diff --git a/cli/src/diagnostics.rs b/cli/src/diagnostics.rs
index b8b7609f..3761214a 100644
--- a/cli/src/diagnostics.rs
+++ b/cli/src/diagnostics.rs
@@ -387,12 +387,28 @@ impl<'a> DiagnosticRenderer<'a> {
             .map(|r| serde_json::json!({ "severity": r.severity.label(), "message": r.message }))
             .collect();
 
+        let suggestions_json: Vec<_> = diag
+            .suggestions
+            .iter()
+            .map(|s| {
+                serde_json::json!({
+                    "message": s.message,
+                    "replacement": s.replacement,
+                    "span": {
+                        "start": s.span.start,
+                        "end": s.span.end,
+                    }
+                })
+            })
+            .collect();
+
         let obj = serde_json::json!({
             "severity": diag.severity.label(),
             "code": diag.code.map(|c| format!("{:?}", c)),
             "message": diag.message,
             "span": span_json,
             "related": related_json,
+            "suggestions": suggestions_json,
         });
 
         obj.to_string()
@@ -480,3 +496,41 @@ impl DiagnosticStats {
         .to_string()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use techscript_common::Span;
+
+    #[test]
+    fn test_fix_suggestion_rendering() {
+        let sm = SourceManager::new();
+        let diag =
+            RichDiagnostic::error("undefined variable `foo`").with_suggestion(FixSuggestion {
+                message: "change to `bar`".into(),
+                span: Span::new(0, 3),
+                replacement: "bar".into(),
+            });
+
+        // Plain output rendering
+        let renderer_plain = DiagnosticRenderer::new(DiagnosticOutput::Plain, &sm);
+        let rendered_plain = renderer_plain.render(&diag);
+        assert!(rendered_plain.contains("suggestion: change to `bar` → `bar`"));
+
+        // Colored output rendering
+        let renderer_colored = DiagnosticRenderer::new(DiagnosticOutput::Colored, &sm);
+        let rendered_colored = renderer_colored.render(&diag);
+        assert!(rendered_colored.contains("suggestion"));
+        assert!(rendered_colored.contains("change to `bar`"));
+        assert!(rendered_colored.contains("bar"));
+
+        // JSON output rendering
+        let renderer_json = DiagnosticRenderer::new(DiagnosticOutput::Json, &sm);
+        let json_str = renderer_json.render(&diag);
+        let parsed: serde_json::Value = serde_json::from_str(&json_str).unwrap();
+        assert_eq!(parsed["suggestions"][0]["message"], "change to `bar`");
+        assert_eq!(parsed["suggestions"][0]["replacement"], "bar");
+        assert_eq!(parsed["suggestions"][0]["span"]["start"], 0);
+        assert_eq!(parsed["suggestions"][0]["span"]["end"], 3);
+    }
+}
diff --git a/examples/threads/threads.txs b/examples/threads/threads.txs
index 7396bb40..34286a5d 100644
--- a/examples/threads/threads.txs
+++ b/examples/threads/threads.txs
@@ -6,12 +6,12 @@ spawn_fn = thread["spawn"]
 join_fn = thread["join"]
 
 do task_a()
-    time.sleep(100)
+    time.sleep(200)
     say "Task A completed on worker thread."
 end
 
 do task_b()
-    time.sleep(50)
+    time.sleep(10)
     say "Task B completed on worker thread."
 end
 
diff --git a/stdlib/tests/stdlib_tests.rs b/stdlib/tests/stdlib_tests.rs
index 05c13a8c..51fdb1dc 100644
--- a/stdlib/tests/stdlib_tests.rs
+++ b/stdlib/tests/stdlib_tests.rs
@@ -519,6 +519,7 @@ fn test_http_module() {
             let response = "HTTP/1.1 200 OK\r\nContent-Length: 13\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\nHello Server!";
             let _ = stream.write_all(response.as_bytes());
             let _ = stream.flush();
+            let _ = stream.shutdown(std::net::Shutdown::Both);
         }
     });