");
-        assertEquals("unknown", event.getType());
+        assertEquals("unknown.event.type", event.getType(),
+                "UnknownSessionEvent should preserve the original type from JSON");
     }
 
     @Test