Add STBareBracketLabelCleanupRule to sanitize bare bracket labels in STMarkdown

- Introduced a new rule to convert bare bracket labels (e.g., `[偏头痛]`, `[咖啡因]`) into plain text, while excluding certain conditions such as valid Markdown links and citation formats.
- Updated `STMarkdownInputSanitizer` to include the new rule in the processing pipeline.
- Enhanced `STMarkdownBlockLayoutCalculator` with methods for handling standalone colon heading paragraphs and their spacing.
- Cleaned up comments and added creation dates in several rendering files for better documentation.

Author: i-stack

Sources/STMarkdown/Parsing/STMarkdownInputSanitizer.swift

@@ -230,6 +230,86 @@ public struct STDoubleNewlineRule: STMarkdownRule {
     }
 }
 
+/// LLM 输出中形如 `[偏头痛]`、`[咖啡因]` 的裸括号标签：cmark 将其解析为引用链接，
+/// 文档内无对应定义时回退为字面文本，方括号原样渲染。此 rule 将其去括号还原为纯文本。
+///
+/// 排除条件（不剥离）：
+/// - 后跟 `(` ——真正的 Markdown 链接
+/// - 内容为纯数字 ——citation 编号
+/// - 内容匹配 citation:N / webpage:N（大小写不限）——引用标签
+/// - 内容含 `[` 或 `]` ——双层括号结构
+/// - 位于 fenced code block 内
+public struct STBareBracketLabelCleanupRule: STMarkdownRule {
+    public let name = "STBareBracketLabelCleanupRule"
+
+    // 匹配 [xxx]，要求 xxx 不含 [ ] \n，且后面不紧跟 (
+    private static let regex = STMarkdownRegexFactory.compile(
+        pattern: #"\[([^\[\]\n]+)\](?!\()"#,
+        owner: "STBareBracketLabelCleanupRule.match"
+    )
+    // citation:N 或 webpage:N（可选冒号、可选空格）
+    private static let citationPattern = STMarkdownRegexFactory.compile(
+        pattern: #"^(?:citation|webpage)\s*:?\s*\d+$"#,
+        options: .caseInsensitive,
+        owner: "STBareBracketLabelCleanupRule.citation"
+    )
+
+    public init() {}
+
+    public func shouldApply(to text: String) -> Bool {
+        text.contains("[")
+    }
+
+    public func apply(to text: String, context: inout STMarkdownPreprocessContext) -> String {
+        let lines = text.components(separatedBy: "\n")
+        var result: [String] = []
+        result.reserveCapacity(lines.count)
+        var fenceState = STMarkdownCodeFenceState()
+
+        for line in lines {
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            fenceState.ingest(trimmedLine: trimmed)
+            if fenceState.isInside {
+                result.append(line)
+                continue
+            }
+            result.append(Self.cleanLine(line))
+        }
+
+        return result.joined(separator: "\n")
+    }
+
+    private static func cleanLine(_ line: String) -> String {
+        let nsLine = line as NSString
+        let matches = Self.regex.matches(
+            in: line,
+            range: NSRange(location: 0, length: nsLine.length)
+        )
+        guard !matches.isEmpty else { return line }
+
+        var output = line
+        for match in matches.reversed() {
+            guard match.numberOfRanges >= 2,
+                  let labelRange = Range(match.range(at: 1), in: output) else { continue }
+            let label = String(output[labelRange])
+            guard !shouldKeep(label) else { continue }
+            // 用 match.range(at: 0) 对应的当前位置在 output 里重新定位
+            guard let fullRange = Range(match.range, in: output) else { continue }
+            output.replaceSubrange(fullRange, with: label)
+        }
+        return output
+    }
+
+    private static func shouldKeep(_ label: String) -> Bool {
+        // 纯数字（citation 编号 standalone）
+        if label.allSatisfy(\.isNumber) { return true }
+        // citation:N / webpage:N
+        let range = NSRange(location: 0, length: (label as NSString).length)
+        if Self.citationPattern.firstMatch(in: label, range: range) != nil { return true }
+        return false
+    }
+}
+
 public struct STTableBlankLineNormalizationRule: STMarkdownRule {
     public let name = "STTableBlankLineNormalizationRule"
 
@@ -367,6 +447,7 @@ public struct STMarkdownInputSanitizer: Sendable {
         STTableBlankLineNormalizationRule(),
         STTableDelimiterNormalizationRule(),
         STDoubleNewlineRule(),
+        STBareBracketLabelCleanupRule(),
     ]
 
     public let rules: [any STMarkdownRule]

Sources/STMarkdown/Rendering/STMarkdownBlockLayoutCalculator.swift

@@ -2,17 +2,13 @@
 //  STMarkdownBlockLayoutCalculator.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/03/16.
+//
 
 import UIKit
 
-/// 块间距与 `NSAttributedString` 分隔符计算工具。
-///
-/// 所有方法均为纯函数，无副作用，可静态调用。
-/// 宿主（如 `NativeMarkdownView`）不再需要在内部维护等效逻辑。
 public enum STMarkdownBlockLayoutCalculator {
 
-    // MARK: - Block Spacing
-
     /// 两个相邻块之间的视觉间距（点）。
     public static func spacing(
         after previousBlock: STMarkdownRenderBlock,
@@ -44,6 +40,9 @@ public enum STMarkdownBlockLayoutCalculator {
         case .codeBlock, .table, .mathBlock, .image, .thematicBreak, .details, .rawHTML:
             return style.blockSpacing
         case .paragraph:
+            if isStandaloneColonHeadingParagraph(block) {
+                return pseudoHeadingTopSpacing(style: style)
+            }
             return style.blockSpacing
         }
     }
@@ -166,4 +165,20 @@ public enum STMarkdownBlockLayoutCalculator {
         if let next = nextBlock, isListBlock(next) { return true }
         return false
     }
+
+    /// `paragraph(only-strong, 文本以冒号结尾)` ——LLM 用 `**xxx：**` 单行模拟标题的模式。
+    public static func isStandaloneColonHeadingParagraph(_ block: STMarkdownRenderBlock) -> Bool {
+        guard isStandaloneStrongParagraph(block),
+              case .paragraph(_, let inlines) = block else { return false }
+        let text = inlineNodesVisibleText(inlines)
+        return text.hasSuffix("：") || text.hasSuffix(":")
+    }
+
+    /// 伪标题的前导间距：等同 h3 heading top spacing，降级为 blockSpacing * 1.6。
+    public static func pseudoHeadingTopSpacing(style: STMarkdownStyle) -> CGFloat {
+        if let topSpacings = style.headingTopSpacing, topSpacings.count >= 3 {
+            return topSpacings[2]   // h3 index
+        }
+        return STMarkdownTypography.headingInsets(for: 3).top
+    }
 }

Sources/STMarkdown/Rendering/STMarkdownCodeBlockMarkerInfo.swift

@@ -2,6 +2,8 @@
 //  STMarkdownCodeBlockMarkerInfo.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/03/16.
+//
 
 import UIKit
 

Sources/STMarkdown/Rendering/STMarkdownInlineCodeBlockRenderer.swift

@@ -2,6 +2,8 @@
 //  STMarkdownInlineCodeBlockRenderer.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/03/16.
+//
 
 import UIKit
 

Sources/STMarkdown/Rendering/STMarkdownMermaidAttachmentFactory.swift

@@ -2,6 +2,8 @@
 //  STMarkdownMermaidAttachmentFactory.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/03/16.
+//
 
 import UIKit
 

Sources/STMarkdown/UI/STMarkdownTextViewLinkHitTest.swift

@@ -2,6 +2,8 @@
 //  STMarkdownTextViewLinkHitTest.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/04/26.
+//
 
 import UIKit
 

Sources/STMarkdown/UI/STMarkdownTextViewMeasure.swift

@@ -2,6 +2,8 @@
 //  STMarkdownTextViewMeasure.swift
 //  STBaseProject
 //
+//  Created by 寒江孤影 on 2019/04/26.
+//
 
 import UIKit