namegen: per-placeholder gender override unreliably contaminates cascade for sibling cascade-aware slots

[serelon]

Summary

When a format string mixes a per-placeholder gender override ({slot:male} / {slot:female}) with cascade-aware slots, the override sometimes contaminates the gender cascade for other slots in the same format. Behavior is probabilistic — sometimes the cascade is preserved, sometimes the override wins.

The guide states (references/nameset-guide.md):

The override is per-placeholder; the cascade still applies to other slots.

The observed behavior contradicts this.

Repro

Nameset (simplified — kin category cascades on gender, firstName includes both genders + unisex):

{
  "namespace": "test",
  "id": "patronym-bug",
  "genderWeights": {"male": 50, "female": 50},
  "formats": {
    "patronym": {"template": "{firstName} {kin} of {firstName:male}"}
  },
  "nameCategories": {
    "firstName": [
      {"name": "Hild", "gender": "female"},
      {"name": "Halric", "gender": "male"},
      {"name": "Ragnhild", "gender": "female"},
      {"name": "Bran", "gender": "male"}
    ],
    "kin": [
      {"name": "son", "gender": "male"},
      {"name": "daughter", "gender": "female"}
    ]
  }
}

Generate ~8 names. Sample output (real, from the-silence:rathenmoor with the same format):

Targ son of Wulfric         ← cascade=male, OK
Edwyn daughter of Heldric   ← cascade=female, OK
Hild son of Halvar          ← Hild is female-tagged, but kin = son ✗
Jarl son of Harald          ← cascade=male, OK
Botric son of Marn          ← cascade=male, OK
Ragnhild son of Thelric     ← Ragnhild is female-tagged, but kin = son ✗

Expected: when {firstName} rolls female, {kin} should roll female (daughter).

Actual: cascade for {kin} is sometimes overridden to male — appears to be influenced by the {firstName:male} override on the parent slot.

Reordering placeholders ({kin} before {firstName:male}) did not reliably help. The bug is intermittent, suggesting the cascade gender state is being mutated by override resolution rather than overrides being scoped per-placeholder.

Workaround

Split into two explicit formats with overrides on every slot — no cascade-aware slots in the same template as a :male/:female override:

"patronym-son":      {"template": "{firstName:male} son of {firstName:male}"},
"patronym-daughter": {"template": "{firstName:female} daughter of {firstName:male}"}

The GM picks via --format. Reliable but loses the cascade-driven mixing.

Suggested fix direction

The per-placeholder override should not mutate the cascade gender state used by other slots — only the slot it appears on. The guide's intent is clear; the implementation appears to leak state.

Environment

• Discovered while building the-silence:rathenmoor nameset for the Covenant of Hands subsetting in solorpg
• Python 3.13, Windows
• rpg-tools commit at the time: develop branch (current submodule HEAD)