Test character slot seed determinism

docs/prompt-pool-routing-map.md

@@ -228,6 +228,12 @@ Common trap: `row_number` participates in `seed_config.axis_rng`. If two
 workflows have the same seeds but different `row_number`, they are not expected
 to match.
 
+Character `slot_seed` is more specific than the `person` axis. A fixed
+`slot_seed` owns that slot's random age/body/appearance/hair choices, so
+rerolling `person_seed` will not drift that character. Leave `slot_seed=-1`
+when the slot should follow `person_seed` or the global seed like the fallback
+cast generator.
+
 Each generated row stores `generation_trace.seed_axes` in `metadata_json`.
 Use it to verify whether an axis followed the main seed or a configured seed,
 and to compare the exact per-axis RNG seed used for the row.

tools/prompt_smoke.py

@@ -7458,6 +7458,70 @@ def smoke_seed_config_policy() -> None:
     deterministic_b = _prompt_row(**deterministic_kwargs)
     _expect(deterministic_a == deterministic_b, "locked seed config should reproduce identical prompt row output")
 
+    slot_descriptor_keys = ("age_band", "body_phrase", "skin", "hair", "eyes", "figure")
+
+    def slot_seed_cast(slot_seed: int) -> str:
+        return pb.build_character_slot_json(
+            subject_type="woman",
+            label="A",
+            slot_seed=slot_seed,
+            age="random",
+            ethnicity="random",
+            figure="random",
+            body="random",
+            hair_color="random",
+            hair_length="random",
+            hair_style="random",
+            descriptor_detail="full",
+        )["character_cast"]
+
+    def slot_seed_row(character_cast: str, reroll_seed: int) -> dict[str, Any]:
+        return _prompt_row(
+            name=f"seed_config_policy_slot_seed_{reroll_seed}",
+            category="Casual clothes",
+            subcategory="Casual clothes / Streetwear",
+            seed=41001,
+            seed_config=pb.build_seed_lock_config_json(
+                base_seed=41001,
+                reroll_axis="person",
+                reroll_seed=reroll_seed,
+            ),
+            character_cast=character_cast,
+            women_count=1,
+            men_count=0,
+        )
+
+    seeded_slot_cast = slot_seed_cast(50123)
+    seeded_slot_a = slot_seed_row(seeded_slot_cast, 60001)
+    seeded_slot_b = slot_seed_row(seeded_slot_cast, 60002)
+    _expect(
+        tuple(seeded_slot_a.get(key) for key in slot_descriptor_keys)
+        == tuple(seeded_slot_b.get(key) for key in slot_descriptor_keys),
+        "slot_seed should keep random character-slot descriptors stable across person-axis rerolls",
+    )
+    seeded_trace_a = seeded_slot_a.get("generation_trace") if isinstance(seeded_slot_a.get("generation_trace"), dict) else {}
+    seeded_trace_b = seeded_slot_b.get("generation_trace") if isinstance(seeded_slot_b.get("generation_trace"), dict) else {}
+    _expect(
+        seeded_trace_a.get("seed_axes", {}).get("person", {}).get("seed")
+        != seeded_trace_b.get("seed_axes", {}).get("person", {}).get("seed"),
+        "slot_seed regression check should actually reroll the person axis",
+    )
+    seeded_krea_a = krea_formatter.format_krea2_prompt("", metadata_json=_json(seeded_slot_a), target="single")
+    seeded_krea_b = krea_formatter.format_krea2_prompt("", metadata_json=_json(seeded_slot_b), target="single")
+    _expect(
+        seeded_krea_a.get("krea_prompt") == seeded_krea_b.get("krea_prompt"),
+        "slot_seed should keep final Krea prompt stable across person-axis rerolls",
+    )
+
+    unseeded_slot_cast = slot_seed_cast(-1)
+    unseeded_slot_a = slot_seed_row(unseeded_slot_cast, 60001)
+    unseeded_slot_b = slot_seed_row(unseeded_slot_cast, 60002)
+    _expect(
+        tuple(unseeded_slot_a.get(key) for key in slot_descriptor_keys)
+        != tuple(unseeded_slot_b.get(key) for key in slot_descriptor_keys),
+        "unseeded random character slot should still follow person-axis rerolls",
+    )
+
     pose_changed = False
     for reroll_seed in range(deterministic_seed + 1, deterministic_seed + 10):
         pose_reroll = _prompt_row(