feh: the wallpaper as a module, its image an archive of its own (hq ADR 0208, ADR 0205)

~/.fehbg stops pointing into the predecessor's tree; the session's xinitrc slot
runs it once; Go tools set (for the session) and current.

modules/feh/cmd/feh-tools/main.go

@@ -0,0 +1,53 @@
+// feh's Go tools bundle (novox/hq ADR 0188, ADR 0193, ADR 0208): the wallpaper's tools, served by the
+// node's runtime as the operator account.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "feh_set",
+			Description: "Set the wallpaper in the operator's session: one image for every monitor, or one per " +
+				"monitor in the X screen order, filled, centred, scaled to fit, stretched or tiled. Lasts until the " +
+				"next session start, when the declared wallpaper returns; the declared one is untouched.",
+			Input: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"images": map[string]any{"type": "array", "items": map[string]any{"type": "string"}, "description": "image files on this machine, absolute or under the account's home; one per monitor, or one for all"},
+					"mode":   map[string]any{"type": "string", "enum": modes, "description": "default fill"},
+				},
+				"required": []string{"images"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				images, err := texts(args, "images")
+				if err != nil {
+					return nil, err
+				}
+				mode, err := text(args, "mode", false)
+				if err != nil {
+					return nil, err
+				}
+				return Set(images, mode)
+			},
+		},
+		{
+			Name: "feh_current",
+			Description: "The wallpaper: the declared one the session start sets (images and mode, read from " +
+				"~/.fehbg), and the one feh_set put up in this session, if any.",
+			Run: func(map[string]any) (any, error) { return Current() },
+		},
+	}
+}