Go codegen: per-event-type data structs

.gitattributes

@@ -1 +1,8 @@
-.github/workflows/*.lock.yml linguist-generated=true merge=ours
+.github/workflows/*.lock.yml linguist-generated=true merge=ours
+
+# Generated files — keep LF line endings so codegen output is deterministic across platforms.
+nodejs/src/generated/* eol=lf linguist-generated=true
+dotnet/src/Generated/* eol=lf linguist-generated=true
+python/copilot/generated/* eol=lf linguist-generated=true
+go/generated_session_events.go eol=lf linguist-generated=true
+go/rpc/generated_rpc.go eol=lf linguist-generated=true

.github/workflows/codegen-check.yml

@@ -47,11 +47,6 @@ jobs:
 
       - name: Check for uncommitted changes
         run: |
-          # TODO: Remove this when https://github.com/github/copilot-sdk/issues/1031 is fixed
-          # Exclude go/generated_session_events.go from the check — it was intentionally
-          # reverted to avoid a breaking DataContent change (see #1031) and will be
-          # regenerated once that issue is resolved.
-          git checkout -- go/generated_session_events.go 2>/dev/null || true
           if [ -n "$(git status --porcelain)" ]; then
             echo "::error::Generated files are out of date. Run 'cd scripts/codegen && npm run generate' and commit the changes."
             git diff --stat

docs/auth/byok.md

@@ -130,7 +130,9 @@ func main() {
         panic(err)
     }
 
-    fmt.Println(*response.Data.Content)
+    if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+        fmt.Println(d.Content)
+    }
 }
 ```
 

docs/features/custom-agents.md

@@ -506,17 +506,17 @@ func main() {
 	})
 
 	session.On(func(event copilot.SessionEvent) {
-		switch event.Type {
-		case "subagent.started":
-			fmt.Printf("▶ Sub-agent started: %s\n", *event.Data.AgentDisplayName)
-			fmt.Printf("  Description: %s\n", *event.Data.AgentDescription)
-			fmt.Printf("  Tool call ID: %s\n", *event.Data.ToolCallID)
-		case "subagent.completed":
-			fmt.Printf("✅ Sub-agent completed: %s\n", *event.Data.AgentDisplayName)
-		case "subagent.failed":
-			fmt.Printf("❌ Sub-agent failed: %s — %v\n", *event.Data.AgentDisplayName, event.Data.Error)
-		case "subagent.selected":
-			fmt.Printf("🎯 Agent selected: %s\n", *event.Data.AgentDisplayName)
+		switch d := event.Data.(type) {
+		case *copilot.SubagentStartedData:
+			fmt.Printf("▶ Sub-agent started: %s\n", d.AgentDisplayName)
+			fmt.Printf("  Description: %s\n", d.AgentDescription)
+			fmt.Printf("  Tool call ID: %s\n", d.ToolCallID)
+		case *copilot.SubagentCompletedData:
+			fmt.Printf("✅ Sub-agent completed: %s\n", d.AgentDisplayName)
+		case *copilot.SubagentFailedData:
+			fmt.Printf("❌ Sub-agent failed: %s — %v\n", d.AgentDisplayName, d.Error)
+		case *copilot.SubagentSelectedData:
+			fmt.Printf("🎯 Agent selected: %s\n", d.AgentDisplayName)
 		}
 	})
 
@@ -530,17 +530,17 @@ func main() {
 
 ```go
 session.On(func(event copilot.SessionEvent) {
-    switch event.Type {
-    case "subagent.started":
-        fmt.Printf("▶ Sub-agent started: %s\n", *event.Data.AgentDisplayName)
-        fmt.Printf("  Description: %s\n", *event.Data.AgentDescription)
-        fmt.Printf("  Tool call ID: %s\n", *event.Data.ToolCallID)
-    case "subagent.completed":
-        fmt.Printf("✅ Sub-agent completed: %s\n", *event.Data.AgentDisplayName)
-    case "subagent.failed":
-        fmt.Printf("❌ Sub-agent failed: %s — %v\n", *event.Data.AgentDisplayName, event.Data.Error)
-    case "subagent.selected":
-        fmt.Printf("🎯 Agent selected: %s\n", *event.Data.AgentDisplayName)
+    switch d := event.Data.(type) {
+    case *copilot.SubagentStartedData:
+        fmt.Printf("▶ Sub-agent started: %s\n", d.AgentDisplayName)
+        fmt.Printf("  Description: %s\n", d.AgentDescription)
+        fmt.Printf("  Tool call ID: %s\n", d.ToolCallID)
+    case *copilot.SubagentCompletedData:
+        fmt.Printf("✅ Sub-agent completed: %s\n", d.AgentDisplayName)
+    case *copilot.SubagentFailedData:
+        fmt.Printf("❌ Sub-agent failed: %s — %v\n", d.AgentDisplayName, d.Error)
+    case *copilot.SubagentSelectedData:
+        fmt.Printf("🎯 Agent selected: %s\n", d.AgentDisplayName)
     }
 })
 

docs/features/streaming-events.md

@@ -137,8 +137,8 @@ func main() {
 	})
 
 	session.On(func(event copilot.SessionEvent) {
-		if event.Type == "assistant.message_delta" {
-			fmt.Print(*event.Data.DeltaContent)
+		if d, ok := event.Data.(*copilot.AssistantMessageDeltaData); ok {
+			fmt.Print(d.DeltaContent)
 		}
 	})
 	_ = session
@@ -148,8 +148,8 @@ func main() {
 
 ```go
 session.On(func(event copilot.SessionEvent) {
-    if event.Type == "assistant.message_delta" {
-        fmt.Print(*event.Data.DeltaContent)
+    if d, ok := event.Data.(*copilot.AssistantMessageDeltaData); ok {
+        fmt.Print(d.DeltaContent)
     }
 })
 ```

docs/getting-started.md

@@ -211,7 +211,9 @@ func main() {
 		log.Fatal(err)
 	}
 
-	fmt.Println(*response.Data.Content)
+	if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+		fmt.Println(d.Content)
+	}
 	os.Exit(0)
 }
 ```
@@ -406,10 +408,11 @@ func main() {
 
 	// Listen for response chunks
 	session.On(func(event copilot.SessionEvent) {
-		if event.Type == "assistant.message_delta" {
-			fmt.Print(*event.Data.DeltaContent)
-		}
-		if event.Type == "session.idle" {
+		switch d := event.Data.(type) {
+		case *copilot.AssistantMessageDeltaData:
+			fmt.Print(d.DeltaContent)
+		case *copilot.SessionIdleData:
+			_ = d
 			fmt.Println()
 		}
 	})
@@ -604,10 +607,12 @@ func main() {
 
 	// Filter by event type in your handler
 	session.On(func(event copilot.SessionEvent) {
-		if event.Type == "session.idle" {
+		switch d := event.Data.(type) {
+		case *copilot.SessionIdleData:
+			_ = d
 			fmt.Println("Session is idle")
-		} else if event.Type == "assistant.message" {
-			fmt.Println("Message:", *event.Data.Content)
+		case *copilot.AssistantMessageData:
+			fmt.Println("Message:", d.Content)
 		}
 	})
 
@@ -625,10 +630,12 @@ unsubscribe := session.On(func(event copilot.SessionEvent) {
 
 // Filter by event type in your handler
 session.On(func(event copilot.SessionEvent) {
-    if event.Type == "session.idle" {
+    switch d := event.Data.(type) {
+    case *copilot.SessionIdleData:
+        _ = d
         fmt.Println("Session is idle")
-    } else if event.Type == "assistant.message" {
-        fmt.Println("Message:", *event.Data.Content)
+    case *copilot.AssistantMessageData:
+        fmt.Println("Message:", d.Content)
     }
 })
 
@@ -897,10 +904,11 @@ func main() {
 	}
 
 	session.On(func(event copilot.SessionEvent) {
-		if event.Type == "assistant.message_delta" {
-			fmt.Print(*event.Data.DeltaContent)
-		}
-		if event.Type == "session.idle" {
+		switch d := event.Data.(type) {
+		case *copilot.AssistantMessageDeltaData:
+			fmt.Print(d.DeltaContent)
+		case *copilot.SessionIdleData:
+			_ = d
 			fmt.Println()
 		}
 	})
@@ -1251,12 +1259,11 @@ func main() {
 	}
 
 	session.On(func(event copilot.SessionEvent) {
-		if event.Type == "assistant.message_delta" {
-			if event.Data.DeltaContent != nil {
-				fmt.Print(*event.Data.DeltaContent)
-			}
-		}
-		if event.Type == "session.idle" {
+		switch d := event.Data.(type) {
+		case *copilot.AssistantMessageDeltaData:
+			fmt.Print(d.DeltaContent)
+		case *copilot.SessionIdleData:
+			_ = d
 			fmt.Println()
 		}
 	})

docs/setup/bundled-cli.md

@@ -130,7 +130,9 @@ func main() {
 
 	session, _ := client.CreateSession(ctx, &copilot.SessionConfig{Model: "gpt-4.1"})
 	response, _ := session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "Hello!"})
-	fmt.Println(*response.Data.Content)
+	if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+		fmt.Println(d.Content)
+	}
 }
 ```
 <!-- /docs-validate: hidden -->
@@ -146,7 +148,9 @@ defer client.Stop()
 
 session, _ := client.CreateSession(ctx, &copilot.SessionConfig{Model: "gpt-4.1"})
 response, _ := session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "Hello!"})
-fmt.Println(*response.Data.Content)
+if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+    fmt.Println(d.Content)
+}
 ```
 
 </details>

docs/setup/local-cli.md

@@ -91,7 +91,9 @@ func main() {
 
 	session, _ := client.CreateSession(ctx, &copilot.SessionConfig{Model: "gpt-4.1"})
 	response, _ := session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "Hello!"})
-	fmt.Println(*response.Data.Content)
+	if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+		fmt.Println(d.Content)
+	}
 }
 ```
 <!-- /docs-validate: hidden -->
@@ -105,7 +107,9 @@ defer client.Stop()
 
 session, _ := client.CreateSession(ctx, &copilot.SessionConfig{Model: "gpt-4.1"})
 response, _ := session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "Hello!"})
-fmt.Println(*response.Data.Content)
+if d, ok := response.Data.(*copilot.AssistantMessageData); ok {
+    fmt.Println(d.Content)
+}
 ```
 
 </details>

go/README.md

@@ -57,12 +57,10 @@ func main() {
     // Set up event handler
     done := make(chan bool)
     session.On(func(event copilot.SessionEvent) {
-        if event.Type == "assistant.message" {
-            if event.Data.Content != nil && event.Data.Content.String != nil {
-                fmt.Println(*event.Data.Content.String)
-            }
-        }
-        if event.Type == "session.idle" {
+        switch d := event.Data.(type) {
+        case *copilot.AssistantMessageData:
+            fmt.Println(d.Content)
+        case *copilot.SessionIdleData:
             close(done)
         }
     })
@@ -404,30 +402,22 @@ func main() {
     done := make(chan bool)
 
     session.On(func(event copilot.SessionEvent) {
-        if event.Type == "assistant.message_delta" {
+        switch d := event.Data.(type) {
+        case *copilot.AssistantMessageDeltaData:
             // Streaming message chunk - print incrementally
-            if event.Data.DeltaContent != nil {
-                fmt.Print(*event.Data.DeltaContent)
-            }
-        } else if event.Type == "assistant.reasoning_delta" {
+            fmt.Print(d.DeltaContent)
+        case *copilot.AssistantReasoningDeltaData:
             // Streaming reasoning chunk (if model supports reasoning)
-            if event.Data.DeltaContent != nil {
-                fmt.Print(*event.Data.DeltaContent)
-            }
-        } else if event.Type == "assistant.message" {
+            fmt.Print(d.DeltaContent)
+        case *copilot.AssistantMessageData:
             // Final message - complete content
             fmt.Println("\n--- Final message ---")
-            if event.Data.Content != nil && event.Data.Content.String != nil {
-                fmt.Println(*event.Data.Content.String)
-            }
-        } else if event.Type == "assistant.reasoning" {
+            fmt.Println(d.Content)
+        case *copilot.AssistantReasoningData:
             // Final reasoning content (if model supports reasoning)
             fmt.Println("--- Reasoning ---")
-            if event.Data.Content != nil && event.Data.Content.String != nil {
-                fmt.Println(*event.Data.Content.String)
-            }
-        }
-        if event.Type == "session.idle" {
+            fmt.Println(d.Content)
+        case *copilot.SessionIdleData:
             close(done)
         }
     })

go/client.go

@@ -20,8 +20,8 @@
 //	}
 //
 //	session.On(func(event copilot.SessionEvent) {
-//	    if event.Type == "assistant.message" {
-//	        fmt.Println(event.Data.Content)
+//	    if d, ok := event.Data.(*copilot.AssistantMessageData); ok {
+//	        fmt.Println(d.Content)
 //	    }
 //	})
 //