Add persitent URLs for year/month/day in the diary

README.md

@@ -69,3 +69,13 @@ FolderName/
 | Day (`DD/`) | Entry content and photo grid |
 
 Days with photos but no `index.md` still appear in the month view and can be created by clicking their heading link.
+
+#### Persistent date links
+
+Each diary root exposes three stable paths intended for browser bookmarks. They redirect to the current dated URL on every visit:
+
+| Path | Redirects to |
+|------|-------------|
+| `<diary>/today/` | `<diary>/YYYY/MM/DD/` (or `…/?edit` if the day folder does not exist yet) |
+| `<diary>/this-month/` | `<diary>/YYYY/MM/` |
+| `<diary>/this-year/` | `<diary>/YYYY/` |

diary.go

@@ -21,6 +21,67 @@ func init() {
 
 type diaryHandler struct{}
 
+// redirect resolves the persistent date links (today, this-month, this-year)
+// inside any diary root to a dated URL. Returns ok=false otherwise.
+func (d *diaryHandler) redirect(root, fsPath, urlPath string) (string, bool) {
+	base := path.Base(strings.TrimSuffix(urlPath, "/"))
+	switch base {
+	case "today", "this-month", "this-year":
+	default:
+		return "", false
+	}
+
+	parentFS := filepath.Dir(fsPath)
+	parentURLPath := parentURL(urlPath)
+	_, diaryRootFS, diaryRootURL, ok := findDiaryContext(root, parentFS, parentURLPath)
+	if !ok {
+		return "", false
+	}
+
+	now := time.Now()
+	year := fmt.Sprintf("%d", now.Year())
+	month := fmt.Sprintf("%02d", int(now.Month()))
+	day := fmt.Sprintf("%02d", now.Day())
+
+	switch base {
+	case "today":
+		target := path.Join(diaryRootURL, year, month, day) + "/"
+		dayFS := filepath.Join(diaryRootFS, year, month, day)
+		if _, err := os.Stat(dayFS); err != nil {
+			target += "?edit"
+		}
+		return target, true
+	case "this-month":
+		return path.Join(diaryRootURL, year, month) + "/", true
+	case "this-year":
+		return path.Join(diaryRootURL, year) + "/", true
+	}
+	return "", false
+}
+
+// defaultHeading returns the German long-form date as the editor pre-fill
+// heading for a diary day folder (depth 3 inside a diary root).
+func (d *diaryHandler) defaultHeading(root, fsPath, urlPath string) (string, bool) {
+	depth, _, _, ok := findDiaryContext(root, fsPath, urlPath)
+	if !ok || depth != 3 {
+		return "", false
+	}
+	day, err := strconv.Atoi(filepath.Base(fsPath))
+	if err != nil {
+		return "", false
+	}
+	monthFS := filepath.Dir(fsPath)
+	month, err := strconv.Atoi(filepath.Base(monthFS))
+	if err != nil || month < 1 || month > 12 {
+		return "", false
+	}
+	year, err := strconv.Atoi(filepath.Base(filepath.Dir(monthFS)))
+	if err != nil {
+		return "", false
+	}
+	return formatGermanDate(time.Date(year, time.Month(month), day, 0, 0, 0, 0, time.UTC)), true
+}
+
 func (d *diaryHandler) handle(root, fsPath, urlPath string) *specialPage {
 	depth, diaryRootFS, diaryRootURL, ok := findDiaryContext(root, fsPath, urlPath)
 	if !ok {

main.go

@@ -37,8 +37,19 @@ type specialPage struct {
 
 // pageTypeHandler is implemented by each special folder type (diary, gallery, …).
 // handle returns nil when the handler does not apply to the given path.
+// redirect returns ok=true with an absolute URL when the request should be
+// short-circuited with a 302 redirect (e.g. persistent date links in a diary).
+// defaultHeading returns ok=true with custom pre-fill heading text for the
+// editor when no index.md exists yet (e.g. German long-form date for a diary
+// day). Handlers that don't need a hook should return the zero value.
+//
+// When adding a new hook, prefer a sibling method here over folding logic
+// into main.go or render.go. If this list grows much beyond three, consider
+// collapsing into a single overrides struct returned per request.
 type pageTypeHandler interface {
 	handle(root, fsPath, urlPath string) *specialPage
+	redirect(root, fsPath, urlPath string) (target string, ok bool)
+	defaultHeading(root, fsPath, urlPath string) (heading string, ok bool)
 }
 
 // pageTypeHandlers is the registry. Each type registers itself via init().
@@ -204,6 +215,13 @@ func (h *handler) serveDir(w http.ResponseWriter, r *http.Request, urlPath, fsPa
 		return
 	}
 
+	for _, ph := range pageTypeHandlers {
+		if target, ok := ph.redirect(h.root, fsPath, urlPath); ok {
+			http.Redirect(w, r, target, http.StatusFound)
+			return
+		}
+	}
+
 	indexPath := filepath.Join(fsPath, "index.md")
 	rawMD, _ := os.ReadFile(indexPath)
 
@@ -255,7 +273,14 @@ func (h *handler) serveDir(w http.ResponseWriter, r *http.Request, urlPath, fsPa
 			rawContent = string(sections[sectionIndex])
 		}
 	} else if editMode && rawContent == "" && urlPath != "/" {
-		rawContent = "# " + pageTitle(urlPath) + "\n\n"
+		heading := pageTitle(urlPath)
+		for _, ph := range pageTypeHandlers {
+			if custom, ok := ph.defaultHeading(h.root, fsPath, urlPath); ok {
+				heading = custom
+				break
+			}
+		}
+		rawContent = "# " + heading + "\n\n"
 	}
 
 	data := pageData{