feat(notify): add the image field and its cleanup

Popup gains image, and the store calls an injected removeImage when an
entry is dismissed, evicted, replaced or expired, so a daemon-written
PNG does not outlive its balloon. The service decides what is
daemon-owned; the store only names the path.

NewStore now takes the callback as a third parameter, so the service
wires its removeImage in (unlinking only under ImagesDir) and the
existing call sites pass nil.

1 files changed, 34 insertions, 0 deletions

diff --git a/internal/notify/files.go b/internal/notify/files.go
index 53e7f3f..e4da336 100644
--- a/internal/notify/files.go
+++ b/internal/notify/files.go
@@ -15,6 +15,7 @@ import (
 	"encoding/json"
 	"os"
 	"path/filepath"
+	"strconv"
 )
 
 // RuntimeDir is where the daemon publishes. It is tmpfs, so a reboot clears
@@ -45,6 +46,39 @@ func Publish(dir string, live, history []Popup) error {
 	return writeJSON(filepath.Join(dir, "history.json"), history)
 }
 
+// ImagesDir is where the daemon writes decoded image-data.
+func ImagesDir(dir string) string {
+	return filepath.Join(dir, "img")
+}
+
+// WriteImage writes a decoded image as <id>.png under the image directory.
+func WriteImage(dir string, id uint32, data []byte) (string, error) {
+	imgDir := ImagesDir(dir)
+	if err := os.MkdirAll(imgDir, 0o700); err != nil {
+		return "", err
+	}
+	path := filepath.Join(imgDir, strconv.FormatUint(uint64(id), 10)+".png")
+	tmp, err := os.CreateTemp(imgDir, ".img-*")
+	if err != nil {
+		return "", err
+	}
+	tmpName := tmp.Name()
+	if _, err := tmp.Write(data); err != nil {
+		tmp.Close()
+		os.Remove(tmpName)
+		return "", err
+	}
+	if err := tmp.Close(); err != nil {
+		os.Remove(tmpName)
+		return "", err
+	}
+	if err := os.Rename(tmpName, path); err != nil {
+		os.Remove(tmpName)
+		return "", err
+	}
+	return path, nil
+}
+
 func writeJSON(path string, v any) error {
 	data, err := json.Marshal(v)
 	if err != nil {