Add support for <br/> tag

Sources/BeautifulMermaid/Layout/SequenceLayout.swift

@@ -379,11 +379,16 @@ public struct SequenceLayout: GraphLayoutAlgorithm {
         // Port of: lines 263-293
         var notes: [PositionedSequenceNote] = []
         for note in diagram.notes {
+            let noteMetrics = measureMultilineText(
+                note.text,
+                fontSize: RenderConfig.shared.fontSizeEdgeLabel,
+                fontWeight: RenderConfig.shared.fontWeightEdgeLabel
+            )
             let noteW = max(
                 c.noteWidth,
-                measureText(note.text, fontSize: RenderConfig.shared.fontSizeEdgeLabel, fontWeight: RenderConfig.shared.fontWeightEdgeLabel) + c.notePadding * 2
+                noteMetrics.width + c.notePadding * 2
             )
-            let noteH = RenderConfig.shared.fontSizeEdgeLabel + c.notePadding * 2
+            let noteH = noteMetrics.height + c.notePadding * 2
 
             // Position based on the message after which it appears
             let refMsg = note.afterIndex >= 0 && note.afterIndex < messages.count ? messages[note.afterIndex] : nil
@@ -538,9 +543,16 @@ public struct SequenceLayout: GraphLayoutAlgorithm {
         return config.estimateTextWidth(text, fontSize: fontSize, fontWeight: fontWeight)
     }
 
-    private func measureNoteHeight(_ text: String) -> CGFloat {
-        let lineCount = max(1, text.components(separatedBy: "\n").count)
-        let lineHeight: CGFloat = 16
-        return CGFloat(lineCount) * lineHeight + SequenceConstants.notePadding * 2
+    private func measureMultilineText(_ text: String,
+                                      fontSize: CGFloat,
+                                      fontWeight: Int,
+                                      lineSpacing: CGFloat = 4) -> (width: CGFloat, height: CGFloat) {
+        let lines = text.components(separatedBy: "\n")
+        let nonEmptyLines = lines.isEmpty ? [""] : lines
+        let maxWidth = nonEmptyLines.map { measureText($0, fontSize: fontSize, fontWeight: fontWeight) }.max() ?? 0
+        let lineCount = max(1, nonEmptyLines.count)
+        let lineHeight = ceil(fontSize)
+        let height = CGFloat(lineCount) * lineHeight + CGFloat(max(0, lineCount - 1)) * lineSpacing
+        return (maxWidth, height)
     }
 }

Sources/BeautifulMermaid/Parser/SequenceParser.swift

@@ -401,7 +401,7 @@ public struct SequenceParser {
             return nil
         }
 
-        let text = textPart.trimmingCharacters(in: .whitespaces)
+        let text = normalizeHtmlBreaks(in: textPart).trimmingCharacters(in: .whitespaces)
 
         return SequenceNote(
             actorIds: actorIds,
@@ -410,4 +410,8 @@ public struct SequenceParser {
             afterIndex: afterIndex
         )
     }
+
+    private func normalizeHtmlBreaks(in text: String) -> String {
+        text.replacingOccurrences(of: #"(?i)<br\s*/?>"#, with: "\n", options: .regularExpression)
+    }
 }

Sources/BeautifulMermaid/Render/LabelRenderer.swift

@@ -125,13 +125,21 @@ public class LabelRenderer {
         context: CGContext,
         color: BMColor,
         font: BMFont,
+        alignment: TextAlignment = .center,
         lineSpacing: CGFloat = 4
     ) {
         guard !text.isEmpty else { return }
 
         let paragraphStyle = NSMutableParagraphStyle()
         paragraphStyle.lineSpacing = lineSpacing
-        paragraphStyle.alignment = .center
+        switch alignment {
+        case .left:
+            paragraphStyle.alignment = .left
+        case .center:
+            paragraphStyle.alignment = .center
+        case .right:
+            paragraphStyle.alignment = .right
+        }
 
         let attributes: [NSAttributedString.Key: Any] = [
             .font: font,

Sources/BeautifulMermaid/Render/SequenceRenderer.swift

@@ -315,14 +315,13 @@ public class SequenceRenderer {
             if !note.text.isEmpty {
                 let textRect = bounds.insetBy(dx: SequenceConstants.notePadding, dy: SequenceConstants.notePadding)
                 let noteFont = RenderConfig.shared.edgeLabelFont()
-                labelRenderer.drawText(
+                labelRenderer.drawMultilineText(
                     note.text,
                     in: textRect,
                     context: context,
                     color: theme.effectiveMuted(),
                     font: noteFont,
-                    alignment: .left,
-                    verticalAlignment: .center
+                    alignment: .left
                 )
             }
         }

Tests/BeautifulMermaidTests/SequenceTests.swift

@@ -285,6 +285,20 @@ final class SequenceTests: XCTestCase {
         XCTAssertEqual(diagram.notes[0].actorIds, ["A", "B"])
     }
 
+    func testNoteHtmlBreaksNormalizeToNewlines() {
+        let source = """
+        sequenceDiagram
+            Note right of B: line 1<br/>line 2<BR>line 3<br />line 4
+            A->>B: Hello
+        """
+
+        let diagram = parseSequenceDiagram(source)
+
+        XCTAssertEqual(diagram.notes.count, 1)
+        XCTAssertEqual(diagram.notes[0].text, "line 1\nline 2\nline 3\nline 4")
+        XCTAssertFalse(diagram.notes[0].text.contains("<br"))
+    }
+
     func testImplicitParticipants() {
         let source = """
         sequenceDiagram
@@ -383,6 +397,30 @@ final class SequenceTests: XCTestCase {
         XCTAssertTrue(positioned.height > 0)
     }
 
+    func testMultilineNoteIncreasesNoteHeight() {
+        let singleSource = """
+        sequenceDiagram
+            participant A
+            participant B
+            Note right of B: Single line
+            A->>B: Hello
+        """
+        let multiSource = """
+        sequenceDiagram
+            participant A
+            participant B
+            Note right of B: Line 1<br/>Line 2
+            A->>B: Hello
+        """
+
+        let single = layoutSequenceDiagram(parseSequenceDiagram(singleSource))
+        let multi = layoutSequenceDiagram(parseSequenceDiagram(multiSource))
+
+        XCTAssertEqual(single.notes.count, 1)
+        XCTAssertEqual(multi.notes.count, 1)
+        XCTAssertGreaterThan(multi.notes[0].bounds.height, single.notes[0].bounds.height)
+    }
+
     // MARK: - Integration Tests
 
     func testFullDiagram() {