Effects

Ongoing conditions and buffs are modeled as ActiveEffect documents — a Foundry-aligned, Pydantic-typed shape. A spell like bless, a poisoned condition, or a magic-item bonus all become ActiveEffects attached to a combatant for the duration of combat.

The model

An ActiveEffect carries:

• id — the template id analog (e.g. "effect:bless").
• origin — what produced it (e.g. "cast:bless:1", "item:sword+1:abc12").
• target_id — the combatant it is attached to.
• duration — an ActiveEffectDuration (see Durations below).
• changes — a list of ActiveEffectChange entries (the mechanical modifications it applies).
• statuses — the set of condition slugs it imposes.
• flags — a free-form dict (Phase 6 uses it for concentration and applicable-action-type metadata).

Durations

ActiveEffectDuration carries three counters, all of which tick at a turn boundary (turn_lifecycle's turn_end hooks). SRD 5.2 §Duration puts a round at about 6 seconds, which is the whole conversion:

Field	Ticks at	Notes
rounds	the caster's turn end (parsed from origin; item/environment origins fall back to the target's)	reaching zero emits EffectExpired(reason="duration")
turns	the target's own turn end	independent of rounds — whichever counter hits zero first expires the effect
seconds	the caster's turn end, as ceil(seconds / 6) rounds	materialised once into rounds; seconds is never mutated. If both are set, rounds wins

flags["until_end_of_next_turn_of"] = "<entity_id>" expresses SRD's "until the end of your next turn": the effect expires at that actor's next turn end, with a one-turn grace if it was applied during that actor's own turn.

Concentration-flagged effects are exempt from all of the above — the concentration cascade and the per-turn repeat save own their lifetime, and the imported packs carry display-only counters on them.

Lifecycle and scope

Effects are combat-scoped and engine-owned. The engine holds active effects in memory during the encounter; concentration and repeat-save linkage key on (target_id, id, origin) identity. You can pass starting effects into start_combat(..., active_effects=...) and read a combatant's current effects during combat with get_actor_active_effects(handle, entity_id).

When combat ends, end_combat returns the final tuple on EndCombatResult.final_active_effects — but the engine itself discards them: effects do not persist across combats. Cross-combat persistence is a host concern, not the engine's. This is a deliberate boundary: the engine is the in-combat effect authority and nothing more.