feat: introduce identity-backed goat

docs/SIMULATION_STATE_SCHEMA.md

@@ -3,7 +3,7 @@
 ## Current contract
 
 `SimulationStateRecord` is the versioned JSON boundary for the current
-simulation. The current world schema is v9 and captures:
+simulation. The current world schema is v10 and captures:
 
 - simulation seed, tick interval, tick count, clock remainder, and elapsed
   clock ticks;
@@ -13,6 +13,8 @@ simulation. The current world schema is v9 and captures:
 - controlled per-NPC wander RNG streams;
 - scene-independent resource state plus the definition facts needed while its
   ResourceNode is unloaded;
+- scene-independent animal identity, position, hunger, feeding history,
+  reservation, and availability state;
 - pantry contents, carried NPC inventory, the ordered economic event stream,
   and its next stable event ID;
 - directed relationship records with familiarity, trust, and the stable event
@@ -29,7 +31,7 @@ The top-level identity is:
 ```json
 {
   "schema": "the_steward.simulation",
-  "schema_version": 9
+  "schema_version": 10
 }
 ```
 
@@ -170,6 +172,21 @@ nested v1/v2 events receive empty/zero defaults, while a new `task_blocked`
 event requires its stable action, source storage, resource, and positive
 requirement contract.
 
+SimulationStateRecord v10 adds the top-level `animals` array and the first
+`AnimalStateRecord` schema. Each animal record stores its stable animal and
+species IDs, display name, authoritative world position, hunger,
+`last_fed_tick`, reservation owner, and enabled/player/NPC feeding flags.
+World schema v9 preserves opportunity history while migrating to an empty
+animal list.
+
+Current-schema parsing requires unique animal IDs that do not collide with
+resource or storage IDs. An animal reservation must belong to an existing NPC
+whose active feed task targets that exact animal. Every `animal_fed` event
+must name the pantry as its source, an existing animal as its destination,
+food as its item, the exact feed action cost, and a valid NPC actor or the
+player sentinel. The latest matching feed event tick must agree with the
+animal's `last_fed_tick`.
+
 The bounded opportunity family accepts at most one open record globally.
 Opportunity, trigger-event, and resolution-event IDs are unique and the next
 ID must remain above restored history. Referenced NPCs, storage, resources, and
@@ -235,6 +252,24 @@ explicitly. Current-schema parsing also canonicalizes numeric, boolean, and ID
 variants so a freshly registered finite source retains a byte-stable checksum
 after a JSON round trip.
 
+## Animal authority
+
+`AnimalCareSystem` owns `AnimalStateRecord` instances independently of the
+scene tree and advances their hunger in stable-ID order. `AnimalNode` binds a
+loaded presentation and interaction point to that authority; the simulation
+position remains canonical while the node is loaded or absent.
+
+Animals are not `ResourceNode` instances and are not inserted into the
+resource discovery grid. The first bounded slice uses a deterministic linear
+loaded-animal query. NPC and player feeding resolve through the same atomic
+care operation: reserve or select the exact animal, withdraw one real food
+from `village_pantry`, reduce that animal's hunger, and append one exact
+`animal_fed` fact. Failed withdrawal changes neither animal nor history.
+
+The persistent hungry/content presentation derives from authoritative hunger.
+The short feed response is transient and is reset rather than serialized or
+replayed after restore.
+
 ## Local quicksave boundary
 
 `SaveSlotStore` writes the existing versioned JSON record to
@@ -253,7 +288,7 @@ This phase does not yet provide:
 
 - a save-slot menu, metadata, thumbnails, autosaves, or multiple profiles;
 - migrations from any historical world schema other than the explicitly
-  supported v1–v8 layouts;
+  supported v1–v9 layouts;
 - player inventory or player relationship records;
 - broader relationship dimensions, line-of-sight/hearing evidence,
   continuous or personalized memory decay, reinforcement, false beliefs, or