Export diagrams as interactive HTML from the app and an agent tool

internal/agents/diagram.go

@@ -44,7 +44,50 @@ func (m *Manager) renderDiagramTool() mcp.Tool {
 	}
 }
 
-func renderDiagram(ctx context.Context, source string) ([]byte, error) {
+func (m *Manager) exportDiagramTool(l *live) mcp.Tool {
+	return mcp.Tool{
+		Name: "export_diagram",
+		Description: "Export a diagram as a self-contained HTML page, drawn exactly as byre's app lays it out and as interactive as its full-size view: clicking a box highlights it, its arrows and its neighbors, each highlight line is a button, and it zooms and pans. " +
+			"Pass the body of a ```diagram block and the file to write; show it with show_page.",
+		InputSchema: json.RawMessage(`{
+			"type": "object",
+			"properties": {
+				"source": {"type": "string", "description": "The block's body, without the fence lines."},
+				"path": {"type": "string", "description": "The HTML file to write, relative to your worktree, absolute, or starting with ~/."}
+			},
+			"required": ["source", "path"]
+		}`),
+		Handler: func(ctx context.Context, raw json.RawMessage) (string, error) {
+			args := struct {
+				Source string `json:"source"`
+				Path   string `json:"path"`
+			}{}
+			err := json.Unmarshal(raw, &args)
+			if err != nil {
+				return "", fmt.Errorf("malformed export_diagram call: %w", err)
+			}
+			full, err := l.resolve(args.Path)
+			if err != nil {
+				return "", err
+			}
+			html, err := renderDiagram(ctx, args.Source, "--html")
+			if err != nil {
+				return "", err
+			}
+			err = os.MkdirAll(filepath.Dir(full), 0o755)
+			if err != nil {
+				return "", err
+			}
+			err = os.WriteFile(full, html, 0o644)
+			if err != nil {
+				return "", err
+			}
+			return fmt.Sprintf("Wrote the diagram to %s.", args.Path), nil
+		},
+	}
+}
+
+func renderDiagram(ctx context.Context, source string, flags ...string) ([]byte, error) {
 	exe, err := os.Executable()
 	if err != nil {
 		return nil, err
@@ -52,7 +95,7 @@ func renderDiagram(ctx context.Context, source string) ([]byte, error) {
 	app := filepath.Join(filepath.Dir(exe), "..", "MacOS", "Byre")
 	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
 	defer cancel()
-	cmd := exec.CommandContext(ctx, app, "render-diagram")
+	cmd := exec.CommandContext(ctx, app, append([]string{"render-diagram"}, flags...)...)
 	cmd.Stdin = strings.NewReader(source)
 	stderr := bytes.Buffer{}
 	cmd.Stderr = &stderr