oAI/Views/Main/MarkdownContentView.swift

@@ -61,8 +61,15 @@ struct MarkdownContentView: View {
             .markdownBlockStyle(\.paragraph) { configuration in
                 configuration.label
                     .markdownMargin(top: 0, bottom: 8)
+                    // MarkdownUI builds mixed-style paragraphs (bold/italic runs alongside
+                    // plain text) as concatenated Text(+) segments, which on macOS report
+                    // their ideal (unwrapped, single-line) size instead of wrapping to the
+                    // width actually available — truncating with "…" mid-word. Forcing the
+                    // height to be recomputed for the given (flexible) width fixes it.
+                    .fixedSize(horizontal: false, vertical: true)
             }
             .textSelection(.enabled)
+            .frame(maxWidth: .infinity, alignment: .leading)
     }
 
     // MARK: - Parsing

oAI/Views/Main/MessageRow.swift

@@ -185,6 +185,7 @@ struct MessageRow: View {
                     .foregroundColor(.oaiSecondary)
                 }
             }
+            .frame(maxWidth: .infinity, alignment: .leading)
         }
         .padding(16)
         .background(Color.messageBackground(for: message.role))