fix(notify): route icon-like content images to the app-icon slot

Clients like kitty, mail and opencode send their icon through the content-image hint, so it drew as a large balloon preview. A theme-name source, an SVG, or a raster small on both sides now fills the app-icon slot instead; a larger raster (a screenshot) stays the preview. An app_icon already present keeps the slot.

3 files changed, 163 insertions, 1 deletions

diff --git a/internal/notify/classify.go b/internal/notify/classify.go
new file mode 100644
index 0000000..c7e0dc8
--- /dev/null
+++ b/internal/notify/classify.go
@@ -0,0 +1,58 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+package notify
+
+import (
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// IconMaxPixels is the long-side bound below which a content image is treated
+// as an icon rather than a preview. A screenshot is far larger; a themed icon
+// or an application logo is not.
+const IconMaxPixels = 128
+
+// IsIconImage reports whether a content image should fill the app-icon slot
+// instead of the large preview. Clients disagree about where the icon goes:
+// kitty, mail and opencode send it through the content-image hint, while a
+// screenshot uses the same hint. The hint is one of the icon forms when the
+// client sent a theme name, when the resolved file is an SVG, or when a raster
+// is small on both sides. raw is the value before ResolveIcon; resolved is the
+// path it resolved to.
+func IsIconImage(raw, resolved string) bool {
+	if raw != "" && !strings.Contains(raw, "/") && !strings.HasPrefix(raw, "file:") {
+		return true
+	}
+	if resolved == "" {
+		return false
+	}
+	if strings.EqualFold(filepath.Ext(resolved), ".svg") {
+		return true
+	}
+	f, err := os.Open(resolved)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+	cfg, _, err := image.DecodeConfig(f)
+	if err != nil {
+		// A format without a registered decoder is not something we can size,
+		// so it stays a preview rather than being silently dropped.
+		return false
+	}
+	return cfg.Width <= IconMaxPixels && cfg.Height <= IconMaxPixels
+}
diff --git a/internal/notify/classify_test.go b/internal/notify/classify_test.go
new file mode 100644
index 0000000..6234008
--- /dev/null
+++ b/internal/notify/classify_test.go
@@ -0,0 +1,95 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+package notify
+
+import (
+	"image"
+	"image/png"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/godbus/dbus/v5"
+)
+
+func writeTestPNG(t *testing.T, path string, w, h int) {
+	t.Helper()
+	f, err := os.Create(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+	if err := png.Encode(f, image.NewRGBA(image.Rect(0, 0, w, h))); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIsIconImage(t *testing.T) {
+	dir := t.TempDir()
+	small := filepath.Join(dir, "logo.png")
+	large := filepath.Join(dir, "shot.png")
+	svg := filepath.Join(dir, "icon.svg")
+	writeTestPNG(t, small, 32, 32)
+	writeTestPNG(t, large, 800, 600)
+	if err := os.WriteFile(svg, []byte("<svg/>"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	cases := []struct {
+		name          string
+		raw, resolved string
+		want          bool
+	}{
+		{"theme name", "utilities-terminal", "/x/apps/16/utilities-terminal.svg", true},
+		{"svg", svg, svg, true},
+		{"small raster", small, small, true},
+		{"large raster", large, large, false},
+		{"missing file", "/no/such.png", "/no/such.png", false},
+		{"empty", "", "", false},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := IsIconImage(c.raw, c.resolved); got != c.want {
+				t.Fatalf("IsIconImage(%q, %q) = %v, want %v", c.raw, c.resolved, got, c.want)
+			}
+		})
+	}
+}
+
+func TestNotifyRoutesContentImageByKind(t *testing.T) {
+	dir := t.TempDir()
+	small := filepath.Join(dir, "logo.png")
+	large := filepath.Join(dir, "shot.png")
+	writeTestPNG(t, small, 32, 32)
+	writeTestPNG(t, large, 800, 600)
+
+	run := func(path string) Popup {
+		var live []Popup
+		s := &Service{dir: t.TempDir(), timers: map[uint32]*time.Timer{}}
+		s.store = NewStore(s.emitClosed, func(l, _ []Popup) { live = l }, s.removeImage)
+		hints := map[string]dbus.Variant{"image-path": dbus.MakeVariant(path)}
+		if _, err := s.Notify("app", 0, "", "s", "b", nil, hints, -1); err != nil {
+			t.Fatal(err)
+		}
+		if len(live) != 1 {
+			t.Fatalf("published %d popups", len(live))
+		}
+		return live[0]
+	}
+
+	if p := run(small); p.Icon != small || p.Image != "" {
+		t.Fatalf("small image: icon=%q image=%q, want icon only", p.Icon, p.Image)
+	}
+	if p := run(large); p.Icon != "" || p.Image != large {
+		t.Fatalf("large image: icon=%q image=%q, want image only", p.Icon, p.Image)
+	}
+}
diff --git a/internal/notify/service.go b/internal/notify/service.go
index 86918d4..a2bf103 100644
--- a/internal/notify/service.go
+++ b/internal/notify/service.go
@@ -120,7 +120,16 @@ func (s *Service) Notify(appName string, replacesID uint32, appIcon, summary, bo
 	if r, ok := ImageDataFromHints(hints); ok {
 		raw = r
 	} else if path, ok := ImagePathFromHints(hints); ok {
-		n.Image = ResolveIcon(path)
+		resolved := ResolveIcon(path)
+		// An icon-like content image (a theme name, an SVG, a small raster) is
+		// the app icon clients like kitty send through this hint; a larger
+		// raster is a screenshot and stays the balloon preview. An app_icon
+		// already provided keeps the slot.
+		if IsIconImage(path, resolved) && n.Icon == "" {
+			n.Icon = resolved
+		} else {
+			n.Image = resolved
+		}
 	} else if r, ok := IconDataFromHints(hints); ok {
 		raw = r
 	}