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AgentiLoopAgentiLoop
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Unified (git) diff highlighting: -/+ red/green with tint, @@ cyan, headers bold; isUnifiedDiffLine for callers
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2 files changed

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‎Sources/AgentColorSyntax/CodeBlockSyntax+Diff.swift‎

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Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@ extension CodeBlockHighlighter {
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/// Highlight a diff code block with red/green backgrounds for removed/added lines,
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/// and line numbers for context. Format: "LINE_NUM -\tcode" or "LINE_NUM +\tcode" or "LINE_NUM\tcode"
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public static func highlightDiffBlock(code: String, font: NSFont) -> NSAttributedString {
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if looksLikeUnifiedDiff(code) { return highlightUnifiedDiff(code: code, font: font) }
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let text = CodeBlockTheme.text
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let result = NSMutableAttributedString(string: code, attributes: [
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.font: font, .foregroundColor: text
@@ -81,4 +82,64 @@ extension CodeBlockHighlighter {
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return result
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}
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// MARK: - Unified (git) diff
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/// Header lines that can appear inside a git diff between hunks.
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private static let unifiedHeaderPrefixes = [
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"diff --git ", "index ", "--- ", "+++ ", "new file mode", "deleted file mode",
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"old mode", "new mode", "similarity index", "rename from", "rename to", "Binary files"
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]
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/// True for `git diff` / `diff -u` output: a `diff --git` header, or `---`/`+++` file headers plus an `@@` hunk.
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public static func looksLikeUnifiedDiff(_ code: String) -> Bool {
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let t = code.drop(while: { $0 == "\n" || $0 == " " })
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if t.hasPrefix("diff --git ") { return true }
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return code.contains("\n@@ ") && code.contains("--- ") && code.contains("+++ ")
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}
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/// True if `line` can belong to a unified diff (header, hunk, context, add, remove, "\ No newline").
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public static func isUnifiedDiffLine(_ line: Substring) -> Bool {
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guard let c = line.first else { return false }
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if c == " " || c == "+" || c == "-" || c == "\\" { return true }
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if line.hasPrefix("@@") { return true }
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return unifiedHeaderPrefixes.contains(where: { line.hasPrefix($0) })
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}
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/// git-style coloring: file headers bold, `@@` hunks cyan, `-` lines red, `+` lines green (with tinted background).
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public static func highlightUnifiedDiff(code: String, font: NSFont) -> NSAttributedString {
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let isDark = CodeBlockTheme.isDark
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let result = NSMutableAttributedString(string: code, attributes: [
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.font: font, .foregroundColor: CodeBlockTheme.text
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])
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let bold = NSFont.monospacedSystemFont(ofSize: font.pointSize, weight: .bold)
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let removedBg = isDark ? NSColor(red: 0.4, green: 0.1, blue: 0.1, alpha: 0.6) : NSColor(red: 1.0, green: 0.88, blue: 0.88, alpha: 1)
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let addedBg = isDark ? NSColor(red: 0.1, green: 0.3, blue: 0.1, alpha: 0.6) : NSColor(red: 0.88, green: 1.0, blue: 0.88, alpha: 1)
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let removedText = isDark ? NSColor(red: 1.0, green: 0.55, blue: 0.55, alpha: 1) : NSColor(red: 0.7, green: 0.0, blue: 0.0, alpha: 1)
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let addedText = isDark ? NSColor(red: 0.55, green: 0.95, blue: 0.55, alpha: 1) : NSColor(red: 0.0, green: 0.5, blue: 0.0, alpha: 1)
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let hunk = isDark ? NSColor(red: 0.4, green: 0.85, blue: 0.85, alpha: 1) : NSColor(red: 0.0, green: 0.5, blue: 0.5, alpha: 1)
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let meta = isDark ? NSColor(red: 0.6, green: 0.6, blue: 0.65, alpha: 1) : NSColor(red: 0.4, green: 0.4, blue: 0.45, alpha: 1)
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let ns = code as NSString
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var loc = 0
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while loc < ns.length {
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let lr = ns.lineRange(for: NSRange(location: loc, length: 0))
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var body = lr
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if body.length > 0, ns.character(at: NSMaxRange(body) - 1) == 10 { body.length -= 1 }
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let line = ns.substring(with: body)
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if line.hasPrefix("diff --git ") || line.hasPrefix("--- ") || line.hasPrefix("+++ ") {
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result.addAttributes([.foregroundColor: CodeBlockTheme.text, .font: bold], range: body)
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} else if line.hasPrefix("@@") {
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result.addAttribute(.foregroundColor, value: hunk, range: body)
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} else if line.hasPrefix("-") {
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result.addAttributes([.foregroundColor: removedText, .backgroundColor: removedBg], range: body)
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} else if line.hasPrefix("+") {
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result.addAttributes([.foregroundColor: addedText, .backgroundColor: addedBg], range: body)
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} else if unifiedHeaderPrefixes.contains(where: { line.hasPrefix($0) }) || line.hasPrefix("\\") {
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result.addAttribute(.foregroundColor, value: meta, range: body)
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}
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loc = NSMaxRange(lr)
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}
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return result
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}
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}

‎Tests/AgentColorSyntaxTests/UnifiedDiffTests.swift‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,64 @@
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import Testing
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import AppKit
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@testable import AgentColorSyntax
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@Suite("Unified diff highlighting")
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struct UnifiedDiffTests {
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private let font = NSFont.monospacedSystemFont(ofSize: 12, weight: .regular)
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private let gitDiff = """
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diff --git a/Package.resolved b/Package.resolved
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index 9d8b2ce4..be58c69d 100644
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--- a/Package.resolved
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+++ b/Package.resolved
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@@ -24,8 +24,8 @@
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"kind" : "remoteSourceControl",
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- "revision" : "5a5e994ad75768bd3593708016c3af19ef3edb12",
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- "version" : "1.2.8"
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+ "revision" : "bf2ad909ca6032adec835f6cfb1ecfc5b66d36a3",
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+ "version" : "1.2.9"
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}
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"""
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private func attr(_ s: NSAttributedString, _ key: NSAttributedString.Key, at text: String) -> Any? {
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let loc = (s.string as NSString).range(of: text).location
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guard loc != NSNotFound else { return nil }
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return s.attribute(key, at: loc, effectiveRange: nil)
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}
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@Test("git diff output is detected; line-numbered D1F diffs are not")
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func detection() {
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#expect(CodeBlockHighlighter.looksLikeUnifiedDiff(gitDiff))
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#expect(!CodeBlockHighlighter.looksLikeUnifiedDiff("12 -\told\n12 +\tnew"))
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}
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@Test("- lines red, + lines green, context plain, @@ distinct, headers bold")
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func colors() {
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let s = CodeBlockHighlighter.highlight(code: gitDiff, language: "diff", font: font)
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let removed = attr(s, .foregroundColor, at: "- \"version\" : \"1.2.8\"") as? NSColor
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let added = attr(s, .foregroundColor, at: "+ \"version\" : \"1.2.9\"") as? NSColor
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let context = attr(s, .foregroundColor, at: "\"kind\"") as? NSColor
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let hunk = attr(s, .foregroundColor, at: "@@ -24") as? NSColor
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#expect(removed != nil && added != nil && removed != added)
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#expect(context == CodeBlockTheme.text)
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#expect(removed != context && added != context)
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#expect(hunk != context && hunk != removed && hunk != added)
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#expect(attr(s, .backgroundColor, at: "- \"version\"") != nil)
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#expect(attr(s, .backgroundColor, at: "\"kind\"") == nil)
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let bold = NSFont.monospacedSystemFont(ofSize: 12, weight: .bold)
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#expect(attr(s, .font, at: "--- a/") as? NSFont == bold)
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#expect(attr(s, .font, at: "+++ b/") as? NSFont == bold)
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// The "--- a/" header must not get removed-line red.
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#expect(attr(s, .foregroundColor, at: "--- a/") as? NSColor != removed)
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}
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@Test("isUnifiedDiffLine accepts diff lines and rejects log lines")
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func lineClassifier() {
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#expect(CodeBlockHighlighter.isUnifiedDiffLine("+x"))
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#expect(CodeBlockHighlighter.isUnifiedDiffLine(" ctx"))
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#expect(CodeBlockHighlighter.isUnifiedDiffLine("@@ -1 +1 @@"))
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#expect(CodeBlockHighlighter.isUnifiedDiffLine("index abc..def 100644"))
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#expect(!CodeBlockHighlighter.isUnifiedDiffLine("[18:52:01] 🔧 xcode(build)"))
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#expect(!CodeBlockHighlighter.isUnifiedDiffLine(""))
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}
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}

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