api refinement

Sources/DHKit/EncounterSession.swift

@@ -223,7 +223,7 @@ public final class EncounterSession: Identifiable, Hashable {
   }
 
   /// Reduce stress on a combat participant by ID, clamping to 0.
-  public func reduceStress(_ amount: Int, from id: UUID) {
+  public func reduceStress(_ amount: Int, for id: UUID) {
     if let i = _adversarySlots.firstIndex(where: { $0.id == id }) {
       let s = _adversarySlots[i]
       _adversarySlots[i] = s.applying(currentStress: max(0, s.currentStress - amount))

Sources/DHKit/EncounterStore.swift

@@ -22,7 +22,7 @@ import Observation
 // MARK: - EncounterStoreError
 
 /// Errors thrown by ``EncounterStore`` operations.
-public enum EncounterStoreError: Error, LocalizedError, Sendable {
+nonisolated public enum EncounterStoreError: Error, LocalizedError, Sendable {
   case notFound(UUID)
   case saveFailed(UUID, String)
   case deleteFailed(UUID, String)
@@ -188,7 +188,10 @@ public final class EncounterStore {
   /// Valid definitions are published via ``definitions``, sorted by
   /// `modifiedAt` descending. Directory-level errors are stored in ``loadError``.
   public func load() async {
-    guard !isLoading else { return }
+    // EncounterStore is a single shared instance loaded once at app startup.
+    // Concurrent calls to load() are a programming error, not a normal operating
+    // condition — use precondition so violations surface immediately in debug builds.
+    precondition(!isLoading, "load() called while a load is already in progress")
     isLoading = true
     loadError = nil
     defer { isLoading = false }

Sources/DHKit/SessionRegistry.swift

@@ -34,15 +34,14 @@ public final class SessionRegistry {
 
   public init() {}
 
-  /// Return the existing session for `definitionID`, or create and store a new one.
+  /// Return the existing session for `definition.id`, or create and store a new one.
   public func session(
-    for definitionID: UUID,
-    definition: EncounterDefinition,
+    for definition: EncounterDefinition,
     compendium: Compendium
   ) -> EncounterSession {
-    if let existing = sessions[definitionID] { return existing }
+    if let existing = sessions[definition.id] { return existing }
     let newSession = EncounterSession.make(from: definition, using: compendium)
-    sessions[definitionID] = newSession
+    sessions[definition.id] = newSession
     return newSession
   }
 
@@ -57,12 +56,11 @@ public final class SessionRegistry {
   /// Use this when the GM wants to restart an encounter from scratch without navigating away.
   @discardableResult
   public func resetSession(
-    for definitionID: UUID,
-    definition: EncounterDefinition,
+    for definition: EncounterDefinition,
     compendium: Compendium
   ) -> EncounterSession {
     let newSession = EncounterSession.make(from: definition, using: compendium)
-    sessions[definitionID] = newSession
+    sessions[definition.id] = newSession
     return newSession
   }
 }

Tests/DHKitTests/EncounterSessionTests.swift

@@ -319,7 +319,7 @@ import Testing
     let slot = session.playerSlots[0]
 
     session.applyStress(4, to: slot.id)
-    session.reduceStress(2, from: slot.id)
+    session.reduceStress(2, for: slot.id)
     #expect(session.playerSlots[0].currentStress == 2)
   }
 

Tests/DHKitTests/SessionRegistryTests.swift

@@ -36,7 +36,7 @@ import Testing
     let compendium = makeCompendium()
     let def = makeDefinition()
 
-    let session = registry.session(for: def.id, definition: def, compendium: compendium)
+    let session = registry.session(for: def, compendium: compendium)
     #expect(session.adversarySlots.count == 1)
   }
 
@@ -45,8 +45,8 @@ import Testing
     let compendium = makeCompendium()
     let def = makeDefinition()
 
-    let s1 = registry.session(for: def.id, definition: def, compendium: compendium)
-    let s2 = registry.session(for: def.id, definition: def, compendium: compendium)
+    let s1 = registry.session(for: def, compendium: compendium)
+    let s2 = registry.session(for: def, compendium: compendium)
     #expect(s1 === s2)
   }
 
@@ -55,7 +55,7 @@ import Testing
     let compendium = makeCompendium()
     let def = makeDefinition()
 
-    _ = registry.session(for: def.id, definition: def, compendium: compendium)
+    _ = registry.session(for: def, compendium: compendium)
     registry.clearSession(for: def.id)
     #expect(registry.sessions[def.id] == nil)
   }
@@ -65,11 +65,11 @@ import Testing
     let compendium = makeCompendium()
     let def1 = makeDefinition(adversaryIDs: ["goblin"])
 
-    let s1 = registry.session(for: def1.id, definition: def1, compendium: compendium)
+    let s1 = registry.session(for: def1, compendium: compendium)
     s1.applyDamage(2, to: s1.adversarySlots[0].id)
     #expect(s1.adversarySlots[0].currentHP == 1)
 
-    let s2 = registry.resetSession(for: def1.id, definition: def1, compendium: compendium)
+    let s2 = registry.resetSession(for: def1, compendium: compendium)
 
     #expect(s2 !== s1)
     #expect(s2.adversarySlots[0].currentHP == 3)
@@ -80,10 +80,10 @@ import Testing
     let compendium = makeCompendium()
     let def = makeDefinition()
 
-    let s1 = registry.session(for: def.id, definition: def, compendium: compendium)
-    let s2 = registry.resetSession(for: def.id, definition: def, compendium: compendium)
+    let s1 = registry.session(for: def, compendium: compendium)
+    let s2 = registry.resetSession(for: def, compendium: compendium)
 
-    let s3 = registry.session(for: def.id, definition: def, compendium: compendium)
+    let s3 = registry.session(for: def, compendium: compendium)
     #expect(s3 === s2)
     #expect(s3 !== s1)
   }
@@ -95,8 +95,8 @@ import Testing
     var def2 = def1
     def2.adversaryIDs = ["goblin", "goblin"]
 
-    _ = registry.session(for: def1.id, definition: def1, compendium: compendium)
-    let s2 = registry.resetSession(for: def2.id, definition: def2, compendium: compendium)
+    _ = registry.session(for: def1, compendium: compendium)
+    let s2 = registry.resetSession(for: def2, compendium: compendium)
 
     #expect(s2.adversarySlots.count == 2)
   }