diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ce450c..d2ac76c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Added
 
+- [`Adventure.party`][osrlib.crawl.adventure.Adventure] records the party an adventure is written for, as a [`PartySpec`][osrlib.crawl.adventure.PartySpec] with the lowest and highest character level and, when the adventure says, the fewest and most characters, the way a published module states it on its cover ("for 6 to 8 characters of levels 1 to 3"). It defaults `None`, so an existing adventure document still loads and no `schema_version` moves. The engine never reads it, so no rule, event, or draw sequence changes. A front end can use it to offer a party that fits, a converter can carry the cover's figures across, and a playtest can pick its characters by level. `PartySpec` is frozen, refuses a level or size below 1, and refuses a maximum below its minimum.
 - [`osrlib.core.creature`][osrlib.core.creature] declares the three protocols a rules function reads its creature argument through: [`Creature`][osrlib.core.creature.Creature] (id, name, alignment, hit points, conditions, stat modifiers), [`Combatant`][osrlib.core.creature.Combatant] (the attack, initiative, and saving-throw numbers), and [`Caster`][osrlib.core.creature.Caster] (level, spell book, memorized spells) (#104). A [`Character`][osrlib.core.character.Character] satisfies all three and a [`MonsterInstance`][osrlib.core.monsters.MonsterInstance] the first two, structurally, so a caller passes either without a cast and annotates its own functions with the protocol that names what they read. Every public creature parameter in [`osrlib.core.combat`][osrlib.core.combat], [`osrlib.core.spells`][osrlib.core.spells], [`osrlib.core.effects`][osrlib.core.effects], and [`osrlib.core.items`][osrlib.core.items] now states the protocol the function reads through it, in place of `Any` and `object`: [`attack_roll`][osrlib.core.combat.attack_roll] takes a `Combatant` attacker and defender, [`has_condition`][osrlib.core.effects.has_condition] a `Creature`, [`cast_spell`][osrlib.core.spells.cast_spell] a `Caster` and a sequence of `Creature` values or the location strings a place-targeted spell takes, and a function that reads what one concrete type alone has takes that type, so [`resolve_breath`][osrlib.core.combat.resolve_breath] takes a `MonsterInstance` and [`sword_control_check`][osrlib.core.items.sword_control_check] a `Character`. The signature is what pyright checks a front end's call against and what the reference links. Runtime behaviour is unchanged, no rule, event, or draw sequence moved, and what changes is what a type checker accepts: a caller that passed an object without the protocol's attributes now fails its own pyright run. [`GameSession.combatant`][osrlib.crawl.session.GameSession.combatant] returns `MonsterInstance | Character | None` rather than `object | None`, so a front end can hand its result straight to a rules function.
 - [`StreamName`][osrlib.core.rng.StreamName] is the one home for every RNG stream key the library draws from, and each public `*_STREAM` constant takes its value from the matching member, so `COMBAT_STREAM` and `StreamName.COMBAT` are one object (#106). Name a stream through the enum rather than writing its key out: a misspelled key raises nothing, because it forks a stream of its own and draws plausible numbers from it, which is the one defect the determinism contract cannot catch. `StreamName` is a `StrEnum`, so a member is its own string and the values are unchanged: [`RngStreams`][osrlib.core.rng.RngStreams] keys by string, a save file records the same keys, and seed material and draw order are untouched.
 - [`MoraleCheckedEvent`][osrlib.core.events.MoraleCheckedEvent]`.held` states whether the side keeps fighting, and [`check_morale`][osrlib.core.combat.check_morale] fills it on every code. `combat.morale.exempt` covers both exemptions, so a front end that wants to tell a side that never fights from one that never breaks reads `held` instead of pairing the code with the score. The default formatter's `combat.morale.exempt` line reads it, and falls back to the score for a log written before schema 4, where the field defaults `None`.
diff --git a/src/osrlib/crawl/adventure.py b/src/osrlib/crawl/adventure.py
index 1a2688b..bdfbadd 100644
--- a/src/osrlib/crawl/adventure.py
+++ b/src/osrlib/crawl/adventure.py
@@ -160,7 +160,11 @@ class PartySpec(BaseModel):
 
     @model_validator(mode="after")
     def _ranges_in_order(self) -> PartySpec:
-        raise NotImplementedError("chunk: party-spec")
+        if self.max_level < self.min_level:
+            raise ValueError("max_level must not be below min_level")
+        if self.min_size is not None and self.max_size is not None and self.max_size < self.min_size:
+            raise ValueError("max_size must not be below min_size")
+        return self
 
 
 class Adventure(BaseModel):
diff --git a/tests/test_adventure_party.py b/tests/test_adventure_party.py
index d6c5af4..ff5ccfe 100644
--- a/tests/test_adventure_party.py
+++ b/tests/test_adventure_party.py
@@ -9,16 +9,12 @@
 from osrlib.crawl.adventure import Adventure, PartySpec
 from osrlib.versioning import SCHEMA_VERSION, check_document, stamp_document
 
-CHUNK = pytest.mark.xfail(reason="chunk: party-spec", raises=NotImplementedError)
 
-
-@CHUNK
 def test_levels_and_size():
     party = PartySpec(min_level=1, max_level=3, min_size=6, max_size=8)
     assert (party.min_level, party.max_level, party.min_size, party.max_size) == (1, 3, 6, 8)
 
 
-@CHUNK
 def test_size_is_optional():
     party = PartySpec(min_level=2, max_level=2)
     assert (party.min_size, party.max_size) == (None, None)
@@ -26,7 +22,6 @@ def test_size_is_optional():
     assert PartySpec(min_level=1, max_level=1, max_size=4).min_size is None
 
 
-@CHUNK
 @pytest.mark.parametrize(
     "fields",
     [
@@ -53,7 +48,6 @@ def test_zero_is_refused(fields):
         PartySpec(**fields)
 
 
-@CHUNK
 def test_party_is_frozen():
     party = PartySpec(min_level=1, max_level=3)
     with pytest.raises(ValidationError):
@@ -64,7 +58,6 @@ def test_an_adventure_without_a_party_has_none():
     assert build_adventure().party is None
 
 
-@CHUNK
 def test_party_round_trips_through_a_stamped_document():
     adventure = build_adventure().model_copy(
         update={"party": PartySpec(min_level=1, max_level=3, min_size=6, max_size=8)}
diff --git a/tests/test_docs_example_output.py b/tests/test_docs_example_output.py
index d3ad870..48e821a 100644
--- a/tests/test_docs_example_output.py
+++ b/tests/test_docs_example_output.py
@@ -82,9 +82,7 @@ def check_block(source: str, filename: str) -> list[str]:
 
 # Blocks the gate fails on today. The lead removes an entry when its chunk merges; a block's id
 # carries its line range, so editing the block retires the mark by itself.
-_EXPECTED_TO_FAIL: dict[str, str] = {
-    "src/osrlib/crawl/adventure.py:140-146": "chunk: party-spec",
-}
+_EXPECTED_TO_FAIL: dict[str, str] = {}
 
 
 def _cases() -> list:
diff --git a/tests/test_docs_examples.py b/tests/test_docs_examples.py
index 79fa020..b908c70 100644
--- a/tests/test_docs_examples.py
+++ b/tests/test_docs_examples.py
@@ -37,9 +37,7 @@
 
 
 # Blocks that fail today because their chunk isn't built. The lead removes an entry when its chunk merges.
-_EXPECTED_TO_FAIL: dict[str, str] = {
-    "src/osrlib/crawl/adventure.py:140-146": "chunk: party-spec",
-}
+_EXPECTED_TO_FAIL: dict[str, str] = {}
 
 
 def _cases() -> list: