fix: re-run scribe on cards a failed chunk left blank; never paint an empty (subjectless) prompt

arcana/build.py

@@ -160,16 +160,18 @@ def design_phase(theme: str, visual_style: str = "rider-waite-smith",
 
 
 def paint_subset(deck: dict, nums: list[int], paint_back: bool = False,
-                 progress: Progress | None = None) -> dict:
+                 progress: Progress | None = None, imagegen=None) -> dict:
     """Paint a SUBSET of the deck's cards (by arcana number), saving each card's PNG +
     display WEBPs and filling its image paths. `paint_back` also presses the deck-back.
     Designed to run in its own @spaces.GPU worker so the 22 cards fan out across GPUs;
-    the saved files land on the shared disk for the main process to serve."""
+    the saved files land on the shared disk for the main process to serve. `imagegen`
+    lets a caller inject a wrapped generator (e.g. the trace harness); defaults to the
+    real one."""
     deck_id = deck["deck_id"]
     out_dir = deck_dir(deck_id)
     os.makedirs(out_dir, exist_ok=True)
     seed_base = deck["seed_base"]
-    ig = get_imagegen(deck_style=deck.get("style_suffix"))
+    ig = imagegen or get_imagegen(deck_style=deck.get("style_suffix"))
 
     nset = set(nums)
     t0 = time.time()
@@ -178,7 +180,10 @@ def paint_subset(deck: dict, nums: list[int], paint_back: bool = False,
         if num not in nset:
             continue
         seed = seed_base + num
-        art = ig.generate(c["art_prompt"], seed=seed)
+        # never hand FLUX an empty prompt: a subjectless styled prompt makes it invent
+        # a generic (often religious) figure. Fall back to the concept as the subject.
+        prompt = (c.get("art_prompt") or "").strip() or c["concept"]
+        art = ig.generate(prompt, seed=seed)
         card = compose_card(art, c["concept"], ROMAN_BY_NUMBER[num])
         base = f"{num:02d}_{slugify(c['concept'])}"
         path = os.path.join(out_dir, base + ".png")