implement favorites functionality

.claude/memory/go-expert.md

@@ -4,6 +4,8 @@ Persistent notes for the go-expert agent on this repo. Local-only (gitignored) 
 
 ## Architecture decisions
 
+- (2026-08-19) Favorites are split into pure `internal/favstore` persistence and a Host-based `internal/ui/favorites` feature. Production storage is initialized explicitly from `ui.Run`, not during viewer construction, so tests never scan the user's real config directory. The first implementation stores only named file lists; disk-backed thumbnail caching remains a separate follow-up.
+- (2026-08-19) Favorite accelerators are positional over the current case-insensitively sorted list: Cmd/Ctrl+1–9 open entries 1–9 and Cmd/Ctrl+0 opens entry 10. Register all ten handlers once in `buildViewer`; `favorites.Feature.Open` resolves a slot against names captured by the latest menu refresh, so add/remove never requires shortcut re-registration.
 - (2026-08-15) A feature that reorders/replaces `v.files`/`v.unsortedFiles` off the UI goroutine gets its *own* staleness generation counter (e.g. `sortGen`), not `v.gen`. `v.gen` is specifically the load/decode/animation generation - every bump site pairs it with `stopAnimation()`, and reusing it for an unrelated async op would spuriously kill a playing GIF or in-flight preload. Precedent: `toast.gen`. When adding a new async op, grep for every existing writer of the state it will eventually overwrite (`grep -rn "v\.files\s*=\|v\.unsortedFiles\s*="` etc.) and bump the new op's own gen at each of those sites too, so a stale background result can't clobber state a *different* feature changed in the meantime - not just a newer instance of the same op.
 - (2026-08-15) Async UI operations in this codebase (scan, sort, ...) all follow one shape: synchronous snapshot of inputs on the UI goroutine -> bump a dedicated gen counter -> show spinner/label + `ForceRepaint()` -> `go func() { compute; fyne.Do(applyResult) }()` -> `applyResult` does `defer close(doneChan)` first, unconditionally resets the spinner/loading flag, *then* checks the gen for staleness before touching shared state. Follow this shape for any future long-running operation instead of inventing a new one. Reference implementations: `sort.go`'s `startSort`/`finishSort` (the generic form, with an `onDone` callback - used by both `SetSortMode` and `drop.go`'s `applyScannedFiles`) and `drop.go`'s `handleDrop`/`applyScanResult`.
 - (2026-08-15) A snapshot handed to one of those background goroutines must be a *defensive copy* when it comes from `v.files`/`v.unsortedFiles`, never a bare slice-header assignment: `RemoveFile` shifts those slices in place (`append(s[:j], s[j+1:]...)`), so an aliased snapshot is a genuine data race with whatever the goroutine reads. Same for merges - copy first, then append, so a spare-capacity append doesn't write into the shared array either. Confirmed reachable under `-race`, not theoretical; guarded by `TestSetSortMode_SnapshotDoesNotAliasUnsortedFiles`.

FyneApp.toml

@@ -2,7 +2,7 @@
 Name = "PicFetch"
 ID = "io.github.frathe.picfetch"
 Version = "0.1.7"
-Build = 299
+Build = 310
 
 [Migrations]
 fyneDo = true

docs/index.html

@@ -351,6 +351,13 @@ <h3>Folders and merging</h3>
       trees. <kbd>M</kbd> makes further drops add to the set instead of
       replacing it.</p>
     </li>
+    <li class="card">
+      <h3>Named favorites</h3>
+      <p>Save the current file list as a collection and reopen it from the
+      Favorites menu after a restart. The first ten are one shortcut away with
+      <kbd>Cmd/Ctrl</kbd>+<kbd>1</kbd>–<kbd>9</kbd> and
+      <kbd>Cmd/Ctrl</kbd>+<kbd>0</kbd>.</p>
+    </li>
   </ul>
 
   <h2 id="downloads">Download</h2>

go.mod

@@ -15,6 +15,7 @@ require (
 require (
 	fyne.io/systray v1.12.2 // indirect
 	github.com/BurntSushi/toml v1.6.0 // indirect
+	github.com/FyshOS/fancyfs v0.0.1 // indirect
 	github.com/anthonynsimon/bild v0.14.0 // indirect
 	github.com/clipperhouse/uax29/v2 v2.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
@@ -32,7 +33,6 @@ require (
 	github.com/hack-pad/safejs v0.1.0 // indirect
 	github.com/jeandeaual/go-locale v0.0.0-20250612000132-0ef82f21eade // indirect
 	github.com/jsummers/gobmp v0.0.0-20230614200233-a9de23ed2e25 // indirect
-	github.com/kr/text v0.2.0 // indirect
 	github.com/mattn/go-runewidth v0.0.24 // indirect
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 // indirect
 	github.com/nicksnyder/go-i18n/v2 v2.5.1 // indirect

go.sum

@@ -4,11 +4,12 @@ fyne.io/systray v1.12.2 h1:Y8DZxgLHsVQt6rY9Zrkkg+j67S7vv/1F2viOWKPpVeA=
 fyne.io/systray v1.12.2/go.mod h1:RVwqP9nYMo7h5zViCBHri2FgjXF7H2cub7MAq4NSoLs=
 github.com/BurntSushi/toml v1.6.0 h1:dRaEfpa2VI55EwlIW72hMRHdWouJeRF7TPYhI+AUQjk=
 github.com/BurntSushi/toml v1.6.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
+github.com/FyshOS/fancyfs v0.0.1 h1:kgvm7VvwOMLkYTqSflplp62SlMVWQ2uAoHw9CXwXHYg=
+github.com/FyshOS/fancyfs v0.0.1/go.mod h1:S5SHVz/5R72iCXOxCqdcyTPSlg3JxNd0gaHyGBSrY8A=
 github.com/anthonynsimon/bild v0.14.0 h1:IFRkmKdNdqmexXHfEU7rPlAmdUZ8BDZEGtGHDnGWync=
 github.com/anthonynsimon/bild v0.14.0/go.mod h1:hcvEAyBjTW69qkKJTfpcDQ83sSZHxwOunsseDfeQhUs=
 github.com/clipperhouse/uax29/v2 v2.2.0 h1:ChwIKnQN3kcZteTXMgb1wztSgaU+ZemkgWdohwgs8tY=
 github.com/clipperhouse/uax29/v2 v2.2.0/go.mod h1:EFJ2TJMRUaplDxHKj1qAEhCtQPW2tJSwu5BF98AuoVM=
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/ebitengine/purego v0.10.1 h1:dewVBCBT2GaMu1SrNTYxQhgQBethzfhiwvZiLGP/qyY=

internal/favstore/favstore.go

@@ -0,0 +1,170 @@
+// Package favstore persists named lists of image files.
+package favstore
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/storage"
+
+	"github.com/frathe/picfetch/internal/trash"
+)
+
+const fileListName = "file-list.json"
+
+// DefaultDir returns the directory used for favorites in production.
+func DefaultDir() string {
+	base, err := os.UserConfigDir()
+	if err != nil || base == "" {
+		base = os.TempDir()
+	}
+	return filepath.Join(base, "picfetch", "favorites")
+}
+
+// ValidName reports whether name is safe to use as one directory component.
+func ValidName(name string) bool {
+	return name != "" &&
+		name != "." &&
+		name != ".." &&
+		!strings.ContainsAny(name, `/\:*?"<>|`)
+}
+
+// Exists reports whether a favorite with name exists.
+func Exists(dir, name string) bool {
+	if !ValidName(name) {
+		return false
+	}
+	info, err := os.Stat(filepath.Join(dir, name, fileListName))
+	return err == nil && !info.IsDir()
+}
+
+// List returns favorite names sorted case-insensitively.
+func List(dir string) ([]string, error) {
+	entries, err := os.ReadDir(dir)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	names := make([]string, 0, len(entries))
+	for _, entry := range entries {
+		if !entry.IsDir() || !ValidName(entry.Name()) {
+			continue
+		}
+		info, err := os.Stat(filepath.Join(dir, entry.Name(), fileListName))
+		if err == nil && !info.IsDir() {
+			names = append(names, entry.Name())
+			continue
+		}
+		if err != nil && !errors.Is(err, os.ErrNotExist) {
+			return nil, err
+		}
+	}
+
+	sort.Slice(names, func(i, j int) bool {
+		left, right := strings.ToLower(names[i]), strings.ToLower(names[j])
+		if left == right {
+			return names[i] < names[j]
+		}
+		return left < right
+	})
+	return names, nil
+}
+
+// Save atomically writes files as the favorite named name.
+func Save(dir, name string, files []fyne.URI) error {
+	if !ValidName(name) {
+		return fmt.Errorf("invalid favorite name %q", name)
+	}
+
+	list := make(map[string]string, len(files))
+	for i, file := range files {
+		if file == nil {
+			return fmt.Errorf("favorite file %d is nil", i)
+		}
+		list[strconv.Itoa(i)] = file.Path()
+	}
+
+	favoriteDir := filepath.Join(dir, name)
+	if err := os.MkdirAll(favoriteDir, 0o755); err != nil {
+		return err
+	}
+
+	tmp, err := os.CreateTemp(favoriteDir, ".file-list-*.json")
+	if err != nil {
+		return err
+	}
+	tmpPath := tmp.Name()
+	defer func() { _ = os.Remove(tmpPath) }()
+
+	if err := tmp.Chmod(0o644); err != nil {
+		_ = tmp.Close()
+		return err
+	}
+	if err := json.NewEncoder(tmp).Encode(list); err != nil {
+		_ = tmp.Close()
+		return err
+	}
+	if err := tmp.Sync(); err != nil {
+		_ = tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	return os.Rename(tmpPath, filepath.Join(favoriteDir, fileListName))
+}
+
+// Load returns the files stored in the favorite named name.
+func Load(dir, name string) ([]fyne.URI, error) {
+	if !ValidName(name) {
+		return nil, fmt.Errorf("invalid favorite name %q", name)
+	}
+
+	data, err := os.ReadFile(filepath.Join(dir, name, fileListName))
+	if err != nil {
+		return nil, err
+	}
+
+	var list map[string]string
+	if err := json.Unmarshal(data, &list); err != nil {
+		return nil, err
+	}
+
+	type indexedPath struct {
+		index int
+		path  string
+	}
+	paths := make([]indexedPath, 0, len(list))
+	for key, path := range list {
+		index, err := strconv.Atoi(key)
+		if err != nil || index < 0 {
+			return nil, fmt.Errorf("invalid file index %q", key)
+		}
+		paths = append(paths, indexedPath{index: index, path: path})
+	}
+	sort.Slice(paths, func(i, j int) bool { return paths[i].index < paths[j].index })
+
+	files := make([]fyne.URI, len(paths))
+	for i, item := range paths {
+		files[i] = storage.NewFileURI(item.path)
+	}
+	return files, nil
+}
+
+// Remove moves the favorite named name to the operating system's trash.
+func Remove(dir, name string) error {
+	if !ValidName(name) {
+		return fmt.Errorf("invalid favorite name %q", name)
+	}
+	return trash.Move(filepath.Join(dir, name))
+}