svg-maker: svgc - .svgd text format -> SVG for agent-helm sharing

Line-based DSL (shapes, text, groups, color vars) with strict
validation and line-numbered errors, SVG emitter with visibility
defaults, truecolor terminal preview (same half-block technique as
spritec), info with bbox + outside-canvas warnings. Verified
end-to-end: svgc build -> helmd share -> visible through the hub.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011KikHkfCiC3yELbsMN8fT9

svg-maker/main.go

@@ -0,0 +1,176 @@
+// svgc builds SVG images from .svgd text descriptions — vector
+// graphics an agent can author, verify (terminal preview + info) and
+// share to agent-helm with `helmd share out.svg`.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gitea.brasse-pc.eu/brasse/agent-tools/svg-maker/svg"
+)
+
+var version = "dev"
+
+const usage = `svgc - SVG maker for agents
+
+Usage:
+  svgc build <file.svgd> [-o out.svg] [--preview] [--width N]
+  svgc preview <file.svgd> [--width N]     draw it in the terminal
+  svgc info <file.svgd>                    counts, colors, bbox, warnings
+  svgc example                             print an annotated example file
+  svgc version
+
+The .svgd format ('#' comments, one element per line):
+  canvas 200 120                       required: width height
+  bg #1a2029                           optional background
+  def accent #4f9cf9                   named color, use as $accent
+  rect 10 10 60 40 fill=$accent rx=6
+  circle 120 40 20 fill=#3fca7c stroke=white stroke-width=2
+  ellipse 60 90 30 12 fill=gray
+  line 10 100 190 100 stroke=red width=3
+  polyline 10,20 30,40 50,10 stroke=white
+  polygon 20,80 40,60 60,80 fill=#e0a63f
+  path M10,10 L50,50 Q70,20 90,50 Z stroke=white
+  text 100 60 "Hello agent-helm" size=14 fill=white anchor=middle bold
+  group stroke=gray stroke-width=1     group attrs are inherited
+    line 0 0 10 10
+  end
+
+Attributes: fill stroke stroke-width|width opacity fill-opacity
+stroke-opacity rx ry anchor size font dash linecap linejoin transform
+id, plus flags bold italic. Colors: #rgb #rrggbb, CSS names, none.
+
+Show the result in agent-helm:  helmd share out.svg --note "diagram"
+`
+
+const exampleFile = `# gauge.svgd - example: a small status card
+canvas 240 120
+bg #12161f
+
+def ok    #3fca7c
+def frame #262d3a
+
+rect 8 8 224 104 fill=none stroke=$frame stroke-width=2 rx=10
+circle 40 60 22 fill=none stroke=$ok stroke-width=6
+path M30,60 L38,68 L52,50 stroke=$ok width=5 linecap=round fill=none
+text 76 54 "backups" size=13 fill=#8a93a5
+text 76 76 "all green" size=17 fill=white bold
+`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Print(usage)
+		os.Exit(2)
+	}
+	switch os.Args[1] {
+	case "build":
+		cmdBuild(os.Args[2:])
+	case "preview":
+		cmdPreview(os.Args[2:])
+	case "info":
+		cmdInfo(os.Args[2:])
+	case "example":
+		fmt.Print(exampleFile)
+	case "version", "--version", "-v":
+		fmt.Println("svgc", version)
+	case "help", "--help", "-h":
+		fmt.Print(usage)
+	default:
+		die("unknown command %q — run 'svgc help'", os.Args[1])
+	}
+}
+
+func cmdBuild(args []string) {
+	fs := flag.NewFlagSet("build", flag.ExitOnError)
+	out := fs.String("o", "", "output file (default: input with .svg)")
+	preview := fs.Bool("preview", false, "also draw the result in the terminal")
+	width := fs.Int("width", 72, "preview width in characters")
+	pos := parseInterspersed(fs, args)
+	if len(pos) != 1 {
+		die("build takes exactly one .svgd file")
+	}
+	xml, doc := load(pos[0])
+	dst := *out
+	if dst == "" {
+		dst = strings.TrimSuffix(pos[0], filepath.Ext(pos[0])) + ".svg"
+	}
+	if err := os.WriteFile(dst, []byte(xml), 0o644); err != nil {
+		die("%v", err)
+	}
+	fmt.Printf("wrote %s (%d bytes)\n", dst, len(xml))
+	fmt.Print(svg.Info(doc))
+	if *preview {
+		fmt.Print(svg.RenderGrid(doc, *width).ANSI())
+	}
+}
+
+func cmdPreview(args []string) {
+	fs := flag.NewFlagSet("preview", flag.ExitOnError)
+	width := fs.Int("width", 72, "preview width in characters")
+	pos := parseInterspersed(fs, args)
+	if len(pos) != 1 {
+		die("preview takes exactly one .svgd file")
+	}
+	_, doc := load(pos[0])
+	fmt.Print(svg.RenderGrid(doc, *width).ANSI())
+}
+
+func cmdInfo(args []string) {
+	if len(args) != 1 {
+		die("info takes exactly one .svgd file")
+	}
+	_, doc := load(args[0])
+	fmt.Print(svg.Info(doc))
+}
+
+// load reads and builds a .svgd file (attrs normalized), dying with
+// the parser's line-numbered error on failure. Returns the SVG XML
+// and the parsed document.
+func load(path string) (string, *svg.Doc) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		die("%v", err)
+	}
+	xml, doc, err := svg.Build(string(data))
+	if err != nil {
+		die("%s: %v", path, err)
+	}
+	return xml, doc
+}
+
+// parseInterspersed lets flags appear before or after positional args.
+func parseInterspersed(fs *flag.FlagSet, args []string) []string {
+	var flags, pos []string
+	for i := 0; i < len(args); i++ {
+		a := args[i]
+		if len(a) > 1 && a[0] == '-' {
+			flags = append(flags, a)
+			name := strings.TrimLeft(a, "-")
+			if eq := strings.Index(name, "="); eq >= 0 {
+				continue
+			}
+			if f := fs.Lookup(name); f != nil {
+				if bf, ok := f.Value.(interface{ IsBoolFlag() bool }); ok && bf.IsBoolFlag() {
+					continue
+				}
+			}
+			if i+1 < len(args) {
+				i++
+				flags = append(flags, args[i])
+			}
+		} else {
+			pos = append(pos, a)
+		}
+	}
+	fs.Parse(flags)
+	return pos
+}
+
+func die(format string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, "svgc: "+format+"\n", args...)
+	os.Exit(1)
+}