Quest-State World Patching

Goal

Replace a tomb levelled-creature spawner after a main-quest stage is reached, without a custom quest script.

Smallest YAML excerpt

instances:
  - conditions:
      - cell_match: tomb
      - object_type: LevelledCreature
      - record_id: ^in_tomb_all_lev%+0$
      - has_journal:
          quest: a1_v_vivecinformants
          index: 50
    once: true
    actions:
      - replace:
          in_tomb_all_lev+2: 1.0

This is the first quest-gated phase in Examples/InstanceModifier_TombSpiceUp.yaml. The %+ escapes the plus in a Lua pattern; the anchors keep the match specific.

Why it works

All listed conditions must pass. cell_match is a case-insensitive substring test; object_type limits the rule to levelled creature objects; has_journal.index is a minimum journal stage; and replace tries the named replacement with the supplied chance. once: true prevents the same rule from repeatedly replacing the object after its first successful application.

For a bounded quest phase, use min and max instead of (or alongside) index. For an exact placed reference, use content_file_target with the content filename and reference number rather than a stale standalone reference-number condition.

Persistence

The once-cache and replacement object's saved state let the successful instance change survive a save/load. If later quest stages need cleanup, express that as another instance rule, as the shipped example does for post-Dagoth-Ur cleanup.

Caveats

• has_journal reads the player's quest state when the object is processed; it is not a continuously running quest listener.
• replace chooses candidates through their chance values. Do not rely on YAML map order to define a weighted distribution.
• The replacement record must exist in the active content files. A failed creation attempt leaves the original target unchanged.
• Broad cell_match: tomb also matches cell IDs containing that text. Narrow it with additional conditions when a quest patch must be local.

See save and update compatibility before applying this to an existing save.