Function overlayModal

internal/tui/completion.go:527–578

overlayModal composites a modal on top of a background, centering the modal.

(background, modal string, screenWidth, screenHeight int)

// overlayModal composites a modal on top of a background, centering the modal.
func overlayModal(background, modal string, screenWidth, screenHeight int) string {
	bgLines := strings.Split(background, "\n")
	modalLines := strings.Split(modal, "\n")

	// Measure modal dimensions
	modalHeight := len(modalLines)
	modalWidth := 0
	for _, line := range modalLines {
		w := lipgloss.Width(line)
		if w > modalWidth {
			modalWidth = w
		}
	}

	// Calculate centering offsets
	offsetY := (screenHeight - modalHeight) / 2
	offsetX := (screenWidth - modalWidth) / 2
	if offsetY < 0 {
		offsetY = 0
	}
	if offsetX < 0 {
		offsetX = 0
	}

	// Pad background to full screen height
	for len(bgLines) < screenHeight {
		bgLines = append(bgLines, strings.Repeat(" ", screenWidth))
	}

	// Overlay modal lines onto background
	for i, mLine := range modalLines {
		bgIdx := offsetY + i
		if bgIdx >= len(bgLines) {
			break
		}

		mWidth := lipgloss.Width(mLine)
		if mWidth == 0 {
			continue
		}

		bgLine := bgLines[bgIdx]

		// Build: bg prefix (ANSI-aware) + modal line + bg suffix (ANSI-aware)
		prefix := ansiTruncate(bgLine, offsetX)
		suffix := ansiSkip(bgLine, offsetX+mWidth)

		bgLines[bgIdx] = prefix + mLine + suffix
	}

	return strings.Join(bgLines[:screenHeight], "\n")
}

// centerModal centers a modal string on the screen.
func centerModal(modal string, screenWidth, screenHeight int) string {