Add manual-art generator (Gemini image API, key via env var)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tools/gen_manual_art.py

@@ -0,0 +1,76 @@
+"""Generate backnforth manual illustrations via Gemini image API (nano banana)."""
+import base64
+import json
+import os
+import sys
+import time
+import urllib.request
+
+# key from disk, never printed
+KEY = os.environ.get("GEMINI_API_KEY")
+if not KEY:
+    sys.exit('set GEMINI_API_KEY in the environment first')
+
+MODELS = ['gemini-2.5-flash-image', 'gemini-2.5-flash-image-preview',
+          'gemini-2.0-flash-preview-image-generation']
+
+STYLE = ("Flat vector cartoon illustration in a warm, friendly picture-book style. "
+         "Soft rounded shapes, thick clean outlines, muted palette of deep teal, warm coral, "
+         "cream and soft mustard yellow. Cozy, calm, reassuring mood. Simple, uncluttered "
+         "composition on a plain cream background. Absolutely no text, no letters, no numbers, "
+         "no words anywhere in the image. Landscape orientation. ")
+
+SCENES = {
+    '01-cover': "A friendly therapist and a relaxed patient sitting in comfy armchairs in a cozy "
+                "counselling room with a potted plant and a soft floor lamp. On a low table between "
+                "them, an open laptop shows a dark screen with a single glowing green dot.",
+    '02-open': "Close-up of gentle hands opening a slightly-worn laptop on a wooden table. The screen "
+               "shows a simple dark page with one large round green play button and a small green dot.",
+    '03-link': "One hand passing an old smartphone to another person's open hand. The phone screen "
+               "glows dark with a single bright green dot. In the soft-focus background, a laptop "
+               "shows the same green dot, suggesting the two screens are connected by a dotted arc.",
+    '04-follow': "Side profile of a calm person's face with a serene expression, eyes looking to one "
+                 "side, following a small glowing green dot that trails a gentle curved motion path "
+                 "from the left side of the image to the right.",
+    '05-adjust': "A hand with one finger adjusting a single very large horizontal slider on a dark "
+                 "tablet screen. At the left end of the slider sits a tiny cute cartoon turtle, at "
+                 "the right end a tiny cute cartoon rabbit.",
+    '06-care': "A therapist leaning forward attentively with a kind expression, offering a glass of "
+               "water to a patient who looks calm and relieved. The laptop on the side table is "
+               "closed. Warm afternoon light through a window.",
+}
+
+OUT = os.path.expanduser('~/Documents/backnforth/img/manual')
+os.makedirs(OUT, exist_ok=True)
+
+
+def generate(prompt):
+    body = json.dumps({'contents': [{'parts': [{'text': prompt}]}]}).encode()
+    last = None
+    for model in MODELS:
+        url = ('https://generativelanguage.googleapis.com/v1beta/models/'
+               '%s:generateContent?key=%s' % (model, KEY))
+        req = urllib.request.Request(url, data=body,
+                                     headers={'Content-Type': 'application/json'})
+        try:
+            with urllib.request.urlopen(req, timeout=120) as r:
+                data = json.load(r)
+            for part in data['candidates'][0]['content']['parts']:
+                if 'inlineData' in part:
+                    return base64.b64decode(part['inlineData']['data']), model
+            last = 'no image part in response from %s' % model
+        except Exception as e:
+            last = '%s: %s' % (model, e)
+    raise RuntimeError(last)
+
+
+for name, scene in SCENES.items():
+    path = os.path.join(OUT, name + '.png')
+    if os.path.exists(path):
+        print(name, 'exists, skipping')
+        continue
+    img, model = generate(STYLE + scene)
+    open(path, 'wb').write(img)
+    print('%s: %d KB via %s' % (name, len(img) // 1024, model))
+    time.sleep(2)
+print('done')