feat: add feed given event handling

- Add FEED_GIVEN to FeedInventoryProjection with apply/revert
- Add give_feed method to FeedService
- Block feed given if no purchase exists <= ts_utc
- Validate feed type and location existence
- 13 new tests for give_feed functionality

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_service_feed.py

@@ -1,13 +1,13 @@
 # ABOUTME: Tests for FeedService operations.
-# ABOUTME: Tests purchase_feed with inventory tracking and price storage.
+# ABOUTME: Tests purchase_feed and give_feed with inventory tracking.
 
 import time
 
 import pytest
 
-from animaltrack.events.payloads import FeedPurchasedPayload
+from animaltrack.events.payloads import FeedGivenPayload, FeedPurchasedPayload
 from animaltrack.events.store import EventStore
-from animaltrack.events.types import FEED_PURCHASED
+from animaltrack.events.types import FEED_GIVEN, FEED_PURCHASED
 from animaltrack.projections import ProjectionRegistry
 from animaltrack.services.feed import FeedService, ValidationError
 
@@ -236,3 +236,211 @@ class TestFeedServicePurchasePriceCalculation:
 
         # (3000 * 3) / (25 * 3) = 9000 / 75 = 120
         assert event.entity_refs["price_per_kg_cents"] == 120
+
+
+# =============================================================================
+# give_feed Tests
+# =============================================================================
+
+
+@pytest.fixture
+def location_id(seeded_db):
+    """Get a valid location_id from seeded data."""
+    row = seeded_db.execute("SELECT id FROM locations LIMIT 1").fetchone()
+    return row[0]
+
+
+def make_given_payload(
+    location_id: str,
+    feed_type_code: str = "layer",
+    amount_kg: int = 5,
+    notes: str | None = None,
+) -> FeedGivenPayload:
+    """Create a give feed payload for testing."""
+    return FeedGivenPayload(
+        location_id=location_id,
+        feed_type_code=feed_type_code,
+        amount_kg=amount_kg,
+        notes=notes,
+    )
+
+
+class TestFeedServiceGive:
+    """Tests for give_feed()."""
+
+    def test_creates_feed_given_event(self, seeded_db, feed_service, location_id):
+        """give_feed creates a FeedGiven event."""
+        # Setup: first purchase some feed
+        purchase_payload = make_purchase_payload(bag_size_kg=20, bags_count=2)
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(purchase_payload, ts_utc, "test_user")
+
+        # Give feed
+        give_payload = make_given_payload(location_id, amount_kg=5)
+        event = feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        assert event.type == FEED_GIVEN
+        assert event.actor == "test_user"
+        assert event.ts_utc == ts_utc + 1000
+
+    def test_event_has_feed_type_in_entity_refs(self, seeded_db, feed_service, location_id):
+        """Event entity_refs contains feed_type_code."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(
+            make_purchase_payload(feed_type_code="starter"), ts_utc, "test_user"
+        )
+
+        give_payload = make_given_payload(location_id, feed_type_code="starter")
+        event = feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        assert event.entity_refs["feed_type_code"] == "starter"
+
+    def test_event_has_location_id_in_entity_refs(self, seeded_db, feed_service, location_id):
+        """Event entity_refs contains location_id."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(make_purchase_payload(), ts_utc, "test_user")
+
+        give_payload = make_given_payload(location_id, amount_kg=5)
+        event = feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        assert event.entity_refs["location_id"] == location_id
+
+    def test_event_has_amount_kg_in_entity_refs(self, seeded_db, feed_service, location_id):
+        """Event entity_refs contains amount_kg."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(make_purchase_payload(), ts_utc, "test_user")
+
+        give_payload = make_given_payload(location_id, amount_kg=7)
+        event = feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        assert event.entity_refs["amount_kg"] == 7
+
+    def test_increments_given_kg(self, seeded_db, feed_service, location_id):
+        """give_feed increments given_kg in feed_inventory."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(
+            make_purchase_payload(bag_size_kg=20, bags_count=2), ts_utc, "test_user"
+        )
+
+        give_payload = make_given_payload(location_id, amount_kg=10)
+        feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        row = seeded_db.execute(
+            "SELECT given_kg FROM feed_inventory WHERE feed_type_code = ?",
+            ("layer",),
+        ).fetchone()
+
+        assert row[0] == 10
+
+    def test_decrements_balance_kg(self, seeded_db, feed_service, location_id):
+        """give_feed decrements balance_kg in feed_inventory."""
+        ts_utc = int(time.time() * 1000)
+        # Purchase 40kg
+        feed_service.purchase_feed(
+            make_purchase_payload(bag_size_kg=20, bags_count=2), ts_utc, "test_user"
+        )
+
+        # Give 15kg
+        give_payload = make_given_payload(location_id, amount_kg=15)
+        feed_service.give_feed(give_payload, ts_utc + 1000, "test_user")
+
+        row = seeded_db.execute(
+            "SELECT purchased_kg, given_kg, balance_kg FROM feed_inventory "
+            "WHERE feed_type_code = ?",
+            ("layer",),
+        ).fetchone()
+
+        assert row[0] == 40  # purchased_kg unchanged
+        assert row[1] == 15  # given_kg
+        assert row[2] == 25  # balance_kg = 40 - 15
+
+    def test_updates_last_given_at_utc(self, seeded_db, feed_service, location_id):
+        """give_feed updates last_given_at_utc."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(make_purchase_payload(), ts_utc, "test_user")
+
+        give_ts = ts_utc + 5000
+        give_payload = make_given_payload(location_id, amount_kg=5)
+        feed_service.give_feed(give_payload, give_ts, "test_user")
+
+        row = seeded_db.execute(
+            "SELECT last_given_at_utc FROM feed_inventory WHERE feed_type_code = ?",
+            ("layer",),
+        ).fetchone()
+
+        assert row[0] == give_ts
+
+    def test_multiple_gives_accumulate(self, seeded_db, feed_service, location_id):
+        """Multiple gives accumulate in given_kg."""
+        ts_utc = int(time.time() * 1000)
+        feed_service.purchase_feed(
+            make_purchase_payload(bag_size_kg=20, bags_count=5), ts_utc, "test_user"
+        )
+
+        # First give: 10kg
+        feed_service.give_feed(
+            make_given_payload(location_id, amount_kg=10), ts_utc + 1000, "test_user"
+        )
+
+        # Second give: 15kg
+        feed_service.give_feed(
+            make_given_payload(location_id, amount_kg=15), ts_utc + 2000, "test_user"
+        )
+
+        row = seeded_db.execute(
+            "SELECT purchased_kg, given_kg, balance_kg FROM feed_inventory "
+            "WHERE feed_type_code = ?",
+            ("layer",),
+        ).fetchone()
+
+        assert row[0] == 100  # purchased_kg (5 bags * 20kg)
+        assert row[1] == 25  # given_kg: 10 + 15
+        assert row[2] == 75  # balance_kg: 100 - 25
+
+
+class TestFeedServiceGiveValidation:
+    """Tests for give_feed() validation."""
+
+    def test_rejects_nonexistent_feed_type(self, seeded_db, feed_service, location_id):
+        """Raises ValidationError for non-existent feed_type_code."""
+        give_payload = make_given_payload(location_id, feed_type_code="nonexistent")
+
+        with pytest.raises(ValidationError, match="not found"):
+            feed_service.give_feed(give_payload, int(time.time() * 1000), "test_user")
+
+    def test_rejects_inactive_feed_type(self, seeded_db, feed_service, location_id):
+        """Raises ValidationError for inactive feed_type."""
+        seeded_db.execute("UPDATE feed_types SET active = 0 WHERE code = 'layer'")
+
+        give_payload = make_given_payload(location_id)
+
+        with pytest.raises(ValidationError, match="inactive"):
+            feed_service.give_feed(give_payload, int(time.time() * 1000), "test_user")
+
+    def test_rejects_nonexistent_location(self, seeded_db, feed_service):
+        """Raises ValidationError for non-existent location_id."""
+        fake_location_id = "01ARZ3NDEKTSV4RRFFQ69G5FAV"
+        give_payload = make_given_payload(fake_location_id)
+
+        with pytest.raises(ValidationError, match="not found"):
+            feed_service.give_feed(give_payload, int(time.time() * 1000), "test_user")
+
+    def test_blocks_without_prior_purchase(self, seeded_db, feed_service, location_id):
+        """Raises ValidationError if no purchase exists for feed type."""
+        give_payload = make_given_payload(location_id)
+
+        with pytest.raises(ValidationError, match="No feed purchased"):
+            feed_service.give_feed(give_payload, int(time.time() * 1000), "test_user")
+
+    def test_blocks_purchase_after_give_timestamp(self, seeded_db, feed_service, location_id):
+        """Raises ValidationError if purchase is after give timestamp."""
+        ts_utc = int(time.time() * 1000)
+
+        # Purchase at ts_utc + 1000
+        feed_service.purchase_feed(make_purchase_payload(), ts_utc + 1000, "test_user")
+
+        # Try to give at ts_utc (before purchase)
+        give_payload = make_given_payload(location_id)
+
+        with pytest.raises(ValidationError, match="No feed purchased"):
+            feed_service.give_feed(give_payload, ts_utc, "test_user")