refactor(tui): address PR review feedback

- Rename CodeBlockCopyLabel -> CodeBlockCopyIcon (and related local
  variables) for naming consistency with other UI affordances.
- Rename cached style ansiCodeBgMuted -> ansiCodeBlockCopyIcon to make
  its purpose explicit; it remains derived from theme-controlled colors
  (codeBg + TextMutedGray) so theme overrides flow through ResetStyles
  as before.
- Replace the magic +2 in IncrementalRenderer.mergeCodeBlocks with a
  named joinSeparatorLines constant tied to joinPrefixAndTail's
  contract.

Author: rumpl

pkg/tui/components/markdown/codeblock.go

@@ -1,16 +1,16 @@
 package markdown
 
-// CodeBlockCopyLabel is the unicode glyph rendered at the top-right corner of
+// CodeBlockCopyIcon is the unicode glyph rendered at the top-right corner of
 // every fenced code block. Clicking on it copies the block's raw content to
 // the clipboard. It matches the glyph used for the message-level copy
 // affordance so the visual language stays consistent; the two are
 // disambiguated by line index, not by glyph.
-const CodeBlockCopyLabel = "\u2398"
+const CodeBlockCopyIcon = "\u2398"
 
 // CodeBlock describes a fenced code block emitted by the renderer.
 //
 // Line is the 0-indexed line, within the renderer's output, where the copy
-// label is rendered on the code block's top padding row. Content holds the
+// icon is rendered on the code block's top padding row. Content holds the
 // raw code (without ANSI styling) so callers can place it on the clipboard.
 type CodeBlock struct {
 	Content string

pkg/tui/components/markdown/fast_renderer.go

@@ -117,19 +117,19 @@ type cachedStyles struct {
 	styleCodeBg lipgloss.Style // kept only because chroma styles inherit its bg color
 
 	// ANSI styles (for fast inline rendering)
-	ansiBold        ansiStyle
-	ansiItalic      ansiStyle
-	ansiBoldItal    ansiStyle
-	ansiStrike      ansiStyle
-	ansiCode        ansiStyle
-	ansiLink        ansiStyle
-	ansiLinkText    ansiStyle
-	ansiText        ansiStyle    // base document text style
-	ansiHeadings    [6]ansiStyle // heading styles for inline restoration
-	ansiBlockquote  ansiStyle    // blockquote style for inline restoration
-	ansiFootnote    ansiStyle    // footnote reference style
-	ansiCodeBg      ansiStyle    // code block background (cached to avoid repeated buildAnsiStyle)
-	ansiCodeBgMuted ansiStyle    // muted foreground on code block background (for code-block chrome like copy label)
+	ansiBold              ansiStyle
+	ansiItalic            ansiStyle
+	ansiBoldItal          ansiStyle
+	ansiStrike            ansiStyle
+	ansiCode              ansiStyle
+	ansiLink              ansiStyle
+	ansiLinkText          ansiStyle
+	ansiText              ansiStyle    // base document text style
+	ansiHeadings          [6]ansiStyle // heading styles for inline restoration
+	ansiBlockquote        ansiStyle    // blockquote style for inline restoration
+	ansiFootnote          ansiStyle    // footnote reference style
+	ansiCodeBg            ansiStyle    // code block background (cached to avoid repeated buildAnsiStyle)
+	ansiCodeBlockCopyIcon ansiStyle    // muted foreground on code block background, used for the per-block copy icon
 
 	// Pre-rendered chrome (computed once, reused across renders)
 	headingPrefixes         [6]string // raw prefix strings (e.g. "## ") for width math
@@ -243,7 +243,7 @@ func getGlobalStyles() *cachedStyles {
 			ansiBlockquote:          buildAnsiStyle(blockquoteLipStyle),
 			ansiFootnote:            buildAnsiStyle(lipgloss.NewStyle().Foreground(styles.TextSecondary).Italic(true)),
 			ansiCodeBg:              buildAnsiStyle(codeBg),
-			ansiCodeBgMuted:         buildAnsiStyle(codeBg.Foreground(styles.TextMutedGray)),
+			ansiCodeBlockCopyIcon:   buildAnsiStyle(codeBg.Foreground(styles.TextMutedGray)),
 			headingPrefixes:         headingPrefixes,
 			styledHeadingPrefixes:   styledPrefixes,
 			styledHeadingContIndent: styledContIndents,
@@ -1936,16 +1936,16 @@ func (p *parser) renderCodeBlockWithIndent(code, lang, indent string, availableW
 	// back to this block's raw content.
 	topLine := strings.Count(p.out.String(), "\n")
 	p.out.WriteString(indent)
-	labelWidth := runewidth.StringWidth(CodeBlockCopyLabel)
-	leftFill := max(availableWidth-paddingRight-labelWidth, 0)
-	if availableWidth >= labelWidth+paddingRight {
+	iconWidth := runewidth.StringWidth(CodeBlockCopyIcon)
+	leftFill := max(availableWidth-paddingRight-iconWidth, 0)
+	if availableWidth >= iconWidth+paddingRight {
 		bgStyle.renderTo(&p.out, spaces(leftFill))
-		p.styles.ansiCodeBgMuted.renderTo(&p.out, CodeBlockCopyLabel)
+		p.styles.ansiCodeBlockCopyIcon.renderTo(&p.out, CodeBlockCopyIcon)
 		if paddingRight > 0 {
 			bgStyle.renderTo(&p.out, spaces(paddingRight))
 		}
 	} else {
-		// Too narrow for the label; fall back to a plain top padding row.
+		// Too narrow for the icon; fall back to a plain top padding row.
 		bgStyle.renderTo(&p.out, fullWidthPad)
 	}
 	p.out.WriteByte('\n')

pkg/tui/components/markdown/fast_renderer_test.go

@@ -2045,7 +2045,7 @@ func TestFastRendererCodeBlocksReturnsRawContent(t *testing.T) {
 	lines := strings.Split(out, "\n")
 	for _, b := range blocks {
 		require.Less(t, b.Line, len(lines), "code block line index out of range")
-		assert.Contains(t, stripANSI(lines[b.Line]), CodeBlockCopyLabel,
+		assert.Contains(t, stripANSI(lines[b.Line]), CodeBlockCopyIcon,
 			"line %d should contain the code block copy label", b.Line)
 	}
 
@@ -2076,6 +2076,6 @@ func TestIncrementalRendererCodeBlocksAggregate(t *testing.T) {
 	lines := strings.Split(out, "\n")
 	for _, b := range blocks2 {
 		require.Less(t, b.Line, len(lines))
-		assert.Contains(t, stripANSI(lines[b.Line]), CodeBlockCopyLabel)
+		assert.Contains(t, stripANSI(lines[b.Line]), CodeBlockCopyIcon)
 	}
 }

pkg/tui/components/markdown/incremental.go

@@ -217,10 +217,15 @@ func (r *IncrementalRenderer) joinPrefixAndTail(prefix, tail string) string {
 	return b.String()
 }
 
+// joinSeparatorLines is the number of extra rendered lines that
+// joinPrefixAndTail inserts between the prefix output and the tail output:
+// one to terminate the prefix's final (untrailing-newlined) line, and one
+// blank-padded separator line. Keep this in sync with joinPrefixAndTail.
+const joinSeparatorLines = 2
+
 // mergeCodeBlocks returns the union of code blocks from a cached prefix output
-// and a freshly rendered tail. Tail block line indices are shifted by the
-// number of lines in the prefix plus one for the blank separator inserted by
-// joinPrefixAndTail.
+// and a freshly rendered tail. Tail block line indices are shifted past the
+// prefix's lines and the separator that joinPrefixAndTail inserts.
 func (r *IncrementalRenderer) mergeCodeBlocks(prefixOut string, prefixBlocks, tailBlocks []CodeBlock) []CodeBlock {
 	if len(prefixBlocks) == 0 && len(tailBlocks) == 0 {
 		return nil
@@ -232,10 +237,7 @@ func (r *IncrementalRenderer) mergeCodeBlocks(prefixOut string, prefixBlocks, ta
 	}
 	offset := 0
 	if prefixOut != "" {
-		// Number of lines in prefix (FastRenderer trims its trailing newline so
-		// the count is newlines + 1) plus one for the blank separator inserted
-		// by joinPrefixAndTail.
-		offset = strings.Count(prefixOut, "\n") + 2
+		offset = strings.Count(prefixOut, "\n") + joinSeparatorLines
 	}
 	for _, b := range tailBlocks {
 		out = append(out, CodeBlock{Content: b.Content, Line: b.Line + offset})

pkg/tui/components/messages/messages.go

@@ -1766,13 +1766,13 @@ func (m *model) codeBlockAt(msgIdx, localLine, col int) (string, bool) {
 		return "", false
 	}
 	plainLine := ansi.Strip(item.lines[localLine])
-	before, _, found := strings.Cut(plainLine, markdown.CodeBlockCopyLabel)
+	before, _, found := strings.Cut(plainLine, markdown.CodeBlockCopyIcon)
 	if !found {
 		return "", false
 	}
-	labelStart := ansi.StringWidth(before)
-	labelEnd := labelStart + ansi.StringWidth(markdown.CodeBlockCopyLabel)
-	if col < labelStart || col >= labelEnd {
+	iconStart := ansi.StringWidth(before)
+	iconEnd := iconStart + ansi.StringWidth(markdown.CodeBlockCopyIcon)
+	if col < iconStart || col >= iconEnd {
 		return "", false
 	}
 	return target.Content, true