diff --git a/README.md b/README.md
index 090729c..95b3c17 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,8 @@ Automated sky / timelapse camera scripts that produce:
 - **Daily sunrise clip** — a speed-adjusted video of the sunrise window, uploaded to Mattermost each morning
 - **Four Seasons timelapse** — daily clips sized to each Vivaldi movement's music duration, assembled automatically into per-movement montages (with music + attribution overlay) and a full-year video
 - **Full-day timelapse** — a fixed-fps timelapse of every image captured that day, kept for a configurable retention window
+- **Nightly moon-track timelapse** — every east night frame where the moon is visible is cropped around the moon and stitched into a short mp4 (the moon roughly held still while clouds and stars drift past)
+- **Monthly moon-phase close-ups** — one composite per phase (full moon, first quarter, third quarter), framed as if east took it through a 65× telephoto.  The sky/halo/parallactic-angle/timing are real-from-east; the lunar surface texture is borrowed from a cached high-res reference (no software can recover detail your camera didn't capture).  Posted to Mattermost.
 
 ---
 
@@ -15,6 +17,7 @@ Automated sky / timelapse camera scripts that produce:
 ```bash
 sudo apt install ffmpeg bc fonts-dejavu curl python3-pip
 pip3 install suntime pytz requests
+pip3 install skyfield Pillow numpy scipy   # moon jobs (moon-track + moon-phase-monthly)
 ```
 
 | Package | Purpose |
@@ -24,6 +27,8 @@ pip3 install suntime pytz requests
 | `fonts-dejavu` | Text overlays (sunrise time, attribution) |
 | `python3` + `suntime pytz` | Astronomical sunrise calculation — pure math, no internet, works indefinitely |
 | `python3` + `requests` | Mattermost upload |
+| `python3` + `skyfield` | Moon phases + altitude/azimuth + parallactic angle (offline after first ephemeris download) |
+| `python3` + `Pillow numpy scipy` | Moon detection + phase compositing |
 
 ### 2. Download
 
@@ -262,6 +267,48 @@ Replace the date list with whatever range you need.  Each run produces one `*-fi
 ./year-end-join.sh 2025 east
 ```
 
+**Moon jobs**:
+```bash
+# Re-run last night's moon-track timelapse for east
+./moon-track.sh east
+
+# Back-fill moon-track for a specific past night
+./moon-track.sh east 2026-04-15
+
+# Auto mode — runs whichever phase composite is due today (no-ops otherwise)
+./moon-phase-monthly.sh
+
+# Force a single phase, picking the most recent occurrence
+./moon-phase-monthly.sh --phase full
+./moon-phase-monthly.sh --phase first-quarter
+./moon-phase-monthly.sh --phase third-quarter
+
+# Build but skip the Mattermost post
+./moon-phase-monthly.sh --phase full --no-upload
+
+# Dry run — find best frame, log it, build nothing
+./moon-phase-monthly.sh --phase third-quarter --dry-run
+
+# Back-fill a specific event by exact UTC moment
+./moon-phase-monthly.sh --phase full --target 2026-04-01T15:51:00Z
+
+# Inspect any moon-related stats for a frame
+python3 moon_detect.py BASE_DIR/east/2026-04-29/21-07-00.jpg --debug /tmp/dbg.png
+python3 moon_phase.py info 2026-04-29T21:07:00Z
+```
+
+**Posting schedule**:
+
+| Job | When the timer fires | When the artifact actually appears |
+|---|---|---|
+| Sunrise video | `SCHEDULE_SUNRISE` (default 03:00 local) | A few minutes after sunrise + `SUNRISE_POST_MIN` |
+| Moon-track timelapse | `SCHEDULE_MOON_TRACK` (default 02:30 local) | ~5 min after the timer, covers the previous night |
+| 🌕 Full Moon composite | `SCHEDULE_MOON_PHASE` (default 09:30 local) | 3 days after exact full moon (configurable: `MOON_FULL_POST_DELAY_DAYS`) |
+| 🌓 First Quarter composite | same timer | 2 days after exact first quarter (configurable: `MOON_QUARTER_POST_DELAY_DAYS`) — best-effort, see geometry note below |
+| 🌗 Third Quarter composite | same timer | 2 days after exact third quarter |
+
+The moon-phase timer fires every day; the script no-ops on days that aren't a post-day for any phase, so you'll see exactly three posts per lunar cycle in Mattermost (sometimes only two if first quarter detection fails — see geometry note in `sky-cam.conf`).
+
 **Check capture status**:
 ```bash
 systemctl --user status sky-cam-capture-east.service
diff --git a/bootstrap.sh b/bootstrap.sh
index affc2d7..ca00f93 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -23,6 +23,7 @@ echo "Done. Next steps:"
 echo "  1. Install system packages (if not already present):"
 echo "       sudo apt install ffmpeg bc fonts-dejavu"
 echo "       pip3 install suntime pytz requests"
+echo "       pip3 install skyfield Pillow numpy scipy   # moon jobs (moon-track, moon-phase-monthly)"
 echo ""
 echo "  2. Edit $TARGET/sky-cam.conf"
 echo "     — SCRIPT_DIR   full path to the directory you'll run scripts from"
diff --git a/install.sh b/install.sh
index a02dae2..2033646 100755
--- a/install.sh
+++ b/install.sh
@@ -225,6 +225,72 @@ EOF
     done
 fi
 
+# ── Moon jobs: nightly tracker + monthly full-moon composite ────────────────
+# Both jobs target the SUNRISE_CAM (the east-facing camera).  They share three
+# Python helpers (moon_phase.py, moon_detect.py, moon_composite.py) and one
+# downloaded asset (the lunar reference texture).
+if [ "${MOON_TRACK_ENABLED:-true}" = "true" ] || [ "${MOON_FULL_ENABLED:-true}" = "true" ]; then
+    # Pre-download skyfield ephemeris so first run doesn't hit the network at
+    # an inopportune moment.  Stored next to the scripts.
+    if [ ! -f "$HERE/de421.bsp" ]; then
+        echo "Downloading skyfield ephemeris (de421.bsp, ~17 MB)..."
+        if curl -fsSL -o "$HERE/de421.bsp" \
+            "https://ssd.jpl.nasa.gov/ftp/eph/planets/bsp/de421.bsp"; then
+            echo "  ok"
+        else
+            echo "  WARNING: ephemeris download failed — moon jobs will retry on first run"
+            rm -f "$HERE/de421.bsp"
+        fi
+    fi
+
+    # Lunar reference texture for moon_phase_monthly.py.  Default URL is the
+    # Wikipedia "FullMoon2010" by Gregory H. Revera (CC BY-SA 3.0), 3500×3500.
+    # Override MOON_REFERENCE_URL in .env to use a different source — any
+    # high-res photo of a full moon on a black background works.
+    ref_dir="${MOON_REFERENCE_DIR:-$HERE/moon-ref}"
+    ref_path="${MOON_REFERENCE_PATH:-$ref_dir/full-moon.jpg}"
+    ref_url="${MOON_REFERENCE_URL:-https://upload.wikimedia.org/wikipedia/commons/e/e1/FullMoon2010.jpg}"
+    if [ ! -f "$ref_path" ]; then
+        mkdir -p "$(dirname "$ref_path")"
+        echo "Downloading lunar reference texture..."
+        if curl -fsSL -o "$ref_path" "$ref_url"; then
+            echo "  ok → $ref_path"
+        else
+            echo "  WARNING: lunar reference download failed"
+            echo "           Drop a high-res full-moon JPEG at $ref_path manually,"
+            echo "           or set MOON_REFERENCE_URL in .env and re-run install.sh."
+            rm -f "$ref_path"
+        fi
+    fi
+fi
+
+# Nightly moon-track job — runs on the SUNRISE_CAM only.
+if [ "${MOON_TRACK_ENABLED:-true}" = "true" ]; then
+    write_service "sky-cam-moon-track" \
+        "$SUNRISE_CAM: nightly moon tracking timelapse" \
+        "moon-track.sh $SUNRISE_CAM"
+    write_timer "sky-cam-moon-track" \
+        "$SUNRISE_CAM: nightly moon tracking timelapse" \
+        "${SCHEDULE_MOON_TRACK:-02:30:00}"
+    timers+=("sky-cam-moon-track")
+fi
+
+# Moon-phase composite job — runs daily; the Python helper internally checks
+# full / first-quarter / third-quarter and only acts when today is the
+# matching post-day for one of them.  One timer covers all three phases.
+if [ "${MOON_FULL_ENABLED:-true}" = "true" ] \
+    || [ "${MOON_FIRST_QUARTER_ENABLED:-true}" = "true" ] \
+    || [ "${MOON_THIRD_QUARTER_ENABLED:-true}" = "true" ]; then
+    write_service "sky-cam-moon-phase" \
+        "$SUNRISE_CAM: monthly moon-phase composite (full + quarters)" \
+        "moon-phase-monthly.sh" \
+        $'After=network-online.target\nWants=network-online.target\n'
+    write_timer "sky-cam-moon-phase" \
+        "$SUNRISE_CAM: monthly moon-phase composite" \
+        "${SCHEDULE_MOON_PHASE:-09:30:00}"
+    timers+=("sky-cam-moon-phase")
+fi
+
 # ── Per-camera Four Seasons jobs ─────────────────────────────────────────────
 # Reads CAMERAS and SCHEDULE_SEASONS_<cam> from sky-cam.conf.
 # Script receives the camera name as $1 so it knows which camera to process.
diff --git a/moon-phase-monthly.sh b/moon-phase-monthly.sh
new file mode 100755
index 0000000..e7f4f3a
--- /dev/null
+++ b/moon-phase-monthly.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+# moon-phase-monthly.sh — thin wrapper around moon_phase_monthly.py.
+#
+# Run via systemd daily.  In auto mode (no flags) the Python helper checks
+# all three phases (full, first-quarter, third-quarter) and runs the composite
+# for any whose post-day equals today UTC.  If you scheduled the timer for
+# 09:30 local, you'll see posts hit Mattermost at:
+#
+#   Full Moon         3 days after exact full moon
+#   First Quarter     2 days after exact first quarter (best-effort — daytime)
+#   Third Quarter     2 days after exact third quarter
+#
+# Manual:
+#   ./moon-phase-monthly.sh                                      # auto mode
+#   ./moon-phase-monthly.sh --dry-run                            # auto, no post
+#   ./moon-phase-monthly.sh --phase full                         # force most recent full
+#   ./moon-phase-monthly.sh --phase third-quarter --target 2026-04-09T11:51:00Z
+
+set -euo pipefail
+
+SCRIPT_DIR="$(dirname "$(realpath "$0")")"
+source "$SCRIPT_DIR/sky-cam.conf"
+export TZ="$TIMEZONE"
+
+exec python3 "$SCRIPT_DIR/moon_phase_monthly.py" "$@"
diff --git a/moon-track.sh b/moon-track.sh
new file mode 100755
index 0000000..2af9fe8
--- /dev/null
+++ b/moon-track.sh
@@ -0,0 +1,106 @@
+#!/bin/bash
+# moon-track.sh — nightly: detect the moon in each east night frame, crop a
+# fixed-size box around it, stitch the cropped sequence into an mp4 that holds
+# the moon roughly centred while clouds, halo and stars drift past.
+#
+# Run once per day from systemd around 02:00, after the night the moon was up.
+# Processes YESTERDAY's frames by default; pass YYYY-MM-DD to back-fill.
+#
+# Output: $MOVIES_DIR/<cam>/moon-track/YYYY/YYYY-MM-DD-moon-track.mp4
+
+set -euo pipefail
+
+SCRIPT_DIR="$(dirname "$(realpath "$0")")"
+source "$SCRIPT_DIR/sky-cam.conf"
+export TZ="$TIMEZONE"
+
+CAM_NAME="${1:-${SUNRISE_CAM:-east}}"
+DATE_ARG="${2:-}"
+if [ -n "$DATE_ARG" ]; then
+    target_date=$(date --date="$DATE_ARG" +%Y-%m-%d)
+else
+    target_date=$(date --date="yesterday" +%Y-%m-%d)
+fi
+
+if [ "${MOON_TRACK_ENABLED:-true}" != "true" ]; then
+    echo "MOON_TRACK_ENABLED=false — skipping"
+    exit 0
+fi
+
+image_dir="$BASE_DIR/$CAM_NAME/$target_date"
+if [ ! -d "$image_dir" ]; then
+    echo "no images for $CAM_NAME on $target_date — skipping"
+    exit 0
+fi
+
+year="${target_date:0:4}"
+out_dir="$MOVIES_DIR/$CAM_NAME/moon-track/$year"
+mkdir -p "$out_dir"
+final="$out_dir/${target_date}-moon-track.mp4"
+
+# Crop size around the detected moon, in source pixels.  At 4K with a ~38 px
+# moon, 480 px gives a comfortable surround with halo and any clouds visible.
+CROP_PX="${MOON_TRACK_CROP_PX:-480}"
+FPS="${MOON_TRACK_FPS:-12}"
+CRF="${MOON_TRACK_CRF:-24}"
+
+work_dir=$(mktemp -d)
+trap 'rm -rf "$work_dir"' EXIT
+
+export SCRIPT_DIR
+echo "Scanning $image_dir for night frames with the moon visible..."
+python3 - "$image_dir" "$work_dir" "$CROP_PX" <<'PY'
+import os, sys
+sys.path.insert(0, os.environ['SCRIPT_DIR'])
+from PIL import Image
+from moon_detect import detect_moon
+
+image_dir = sys.argv[1]
+work_dir  = sys.argv[2]
+crop_px   = int(sys.argv[3])
+half = crop_px // 2
+
+frames = sorted(f for f in os.listdir(image_dir) if f.endswith('.jpg'))
+n = len(frames)
+written = 0
+for i, name in enumerate(frames):
+    p = os.path.join(image_dir, name)
+    det = detect_moon(p)
+    if det is None:
+        continue
+    cx, cy = det.centroid_xy
+    im = Image.open(p)
+    w, h = im.size
+    left = max(0, min(int(cx - half), w - crop_px))
+    top  = max(0, min(int(cy - half), h - crop_px))
+    crop = im.crop((left, top, left + crop_px, top + crop_px))
+    out = os.path.join(work_dir, f'{written:06d}.jpg')
+    crop.save(out, quality=88)
+    written += 1
+    if (i + 1) % 200 == 0 or i + 1 == n:
+        print(f'  scanned {i + 1}/{n} frames, kept {written}', flush=True)
+print(f'moon-detected frames: {written}')
+PY
+
+count=$(find "$work_dir" -maxdepth 1 -name '*.jpg' | wc -l)
+if [ "$count" -lt 10 ]; then
+    echo "only $count moon-visible frames on $target_date — skipping video build"
+    exit 0
+fi
+
+echo "encoding $count frames into $final ..."
+ffmpeg -loglevel warning -y \
+    -framerate "$FPS" \
+    -i "$work_dir/%06d.jpg" \
+    -c:v libx264 -pix_fmt yuv420p -preset "${ENCODE_PRESET:-slow}" \
+    -crf "$CRF" \
+    "$final"
+
+echo "moon-track: $final ($(du -h "$final" | cut -f1))"
+
+# Retention sweep
+RETENTION="${MOON_TRACK_RETENTION_DAYS:-90}"
+if [ "$RETENTION" -gt 0 ]; then
+    find "$MOVIES_DIR/$CAM_NAME/moon-track" -type f -name '*-moon-track.mp4' \
+         -mtime +"$RETENTION" -delete 2>/dev/null || true
+fi
diff --git a/moon_composite.py b/moon_composite.py
new file mode 100755
index 0000000..c82f15a
--- /dev/null
+++ b/moon_composite.py
@@ -0,0 +1,237 @@
+#!/usr/bin/env python3
+"""moon_composite.py — paint a high-res lunar texture into a sky-cam frame.
+
+Goal: from a frame east captured of a small white blob (~38 px), produce a
+1920x1080 image that looks like east took it through a 65x telephoto.
+
+What's real, from east:
+  - Sky color, atmospheric halo, any clouds drifting past
+  - Time, parallactic angle (orientation of "up" on the moon)
+  - Position of the moon in the frame at that instant
+
+What's borrowed:
+  - The lunar surface texture (one cached high-res reference image)
+
+Library entry point:
+
+  from moon_composite import composite_full_moon
+  composite_full_moon(
+      source_jpg='/data/east/2026-04-29/21-07-00.jpg',
+      detection=detect_moon(...),
+      when_utc=datetime(2026, 4, 29, 21, 7, 0, tzinfo=timezone.utc),
+      ref_moon_path='/path/to/full-moon.jpg',
+      out_path='/movies/east/full-moons/2026-04-full-moon.jpg',
+  )
+
+CLI:
+
+  python3 moon_composite.py SOURCE.jpg WHEN_UTC REF_MOON.jpg OUT.jpg
+"""
+from __future__ import annotations
+
+import argparse
+import math
+import sys
+from datetime import datetime, timezone
+from pathlib import Path
+
+import numpy as np
+from PIL import Image, ImageDraw, ImageFilter
+
+# Pillow ≥ 10 renamed resampling constants
+try:
+    LANCZOS = Image.Resampling.LANCZOS
+    BICUBIC = Image.Resampling.BICUBIC
+except AttributeError:  # Pillow < 10
+    LANCZOS = Image.LANCZOS
+    BICUBIC = Image.BICUBIC
+
+
+def _square_crop_to_disk(ref: Image.Image, threshold: int = 25) -> Image.Image:
+    """Tight-crop a reference moon image to the disk's bounding square.
+
+    Most lunar reference photos have the disk on a large black field with
+    significant padding.  We threshold on luminance and crop to bbox + small
+    margin so the disk fills our target square evenly.
+    """
+    g = np.asarray(ref.convert('L'))
+    mask = g >= threshold
+    ys, xs = np.where(mask)
+    if len(xs) == 0:
+        return ref
+    x0, x1 = int(xs.min()), int(xs.max())
+    y0, y1 = int(ys.min()), int(ys.max())
+    cx = (x0 + x1) // 2
+    cy = (y0 + y1) // 2
+    half = max(x1 - x0, y1 - y0) // 2 + 4  # tiny margin
+    left = max(0, cx - half)
+    top = max(0, cy - half)
+    right = min(ref.width, cx + half)
+    bottom = min(ref.height, cy + half)
+    return ref.crop((left, top, right, bottom))
+
+
+def _disk_mask(size: int, feather_px: int = 6) -> Image.Image:
+    """Soft circular alpha mask the size of the reference moon image."""
+    m = Image.new('L', (size, size), 0)
+    draw = ImageDraw.Draw(m)
+    # Inset slightly so the feather sits inside the disk edge
+    draw.ellipse((feather_px, feather_px, size - feather_px, size - feather_px),
+                 fill=255)
+    if feather_px > 0:
+        m = m.filter(ImageFilter.GaussianBlur(radius=feather_px))
+    return m
+
+
+def _apply_phase_shadow(disk: Image.Image, phase_angle_deg: float,
+                        waxing: bool) -> Image.Image:
+    """Darken the un-lit portion of the disk based on phase.
+
+    phase_angle_deg: 0 = full, 90 = quarter, 180 = new.
+    waxing: True = lit on right, False = lit on left.
+
+    Implementation: the terminator is an ellipse whose semi-minor axis is
+    cos(phase_angle).  Pixels on the un-lit side are multiplied by a small
+    factor (not zero, so the un-lit limb stays visible like real earthshine).
+    """
+    if phase_angle_deg < 1.0:
+        return disk  # full enough that shadow would be a single-pixel sliver
+    w, h = disk.size
+    # Build a mask: 1.0 in lit area, 0.04 in un-lit area, soft transition near
+    # the terminator.
+    cx, cy = w / 2.0, h / 2.0
+    r = min(w, h) / 2.0
+    yy, xx = np.mgrid[0:h, 0:w].astype(np.float32)
+    # Normalise to disk coords (-1..1)
+    nx = (xx - cx) / r
+    ny = (yy - cy) / r
+    # Distance from disk centre (we still want to clip to the disk)
+    in_disk = (nx * nx + ny * ny) <= 1.0
+    # Terminator equation: x_norm = cos(phase)  on the appropriate side.
+    # For waxing moon, the lit portion is right of the terminator (nx > x_t).
+    cos_p = math.cos(math.radians(phase_angle_deg))
+    # When the moon is more than half lit (cos_p > 0), terminator is on the
+    # un-lit side and the lit portion is broader.  When less than half
+    # (cos_p < 0), terminator is on the lit side.
+    # Distance from terminator (positive = lit side)
+    if waxing:
+        d = nx - (-cos_p)
+    else:
+        d = -(nx - cos_p)
+    # Smooth step around the terminator (~2% of radius)
+    soft_px = max(1.5 / r, 0.01)
+    lit = np.clip(0.5 + d / (2 * soft_px), 0.04, 1.0)
+    lit = np.where(in_disk, lit, 1.0)  # leave outside-disk untouched
+    arr = np.asarray(disk).astype(np.float32)
+    arr = arr * lit[..., None]
+    return Image.fromarray(np.clip(arr, 0, 255).astype(np.uint8), disk.mode)
+
+
+def composite_full_moon(
+    source_jpg: str,
+    detection,                                  # MoonDetection from moon_detect
+    when_utc: datetime,
+    ref_moon_path: str,
+    out_path: str,
+    output_size: tuple[int, int] = (1920, 1080),
+    moon_height_pct: float = 0.70,
+    caption: str | None = None,
+):
+    """Build the full-moon close-up composite and write it to out_path."""
+    # Lazy import — avoids loading skyfield when caller doesn't need it
+    import moon_phase
+
+    src = Image.open(source_jpg).convert('RGB')
+    cx, cy = detection.centroid_xy
+    src_diam = detection.diameter_px
+
+    # ── Crop east around the moon, sized so the moon fills moon_height_pct ──
+    crop_h = int(round(src_diam / moon_height_pct))
+    crop_w = int(round(crop_h * output_size[0] / output_size[1]))
+    sw, sh = src.size
+    crop_w = min(crop_w, sw)
+    crop_h = min(crop_h, sh)
+    left = int(round(cx - crop_w / 2))
+    top = int(round(cy - crop_h / 2))
+    left = max(0, min(left, sw - crop_w))
+    top = max(0, min(top, sh - crop_h))
+    crop = src.crop((left, top, left + crop_w, top + crop_h))
+    bg = crop.resize(output_size, LANCZOS)
+
+    # ── Where is the moon's center within the upscaled background? ──
+    moon_x_in_crop = cx - left
+    moon_y_in_crop = cy - top
+    scale = output_size[1] / crop_h
+    out_moon_cx = moon_x_in_crop * scale
+    out_moon_cy = moon_y_in_crop * scale
+
+    # ── Load reference texture, tight-crop to disk ──
+    ref = Image.open(ref_moon_path).convert('RGB')
+    ref = _square_crop_to_disk(ref)
+    target_size = int(round(output_size[1] * moon_height_pct))
+    target_size += target_size % 2  # even
+    ref_resized = ref.resize((target_size, target_size), LANCZOS)
+
+    # ── Phase shadow (skip when essentially full) ──
+    illum = moon_phase.illumination(when_utc)
+    pa = moon_phase.phase_angle(when_utc)
+    if illum < 0.995:
+        wax = moon_phase.waxing(when_utc)
+        ref_resized = _apply_phase_shadow(ref_resized, pa, wax)
+
+    # ── Parallactic-angle rotation ──
+    par = moon_phase.parallactic_angle(when_utc)
+    # PIL rotates counter-clockwise for positive angles; we want celestial
+    # north to end up "up" in the camera image.  Negate so the rotation
+    # direction matches image-space y-down convention.
+    ref_rot = ref_resized.rotate(-par, resample=BICUBIC, expand=False)
+
+    # ── Composite with feathered circular mask ──
+    feather = max(4, target_size // 200)
+    mask = _disk_mask(target_size, feather_px=feather)
+
+    paste_x = int(round(out_moon_cx - target_size / 2))
+    paste_y = int(round(out_moon_cy - target_size / 2))
+    # Clamp so the disk stays fully on canvas (recenter if needed)
+    paste_x = max(0, min(paste_x, output_size[0] - target_size))
+    paste_y = max(0, min(paste_y, output_size[1] - target_size))
+    bg.paste(ref_rot, (paste_x, paste_y), mask)
+
+    # ── Caption ──
+    if caption:
+        draw = ImageDraw.Draw(bg)
+        # Drop shadow for legibility
+        draw.text((24, output_size[1] - 44), caption, fill=(0, 0, 0))
+        draw.text((22, output_size[1] - 46), caption, fill=(220, 220, 220))
+
+    Path(out_path).parent.mkdir(parents=True, exist_ok=True)
+    bg.save(out_path, quality=92)
+    return out_path
+
+
+def _cli():
+    p = argparse.ArgumentParser()
+    p.add_argument('source')
+    p.add_argument('when_utc', help='ISO 8601 UTC, e.g. 2026-04-29T21:07:00Z')
+    p.add_argument('ref_moon')
+    p.add_argument('out')
+    p.add_argument('--caption', default=None)
+    p.add_argument('--moon-pct', type=float, default=0.70)
+    args = p.parse_args()
+
+    from moon_detect import detect_moon
+    det = detect_moon(args.source)
+    if det is None:
+        print('ERROR: no moon detected in source', file=sys.stderr)
+        return 2
+    when = datetime.fromisoformat(args.when_utc.replace('Z', '+00:00'))
+    composite_full_moon(
+        args.source, det, when, args.ref_moon, args.out,
+        moon_height_pct=args.moon_pct, caption=args.caption,
+    )
+    print(f'wrote {args.out}')
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(_cli())
diff --git a/moon_detect.py b/moon_detect.py
new file mode 100755
index 0000000..0d1d1e1
--- /dev/null
+++ b/moon_detect.py
@@ -0,0 +1,217 @@
+#!/usr/bin/env python3
+"""moon_detect.py — find the moon disk in a sky-cam frame.
+
+Returns centroid, radius, and a quality score derived from:
+  - roundness  (area / (pi * r^2))
+  - isolation  (no comparable bright blob within IGNORE_RADIUS_PX)
+  - sky        (low halo extent → clearer sky around the moon)
+
+Used as a library:
+
+  from moon_detect import detect_moon
+  result = detect_moon('/path/to/frame.jpg')
+  if result is not None:
+      cx, cy = result['centroid']
+      r      = result['radius']
+      score  = result['quality']
+
+CLI (handy for tuning):
+
+  python3 moon_detect.py /path/to/frame.jpg
+  python3 moon_detect.py /path/to/frame.jpg --debug debug.png
+
+The detector ignores the bottom OVERLAY_PX rows because capture frames carry a
+burnt-in timestamp that contains saturated pixels.
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import math
+import sys
+from dataclasses import dataclass
+
+import numpy as np
+from PIL import Image, ImageDraw
+from scipy import ndimage
+
+# --- Tuning constants --------------------------------------------------------
+SATURATED_THRESHOLD = 240   # 0..255 — pixels at or above this count as "moon disk"
+HALO_THRESHOLD = 100        # 0..255 — pixels above this count toward halo extent
+OVERLAY_PX = 200            # bottom rows to ignore (timestamp overlay)
+MIN_DIAMETER_PX = 10        # blob smaller than this is noise
+MAX_DIAMETER_PX = 120       # blob bigger than this is probably the sun, not the moon
+MIN_ROUNDNESS = 0.55        # area / (pi * r^2) — perfect circle = 1
+ISOLATION_PX = 200          # other comparable blob this close → reject
+# Halo extent — typical moon halo is ~3.5x disk radius; >5x means thick clouds
+MAX_HALO_RATIO = 6.0
+
+
+@dataclass
+class MoonDetection:
+    centroid_xy: tuple[float, float]
+    radius_px: float
+    diameter_px: float
+    blob_pixels: int
+    roundness: float
+    halo_radius_px: float
+    halo_ratio: float
+    isolation_px: float
+    quality: float
+
+    def asdict(self) -> dict:
+        return {
+            'centroid': list(self.centroid_xy),
+            'radius': self.radius_px,
+            'diameter': self.diameter_px,
+            'blob_pixels': self.blob_pixels,
+            'roundness': self.roundness,
+            'halo_radius': self.halo_radius_px,
+            'halo_ratio': self.halo_ratio,
+            'isolation': self.isolation_px,
+            'quality': self.quality,
+        }
+
+
+def _grayscale_array(image_path: str) -> np.ndarray:
+    im = Image.open(image_path).convert('L')
+    return np.asarray(im)
+
+
+def _largest_round_blob(mask: np.ndarray) -> tuple[int, np.ndarray, np.ndarray] | None:
+    labels, n = ndimage.label(mask)
+    if n == 0:
+        return None
+    sizes = ndimage.sum(mask, labels, range(1, n + 1))
+    # Sort blobs by size descending; check roundness on the top few
+    order = np.argsort(sizes)[::-1]
+    for idx in order[:8]:
+        label_id = idx + 1
+        ys, xs = np.where(labels == label_id)
+        if len(xs) < 4:
+            continue
+        bbw = xs.max() - xs.min() + 1
+        bbh = ys.max() - ys.min() + 1
+        diam = max(bbw, bbh)
+        if diam < MIN_DIAMETER_PX or diam > MAX_DIAMETER_PX:
+            continue
+        radius = diam / 2.0
+        roundness = len(xs) / (math.pi * radius * radius)
+        if roundness < MIN_ROUNDNESS:
+            continue
+        return label_id, ys, xs
+    return None
+
+
+def detect_moon(image_path: str) -> MoonDetection | None:
+    """Return MoonDetection or None if no acceptable moon is found."""
+    a = _grayscale_array(image_path)
+    if OVERLAY_PX > 0:
+        a = a.copy()
+        a[-OVERLAY_PX:, :] = 0
+    mask = a >= SATURATED_THRESHOLD
+    if not mask.any():
+        return None
+
+    found = _largest_round_blob(mask)
+    if found is None:
+        return None
+    _, ys, xs = found
+
+    cx = float(xs.mean())
+    cy = float(ys.mean())
+    blob_pixels = int(len(xs))
+    bbw = xs.max() - xs.min() + 1
+    bbh = ys.max() - ys.min() + 1
+    diameter = float(max(bbw, bbh))
+    radius = diameter / 2.0
+    roundness = blob_pixels / (math.pi * radius * radius)
+
+    # Isolation: any other saturated blob nearby of comparable size?
+    labels_full, n_full = ndimage.label(mask)
+    own_label = labels_full[int(round(cy)), int(round(cx))]
+    isolation = float('inf')
+    for label_id in range(1, n_full + 1):
+        if label_id == own_label:
+            continue
+        ys2, xs2 = np.where(labels_full == label_id)
+        if len(xs2) < blob_pixels * 0.3:
+            continue
+        d = math.hypot(xs2.mean() - cx, ys2.mean() - cy)
+        if d < isolation:
+            isolation = d
+    if isolation < ISOLATION_PX:
+        return None
+
+    # Halo: connected component above HALO_THRESHOLD that contains the centroid
+    halo_mask = a >= HALO_THRESHOLD
+    halo_labels, _ = ndimage.label(halo_mask)
+    halo_id = halo_labels[int(round(cy)), int(round(cx))]
+    if halo_id == 0:
+        halo_radius = radius
+    else:
+        yh, xh = np.where(halo_labels == halo_id)
+        halo_radius = max(xh.max() - xh.min(), yh.max() - yh.min()) / 2.0
+    halo_ratio = halo_radius / radius if radius > 0 else 1.0
+    if halo_ratio > MAX_HALO_RATIO:
+        return None  # too much glow → probably thick cloud cover
+
+    # Quality score: roundness (0..1), low halo (1 = clear, 0 = thick cloud),
+    # isolation factor (1 if very isolated, less if close to other lights).
+    halo_clean = max(0.0, min(1.0, (MAX_HALO_RATIO - halo_ratio) / (MAX_HALO_RATIO - 1.5)))
+    iso_factor = 1.0 if isolation == float('inf') else min(1.0, isolation / 600.0)
+    quality = 0.5 * roundness + 0.35 * halo_clean + 0.15 * iso_factor
+
+    return MoonDetection(
+        centroid_xy=(cx, cy),
+        radius_px=radius,
+        diameter_px=diameter,
+        blob_pixels=blob_pixels,
+        roundness=roundness,
+        halo_radius_px=halo_radius,
+        halo_ratio=halo_ratio,
+        isolation_px=isolation if isolation != float('inf') else -1.0,
+        quality=quality,
+    )
+
+
+def _draw_debug(image_path: str, detection: MoonDetection | None, out_path: str):
+    im = Image.open(image_path).convert('RGB')
+    draw = ImageDraw.Draw(im)
+    if detection is None:
+        draw.text((20, 20), 'NO MOON DETECTED', fill='red')
+    else:
+        cx, cy = detection.centroid_xy
+        r = detection.radius_px
+        hr = detection.halo_radius_px
+        draw.ellipse((cx - r, cy - r, cx + r, cy + r), outline='yellow', width=4)
+        draw.ellipse((cx - hr, cy - hr, cx + hr, cy + hr), outline='cyan', width=2)
+        draw.text((20, 20), f'q={detection.quality:.2f} r={r:.1f} halo={hr:.1f}',
+                  fill='yellow')
+    im.save(out_path)
+
+
+def _cli():
+    p = argparse.ArgumentParser()
+    p.add_argument('image')
+    p.add_argument('--debug', help='write annotated PNG to this path')
+    p.add_argument('--json', action='store_true', help='emit JSON for scripting')
+    args = p.parse_args()
+
+    det = detect_moon(args.image)
+    if args.json:
+        print(json.dumps(det.asdict() if det else None))
+    elif det is None:
+        print('no moon detected')
+    else:
+        d = det.asdict()
+        for k, v in d.items():
+            print(f'{k}={v}')
+    if args.debug:
+        _draw_debug(args.image, det, args.debug)
+        print(f'debug image written: {args.debug}', file=sys.stderr)
+    return 0 if det else 2
+
+
+if __name__ == '__main__':
+    sys.exit(_cli())
diff --git a/moon_phase.py b/moon_phase.py
new file mode 100755
index 0000000..605a280
--- /dev/null
+++ b/moon_phase.py
@@ -0,0 +1,264 @@
+#!/usr/bin/env python3
+"""moon_phase.py — moon ephemeris lookups for sky-cam.
+
+Provides:
+  - full_moons_in_range(start, end)           list of UTC datetimes of full moons
+  - nearest_full_moon(when)                   UTC datetime of full moon nearest 'when'
+  - illumination(when)                        0.0..1.0 fraction lit
+  - phase_angle(when)                         degrees, 0=full, 180=new
+  - waxing(when)                              True if moon is waxing
+  - altaz(when, lat, lon)                     (altitude_deg, azimuth_deg)
+  - parallactic_angle(when, lat, lon)         degrees, rotation to put celestial north up
+
+Used as a library by other scripts and as a CLI:
+
+  python3 moon_phase.py next-full              # next full moon UTC + local
+  python3 moon_phase.py altaz <ISO-UTC>        # alt/az from configured location
+  python3 moon_phase.py info <ISO-UTC>         # everything for one timestamp
+
+All times assume UTC unless tagged otherwise.  Local timezone comes from
+sky-cam.conf TIMEZONE for display only.
+"""
+from __future__ import annotations
+
+import math
+import os
+import pathlib
+import re
+import sys
+from datetime import datetime, timedelta, timezone
+
+_here = pathlib.Path(__file__).resolve().parent
+
+
+def _read_conf(path):
+    conf = {}
+    try:
+        with open(path) as f:
+            for line in f:
+                line = line.strip()
+                if not line or line.startswith('#') or '=' not in line:
+                    continue
+                k, v = line.split('=', 1)
+                k = k.strip()
+                v = v.strip()
+                v = re.sub(r'\s+#.*$', '', v)
+                v = v.strip('"').strip("'")
+                m = re.match(r'^\$\{[^}]+:-([^}]*)\}$', v)
+                if m:
+                    v = m.group(1).strip('"').strip("'")
+                conf[k] = v
+    except FileNotFoundError:
+        pass
+    return conf
+
+
+_conf = _read_conf(_here / 'sky-cam.conf')
+_conf.update(_read_conf(_here / '.env'))
+
+LATITUDE = float(_conf.get('LATITUDE') or 0.0)
+LONGITUDE = float(_conf.get('LONGITUDE') or 0.0)
+TIMEZONE = _conf.get('TIMEZONE', 'UTC')
+
+# Cached ephemeris — bootstrap.sh pre-downloads de421.bsp into SCRIPT_DIR so
+# this never needs to hit the network at run time.
+_EPH_PATH = _here / 'de421.bsp'
+
+_ts = None
+_eph = None
+_observer = None
+
+
+def _lazy():
+    """Defer skyfield import + ephemeris load until first use.
+
+    Lets the module be imported by tests and by --help paths even when
+    skyfield is missing or the ephemeris hasn't been downloaded yet.
+    """
+    global _ts, _eph, _observer
+    if _ts is not None:
+        return
+    from skyfield.api import Loader, wgs84
+    loader = Loader(str(_here), verbose=False)
+    _ts = loader.timescale()
+    if _EPH_PATH.exists():
+        _eph = loader('de421.bsp')
+    else:
+        _eph = loader('de421.bsp')  # downloads on first run
+    _observer = _eph['earth'] + wgs84.latlon(LATITUDE, LONGITUDE)
+
+
+def _to_utc(when: datetime) -> datetime:
+    if when.tzinfo is None:
+        return when.replace(tzinfo=timezone.utc)
+    return when.astimezone(timezone.utc)
+
+
+def _t(when: datetime):
+    _lazy()
+    w = _to_utc(when)
+    return _ts.from_datetime(w)
+
+
+def full_moons_in_range(start: datetime, end: datetime) -> list[datetime]:
+    """Return UTC datetimes of every full moon between start and end (inclusive)."""
+    return phase_events_in_range(start, end, 2)
+
+
+def phase_events_in_range(start: datetime, end: datetime, phase_index: int) -> list[datetime]:
+    """Return UTC datetimes of every occurrence of `phase_index` between start and end.
+
+    skyfield phase indices: 0 = new, 1 = first quarter, 2 = full, 3 = last quarter.
+    """
+    _lazy()
+    from skyfield.almanac import find_discrete, moon_phases
+    t0 = _t(start)
+    t1 = _t(end)
+    times, phases = find_discrete(t0, t1, moon_phases(_eph))
+    return [t.utc_datetime() for t, p in zip(times, phases) if p == phase_index]
+
+
+def nearest_full_moon(when: datetime) -> datetime:
+    """Full moon UTC nearest 'when' — searches a 45-day window centred on it."""
+    w = _to_utc(when)
+    candidates = full_moons_in_range(w - timedelta(days=45), w + timedelta(days=45))
+    return min(candidates, key=lambda d: abs(d - w))
+
+
+def illumination(when: datetime) -> float:
+    """Fraction of the moon's disk that is illuminated (0..1)."""
+    _lazy()
+    from skyfield.almanac import fraction_illuminated
+    return float(fraction_illuminated(_eph, 'moon', _t(when)))
+
+
+def phase_angle(when: datetime) -> float:
+    """Sun-Moon-Earth phase angle in degrees: 0=full, 90=quarter, 180=new."""
+    _lazy()
+    earth = _eph['earth']
+    sun = _eph['sun']
+    moon = _eph['moon']
+    t = _t(when)
+    e = earth.at(t)
+    s_from_moon = (sun - moon).at(t)
+    e_from_moon = (e.position.au - moon.at(t).position.au)
+    # angle between sun→moon→earth
+    a = s_from_moon.position.au
+    b = e_from_moon
+    cosang = (a[0]*b[0] + a[1]*b[1] + a[2]*b[2]) / (
+        math.sqrt(a[0]**2 + a[1]**2 + a[2]**2)
+        * math.sqrt(b[0]**2 + b[1]**2 + b[2]**2)
+    )
+    cosang = max(-1.0, min(1.0, cosang))
+    return math.degrees(math.acos(cosang))
+
+
+def waxing(when: datetime) -> bool:
+    """True if moon is waxing (illumination growing)."""
+    now = illumination(when)
+    later = illumination(when + timedelta(hours=6))
+    return later > now
+
+
+def altaz(when: datetime, lat: float | None = None, lon: float | None = None):
+    """Apparent altitude/azimuth in degrees as seen from (lat, lon).
+
+    Falls back to configured LATITUDE/LONGITUDE if not specified.
+    """
+    _lazy()
+    from skyfield.api import wgs84
+    if lat is None and lon is None:
+        obs = _observer
+    else:
+        obs = _eph['earth'] + wgs84.latlon(
+            LATITUDE if lat is None else lat,
+            LONGITUDE if lon is None else lon,
+        )
+    t = _t(when)
+    alt, az, _ = obs.at(t).observe(_eph['moon']).apparent().altaz()
+    return float(alt.degrees), float(az.degrees)
+
+
+def parallactic_angle(when: datetime, lat: float | None = None, lon: float | None = None) -> float:
+    """Parallactic angle in degrees — rotates a moon image so celestial north is up.
+
+    sin(q) = sin(H) * cos(lat) / cos(alt)
+    where H is the hour angle and alt is the altitude.
+
+    Returned value is the angle to rotate the lunar texture clockwise (in the
+    image sense, y-down) so celestial north points up in the camera frame.
+    """
+    _lazy()
+    from skyfield.api import wgs84
+    if lat is None:
+        lat = LATITUDE
+    if lon is None:
+        lon = LONGITUDE
+    obs = _eph['earth'] + wgs84.latlon(lat, lon)
+    t = _t(when)
+    apparent = obs.at(t).observe(_eph['moon']).apparent()
+    alt, _, _ = apparent.altaz()
+    ra, dec, _ = apparent.radec(epoch='date')
+    # local sidereal time at observer's longitude → hour angle
+    lst = t.gast * 15.0 + lon  # gast in hours → degrees, plus longitude
+    H = math.radians(lst - ra._degrees)
+    phi = math.radians(lat)
+    delta = math.radians(dec.degrees)
+    # Standard parallactic angle formula
+    q = math.atan2(math.sin(H), math.tan(phi) * math.cos(delta) - math.sin(delta) * math.cos(H))
+    return math.degrees(q)
+
+
+def _format_local(dt_utc: datetime) -> str:
+    try:
+        import pytz
+        tz = pytz.timezone(TIMEZONE)
+        return dt_utc.astimezone(tz).strftime('%Y-%m-%d %H:%M:%S %Z')
+    except Exception:
+        return dt_utc.strftime('%Y-%m-%d %H:%M:%S UTC')
+
+
+def _cli():
+    if len(sys.argv) < 2:
+        print(__doc__.strip())
+        return 1
+    cmd = sys.argv[1]
+    if cmd == 'next-full':
+        now = datetime.now(timezone.utc)
+        fm = full_moons_in_range(now, now + timedelta(days=45))
+        if not fm:
+            print('No full moon found in the next 45 days?', file=sys.stderr)
+            return 1
+        next_fm = fm[0]
+        print(f'next_full_moon_utc={next_fm.strftime("%Y-%m-%dT%H:%M:%SZ")}')
+        print(f'next_full_moon_local={_format_local(next_fm)}')
+        return 0
+    if cmd == 'nearest-full':
+        when = datetime.fromisoformat(sys.argv[2].replace('Z', '+00:00'))
+        fm = nearest_full_moon(when)
+        print(f'nearest_full_moon_utc={fm.strftime("%Y-%m-%dT%H:%M:%SZ")}')
+        return 0
+    if cmd == 'altaz':
+        when = datetime.fromisoformat(sys.argv[2].replace('Z', '+00:00'))
+        alt, az = altaz(when)
+        print(f'altitude_deg={alt:.3f}')
+        print(f'azimuth_deg={az:.3f}')
+        return 0
+    if cmd == 'info':
+        when = datetime.fromisoformat(sys.argv[2].replace('Z', '+00:00'))
+        alt, az = altaz(when)
+        print(f'utc={when.strftime("%Y-%m-%dT%H:%M:%SZ")}')
+        print(f'local={_format_local(when)}')
+        print(f'illumination={illumination(when):.4f}')
+        print(f'phase_angle_deg={phase_angle(when):.2f}')
+        print(f'waxing={waxing(when)}')
+        print(f'altitude_deg={alt:.3f}')
+        print(f'azimuth_deg={az:.3f}')
+        print(f'parallactic_angle_deg={parallactic_angle(when):.3f}')
+        return 0
+    print(f'unknown command: {cmd}', file=sys.stderr)
+    return 1
+
+
+if __name__ == '__main__':
+    sys.exit(_cli())
diff --git a/moon_phase_monthly.py b/moon_phase_monthly.py
new file mode 100755
index 0000000..8801d3a
--- /dev/null
+++ b/moon_phase_monthly.py
@@ -0,0 +1,412 @@
+#!/usr/bin/env python3
+"""moon_phase_monthly.py — build the monthly moon-phase composite.
+
+Handles three phases, controlled by --phase:
+
+  full              ~100% lit, posted MOON_FULL_POST_DELAY_DAYS after exact full
+  first-quarter     ~50% lit waxing (right half lit in northern hemisphere)
+  third-quarter     ~50% lit waning (left half lit in northern hemisphere)
+
+Algorithm (per phase):
+  1. Find the most recent occurrence of the target phase (or honour --target).
+  2. Scan east frames across the collection window (D-Δb .. D+Δa).
+  3. Filter to frames where:
+       quality      >= MOON_MIN_QUALITY
+       altitude_deg >= MOON_MIN_ALTITUDE_DEG
+       illumination is within the phase's illumination band
+       waxing-state matches the phase target
+  4. Pick the qualifying frame closest in time to exact phase UTC.
+  5. Composite the cached lunar texture into it (real sky + halo from east,
+     borrowed surface detail from the cached reference).
+  6. Optionally upload to Mattermost.
+
+Geometry note — first-quarter from east is HARD: at first quarter the moon is
+up from noon to midnight, but east only sees the eastern sky, so it captures
+the moon during DAYTIME only (with a bright sky background).  The detector is
+brightness-based and may often fail to find a daytime moon.  Set
+MOON_FIRST_QUARTER_ENABLED=false in sky-cam.conf if you'd rather not chase it.
+Full moon and third-quarter both rise after dark and stay in east's view —
+those should land cleanly most months.
+
+Usage:
+  moon_phase_monthly.py                  # auto: run any phase whose post-day = today
+  moon_phase_monthly.py --phase full     # force a single phase
+  moon_phase_monthly.py --phase third-quarter --target 2026-04-09T11:51:00Z --dry-run
+"""
+from __future__ import annotations
+
+import argparse
+import os
+import pathlib
+import re
+import subprocess
+import sys
+from datetime import datetime, timedelta, timezone
+
+_here = pathlib.Path(__file__).resolve().parent
+sys.path.insert(0, str(_here))
+
+
+def _read_conf(path):
+    conf = {}
+    try:
+        with open(path) as f:
+            for line in f:
+                line = line.strip()
+                if not line or line.startswith('#') or '=' not in line:
+                    continue
+                k, v = line.split('=', 1)
+                k = k.strip()
+                v = v.strip()
+                v = re.sub(r'\s+#.*$', '', v)
+                v = v.strip('"').strip("'")
+                m = re.match(r'^\$\{[^}]+:-([^}]*)\}$', v)
+                if m:
+                    v = m.group(1).strip('"').strip("'")
+                conf[k] = v
+    except FileNotFoundError:
+        pass
+    return conf
+
+
+CONF = _read_conf(_here / 'sky-cam.conf')
+CONF.update(_read_conf(_here / '.env'))
+
+BASE_DIR = CONF.get('BASE_DIR') or str(_here / 'data')
+MOVIES_DIR = CONF.get('MOVIES_DIR') or f'{BASE_DIR}/movies'
+SUNRISE_CAM = CONF.get('SUNRISE_CAM', 'east')
+TIMEZONE = CONF.get('TIMEZONE', 'UTC')
+
+MIN_QUALITY = float(CONF.get('MOON_MIN_QUALITY', CONF.get('MOON_FULL_MIN_QUALITY', 0.55)))
+MIN_ALTITUDE = float(CONF.get('MOON_MIN_ALTITUDE_DEG', CONF.get('MOON_FULL_MIN_ALTITUDE_DEG', 15.0)))
+OUT_W = int(CONF.get('MOON_OUTPUT_W', CONF.get('MOON_FULL_OUTPUT_W', 1920)))
+OUT_H = int(CONF.get('MOON_OUTPUT_H', CONF.get('MOON_FULL_OUTPUT_H', 1080)))
+MOON_PCT = float(CONF.get('MOON_HEIGHT_PCT', CONF.get('MOON_FULL_HEIGHT_PCT', 0.70)))
+REF_PATH = CONF.get('MOON_REFERENCE_PATH') or str(_here / 'moon-ref' / 'full-moon.jpg')
+
+
+PHASE_SPEC = {
+    'full': {
+        'index': 2,
+        'label': 'Full Moon',
+        'emoji': '🌕',
+        'illum_min': float(CONF.get('MOON_FULL_MIN_ILLUMINATION', 0.95)),
+        'illum_max': 1.01,
+        'waxing': None,
+        'window_before': int(CONF.get('MOON_FULL_WINDOW_BEFORE_DAYS', 1)),
+        'window_after': int(CONF.get('MOON_FULL_WINDOW_AFTER_DAYS', 2)),
+        'post_delay': int(CONF.get('MOON_FULL_POST_DELAY_DAYS', 3)),
+        'enabled_key': 'MOON_FULL_ENABLED',
+    },
+    'first-quarter': {
+        'index': 1,
+        'label': 'First Quarter (Waxing Half)',
+        'emoji': '🌓',
+        'illum_min': float(CONF.get('MOON_QUARTER_MIN_ILLUMINATION', 0.40)),
+        'illum_max': float(CONF.get('MOON_QUARTER_MAX_ILLUMINATION', 0.65)),
+        'waxing': True,
+        'window_before': int(CONF.get('MOON_QUARTER_WINDOW_BEFORE_DAYS', 1)),
+        'window_after': int(CONF.get('MOON_QUARTER_WINDOW_AFTER_DAYS', 1)),
+        'post_delay': int(CONF.get('MOON_QUARTER_POST_DELAY_DAYS', 2)),
+        'enabled_key': 'MOON_FIRST_QUARTER_ENABLED',
+    },
+    'third-quarter': {
+        'index': 3,
+        'label': 'Third Quarter (Waning Half)',
+        'emoji': '🌗',
+        'illum_min': float(CONF.get('MOON_QUARTER_MIN_ILLUMINATION', 0.40)),
+        'illum_max': float(CONF.get('MOON_QUARTER_MAX_ILLUMINATION', 0.65)),
+        'waxing': False,
+        'window_before': int(CONF.get('MOON_QUARTER_WINDOW_BEFORE_DAYS', 1)),
+        'window_after': int(CONF.get('MOON_QUARTER_WINDOW_AFTER_DAYS', 1)),
+        'post_delay': int(CONF.get('MOON_QUARTER_POST_DELAY_DAYS', 2)),
+        'enabled_key': 'MOON_THIRD_QUARTER_ENABLED',
+    },
+}
+
+_FRAME_RE = re.compile(r'^(\d{2})-(\d{2})-(\d{2})\.jpg$')
+
+
+def _local_tz():
+    try:
+        import pytz
+        return pytz.timezone(TIMEZONE)
+    except Exception:
+        return timezone.utc
+
+
+def _frame_local_dt(date_str: str, fname: str):
+    m = _FRAME_RE.match(fname)
+    if not m:
+        return None
+    h, mn, s = (int(x) for x in m.groups())
+    y, mo, d = (int(x) for x in date_str.split('-'))
+    naive = datetime(y, mo, d, h, mn, s)
+    tz = _local_tz()
+    if hasattr(tz, 'localize'):
+        return tz.localize(naive)
+    return naive.replace(tzinfo=tz)
+
+
+def _candidate_frames(cam: str, dates: list[str]) -> list[tuple[str, datetime]]:
+    out = []
+    for d in dates:
+        fdir = pathlib.Path(BASE_DIR) / cam / d
+        if not fdir.is_dir():
+            continue
+        for fname in sorted(os.listdir(fdir)):
+            if not fname.endswith('.jpg'):
+                continue
+            local_dt = _frame_local_dt(d, fname)
+            if local_dt is None:
+                continue
+            out.append((str(fdir / fname), local_dt.astimezone(timezone.utc)))
+    return out
+
+
+def _format_local(dt_utc: datetime) -> str:
+    return dt_utc.astimezone(_local_tz()).strftime('%Y-%m-%d %H:%M:%S %Z')
+
+
+def _notify(title: str, body: str):
+    try:
+        subprocess.run([str(_here / 'notify.sh'), title, body], check=False)
+    except FileNotFoundError:
+        pass
+
+
+def _post_to_mattermost(image_path: str, message: str) -> bool:
+    import requests
+    base = CONF.get('mattermost_url', '').rstrip('/')
+    token = CONF.get('access_token', '')
+    channel_id = CONF.get('channel_id', '')
+    if not all([base, token, channel_id]):
+        print('mattermost credentials missing — skipping upload', file=sys.stderr)
+        return False
+    headers = {'Authorization': f'Bearer {token}'}
+    with open(image_path, 'rb') as f:
+        r = requests.post(
+            f'{base}/api/v4/files',
+            headers=headers,
+            files={'files': f},
+            data={'channel_id': channel_id},
+        )
+    if r.status_code != 201:
+        print(f'mattermost upload failed: {r.status_code} {r.text}', file=sys.stderr)
+        return False
+    file_id = r.json()['file_infos'][0]['id']
+    r = requests.post(
+        f'{base}/api/v4/posts',
+        headers=headers,
+        json={'channel_id': channel_id, 'message': message, 'file_ids': [file_id]},
+    )
+    if r.status_code != 201:
+        print(f'mattermost post failed: {r.status_code} {r.text}', file=sys.stderr)
+        return False
+    return True
+
+
+def _output_subdir(phase: str) -> str:
+    return {
+        'full': 'full-moons',
+        'first-quarter': 'first-quarter',
+        'third-quarter': 'third-quarter',
+    }[phase]
+
+
+def _output_filename(phase: str, target_utc: datetime) -> str:
+    slug = {'full': 'full', 'first-quarter': 'first-quarter', 'third-quarter': 'third-quarter'}[phase]
+    return f"{target_utc.strftime('%Y-%m')}-{slug}.jpg"
+
+
+def run_phase(phase: str, target_utc: datetime | None, cam: str,
+              dry_run: bool, no_upload: bool, out_path: str | None) -> int:
+    spec = PHASE_SPEC[phase]
+    if CONF.get(spec['enabled_key'], 'true').lower() == 'false':
+        print(f'{spec["enabled_key"]}=false — skipping {phase}')
+        return 0
+
+    import moon_phase
+    from moon_detect import detect_moon
+
+    if target_utc is None:
+        now = datetime.now(timezone.utc)
+        events = moon_phase.phase_events_in_range(
+            now - timedelta(days=45), now, spec['index'])
+        if not events:
+            print(f'no recent {phase} found in past 45 days', file=sys.stderr)
+            return 1
+        target_utc = events[-1]
+
+    print(f'target {phase}: {target_utc.isoformat()}  ({_format_local(target_utc)})')
+
+    tz = _local_tz()
+    target_local = target_utc.astimezone(tz)
+    dates = []
+    for i in range(-spec['window_before'], spec['window_after'] + 1):
+        d = (target_local + timedelta(days=i)).date()
+        dates.append(d.strftime('%Y-%m-%d'))
+    print(f'scanning dates: {dates}')
+
+    candidates = _candidate_frames(cam, dates)
+    print(f'frame count in window: {len(candidates)}')
+    if not candidates:
+        msg = (
+            f'No frames for {cam} in window {dates[0]}..{dates[-1]} '
+            f'around {phase} {target_utc.strftime("%Y-%m-%d %H:%MZ")}.'
+        )
+        _notify(f'{spec["emoji"]} {spec["label"]} — no frames available', msg)
+        print(msg)
+        return 0
+
+    qualifying = []
+    for path, utc_dt in candidates:
+        try:
+            alt, _ = moon_phase.altaz(utc_dt)
+        except Exception as e:
+            print(f'ERROR: moon_phase.altaz failed: {e}', file=sys.stderr)
+            return 2
+        if alt < MIN_ALTITUDE:
+            continue
+        det = detect_moon(path)
+        if det is None or det.quality < MIN_QUALITY:
+            continue
+        illum = moon_phase.illumination(utc_dt)
+        if illum < spec['illum_min'] or illum > spec['illum_max']:
+            continue
+        if spec['waxing'] is not None:
+            if moon_phase.waxing(utc_dt) != spec['waxing']:
+                continue
+        qualifying.append((path, utc_dt, det, alt, illum))
+
+    print(f'qualifying frames: {len(qualifying)}')
+    if not qualifying:
+        msg = (
+            f'No clear-shot {phase} frame in window {dates[0]}..{dates[-1]} '
+            f'(need quality≥{MIN_QUALITY}, altitude≥{MIN_ALTITUDE}°, '
+            f'illumination {spec["illum_min"]:.2f}-{spec["illum_max"]:.2f}). '
+        )
+        if phase == 'first-quarter':
+            msg += ('First quarter from east is best-effort because the moon is '
+                    'only up during daylight hours — daytime detection often '
+                    'fails. Lower MOON_MIN_QUALITY or accept that some months '
+                    'will skip.')
+        else:
+            msg += 'Likely cloudy across the whole window.'
+        _notify(f'{spec["emoji"]} {spec["label"]} — no clear shot {target_utc.strftime("%B %Y")}', msg)
+        print(msg)
+        return 0
+
+    best = min(qualifying, key=lambda t: abs(t[1] - target_utc))
+    path, when_utc, det, alt, illum = best
+    delta_min = (when_utc - target_utc).total_seconds() / 60.0
+    local_dt = when_utc.astimezone(tz)
+    print(f'picked: {path}')
+    print(f'  when_utc={when_utc.isoformat()}  local={local_dt}  '
+          f'altitude={alt:.1f}°  illum={illum:.4f}  quality={det.quality:.3f}  '
+          f'Δtarget={delta_min:+.1f} min')
+
+    if dry_run:
+        return 0
+
+    if not pathlib.Path(REF_PATH).is_file():
+        msg = (f'Lunar reference image missing at {REF_PATH}. Re-run install.sh '
+               f'or drop a high-res full moon JPEG there manually.')
+        _notify(f'{spec["emoji"]} {spec["label"]} — reference missing', msg)
+        print(msg, file=sys.stderr)
+        return 3
+
+    if out_path is None:
+        out_dir = pathlib.Path(MOVIES_DIR) / cam / _output_subdir(phase)
+        out_dir.mkdir(parents=True, exist_ok=True)
+        out_path = str(out_dir / _output_filename(phase, target_utc))
+
+    from moon_composite import composite_full_moon
+    caption = (
+        f"{spec['label']} — {target_utc.strftime('%B %Y')} — "
+        f"sky-cam {cam} {local_dt.strftime('%Y-%m-%d %H:%M:%S %Z')}"
+    )
+    composite_full_moon(
+        path, det, when_utc, REF_PATH, out_path,
+        output_size=(OUT_W, OUT_H), moon_height_pct=MOON_PCT,
+        caption=caption,
+    )
+    print(f'wrote {out_path}')
+
+    if no_upload:
+        _notify(
+            f'{spec["emoji"]} {spec["label"]} {target_utc.strftime("%B %Y")} (built, not posted)',
+            f'{out_path} — picked {local_dt}, Δtarget {delta_min:+.0f} min',
+        )
+        return 0
+
+    posted = _post_to_mattermost(
+        out_path,
+        f"{spec['emoji']} {spec['label']} — {target_utc.strftime('%B %Y')}\n"
+        f"Captured by sky-cam {cam} at {local_dt.strftime('%Y-%m-%d %H:%M:%S %Z')} "
+        f"({delta_min:+.0f} min from exact {phase}).",
+    )
+    if posted:
+        _notify(
+            f'{spec["emoji"]} {spec["label"]} {target_utc.strftime("%B %Y")} posted',
+            f'Picked {local_dt} — Δtarget {delta_min:+.0f} min — {out_path}',
+        )
+    else:
+        _notify(
+            f'FAILED: {spec["emoji"]} {spec["label"]} {target_utc.strftime("%B %Y")} upload',
+            f'Composite built at {out_path} but Mattermost upload failed.',
+        )
+    return 0
+
+
+def auto_run(cam: str, dry_run: bool, no_upload: bool) -> int:
+    """Daily check: run any phase whose post-day equals today (UTC)."""
+    import moon_phase
+    today_utc = datetime.now(timezone.utc).date()
+    ran_any = False
+    rc = 0
+    for phase, spec in PHASE_SPEC.items():
+        if CONF.get(spec['enabled_key'], 'true').lower() == 'false':
+            print(f'-- {phase}: {spec["enabled_key"]}=false → skip')
+            continue
+        events = moon_phase.phase_events_in_range(
+            datetime.combine(today_utc - timedelta(days=45), datetime.min.time(), tzinfo=timezone.utc),
+            datetime.now(timezone.utc),
+            spec['index'])
+        if not events:
+            continue
+        last_event = events[-1]
+        days_since = (today_utc - last_event.date()).days
+        if days_since == spec['post_delay']:
+            print(f'== running {phase} (last event {last_event.date()}, +{spec["post_delay"]} days = today) ==')
+            sub = run_phase(phase, last_event, cam, dry_run, no_upload, None)
+            rc = rc or sub
+            ran_any = True
+        else:
+            print(f'-- {phase}: last {last_event.date()}, days_since={days_since}, post_delay={spec["post_delay"]} → skip')
+    if not ran_any:
+        print('no phase scheduled for today')
+    return rc
+
+
+def main():
+    p = argparse.ArgumentParser()
+    p.add_argument('--phase', choices=list(PHASE_SPEC.keys()),
+                   help='Run a single phase regardless of schedule')
+    p.add_argument('--target', help='Override phase event UTC, ISO 8601 (requires --phase)')
+    p.add_argument('--cam', default=SUNRISE_CAM)
+    p.add_argument('--dry-run', action='store_true')
+    p.add_argument('--no-upload', action='store_true')
+    p.add_argument('--out', help='Override output path (requires --phase)')
+    args = p.parse_args()
+
+    if args.phase:
+        target = None
+        if args.target:
+            target = datetime.fromisoformat(args.target.replace('Z', '+00:00'))
+        return run_phase(args.phase, target, args.cam, args.dry_run, args.no_upload, args.out)
+    return auto_run(args.cam, args.dry_run, args.no_upload)
+
+
+if __name__ == '__main__':
+    sys.exit(main())
diff --git a/sky-cam.conf b/sky-cam.conf
index f4d6dea..e115faf 100644
--- a/sky-cam.conf
+++ b/sky-cam.conf
@@ -47,6 +47,18 @@
 #                             on the last day of a movement, auto-triggers
 #                             montage-mvt.sh
 #
+#    moon-track.sh          — nightly at SCHEDULE_MOON_TRACK (SUNRISE_CAM only)
+#                             detects the moon in each east night frame, crops
+#                             a tracked sequence, stitches into an mp4
+#
+#    moon-phase-monthly.sh  — daily at SCHEDULE_MOON_PHASE (SUNRISE_CAM only)
+#                             no-ops except on phase post-days, when it picks
+#                             the best east frame from the collection window,
+#                             composites a high-res lunar texture into it,
+#                             and posts to Mattermost.  Handles full moon,
+#                             first quarter (waxing half), and third quarter
+#                             (waning half).
+#
 #
 #    install.sh             — run once at setup, and again if this file changes
 #                             generates and installs systemd units from conf
@@ -135,6 +147,25 @@
 #    ← run manually only; no script calls it
 #    → safe to rename with no other changes needed
 #
+#  moon-track.sh
+#    ← called by systemd sky-cam-moon-track.timer (SCHEDULE_MOON_TRACK)
+#    → if renamed: update install.sh (the moon-track write_service block)
+#    calls → moon_detect.py (Python lib via heredoc), ffmpeg
+#
+#  moon-phase-monthly.sh
+#    ← called by systemd sky-cam-moon-phase.timer (SCHEDULE_MOON_PHASE)
+#    → if renamed: update install.sh (the moon-phase write_service block)
+#    calls → moon_phase_monthly.py
+#
+#  moon_phase_monthly.py
+#    ← called by moon-phase-monthly.sh
+#    → if renamed: update moon-phase-monthly.sh (the exec line at the bottom)
+#    calls → moon_phase.py, moon_detect.py, moon_composite.py, notify.sh
+#
+#  moon_phase.py / moon_detect.py / moon_composite.py
+#    ← Python libraries used by moon-track.sh and moon_phase_monthly.py
+#    → if renamed: update moon-track.sh, moon_phase_monthly.py, README
+#
 # =============================================================================
 
 # ── Install location ──────────────────────────────────────────────────────────
@@ -235,6 +266,10 @@ SUNRISE_CAM=east                   # which camera faces east (gets the sunrise v
 #
 SCHEDULE_SUNRISE=03:00:00
 
+# Moon jobs (see "Moon jobs" section further down)
+SCHEDULE_MOON_TRACK=02:30:00       # nightly tracker — runs after midnight, before seasons
+SCHEDULE_MOON_PHASE=09:30:00       # daily check; no-ops except on phase post-days
+
 # Four Seasons daily clip — one per camera, staggered 30 min apart.
 # Processes yesterday's images; on the last day of a movement auto-triggers
 # montage-mvt.sh.  Space cameras at least 30 min apart to avoid disk contention.
@@ -397,6 +432,80 @@ AMBIENT_RETENTION_DAYS=30              # global default; 0 = keep forever
 #AMBIENT_RETENTION_DAYS_north=30
 #AMBIENT_RETENTION_DAYS_south=60       # keep south longer for nature sound library
 
+# ── Moon jobs (nightly tracker + monthly phase close-ups) ────────────────────
+# All moon jobs operate on the SUNRISE_CAM (the east-facing camera that already
+# has a clear view of the eastern sky).  They share three Python helpers
+# (moon_phase.py, moon_detect.py, moon_composite.py) and one cached lunar
+# reference texture downloaded by install.sh.
+#
+#   moon-track.sh             nightly batch — detects the moon in each frame,
+#                             crops a 480×480 box around it, stitches the
+#                             tracked sequence into an mp4.  Output:
+#                             $MOVIES_DIR/<cam>/moon-track/YYYY/YYYY-MM-DD-moon-track.mp4
+#
+#   moon-phase-monthly.sh     daily check; runs whichever phase composite is
+#                             due today.  Three phases handled:
+#                               🌕 Full Moon          posts D + MOON_FULL_POST_DELAY_DAYS
+#                               🌓 First Quarter      posts D + MOON_QUARTER_POST_DELAY_DAYS
+#                               🌗 Third Quarter      posts D + MOON_QUARTER_POST_DELAY_DAYS
+#                             Each picks the frame closest in time to the
+#                             exact phase moment that meets quality / altitude
+#                             / illumination thresholds, composites the
+#                             cached lunar texture into it (sky/halo/angle
+#                             real from east, surface detail borrowed),
+#                             uploads to Mattermost.  Output:
+#                             $MOVIES_DIR/<cam>/full-moons/YYYY-MM-full.jpg
+#                             $MOVIES_DIR/<cam>/first-quarter/YYYY-MM-first-quarter.jpg
+#                             $MOVIES_DIR/<cam>/third-quarter/YYYY-MM-third-quarter.jpg
+#
+# Honest-by-design: the surface texture is not from your camera (no software
+# can recover detail your camera didn't capture).  The framing — sky color,
+# halo, parallactic angle, exact moment of capture — is all real-from-east.
+#
+# Geometry caveat: east only sees the eastern sky.  At first quarter the moon
+# is up only from noon to midnight, transiting south at sunset, so east only
+# catches it during DAYTIME.  The brightness-based detector often fails on
+# daytime moon shots — first quarter is best-effort.  Full moon and third
+# quarter both rise after dark and stay in east's view; those should land
+# cleanly most months.
+#
+# Toggles (any can be disabled independently):
+MOON_TRACK_ENABLED=true
+MOON_FULL_ENABLED=true
+MOON_FIRST_QUARTER_ENABLED=true    # set false if daytime-detection misses are noisy
+MOON_THIRD_QUARTER_ENABLED=true
+
+# Nightly tracker tuning ──────────────────────────────────────────────────────
+MOON_TRACK_CROP_PX=480             # pixels — box size around the moon (source coords)
+MOON_TRACK_FPS=12                  # output mp4 framerate
+MOON_TRACK_CRF=24                  # output mp4 CRF
+MOON_TRACK_RETENTION_DAYS=90       # delete tracker mp4s older than this; 0 = forever
+
+# Full-moon monthly tuning ────────────────────────────────────────────────────
+# How many days after the exact full moon to post.  3 = waits for D-1..D+2
+# nights to be on disk, then runs the morning of D+3.
+MOON_FULL_POST_DELAY_DAYS=3
+
+# Frame-acceptance thresholds — a candidate must beat all three to qualify.
+# Lower = more permissive (accept hazier nights / lower moon).  If you find
+# the script never finds a clear shot, loosen these.
+MOON_FULL_MIN_QUALITY=0.55         # 0..1 from moon_detect (roundness × halo × isolation)
+MOON_FULL_MIN_ALTITUDE_DEG=15      # below this the moon is in trees / on the horizon
+MOON_FULL_MIN_ILLUMINATION=0.95    # 0..1 — ~95% lit covers ±2 days from exact full
+
+# Output frame.  Default 1920×1080 to match the sunrise videos.
+MOON_FULL_OUTPUT_W=1920
+MOON_FULL_OUTPUT_H=1080
+MOON_FULL_HEIGHT_PCT=0.70          # moon disk fills this fraction of frame height
+
+# Lunar reference texture — downloaded once by install.sh, reused forever.
+# Override MOON_REFERENCE_URL in .env to use a different image.  Any high-res
+# photo of a full moon on a black background works.  Default is the Wikipedia
+# "FullMoon2010" by Gregory H. Revera (CC BY-SA 3.0), 3500×3500.
+#MOON_REFERENCE_URL=https://upload.wikimedia.org/wikipedia/commons/e/e1/FullMoon2010.jpg
+#MOON_REFERENCE_DIR="$SCRIPT_DIR/moon-ref"
+#MOON_REFERENCE_PATH="$MOON_REFERENCE_DIR/full-moon.jpg"
+
 # ── Mattermost — daily sunrise upload ─────────────────────────────────────────
 # mattermost_url, access_token, channel_id go in .env (see bottom of this file).