feat(icons): spectrum aperture icon set + dedicated tray variant

Regenerate the LedGrab icon family from a single Pillow script
(build/generate_icon.py): a rounded-square aperture traced by a
continuous RGB color-wheel stroke over a vignette canvas with a soft
chromatic bloom. 4x supersampled then downsampled per output for
crispness. Outputs 192/512 standard, 512 maskable (safe-area padded
for PWA round-crops), and a new 256 transparent-background tray
variant so the taskbar icon reads cleanly against light themes
instead of showing a dark tile.

icon.ico now embeds 16/24/32/48/64/128/256 frames sourced from the
transparent tray master, fixing the dark-square halo around the
file/taskbar icon on light Windows themes.

__main__ picks icon-tray.png for the tray and falls back to
icon-192.png when the tray asset isn't present (older bundles /
forks).

build/generate_icon.py

@@ -0,0 +1,327 @@
+"""Generate LedGrab app icon assets.
+
+Concept: "Spectrum Aperture" — a rounded-square frame (the screen/display)
+traced by a continuous RGB color-wheel stroke (the bias-light LED strip),
+on a near-black canvas with a soft chromatic bloom behind it.
+
+Outputs:
+    server/src/ledgrab/static/icons/icon-512.png           (standard, opaque vignette bg)
+    server/src/ledgrab/static/icons/icon-192.png           (downscale of 512)
+    server/src/ledgrab/static/icons/icon-512-maskable.png  (safe-area padded, opaque)
+    server/src/ledgrab/static/icons/icon-tray.png          (256, transparent bg, frame + glow)
+    server/src/ledgrab/static/icons/icon.ico               (16/24/32/48/64/128/256)
+
+Run from repo root:
+    py -3.13 build/generate_icon.py
+"""
+
+from __future__ import annotations
+
+import colorsys
+import math
+from pathlib import Path
+
+from PIL import Image, ImageDraw, ImageFilter
+
+# ── Tunables ────────────────────────────────────────────────────────────
+SUPERSAMPLE = 4  # render at 4x and downsample for crispness
+BASE = 1024  # logical canvas size
+HQ = BASE * SUPERSAMPLE  # render canvas
+
+BG_TOP = (12, 14, 22)  # near-black, faint cool tint
+BG_BOTTOM = (6, 7, 12)  # darker at edges (vignette feel)
+
+FRAME_INSET = 0.18  # margin from canvas edge to frame (fraction)
+FRAME_RADIUS = 0.22  # corner radius (fraction of frame side)
+FRAME_STROKE = 0.085  # stroke width (fraction of canvas)
+BLOOM_OPACITY = 0.62  # outer bloom strength (0–1)
+INNER_GLOW_OPACITY = 0.38  # inner chromatic reflection strength
+
+# Hue rotation offset so red sits at the top
+HUE_OFFSET = -90.0  # degrees (negative = counter-clockwise shift)
+
+
+def lerp(a: float, b: float, t: float) -> float:
+    return a + (b - a) * t
+
+
+def hue_to_rgb(hue_deg: float) -> tuple[int, int, int]:
+    """Bright, slightly desaturated spectral color (LED-like)."""
+    h = (hue_deg % 360) / 360.0
+    r, g, b = colorsys.hls_to_rgb(h, 0.58, 0.92)
+    return int(r * 255), int(g * 255), int(b * 255)
+
+
+def vignette_background(size: int) -> Image.Image:
+    """Dark canvas with a soft radial vignette + faint scanline noise."""
+    img = Image.new("RGB", (size, size), BG_TOP)
+    px = img.load()
+    cx, cy = size / 2, size / 2
+    max_r = math.hypot(cx, cy)
+    for y in range(size):
+        for x in range(size):
+            d = math.hypot(x - cx, y - cy) / max_r
+            t = min(1.0, d**1.6)
+            px[x, y] = (
+                int(lerp(BG_TOP[0], BG_BOTTOM[0], t)),
+                int(lerp(BG_TOP[1], BG_BOTTOM[1], t)),
+                int(lerp(BG_TOP[2], BG_BOTTOM[2], t)),
+            )
+    return img
+
+
+def draw_chromatic_bloom(size: int) -> Image.Image:
+    """Soft, large chromatic glow behind the frame — the bias-light effect."""
+    layer = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    draw = ImageDraw.Draw(layer)
+
+    cx, cy = size / 2, size / 2
+    radius = size * 0.36
+    blob_r = int(size * 0.30)
+    n_blobs = 24
+
+    for i in range(n_blobs):
+        a = i / n_blobs * 360.0
+        bx = cx + math.cos(math.radians(a - 90)) * radius
+        by = cy + math.sin(math.radians(a - 90)) * radius
+        r, g, b = hue_to_rgb(a + HUE_OFFSET)
+        alpha = int(255 * BLOOM_OPACITY * 0.55)
+        draw.ellipse(
+            (bx - blob_r, by - blob_r, bx + blob_r, by + blob_r),
+            fill=(r, g, b, alpha),
+        )
+
+    # Heavy blur → continuous, dreamy halo
+    layer = layer.filter(ImageFilter.GaussianBlur(radius=size * 0.10))
+    return layer
+
+
+def rounded_rect_mask(size: int, inset: int, radius: int, stroke: int) -> Image.Image:
+    """L-mode mask of a rounded-rect ring (the frame stroke region)."""
+    mask = Image.new("L", (size, size), 0)
+    draw = ImageDraw.Draw(mask)
+    box_outer = (inset, inset, size - inset, size - inset)
+    box_inner = (
+        inset + stroke,
+        inset + stroke,
+        size - inset - stroke,
+        size - inset - stroke,
+    )
+    r_outer = radius
+    r_inner = max(0, radius - stroke)
+    draw.rounded_rectangle(box_outer, radius=r_outer, fill=255)
+    draw.rounded_rectangle(box_inner, radius=r_inner, fill=0)
+    return mask
+
+
+def draw_spectrum_frame(size: int) -> Image.Image:
+    """Draw the rounded-square frame stroke filled with a hue-rotation gradient.
+
+    Strategy: paint a full-canvas angular hue gradient (centered), then
+    clip it with the rounded-ring mask. This guarantees a continuous,
+    seam-free color flow around the entire frame.
+    """
+    cx, cy = size / 2, size / 2
+
+    gradient = Image.new("RGB", (size, size), (0, 0, 0))
+    gpx = gradient.load()
+    for y in range(size):
+        dy = y - cy
+        for x in range(size):
+            dx = x - cx
+            ang = math.degrees(math.atan2(dy, dx)) + 90.0  # 0° = top
+            r, g, b = hue_to_rgb(ang + HUE_OFFSET)
+            gpx[x, y] = (r, g, b)
+
+    inset = int(size * FRAME_INSET)
+    frame_side = size - 2 * inset
+    stroke = int(size * FRAME_STROKE)
+    radius = int(frame_side * FRAME_RADIUS)
+
+    mask = rounded_rect_mask(size, inset, radius, stroke)
+
+    out = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    out.paste(gradient, (0, 0), mask)
+    return out
+
+
+def draw_inner_screen(size: int) -> Image.Image:
+    """Subtle dark rounded square inside the frame, with faint chromatic
+    inner reflection along the edges — like a screen catching ambient light."""
+    inset = int(size * FRAME_INSET)
+    stroke = int(size * FRAME_STROKE)
+    frame_side = size - 2 * inset
+    radius = int(frame_side * FRAME_RADIUS)
+
+    pad = int(stroke * 0.35)
+    box = (
+        inset + stroke + pad,
+        inset + stroke + pad,
+        size - inset - stroke - pad,
+        size - inset - stroke - pad,
+    )
+    r_inner = max(0, radius - stroke - pad)
+
+    layer = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    draw = ImageDraw.Draw(layer)
+    # Dark fill, very slight cool tint
+    draw.rounded_rectangle(box, radius=r_inner, fill=(10, 12, 18, 255))
+
+    # Inner chromatic glow: same spectrum, very soft, clipped to the screen
+    bloom = draw_chromatic_bloom(size)
+    screen_mask = Image.new("L", (size, size), 0)
+    ImageDraw.Draw(screen_mask).rounded_rectangle(box, radius=r_inner, fill=255)
+
+    bloom_alpha = bloom.split()[-1].point(lambda v: int(v * INNER_GLOW_OPACITY))
+    bloom.putalpha(bloom_alpha)
+
+    masked_bloom = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    masked_bloom.paste(bloom, (0, 0), screen_mask)
+    layer.alpha_composite(masked_bloom)
+
+    # Faint highlight glint top-left
+    glint = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    gdraw = ImageDraw.Draw(glint)
+    glint_box = (
+        box[0] + int(frame_side * 0.04),
+        box[1] + int(frame_side * 0.04),
+        box[0] + int(frame_side * 0.42),
+        box[1] + int(frame_side * 0.18),
+    )
+    gdraw.rounded_rectangle(glint_box, radius=int(frame_side * 0.05), fill=(255, 255, 255, 22))
+    glint = glint.filter(ImageFilter.GaussianBlur(radius=size * 0.012))
+    masked_glint = Image.new("RGBA", (size, size), (0, 0, 0, 0))
+    masked_glint.paste(glint, (0, 0), screen_mask)
+    layer.alpha_composite(masked_glint)
+
+    return layer
+
+
+def add_outer_frame_glow(frame_rgba: Image.Image) -> Image.Image:
+    """Take the spectrum frame and produce a blurred, brightened copy for glow."""
+    glow = frame_rgba.copy()
+    # Slightly inflate brightness for glow
+    r, g, b, a = glow.split()
+    glow = Image.merge("RGBA", (r, g, b, a.point(lambda v: min(255, int(v * 0.85)))))
+    glow = glow.filter(ImageFilter.GaussianBlur(radius=glow.width * 0.025))
+    return glow
+
+
+def render_tray(size: int) -> Image.Image:
+    """Render a tray-optimised icon: transparent background, bolder frame,
+    tight outer glow. Designed to read clearly at 16–32 px on top of any
+    taskbar color."""
+    hq = size * SUPERSAMPLE
+
+    # Pull the frame inward a touch and beef up the stroke so it reads at 16 px.
+    global FRAME_INSET, FRAME_STROKE
+    saved_inset, saved_stroke = FRAME_INSET, FRAME_STROKE
+    FRAME_INSET = 0.13
+    FRAME_STROKE = 0.115
+    try:
+        frame = draw_spectrum_frame(hq)
+    finally:
+        FRAME_INSET, FRAME_STROKE = saved_inset, saved_stroke
+
+    # Tight, bright glow that doesn't bleed past the tray cell.
+    glow = frame.copy()
+    r, g, b, a = glow.split()
+    glow = Image.merge("RGBA", (r, g, b, a.point(lambda v: min(255, int(v * 0.95)))))
+    glow = glow.filter(ImageFilter.GaussianBlur(radius=hq * 0.012))
+
+    canvas = Image.new("RGBA", (hq, hq), (0, 0, 0, 0))
+    canvas.alpha_composite(glow)
+    canvas.alpha_composite(frame)
+
+    return canvas.resize((size, size), Image.LANCZOS)
+
+
+def render(size: int, *, maskable: bool = False) -> Image.Image:
+    """Render the full icon at the given size."""
+    hq = size * SUPERSAMPLE
+
+    if maskable:
+        # Maskable: pad inward so the entire icon survives a circular crop.
+        # We render the standard composition at 80% of canvas size, centered.
+        bg = Image.new("RGB", (hq, hq), BG_BOTTOM).convert("RGBA")
+        bg.paste(vignette_background(hq), (0, 0))
+
+        inner = render(size, maskable=False).resize((int(hq * 0.78), int(hq * 0.78)), Image.LANCZOS)
+        # Strip the bg from the inner render: composite the spectrum
+        # parts on top of our maskable background.
+        ox = (hq - inner.width) // 2
+        oy = (hq - inner.height) // 2
+        bg.alpha_composite(inner, (ox, oy))
+        return bg.resize((size, size), Image.LANCZOS)
+
+    bg = vignette_background(hq).convert("RGBA")
+    bloom = draw_chromatic_bloom(hq)
+    frame = draw_spectrum_frame(hq)
+    frame_glow = add_outer_frame_glow(frame)
+    inner_screen = draw_inner_screen(hq)
+
+    # Composite order: bg → bloom → frame_glow → inner_screen → frame
+    canvas = Image.new("RGBA", (hq, hq), (0, 0, 0, 0))
+    canvas.alpha_composite(bg)
+    canvas.alpha_composite(bloom)
+    canvas.alpha_composite(frame_glow)
+    canvas.alpha_composite(inner_screen)
+    canvas.alpha_composite(frame)
+
+    return canvas.resize((size, size), Image.LANCZOS)
+
+
+def main() -> None:
+    repo_root = Path(__file__).resolve().parent.parent
+    targets = [
+        repo_root / "server" / "src" / "ledgrab" / "static" / "icons",
+        repo_root
+        / "android"
+        / "app"
+        / "build"
+        / "python"
+        / "sources"
+        / "debug"
+        / "ledgrab"
+        / "static"
+        / "icons",
+    ]
+
+    print("Rendering 1024 master...")
+    master = render(1024, maskable=False)
+
+    print("Rendering maskable 1024 master...")
+    maskable_master = render(1024, maskable=True)
+
+    print("Rendering tray 512 master (transparent bg)...")
+    tray_master = render_tray(512)
+
+    for icons_dir in targets:
+        if not icons_dir.exists():
+            print(f"  skip (missing): {icons_dir}")
+            continue
+
+        out_512 = icons_dir / "icon-512.png"
+        out_192 = icons_dir / "icon-192.png"
+        out_mask = icons_dir / "icon-512-maskable.png"
+        out_tray = icons_dir / "icon-tray.png"
+        out_ico = icons_dir / "icon.ico"
+
+        master.resize((512, 512), Image.LANCZOS).save(out_512, "PNG", optimize=True)
+        master.resize((192, 192), Image.LANCZOS).save(out_192, "PNG", optimize=True)
+        maskable_master.resize((512, 512), Image.LANCZOS).save(out_mask, "PNG", optimize=True)
+        tray_master.save(out_tray, "PNG", optimize=True)
+
+        # Pre-resize each frame from the 1024 master for maximum crispness.
+        # Pass them via the `sizes` arg so Pillow embeds every variant.
+        ico_sizes = [(16, 16), (24, 24), (32, 32), (48, 48), (64, 64), (128, 128), (256, 256)]
+        # Use the tray (transparent-bg) variant for ICO frames so the file/
+        # taskbar icon doesn't show a dark tile against light backgrounds.
+        ico_source = tray_master.resize((256, 256), Image.LANCZOS)
+        ico_source.save(out_ico, format="ICO", sizes=ico_sizes)
+
+        print(f"  wrote: {icons_dir}")
+
+
+if __name__ == "__main__":
+    main()

server/src/ledgrab/__main__.py

@@ -49,7 +49,8 @@ from ledgrab.utils.win_shutdown import WindowsShutdownGuard  # noqa: E402
 setup_logging()
 logger = get_logger(__name__)
 
-_ICON_PATH = Path(__file__).parent / "static" / "icons" / "icon-192.png"
+_ICON_PATH = Path(__file__).parent / "static" / "icons" / "icon-tray.png"
+_ICON_FALLBACK_PATH = Path(__file__).parent / "static" / "icons" / "icon-192.png"
 
 
 def _run_server(server: uvicorn.Server) -> None:
@@ -154,8 +155,9 @@ def main() -> None:
             ).start()
 
         # Tray on main thread (blocking)
+        tray_icon = _ICON_PATH if _ICON_PATH.exists() else _ICON_FALLBACK_PATH
         tray = TrayManager(
-            icon_path=_ICON_PATH,
+            icon_path=tray_icon,
             port=config.server.port,
             on_exit=lambda: _request_shutdown(server),
         )