Add integration icon

Home Assistant 2026.3+ shows custom integrations' own brand images from
custom_components/<domain>/brand/. Add a radiator with a forecast curve
(solid past, "now" marker, dashed prediction) as icon.png/icon@2x.png
(256/512 px, transparent) plus dark-theme variants, so the integration
is easy to spot in Devices & services. Older HA versions ignore the
folder and show the generic placeholder; the integration is unaffected.

scripts/make_brand_icons.py regenerates the images with Pillow from the
test requirements; the package check verifies sizes and transparency.
Listed under 0.2.3, which has not been deployed yet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -25,6 +25,9 @@ A stale or failed room sensor no longer pauses the whole integration. Still
 - Status attributes `excluded_rooms` and `weight_coverage` (share of the total
   comfort weight covered by the rooms used), and a per-room `used` flag in
   `input_quality`.
+- Integration icon (a radiator with a forecast curve) in **Settings → Devices &
+  services**, with a dark-theme variant. Needs Home Assistant 2026.3 or newer;
+  older versions show the generic placeholder.
 
 ### Upgrade notes
 

README.md

@@ -14,6 +14,8 @@ This project targets Home Assistant OS on a Raspberry Pi 5, with one existing ON
 6. Choose *ordered lists* of **outdoor sensor entity IDs**. First valid sensor is active; if missing, unavailable, nonnumeric or outside reasonable bounds, the next valid sensor is used automatically.
 7. Assign a relative comfort weight (0.1–10) to each selected room.
 
+On Home Assistant 2026.3 or newer the integration shows its own icon (a radiator with a forecast curve) in **Devices & services**; older versions show a generic placeholder.
+
 **No entity IDs are hard-coded.** Every room and outdoor measurement can be changed later via **Configure**, without editing YAML or Python.
 
 ## Reconfigurable weather inputs
@@ -155,6 +157,10 @@ run without Home Assistant installed:
 python -m unittest discover -s tests -v
 ```
 
+The brand icons in `custom_components/heating_mpc/brand/` are drawn by
+`python scripts/make_brand_icons.py` (uses Pillow from the test requirements);
+the package check verifies their sizes and transparency.
+
 HA tests cover setup, config/options forms, migration, reload and entity cleanup,
 scheduled sampling and poll cancellation, the relay listener, stored model
 restoration, retention and deletion, missing inputs, manual off/presets, optimizer

scripts/make_brand_icons.py

@@ -0,0 +1,104 @@
+"""Render the integration's brand icons (radiator with a forecast curve).
+
+Home Assistant 2026.3+ shows custom_components/<domain>/brand/ images in
+Settings -> Devices & services. Development-only: needs Pillow, which the HA test
+requirements already install. Run: python scripts/make_brand_icons.py
+"""
+from math import hypot
+from pathlib import Path
+
+from PIL import Image, ImageDraw
+
+OUT = Path(__file__).resolve().parents[1] / "custom_components" / "heating_mpc" / "brand"
+DESIGN = 512  # coordinates below are in a 512x512 design space
+SUPERSAMPLE = 8
+THEMES = {
+    "": {"radiator": "#F4511E", "forecast": "#1E88E5"},       # for light backgrounds
+    "dark_": {"radiator": "#FF7043", "forecast": "#64B5F6"},  # for dark backgrounds
+}
+
+
+def bezier(p0, p1, p2, p3, steps=400):
+    points = []
+    for i in range(steps + 1):
+        t = i / steps
+        u = 1 - t
+        points.append(tuple(u**3 * a + 3 * u * u * t * b + 3 * u * t * t * c + t**3 * d
+                            for a, b, c, d in zip(p0, p1, p2, p3)))
+    return points
+
+
+def stroke(draw, points, width, color):
+    """Smooth round-capped stroke: overlapping discs along the path.
+
+    Pillow's wide polylines show seams between many short segments.
+    """
+    r = width / 2
+    for (x0, y0), (x1, y1) in zip(points, points[1:]):
+        steps = max(1, int(hypot(x1 - x0, y1 - y0) / (r / 8)))
+        for i in range(steps + 1):
+            x, y = x0 + (x1 - x0) * i / steps, y0 + (y1 - y0) * i / steps
+            draw.ellipse((x - r, y - r, x + r, y + r), fill=color)
+
+
+def split_dashes(points, dash, gap):
+    """Cut a polyline into dash polylines of the given arc lengths."""
+    dashes, current, travelled, drawing = [], [points[0]], 0.0, True
+    for (x0, y0), (x1, y1) in zip(points, points[1:]):
+        travelled += hypot(x1 - x0, y1 - y0)
+        if drawing:
+            current.append((x1, y1))
+        limit = dash if drawing else gap
+        if travelled >= limit:
+            if drawing and len(current) > 1:
+                dashes.append(current)
+            current, travelled, drawing = [(x1, y1)], 0.0, not drawing
+    if drawing and len(current) > 1:
+        dashes.append(current)
+    return dashes
+
+
+def render(colors):
+    s = SUPERSAMPLE
+    image = Image.new("RGBA", (DESIGN * s, DESIGN * s), (0, 0, 0, 0))
+    draw = ImageDraw.Draw(image)
+    scale = lambda pts: [(x * s, y * s) for x, y in pts]
+
+    # Radiator: five rounded columns joined by two headers.
+    fins, left, right, top, bottom = 5, 12, 500, 250, 500
+    gap = 22
+    width = (right - left - gap * (fins - 1)) / fins
+    for i in range(fins):
+        x0 = left + i * (width + gap)
+        draw.rounded_rectangle((x0 * s, top * s, (x0 + width) * s, bottom * s),
+                               radius=width / 2 * s, fill=colors["radiator"])
+    for y in (296, 420):
+        draw.rectangle(((left + width / 2) * s, y * s, (right - width / 2) * s, (y + 34) * s),
+                       fill=colors["radiator"])
+
+    # Forecast: measured past (solid), "now" marker, predicted future (dashed).
+    line = 40
+    curve = bezier((32, 192), (170, 192), (300, 146), (480, 32))
+    now = next(i for i, (x, _) in enumerate(curve) if x >= 220)
+    stroke(draw, scale(curve[:now + 1]), line * s, colors["forecast"])
+    for dash in split_dashes(curve[now:], 64, 44)[1:]:
+        stroke(draw, scale(dash), line * s, colors["forecast"])
+    x, y = curve[now]
+    radius = 40
+    draw.ellipse(((x - radius) * s, (y - radius) * s, (x + radius) * s, (y + radius) * s),
+                 fill=colors["forecast"])
+    return image
+
+
+def main():
+    OUT.mkdir(exist_ok=True)
+    for prefix, colors in THEMES.items():
+        image = render(colors)
+        for suffix, size in (("", 256), ("@2x", 512)):
+            path = OUT / f"{prefix}icon{suffix}.png"
+            image.resize((size, size), Image.LANCZOS).save(path, optimize=True)
+            print(f"wrote {path.relative_to(OUT.parents[2])}")
+
+
+if __name__ == "__main__":
+    main()

scripts/validate_package.py

@@ -1,6 +1,7 @@
 """Small local packaging and translation checks; not a replacement for hassfest."""
 import json
 from pathlib import Path
+import struct
 import subprocess
 
 root = Path(__file__).resolve().parents[1]
@@ -26,6 +27,14 @@ strings = json.loads((component / "strings.json").read_text())
 for language in ("en", "ro"):
     translated = json.loads((component / "translations" / f"{language}.json").read_text())
     assert keys(strings) == keys(translated), f"Translation keys differ: {language}"
+# Brand icons (HA 2026.3+): square transparent PNGs; see scripts/make_brand_icons.py.
+for name, size in (("icon.png", 256), ("icon@2x.png", 512),
+                   ("dark_icon.png", 256), ("dark_icon@2x.png", 512)):
+    png = (component / "brand" / name).read_bytes()
+    assert png[:8] == b"\x89PNG\r\n\x1a\n" and png[12:16] == b"IHDR", f"{name} is not a PNG"
+    width, height, _depth, color_type = struct.unpack(">IIBB", png[16:26])
+    assert (width, height) == (size, size), f"{name} is {width}x{height}, expected {size}x{size}"
+    assert color_type == 6, f"{name} needs an alpha channel"
 tracked = subprocess.check_output(["git", "ls-files", "custom_components"], cwd=root, text=True).splitlines()
 assert not any("__pycache__" in path or path.endswith((".pyc", ".pyo")) for path in tracked)
-print("Package metadata, translations and tracked component files passed")
+print("Package metadata, translations, brand icons and tracked component files passed")