Add per-event NASA moon images with east-sky cloud veil

Three changes driven by the same goal: make each monthly moon post
look like east captured it at that exact moment.

Tighter illumination windows (±4% of target phase):
  Full moon:   95% → 96–100%  (was a 5-point band; now hugs exact full)
  Quarters:    40–65% → 46–54%  (was a 25-point band; now ±4% of 50%)
This ensures the NASA Dial-a-Moon render timestamp is pulled within
4 percentage points of the true phase, making the fetched image
genuinely represent that night's moon.  One fresh fetch per event,
~3/month, cached by hour — never reused across months.

Atmospheric cloud veil from east's surrounding sky:
  _extract_cloud_veil() samples the annular sky region just outside
  east's moon disk (2×–5× radius), scales it to the output frame,
  blurs heavily (GaussianBlur r≈output_width/10) so it reads as haze
  rather than an upscaled photo, then blends it over the NASA composite
  at an opacity proportional to sky brightness:
    sky < 5% mean brightness → no veil (clear dark night)
    sky ~10%                 → ~17% veil (thin haze / airglow)
    sky ≥ 20%                → 40% veil (max, MOON_CLOUD_OVERLAY_MAX_OPACITY)
  After the veil pass the NASA moon disk is re-pasted sharply so the
  haze sits naturally behind the crisp lunar surface.
  This is the honest answer to "east can't capture high-res clouds":
  east's real atmospheric fingerprint becomes the veil texture.

New sky-cam.conf keys:
  MOON_CLOUD_OVERLAY_ENABLED=true
  MOON_CLOUD_OVERLAY_MAX_OPACITY=0.40
  #MOON_CLOUD_OVERLAY_BLUR=0  (0 = auto)

https://claude.ai/code/session_01HkTxpNSTWtViZzxbrbKytR

moon_composite.py

@@ -209,6 +209,63 @@ def composite_full_moon(
     return out_path
 
 
+def _extract_cloud_veil(
+    east_frame_path: str,
+    cx: float,
+    cy: float,
+    moon_radius_px: float,
+    output_size: tuple[int, int],
+    blur_radius: int = 0,
+    max_opacity: float = 0.40,
+) -> tuple[Image.Image, float] | None:
+    """Extract sky texture around the moon from east frame as an atmospheric veil.
+
+    Samples an annular region just outside the moon disk (2x–5x radius),
+    scales it to output_size, then blurs heavily so it reads as atmospheric
+    haze rather than an upscaled photo.  Opacity is proportional to how
+    bright the surrounding sky is — dark clear sky returns None, thin cloud
+    returns a partial veil, bright overcast returns max_opacity.
+
+    Returns (image, opacity) or None if the sky is too dark to matter.
+    """
+    src = Image.open(east_frame_path).convert('RGB')
+    arr = np.asarray(src).astype(np.float32)
+    src_h, src_w = arr.shape[:2]
+
+    inner_r = moon_radius_px * 2.0
+    outer_r = min(moon_radius_px * 5.0, min(src_h, src_w) * 0.40)
+    if outer_r <= inner_r:
+        return None
+
+    yy, xx = np.mgrid[0:src_h, 0:src_w]
+    dist = np.sqrt((xx - cx) ** 2 + (yy - cy) ** 2)
+    annulus = (dist >= inner_r) & (dist <= outer_r)
+    if not annulus.any():
+        return None
+
+    mean_brightness = float(arr[annulus].mean()) / 255.0
+    if mean_brightness < 0.05:
+        return None  # clear dark sky — nothing to veil
+
+    # Opacity scales from 0 at 5% brightness to max_opacity at ~20% brightness.
+    opacity = min(max_opacity, (mean_brightness - 0.05) * (max_opacity / 0.15))
+    if opacity <= 0:
+        return None
+
+    x0 = max(0, int(cx - outer_r))
+    x1 = min(src_w, int(cx + outer_r))
+    y0 = max(0, int(cy - outer_r))
+    y1 = min(src_h, int(cy + outer_r))
+    patch = src.crop((x0, y0, x1, y1))
+
+    cloud = patch.resize(output_size, LANCZOS)
+    # Blur radius: large enough to erase camera detail, keep only haze shape
+    r = blur_radius if blur_radius > 0 else max(8, output_size[0] // 10)
+    cloud = cloud.filter(ImageFilter.GaussianBlur(radius=r))
+
+    return cloud, opacity
+
+
 def render_phase_closeup(
     nasa_render_path: str,
     out_path: str,
@@ -216,14 +273,24 @@ def render_phase_closeup(
     moon_height_pct: float = 0.92,
     caption: str | None = None,
     background: tuple[int, int, int] = (0, 0, 0),
+    east_frame_path: str | None = None,
+    east_detection=None,
+    cloud_overlay_enabled: bool = True,
+    cloud_overlay_max_opacity: float = 0.40,
+    cloud_overlay_blur: int = 0,
 ):
     """Full-screen close-up rendering using a NASA SVS Dial-a-Moon image.
 
     The dial-a-moon render already has the correct phase, libration and
-    crater shadows for the requested timestamp, so we simply size it to fill
-    the output frame on a black background and add a caption.  No east
-    compositing — the moon dominates the frame the way a 65× telephoto shot
-    would.
+    crater shadows for the requested timestamp, so we size it to fill the
+    output frame on a black background and add a caption.
+
+    When east_frame_path and east_detection are provided the function also
+    extracts the sky around east's moon detection and blends it as a
+    subtle atmospheric veil over the composite.  This lets thin cloud or
+    haze from east's actual observation show through — the opacity is
+    proportional to how bright the surrounding sky was.  Set
+    cloud_overlay_enabled=False to always skip this step.
     """
     bg = Image.new('RGB', output_size, background)
     moon = Image.open(nasa_render_path).convert('RGB')
@@ -240,6 +307,21 @@ def render_phase_closeup(
     py = (output_size[1] - target) // 2
     bg.paste(moon_resized, (px, py), mask)
 
+    # ── Atmospheric veil from east's surrounding sky ──────────────────────
+    if cloud_overlay_enabled and east_frame_path and east_detection is not None:
+        cx, cy = east_detection.centroid_xy
+        radius_px = east_detection.diameter_px / 2
+        veil = _extract_cloud_veil(
+            east_frame_path, cx, cy, radius_px, output_size,
+            blur_radius=cloud_overlay_blur,
+            max_opacity=cloud_overlay_max_opacity,
+        )
+        if veil is not None:
+            cloud_img, opacity = veil
+            bg = Image.blend(bg, cloud_img, alpha=opacity)
+            # Re-paste the moon sharply on top so haze sits behind disk edge
+            bg.paste(moon_resized, (px, py), mask)
+
     if caption:
         draw = ImageDraw.Draw(bg)
         draw.text((24, output_size[1] - 44), caption, fill=(0, 0, 0))