chore: import upstream snapshot with attribution

pkg/octicons/octicons.go

@@ -0,0 +1,84 @@
+// Package octicons provides helpers for working with GitHub Octicon icons.
+// See https://primer.style/foundations/icons for available icons.
+package octicons
+
+import (
+	"bufio"
+	"embed"
+	"encoding/base64"
+	"fmt"
+	"strings"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+//go:embed icons/*.png
+var iconsFS embed.FS
+
+//go:embed required_icons.txt
+var requiredIconsTxt string
+
+// RequiredIcons returns the list of icon names from required_icons.txt.
+// This is the single source of truth for which icons should be embedded.
+func RequiredIcons() []string {
+	var icons []string
+	scanner := bufio.NewScanner(strings.NewReader(requiredIconsTxt))
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		// Skip empty lines and comments
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		icons = append(icons, line)
+	}
+	return icons
+}
+
+// Theme represents the color theme of an icon.
+type Theme string
+
+const (
+	// ThemeLight is for light backgrounds (dark/black icons).
+	ThemeLight Theme = "light"
+	// ThemeDark is for dark backgrounds (light/white icons).
+	ThemeDark Theme = "dark"
+)
+
+// DataURI returns a data URI for the embedded Octicon PNG.
+// The theme parameter specifies which variant to use:
+// - ThemeLight: dark icons for light backgrounds
+// - ThemeDark: light icons for dark backgrounds
+// If the icon is not found in the embedded filesystem, it returns an empty string.
+func DataURI(name string, theme Theme) string {
+	filename := fmt.Sprintf("icons/%s-%s.png", name, theme)
+	data, err := iconsFS.ReadFile(filename)
+	if err != nil {
+		return ""
+	}
+	return "data:image/png;base64," + base64.StdEncoding.EncodeToString(data)
+}
+
+// Icons returns MCP Icon objects for the given octicon name in light and dark themes.
+// Icons are embedded as 24x24 PNG data URIs for offline use and faster loading.
+// The name should be the base octicon name without size suffix (e.g., "repo" not "repo-16").
+// See https://primer.style/foundations/icons for available icons.
+//
+// Note: The Sizes field is omitted for backward compatibility with older MCP clients
+// that expect it to be a string rather than an array per the 2025-11-25 MCP spec.
+func Icons(name string) []mcp.Icon {
+	if name == "" {
+		return nil
+	}
+	return []mcp.Icon{
+		{
+			Source:   DataURI(name, ThemeLight),
+			MIMEType: "image/png",
+			Theme:    mcp.IconThemeLight,
+		},
+		{
+			Source:   DataURI(name, ThemeDark),
+			MIMEType: "image/png",
+			Theme:    mcp.IconThemeDark,
+		},
+	}
+}