Add configurable display mode: rolling window or daily reset

New config options:
- mode = "window" (rolling hours, default) or "today" (daily reset)
- start_time = "06:00" (when today mode resets)
- hold_overnight = true (keep overnight collage until first bird)

In "today" mode the collage only shows birds since start_time,
growing through the day. With hold_overnight=true, the display
keeps the previous full collage until the first bird is detected
after start_time (no blank screen at dawn).

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

frame/display.py

@@ -45,6 +45,9 @@ DEFAULTS = {
     "bw_days": 7,           # BirdWeather lookback window, in days
     "bw_country": "us",     # geocoder country for the ZIP
     "hours": 24,
+    "mode": "window",           # "window" = rolling hours; "today" = daily reset
+    "start_time": "06:00",      # "today" mode: collage resets at this time
+    "hold_overnight": True,     # "today" mode: keep overnight collage until first bird
     "image": "",            # local PNG written by the shooter
     "image_url": "",        # or a published screenshot URL
     "shoot": False,         # or capture inline (needs a browser; the 3 A+ and Zero 2 W both handle it)
@@ -109,6 +112,27 @@ def fetch_species(cfg, auth=None):
     return fetch_recent(cfg["base_url"], cfg["hours"], cfg["timeout"], auth)
 
 
+def _today_hours(cfg):
+    """Compute the hours window for 'today' mode.
+
+    Returns hours since start_time today (or since yesterday's start_time
+    if we haven't reached it yet today).
+    """
+    now = datetime.now()
+    parts = cfg["start_time"].split(":")
+    start_h, start_m = int(parts[0]), int(parts[1]) if len(parts) > 1 else 0
+    start_today = now.replace(hour=start_h, minute=start_m, second=0, microsecond=0)
+
+    if now < start_today:
+        from datetime import timedelta
+        yesterday_start = start_today - timedelta(days=1)
+        hours = (now - yesterday_start).total_seconds() / 3600
+        return max(1, hours)
+
+    hours = (now - start_today).total_seconds() / 3600
+    return max(1, hours)
+
+
 # --- image ------------------------------------------------------------------
 def get_image(src, timeout, auth=None):
     if re.match(r"^https?://", src):
@@ -317,7 +341,7 @@ def in_quiet_hours(cfg, hour):
 
 
 # --- run --------------------------------------------------------------------
-def obtain_image(cfg, species=None):
+def obtain_image(cfg, species=None, window_hours=None):
     if cfg.get("species_source") == "birdweather":
         from shoot import shoot_birdweather
         if species is None:  # gate skipped (--no-signature): fetch the list to render
@@ -335,6 +359,7 @@ def obtain_image(cfg, species=None):
               headline_px=cfg["shoot_headline_px"], eyebrow_px=cfg["shoot_eyebrow_px"],
               lowercase=cfg["shoot_lowercase"], mat=cfg["shoot_mat"],
               small_floor=cfg["shoot_small_floor"], count_exp=cfg["shoot_count_exp"], timeout_ms=cfg["timeout"] * 1000,
+              window_hours=int(window_hours) if window_hours else None,
               user=cfg["basic_user"], password=cfg["basic_pass"])
         return Image.open(out).convert("RGB")
     src = cfg["image_url"] or cfg["image"]
@@ -348,8 +373,17 @@ def run(cfg, preview=None, force=False, use_signature=True, mat_box=False):
     state = load_state(cfg["state"])
     sig = None
     species = None
+    window_hours = None
+    if cfg["mode"] == "today":
+        window_hours = _today_hours(cfg)
     if use_signature:
         try:
+            if cfg["mode"] == "today":
+                species = fetch_recent(cfg["base_url"], max(1, int(window_hours + 0.5)), cfg["timeout"], _auth(cfg))
+                if not species and cfg["hold_overnight"]:
+                    print("today mode: no birds yet, holding overnight collage")
+                    return
+            else:
                 species = fetch_species(cfg, _auth(cfg))
             sig = signature(species)
         except Exception as e:
@@ -366,7 +400,7 @@ def run(cfg, preview=None, force=False, use_signature=True, mat_box=False):
         print("refresh:", "changed" if changed else "heal")
 
     try:
-        img = fit_panel(obtain_image(cfg, species))
+        img = fit_panel(obtain_image(cfg, species, window_hours))
     except Exception as e:
         print(f"could not get image: {e}", file=sys.stderr)  # keep last panel image
         return