Pin the sprite generator to Nano Banana Pro on OpenRouter

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

assets/_regen.py

@@ -20,6 +20,8 @@ HERE = os.path.dirname(os.path.abspath(__file__))
 SCRATCH = os.environ.get('SPLAT_SCRATCH', '/tmp/splatter-regen')
 GEN = os.path.expanduser('~/.claude/skills/generate-image/scripts/generate_image.py')
 PY = os.environ.get('SPLAT_PY', sys.executable)
+# Nano Banana Pro via OpenRouter, pinned here so the skill script's default can't drift under us.
+MODEL = os.environ.get('SPLAT_MODEL', 'google/gemini-3-pro-image')
 
 # The style block is in three parts because the middle one is a REDRAW instruction and only a redraw
 # wants it. "Keep every pose and colour exactly as in the reference" is right when the job is
@@ -188,7 +190,7 @@ def run(name, spec, dry=False):
     if dry:
         print(f'[{name}] would generate {len(sprites)} frames: {", ".join(sprites)}'); return True
     print(f'[{name}] generating {len(sprites)} frames...')
-    r = subprocess.run([PY, GEN, prompt, '--input', ref, '--output', sheet],
+    r = subprocess.run([PY, GEN, prompt, '--model', MODEL, '--input', ref, '--output', sheet],
                        capture_output=True, text=True, cwd=os.path.dirname(HERE))
     if not os.path.exists(sheet):
         print(f'[{name}] FAILED: generator returned no image\n{r.stdout[-400:]}'); return False