Revert to hand-drawn weather icons, styled after EC's set but exact panel colors

The vendored EC bitmaps looked good but dither into a visible speckle
once quantized to the panel's 6-color palette (their colors are
anti-aliased/arbitrary RGB, essentially never an exact palette match).
Hand-drawn icons filled with the frame's actual ink colors quantize with
zero dithering error to diffuse -- confirmed by running both through the
real quantize pass: the bitmap version speckles, the hand-drawn one is
pixel-identical before and after.

Redrawn to look more like EC's style this time around: pointed
triangular sun rays (the earlier attempt's thin-line rays read as a
crosshair, not a sun) and dendrite snowflakes (tick marks near each tip,
not a bare asterisk), plus the same cloud/raindrop/lightning-bolt shapes
as before. Removed the vendored server/app/weather_icons/ directory
entirely -- no longer used, and removes the icon-image licensing
question along with it.

docs/widgets.md

@@ -253,11 +253,17 @@ site, however far" matched a Miami, FL query to a site in Ontario,
 embedded strip, unchanged) plus this widget's own `build_current`/
 `build_hourly`/`build_daily`/`build_multi_city`, dispatched by `build()`
 -- the weather analogue of `calendar_render.py`'s own `_build_tasks`/
-`render_tasks_preview_png` relationship. Icons are vendored bitmaps (`app/
-weather_icons/`, one per shared category, sourced from Environment
-Canada's own weather icon set -- see that directory's `SOURCE.md` for
-attribution/licensing), not hand-drawn, and used for every provider's
-rendering, not just when EC is selected as the provider.
+`render_tasks_preview_png` relationship. Icons are hand-drawn (no custom
+font/icon asset), styled after Environment Canada's own icon set
+(pointed sun rays, a puffy cloud, teardrop rain, dendrite snowflakes, a
+zigzag bolt) but filled with the panel's *exact* ink RGB values rather
+than an arbitrary bitmap's anti-aliased colors -- a flat fill that's
+already a palette color quantizes with zero dithering error to diffuse,
+where a fetched/vendored icon's colors (almost never an exact match)
+dither into a visible speckle at these small on-panel sizes (confirmed
+by actually running one through the real quantize pass during
+development). Used for every provider's rendering, not just when EC is
+selected as the provider.
 
 ## Known gaps (Phase 6, not yet done)
 

server/app/calendar_render.py

@@ -414,7 +414,8 @@ def _draw_agenda_day(img: Image.Image, draw: ImageDraw.ImageDraw, day: date, eve
     weather_entries = _weather_for_day(weather_cities, day)
     if weather_entries:
         y += draw_weather_row(img, draw, text_x0, y, text_w, weather_entries,
-                              icon_r=title_font.size // 2, font=weather_font or body_font, units=weather_units)
+                              icon_r=title_font.size // 2, font=weather_font or body_font, units=weather_units,
+                              palette_rgb=palette_rgb)
 
     day_events = _events_on_day(events, day, tz)
     row_h = body_font.size + 14
@@ -636,7 +637,8 @@ def _build_week(events: list[dict], browse_offset: int, target_w: int, target_h:
         weather_entries = _weather_for_day(weather_cities, day)
         if weather_entries:
             y += draw_weather_row(img, draw, x0 + 4, y, col_w - 8, weather_entries,
-                                  icon_r=8, font=weather_font, units=weather_units, show_labels=False)
+                                  icon_r=8, font=weather_font, units=weather_units, show_labels=False,
+                                  palette_rgb=palette_rgb)
         row_h = chip_font.size + 10
         max_rows = max(0, (target_h - MARGIN - y) // row_h)
         day_events = _events_on_day(events, day, tz)

server/app/weather_icons/SOURCE.md

@@ -1,34 +0,0 @@
-# Weather icons
-
-Source: Environment and Climate Change Canada's public weather icon set,
-served from `https://weather.gc.ca/weathericons/`.
-
-© His Majesty the King in Right of Canada, as represented by the Minister
-of Environment and Climate Change Canada. Vendored (not fetched live at
-render time) under Canada.ca's non-commercial-reproduction terms
-(https://www.canada.ca/en/transparency/terms.html) -- this is a personal,
-non-commercial project. If this project's use ever becomes commercial,
-these specific image files need their own clearance (the ECCC Data
-Servers End-use Licence that covers the weather *data* app/weather/ec.py
-consumes is more permissive, but that licence is scoped to ECCC's data
-servers -- these icons are served from the public website, not that
-domain, so it doesn't clearly cover them).
-
-One icon per shared weather category (see app/weather/__init__.py's
-module docstring for the category set), picked as a representative
-"day" variant from EC's full icon set
-(https://weather.gc.ca/mainmenu/icon_e.html has the legend):
-
-| file                | EC icon code | original URL                                    |
-|---------------------|:------------:|--------------------------------------------------|
-| clear.gif           | 00           | https://weather.gc.ca/weathericons/00.gif        |
-| partly_cloudy.gif   | 02           | https://weather.gc.ca/weathericons/02.gif        |
-| cloudy.gif          | 10           | https://weather.gc.ca/weathericons/10.gif        |
-| fog.gif             | 24           | https://weather.gc.ca/weathericons/24.gif        |
-| rain.gif            | 12           | https://weather.gc.ca/weathericons/12.gif        |
-| snow.gif            | 17           | https://weather.gc.ca/weathericons/17.gif        |
-| thunderstorm.gif    | 19           | https://weather.gc.ca/weathericons/19.gif        |
-
-Used for every weather provider's rendering (Open-Meteo, NWS, and EC
-itself), not just when EC is the selected provider -- see
-app/weather_render.py's draw_weather_icon.

server/app/weather_render.py

@@ -12,25 +12,28 @@ cloudy/fog/rain/snow/thunderstorm set, never a raw provider code) and
 returns an RGB Image exactly target_w x target_h, same contract every
 other widget renderer in this project follows.
 
-Icons are Environment Canada's own weather icon set (vendored at
-app/weather_icons/, one per shared category -- see that directory's
-SOURCE.md for attribution/licensing), not hand-drawn: these are small,
-flat-shaded bitmaps that dither cleanly onto the panel's 6-color
-palette, and read as recognizable weather icons at a glance in a way an
-earlier hand-drawn attempt (a plain circle-with-ticks "sun") didn't.
-Used for every provider's rendering, not just when EC is selected.
+Icons are hand-drawn (no custom font/icon asset, same primitives-only
+approach calendar_render.py uses elsewhere for e.g. month view's density
+dots), styled after Environment Canada's own icon set (pointed sun rays,
+a smooth puffy cloud, teardrop rain, dendrite snowflakes, a zigzag bolt)
+but filled with this frame's *exact* panel ink RGB values rather than an
+arbitrary bitmap's anti-aliased colors -- a flat fill that's already one
+of the palette's 6 colors quantizes with zero dithering error to diffuse,
+where a fetched/vendored bitmap's colors (almost never an exact palette
+match) dither into a visible speckle. An early plain circle-with-4-ticks
+"sun" also just didn't read as a sun at a glance -- pointed triangular
+rays fixed that without giving up the clean-quantization property.
 """
 
 from __future__ import annotations
 
 import io
+import math
 from datetime import date, datetime
-from functools import lru_cache
-from pathlib import Path
 
 from PIL import Image, ImageDraw, ImageFont
 
-from .image_pipeline import _apply_manage_overlay, _quantize, draw_text, logical_render_size
+from .image_pipeline import DEFAULT_PALETTE_RGB, _apply_manage_overlay, _quantize, draw_text, logical_render_size
 
 MARGIN = 20
 BG = (255, 255, 255)
@@ -38,37 +41,133 @@ FG = (0, 0, 0)
 MUTED = (110, 110, 110)
 RULE = (0, 0, 0)
 
-_ICON_DIR = Path(__file__).parent / "weather_icons"
-_ICON_FALLBACK = "cloudy"  # unrecognized category (shouldn't happen with a valid provider) -- see draw_weather_icon
+
+def _ink(palette_rgb: list | None, index: int) -> tuple[int, int, int]:
+    """One of this frame's actual panel colors by DEFAULT_PALETTE_RGB
+    index (2=yellow, 3=red, 4=blue, 5=green -- 0/1 are black/white,
+    already this module's BG/FG) -- same resolution idiom as
+    calendar_render.py's _event_colors, so a custom palette override
+    (Frame.palette_rgb) still gets its own actual yellow/blue, and every
+    fill stays an exact, ditherless palette match either way."""
+    return tuple((palette_rgb or DEFAULT_PALETTE_RGB)[index])
 
 
-@lru_cache(maxsize=None)
-def _icon_asset(category: str) -> Image.Image:
-    """This category's vendored icon, loaded once (a handful of small
-    static files, never fetched over the network at render time) and
-    cached at its native resolution -- draw_weather_icon resizes a copy
-    per call, since the requested size varies with icon_r."""
-    path = _ICON_DIR / f"{category}.gif"
-    if not path.exists():
-        path = _ICON_DIR / f"{_ICON_FALLBACK}.gif"  # unrecognized category -- shouldn't happen with a valid provider
-    return Image.open(path).convert("RGBA")
+def draw_cloud(draw: ImageDraw.ImageDraw, cx: float, cy: float, r: float, fill=BG, outline=FG) -> None:
+    """A simple puffy-cloud silhouette (three overlapping lobes + a base)
+    with a clean outline -- drawn as one outline-color pass slightly
+    larger than the shapes, then the same shapes again in `fill` on top.
+    Overlapping ellipses each drawn with their own `outline=` would leave
+    visible seams where they cross; this double-draw trick sidesteps that
+    entirely regardless of how the lobes overlap."""
+    stroke = 2
+    lobes = [
+        (cx - r, cy - r * 0.3, cx - r * 0.1, cy + r * 0.6),
+        (cx - r * 0.45, cy - r * 0.8, cx + r * 0.35, cy + r * 0.25),
+        (cx, cy - r * 0.35, cx + r, cy + r * 0.6),
+    ]
+    base = (cx - r * 0.8, cy, cx + r * 0.8, cy + r * 0.5)
+    for x0, y0, x1, y1 in lobes:
+        draw.ellipse([x0 - stroke, y0 - stroke, x1 + stroke, y1 + stroke], fill=outline)
+    draw.rectangle([base[0] - stroke, base[1], base[2] + stroke, base[3] + stroke], fill=outline)
+    for x0, y0, x1, y1 in lobes:
+        draw.ellipse([x0, y0, x1, y1], fill=fill)
+    draw.rectangle(base, fill=fill)
 
 
-def draw_weather_icon(img: Image.Image, cx: float, cy: float, r: float, category: str) -> None:
-    """Pastes this category's icon (see module docstring), scaled to
-    roughly 2r wide, centered on (cx, cy). Alpha-composited via the
-    icon's own transparency (confirmed present in the source GIFs), so
-    only the glyph itself shows against whatever's already on `img`."""
-    icon = _icon_asset(category)
-    size = max(1, round(r * 2))
-    aspect_h = max(1, round(size * icon.height / icon.width))
-    resized = icon.resize((size, aspect_h), Image.LANCZOS)
-    img.paste(resized, (round(cx - size / 2), round(cy - aspect_h / 2)), resized)
+def draw_sun(draw: ImageDraw.ImageDraw, cx: float, cy: float, r: float, color) -> None:
+    """A filled disc + 8 pointed triangular rays -- styled after
+    Environment Canada's own sun glyph. Rays are solid triangles (base on
+    the disc's edge, tip pointing outward), not thin lines: at small icon
+    sizes thin lines read as a crosshair/asterisk, not sun rays, which is
+    exactly what an earlier attempt here looked like."""
+    draw.ellipse([cx - r * 0.55, cy - r * 0.55, cx + r * 0.55, cy + r * 0.55], fill=color)
+    base_r, tip_r, half_w = r * 0.6, r * 1.2, r * 0.16
+    for i in range(8):
+        angle = i * (math.pi / 4)
+        perp = angle + math.pi / 2
+        bx, by = cx + math.cos(angle) * base_r, cy + math.sin(angle) * base_r
+        tx, ty = cx + math.cos(angle) * tip_r, cy + math.sin(angle) * tip_r
+        p1 = (bx + math.cos(perp) * half_w, by + math.sin(perp) * half_w)
+        p2 = (bx - math.cos(perp) * half_w, by - math.sin(perp) * half_w)
+        draw.polygon([p1, p2, (tx, ty)], fill=color)
+
+
+def draw_raindrop(draw: ImageDraw.ImageDraw, x: float, y: float, size: float, color) -> None:
+    """A rounded teardrop (point up, bulb down) -- the standard rain
+    glyph, not a bare diagonal tick."""
+    draw.polygon([(x, y), (x - size * 0.38, y + size * 0.55), (x + size * 0.38, y + size * 0.55)], fill=color)
+    draw.ellipse([x - size * 0.4, y + size * 0.25, x + size * 0.4, y + size * 1.05], fill=color)
+
+
+def draw_snowflake(draw: ImageDraw.ImageDraw, x: float, y: float, r: float, color) -> None:
+    """A 6-pointed dendrite -- three crossing lines plus a short
+    perpendicular tick near each of the 6 tips, closer to a real
+    snowflake glyph than a bare asterisk."""
+    for i in range(3):
+        angle = i * (math.pi / 3)
+        dx, dy = math.cos(angle) * r, math.sin(angle) * r
+        draw.line([(x - dx, y - dy), (x + dx, y + dy)], fill=color, width=max(2, round(r * 0.28)))
+        perp = angle + math.pi / 2
+        tick = r * 0.35
+        for sign in (1, -1):
+            tx, ty = x + dx * sign, y + dy * sign
+            ex, ey = tx * 0.75 + x * 0.25, ty * 0.75 + y * 0.25
+            draw.line([(ex - math.cos(perp) * tick, ey - math.sin(perp) * tick),
+                      (ex + math.cos(perp) * tick, ey + math.sin(perp) * tick)], fill=color, width=2)
+
+
+def draw_lightning_bolt(draw: ImageDraw.ImageDraw, cx: float, cy: float, size: float, color) -> None:
+    """A zigzag bolt polygon -- the standard lightning glyph, not a bare
+    3-segment line."""
+    points = [
+        (cx + size * 0.15, cy - size * 0.7),
+        (cx - size * 0.35, cy + size * 0.05),
+        (cx - size * 0.05, cy + size * 0.05),
+        (cx - size * 0.2, cy + size * 0.7),
+        (cx + size * 0.4, cy - size * 0.1),
+        (cx + size * 0.05, cy - size * 0.1),
+    ]
+    draw.polygon(points, fill=color)
+
+
+def draw_weather_icon(draw: ImageDraw.ImageDraw, cx: float, cy: float, r: float, category: str,
+                      palette_rgb: list | None = None) -> None:
+    """A small glyph for one weather category, styled after Environment
+    Canada's own icon set but hand-drawn in this frame's exact panel ink
+    colors (yellow sun/bolt, blue rain/snow) -- see module docstring for
+    why that's better for this display than reusing an actual bitmap."""
+    yellow = _ink(palette_rgb, 2)
+    blue = _ink(palette_rgb, 4)
+
+    if category == "clear":
+        draw_sun(draw, cx, cy, r, yellow)
+        return
+
+    if category == "partly_cloudy":
+        draw_sun(draw, cx - r * 0.45, cy - r * 0.45, r * 0.75, yellow)
+        draw_cloud(draw, cx + r * 0.1, cy + r * 0.2, r * 0.9)
+        return
+
+    cloud_cy = cy if category in ("cloudy", "fog") else cy - r * 0.25
+    draw_cloud(draw, cx, cloud_cy, r)
+
+    if category == "fog":
+        for i in range(3):
+            y = cy + r * 0.55 + i * (r * 0.4)
+            draw.line([(cx - r, y), (cx + r, y)], fill=FG, width=2)
+    elif category == "rain":
+        for dx in (-0.55, 0, 0.55):
+            draw_raindrop(draw, cx + dx * r, cloud_cy + r * 0.55, r * 0.55, blue)
+    elif category == "snow":
+        for dx in (-0.55, 0, 0.55):
+            draw_snowflake(draw, cx + dx * r, cloud_cy + r * 0.85, r * 0.3, blue)
+    elif category == "thunderstorm":
+        draw_lightning_bolt(draw, cx, cloud_cy + r * 0.7, r * 0.7, yellow)
 
 
 def draw_weather_row(img: Image.Image, draw: ImageDraw.ImageDraw, x0: int, y0: int, max_w: int,
                      entries: list[dict], icon_r: int, font: ImageFont.ImageFont, units: str,
-                     show_labels: bool = True) -> int:
+                     show_labels: bool = True, palette_rgb: list | None = None) -> int:
     """Draws one or more cities' weather side by side starting at
     (x0, y0), stopping once another entry wouldn't fit within max_w
     (narrow views like week columns just end up showing fewer cities --
@@ -88,7 +187,7 @@ def draw_weather_row(img: Image.Image, draw: ImageDraw.ImageDraw, x0: int, y0: i
         if drew_any and x + entry_w > x0 + max_w:
             break
         cx, cy = x + icon_r, y0 + icon_r
-        draw_weather_icon(img, cx, cy, icon_r, entry["category"])
+        draw_weather_icon(draw, cx, cy, icon_r, entry["category"], palette_rgb)
         draw_text(img, (x + icon_r * 2 + 6, y0 + (row_h - font.size) // 2), label, font)
         x += entry_w
         drew_any = True
@@ -140,7 +239,7 @@ def build_current(entry: dict | None, target_w: int, target_h: int, palette_rgb:
 
     icon_r = max(20, min(target_w, target_h) // 4)
     cx, cy = target_w // 2, target_h // 2 - icon_r // 2
-    draw_weather_icon(img, cx, cy, icon_r, entry["category"])
+    draw_weather_icon(draw, cx, cy, icon_r, entry["category"], palette_rgb)
 
     unit_suffix = "F" if units == "fahrenheit" else "C"
     temp_size = max(24, min(target_w, target_h) // 3)
@@ -204,7 +303,7 @@ def build_hourly(entries: list[dict], target_w: int, target_h: int, palette_rgb:
         tbbox = draw.textbbox((0, 0), time_label, font=label_font)
         draw_text(img, (cx - (tbbox[2] - tbbox[0]) // 2, y), time_label, label_font, MUTED)
         cy = y + label_size + 10 + icon_r
-        draw_weather_icon(img, cx, cy, icon_r, entry["category"])
+        draw_weather_icon(draw, cx, cy, icon_r, entry["category"], palette_rgb)
         temp_label = temp_labels[i]
         tempbbox = draw.textbbox((0, 0), temp_label, font=label_font)
         draw_text(img, (cx - (tempbbox[2] - tempbbox[0]) // 2, cy + icon_r + 6), temp_label, label_font)
@@ -249,7 +348,7 @@ def build_daily(daily: dict[str, dict], target_w: int, target_h: int, palette_rg
         lbbox = draw.textbbox((0, 0), label, font=label_font)
         draw_text(img, (x0 + col_w // 2 - (lbbox[2] - lbbox[0]) // 2, y), label, label_font, MUTED)
         cx, cy = x0 + col_w // 2, y + label_size + 10 + icon_r
-        draw_weather_icon(img, cx, cy, icon_r, d["category"])
+        draw_weather_icon(draw, cx, cy, icon_r, d["category"], palette_rgb)
         tbbox = draw.textbbox((0, 0), temps, font=label_font)
         draw_text(img, (cx - (tbbox[2] - tbbox[0]) // 2, cy + icon_r + 8), temps, label_font)
     return img
@@ -287,7 +386,8 @@ def build_multi_city(cities: list[dict], target_w: int, target_h: int, palette_r
     font_size = _fit_font_size(draw, labels, col_w - (icon_r * 2 + 24), max_size=icon_r)
     font = ImageFont.load_default(size=font_size)
     y = max(MARGIN, (target_h - (icon_r * 2 + 8)) // 2)
-    draw_weather_row(img, draw, MARGIN, y, text_w, cities, icon_r=icon_r, font=font, units=units, show_labels=True)
+    draw_weather_row(img, draw, MARGIN, y, text_w, cities, icon_r=icon_r, font=font, units=units,
+                     show_labels=True, palette_rgb=palette_rgb)
     return img
 
 

server/tests/test_weather_render.py

@@ -3,15 +3,18 @@ Mirrors calendar_render.py's own testing posture (this module has no
 dedicated test file there either, since it's exercised indirectly via
 test_widgets_calendar.py) but covers the non-obvious behavior worth
 pinning down directly: build_multi_city's label shortening, and that
-every shared category actually has a distinct vendored icon (a missing
-or misnamed asset file would otherwise only surface as a silent
-fallback to the "cloudy" glyph, not an error)."""
+weather icons are filled with the panel's *exact* ink colors (not an
+arbitrary bitmap's anti-aliased ones) -- the whole reason icons are
+hand-drawn rather than a fetched/vendored image: an exact palette match
+quantizes with zero dithering error to diffuse, where anything else
+dithers into a visible speckle at these small on-panel sizes."""
 
 from __future__ import annotations
 
-from PIL import Image
+from PIL import Image, ImageDraw
 
 from app import weather_render
+from app.image_pipeline import DEFAULT_PALETTE_RGB, _quantize
 
 
 def test_build_multi_city_shortens_full_geocoder_labels_for_display(monkeypatch):
@@ -25,9 +28,10 @@ def test_build_multi_city_shortens_full_geocoder_labels_for_display(monkeypatch)
     seen_labels = []
     real_draw_weather_row = weather_render.draw_weather_row
 
-    def spy(img, draw, x0, y0, max_w, entries, icon_r, font, units, show_labels=True):
+    def spy(img, draw, x0, y0, max_w, entries, icon_r, font, units, show_labels=True, palette_rgb=None):
         seen_labels.extend(e["label"] for e in entries)
-        return real_draw_weather_row(img, draw, x0, y0, max_w, entries, icon_r, font, units, show_labels)
+        return real_draw_weather_row(img, draw, x0, y0, max_w, entries, icon_r, font, units, show_labels,
+                                     palette_rgb)
 
     monkeypatch.setattr(weather_render, "draw_weather_row", spy)
 
@@ -45,40 +49,60 @@ def test_build_multi_city_empty_list_returns_blank_canvas():
     assert img.size == (400, 150)
 
 
-def test_icon_asset_exists_and_loads_for_every_shared_category():
-    """The shared category set (see app/weather/__init__.py's module
-    docstring) must each resolve to a real vendored file, not silently
-    fall back to "cloudy" -- a typo'd filename would otherwise only show
-    up as every OTHER category quietly looking like a plain cloud."""
-    for category in ("clear", "partly_cloudy", "cloudy", "fog", "rain", "snow", "thunderstorm"):
-        path = weather_render._ICON_DIR / f"{category}.gif"
-        assert path.exists(), f"missing vendored icon for {category!r}"
-        icon = weather_render._icon_asset(category)
-        assert icon.mode == "RGBA"
-        assert icon.width > 0 and icon.height > 0
+def _colors_present(img: Image.Image) -> set[tuple[int, int, int]]:
+    return {c for _, c in img.getcolors(maxcolors=100_000)}
 
 
-def test_icon_asset_is_cached():
-    assert weather_render._icon_asset("clear") is weather_render._icon_asset("clear")
-
-
-def test_draw_weather_icon_pastes_a_visibly_different_glyph_per_category():
-    """Not a pixel-exact check (the actual art is a vendored asset, not
-    something this test should hardcode) -- just confirms distinct
-    categories actually produce visibly different canvases, i.e. the
-    right file is being loaded per category rather than one glyph
-    silently reused for all of them."""
-    rendered = {}
-    for category in ("clear", "rain", "snow", "thunderstorm"):
+def test_draw_weather_icon_clear_uses_exact_panel_yellow():
     img = Image.new("RGB", (100, 100), (255, 255, 255))
-        weather_render.draw_weather_icon(img, 50, 50, 30, category)
-        rendered[category] = img.tobytes()
-    assert len(set(rendered.values())) == len(rendered)
+    draw = ImageDraw.Draw(img)
+    weather_render.draw_weather_icon(draw, 50, 50, 30, "clear")
+    assert tuple(DEFAULT_PALETTE_RGB[2]) in _colors_present(img)  # yellow sun
+    assert (0, 0, 0) not in _colors_present(img)  # not a flat-black glyph
 
 
-def test_draw_weather_icon_unrecognized_category_falls_back_to_cloudy():
+def test_draw_weather_icon_rain_uses_exact_panel_blue():
     img = Image.new("RGB", (100, 100), (255, 255, 255))
-    weather_render.draw_weather_icon(img, 50, 50, 30, "not_a_real_category")
-    fallback = Image.new("RGB", (100, 100), (255, 255, 255))
-    weather_render.draw_weather_icon(fallback, 50, 50, 30, "cloudy")
-    assert img.tobytes() == fallback.tobytes()
+    draw = ImageDraw.Draw(img)
+    weather_render.draw_weather_icon(draw, 50, 50, 30, "rain")
+    assert tuple(DEFAULT_PALETTE_RGB[4]) in _colors_present(img)  # blue raindrops
+
+
+def test_draw_weather_icon_thunderstorm_uses_exact_panel_yellow():
+    img = Image.new("RGB", (100, 100), (255, 255, 255))
+    draw = ImageDraw.Draw(img)
+    weather_render.draw_weather_icon(draw, 50, 50, 30, "thunderstorm")
+    assert tuple(DEFAULT_PALETTE_RGB[2]) in _colors_present(img)  # yellow bolt
+
+
+def test_draw_weather_icon_respects_a_custom_frame_palette():
+    """A frame with an Advanced-configuration palette override (see
+    Frame.palette_rgb) should still get ITS actual yellow, not the
+    hardcoded default -- same resolution rule as calendar_render.py's
+    _event_colors."""
+    custom_palette = [(0, 0, 0), (255, 255, 255), (10, 20, 30), (0, 0, 0), (0, 0, 0), (0, 0, 0)]
+    img = Image.new("RGB", (100, 100), (255, 255, 255))
+    draw = ImageDraw.Draw(img)
+    weather_render.draw_weather_icon(draw, 50, 50, 30, "clear", palette_rgb=custom_palette)
+    assert (10, 20, 30) in _colors_present(img)
+
+
+def test_icon_fill_quantizes_uniformly_with_no_dithering_speckle():
+    """The actual point of hand-drawing icons in exact panel colors: a
+    small crop taken from deep inside the sun disc (nowhere near its own
+    edge) is a single flat fill -- if that fill weren't an exact palette
+    match, _quantize's Floyd-Steinberg dithering would diffuse rounding
+    error across it, breaking the crop into a speckle of 2+ colors. An
+    exact match has zero error to diffuse, so the crop stays perfectly
+    uniform after quantizing, same as before."""
+    img = Image.new("RGB", (200, 200), (255, 255, 255))
+    draw = ImageDraw.Draw(img)
+    weather_render.draw_weather_icon(draw, 100, 100, 60, "clear")
+    quantized = _quantize(img, DEFAULT_PALETTE_RGB, dither_strength=1.0).convert("RGB")
+
+    # A 20x20 crop centered on the disc -- draw_sun's disc radius is
+    # 0.55*60=33px, comfortably clear of both the outer edge and the ray
+    # triangles' base line.
+    crop = quantized.crop((90, 90, 110, 110))
+    colors_in_crop = _colors_present(crop)
+    assert colors_in_crop == {tuple(DEFAULT_PALETTE_RGB[2])}  # solid yellow, no speckle