feat(ios): W1 leaf packages — ReconnectMachine/PingScheduler, GateState/AwayDigest, HostRegistry, APIClient+pairing probe

T-iOS-5: pure reconnect reducer (1s→30s cap, mirrors terminal-session.ts) + 25s PingScheduler, 16 tests
T-iOS-6: gate epoch tracker (rising-edge semantics, canDecide guard) + AwayDigest reducer, 25 tests
T-iOS-7: HostRegistry with SecItemShim keychain seam, 30 tests, 88.1% own-src coverage
T-iOS-8: APIClient (Origin iff-G invariant) + two-step pairing probe, 45 tests, 98.1% coverage
Contract ruling: probe returns Result<HostEndpoint,_> (Host{id,name} built by pairing VM) —
resolves frozen-contract contradiction reported via BLOCKED protocol; adds Tunables.pairingProbeTimeout(10s)
Verified: 178 tests green across 5 packages; coverage gates pass; zero Owns violations

ios/Packages/HostRegistry/Tests/HostRegistryTests/FakeSecItemShim.swift

@@ -0,0 +1,97 @@
+import Foundation
+import Security
+import os
+import HostRegistry
+
+/// In-memory keychain double behind the `SecItemShim` seam (plan §3.3):
+/// unsigned `swift test` binaries get errSecMissingEntitlement (-34018) from
+/// the real data-protection keychain, so store logic is tested against this.
+///
+/// Behavioral single-slot model (the store uses exactly one service+account):
+/// - add: duplicate if a value is stored; otherwise stores kSecValueData
+/// - update: itemNotFound when empty; otherwise replaces the stored value
+/// - copyMatching: itemNotFound when empty; otherwise returns the stored value
+/// - delete: itemNotFound when empty; otherwise clears
+///
+/// `force*` knobs override the next status/result (forced statuses do NOT
+/// touch storage — the fake stays dumb). All calls are recorded verbatim so
+/// tests can assert the §5.3 attribute dictionaries character-for-character.
+final class FakeSecItemShim: SecItemShim, Sendable {
+    struct UpdateCall: Sendable {
+        let query: [String: any Sendable]
+        let attributes: [String: any Sendable]
+    }
+
+    private struct State: Sendable {
+        var storedData: Data?
+        var addCalls: [[String: any Sendable]] = []
+        var updateCalls: [UpdateCall] = []
+        var copyCalls: [[String: any Sendable]] = []
+        var deleteCalls: [[String: any Sendable]] = []
+        var forcedAddStatus: OSStatus?
+        var forcedUpdateStatus: OSStatus?
+        var forcedCopyStatus: OSStatus?
+        var forcedDeleteStatus: OSStatus?
+        var forcedCopyData: Data?
+    }
+
+    private let state = OSAllocatedUnfairLock(initialState: State())
+
+    // MARK: - SecItemShim
+
+    func add(_ attributes: [String: any Sendable]) -> OSStatus {
+        state.withLock { s in
+            s.addCalls.append(attributes)
+            if let forced = s.forcedAddStatus { return forced }
+            guard s.storedData == nil else { return errSecDuplicateItem }
+            s.storedData = attributes[kSecValueData as String] as? Data
+            return errSecSuccess
+        }
+    }
+
+    func update(query: [String: any Sendable],
+                attributesToUpdate: [String: any Sendable]) -> OSStatus {
+        state.withLock { s in
+            s.updateCalls.append(UpdateCall(query: query, attributes: attributesToUpdate))
+            if let forced = s.forcedUpdateStatus { return forced }
+            guard s.storedData != nil else { return errSecItemNotFound }
+            s.storedData = attributesToUpdate[kSecValueData as String] as? Data
+            return errSecSuccess
+        }
+    }
+
+    func copyMatching(_ query: [String: any Sendable]) -> (status: OSStatus, data: Data?) {
+        state.withLock { s in
+            s.copyCalls.append(query)
+            if let forced = s.forcedCopyStatus { return (forced, nil) }
+            if let forcedData = s.forcedCopyData { return (errSecSuccess, forcedData) }
+            guard let data = s.storedData else { return (errSecItemNotFound, nil) }
+            return (errSecSuccess, data)
+        }
+    }
+
+    func delete(_ query: [String: any Sendable]) -> OSStatus {
+        state.withLock { s in
+            s.deleteCalls.append(query)
+            if let forced = s.forcedDeleteStatus { return forced }
+            guard s.storedData != nil else { return errSecItemNotFound }
+            s.storedData = nil
+            return errSecSuccess
+        }
+    }
+
+    // MARK: - Test controls
+
+    func forceAddStatus(_ status: OSStatus) { state.withLock { $0.forcedAddStatus = status } }
+    func forceUpdateStatus(_ status: OSStatus) { state.withLock { $0.forcedUpdateStatus = status } }
+    func forceCopyStatus(_ status: OSStatus) { state.withLock { $0.forcedCopyStatus = status } }
+    func forceDeleteStatus(_ status: OSStatus) { state.withLock { $0.forcedDeleteStatus = status } }
+    func forceCopyData(_ data: Data) { state.withLock { $0.forcedCopyData = data } }
+
+    // MARK: - Recorded calls
+
+    var recordedAdds: [[String: any Sendable]] { state.withLock { $0.addCalls } }
+    var recordedUpdates: [UpdateCall] { state.withLock { $0.updateCalls } }
+    var recordedCopies: [[String: any Sendable]] { state.withLock { $0.copyCalls } }
+    var recordedDeletes: [[String: any Sendable]] { state.withLock { $0.deleteCalls } }
+}

ios/Packages/HostRegistry/Tests/HostRegistryTests/HostTests.swift

@@ -0,0 +1,28 @@
+import Foundation
+import Testing
+import WireProtocol
+import HostRegistry
+
+@Test("Host Codable 往返:id/name/endpoint 全保真(originHeader 重派生一致)")
+func hostCodableRoundTripPreservesAllFields() throws {
+    // Arrange
+    let host = Fixtures.makeHost(name: "studio", urlString: "https://mac.ts.net:8443")
+
+    // Act
+    let data = try JSONEncoder().encode(host)
+    let decoded = try JSONDecoder().decode(Host.self, from: data)
+
+    // Assert
+    #expect(decoded == host)
+    #expect(decoded.endpoint.originHeader == "https://mac.ts.net:8443")
+}
+
+@Test("Identifiable:Host.id 即协议 id")
+func hostIdentifiableIdIsItsOwnId() {
+    // Arrange / Act
+    let host = Fixtures.makeHost()
+
+    // Assert
+    let identifiable: any Identifiable<UUID> = host
+    #expect(identifiable.id == host.id)
+}

ios/Packages/HostRegistry/Tests/HostRegistryTests/InMemoryHostStoreTests.swift

@@ -0,0 +1,77 @@
+import Foundation
+import Testing
+import HostRegistry
+
+// HostStore protocol contract, tested against the in-Sources InMemory double
+// (plan T-iOS-7: "用 InMemory 替身测协议契约").
+
+@Test("upsert 新 host:返回的新集合含它,loadAll 一致")
+func upsertNewHostAppearsInReturnedCollectionAndLoadAll() async throws {
+    // Arrange
+    let store = InMemoryHostStore()
+    let host = Fixtures.makeHost()
+
+    // Act
+    let result = try await store.upsert(host)
+
+    // Assert
+    #expect(result == [host])
+    #expect(try await store.loadAll() == [host])
+}
+
+@Test("同 id 再 upsert:替换不重复,且保持原位置")
+func upsertSameIdReplacesWithoutDuplicatingAndKeepsPosition() async throws {
+    // Arrange
+    let first = Fixtures.makeHost(name: "old-name")
+    let second = Fixtures.makeHost(name: "other", urlString: "https://mac.ts.net")
+    let store = InMemoryHostStore(hosts: [first, second])
+    let renamed = Host(id: first.id, name: "new-name", endpoint: first.endpoint)
+
+    // Act
+    let result = try await store.upsert(renamed)
+
+    // Assert
+    #expect(result == [renamed, second])
+    #expect(try await store.loadAll() == [renamed, second])
+}
+
+@Test("remove 已存在 id:集合不再含它")
+func removeExistingIdDropsItFromCollection() async throws {
+    // Arrange
+    let keep = Fixtures.makeHost(name: "keep")
+    let doomed = Fixtures.makeHost(name: "doomed", urlString: "http://10.0.0.7:3000")
+    let store = InMemoryHostStore(hosts: [keep, doomed])
+
+    // Act
+    let result = try await store.remove(id: doomed.id)
+
+    // Assert
+    #expect(result == [keep])
+    #expect(try await store.loadAll() == [keep])
+}
+
+@Test("remove 不存在的 id:集合不变、不 throw(显式返回原集合)")
+func removeUnknownIdReturnsUnchangedCollectionWithoutThrowing() async throws {
+    // Arrange
+    let host = Fixtures.makeHost()
+    let store = InMemoryHostStore(hosts: [host])
+
+    // Act
+    let result = try await store.remove(id: UUID())
+
+    // Assert
+    #expect(result == [host])
+    #expect(try await store.loadAll() == [host])
+}
+
+@Test("init 种子集合:loadAll 原样返回")
+func initSeedsCollectionVerbatim() async throws {
+    // Arrange
+    let hosts = [Fixtures.makeHost(name: "a"), Fixtures.makeHost(name: "b")]
+
+    // Act
+    let store = InMemoryHostStore(hosts: hosts)
+
+    // Assert
+    #expect(try await store.loadAll() == hosts)
+}

ios/Packages/HostRegistry/Tests/HostRegistryTests/KeychainHostStoreTests.swift

@@ -0,0 +1,292 @@
+import Foundation
+import Security
+import Testing
+import HostRegistry
+
+// KeychainHostStore logic against the fake SecItemShim (plan T-iOS-7:
+// add/update/delete 走对分支、错误码显式映射;真 keychain 归 xcodebuild 模拟器测试)。
+
+// MARK: - Branch selection
+
+@Test("upsert 新 host:走 add 分支,不碰 update")
+func upsertNewHostTakesAddBranchOnly() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+
+    // Act
+    let result = try await store.upsert(host)
+
+    // Assert
+    #expect(result == [host])
+    #expect(shim.recordedAdds.count == 1)
+    #expect(shim.recordedUpdates.isEmpty)
+    #expect(try await store.loadAll() == [host])
+}
+
+@Test("已有条目再 upsert:add 撞 errSecDuplicateItem → 走 update 分支")
+func upsertOntoExistingItemFallsBackToUpdateBranch() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let first = Fixtures.makeHost(name: "first")
+    _ = try await store.upsert(first)
+    let second = Fixtures.makeHost(name: "second", urlString: "http://10.0.0.9:3000")
+
+    // Act
+    let result = try await store.upsert(second)
+
+    // Assert
+    #expect(result == [first, second])
+    #expect(shim.recordedUpdates.count == 1)
+    #expect(try await store.loadAll() == [first, second])
+}
+
+@Test("同 id 再 upsert:替换不重复(keychain 持久化后仍只一条)")
+func upsertSameIdReplacesInsteadOfDuplicating() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost(name: "old")
+    _ = try await store.upsert(host)
+    let renamed = Host(id: host.id, name: "new", endpoint: host.endpoint)
+
+    // Act
+    let result = try await store.upsert(renamed)
+
+    // Assert
+    #expect(result == [renamed])
+    #expect(try await store.loadAll() == [renamed])
+}
+
+@Test("remove 到空集合:走 delete 分支清掉整个 item")
+func removeLastHostTakesDeleteBranch() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+    _ = try await store.upsert(host)
+
+    // Act
+    let result = try await store.remove(id: host.id)
+
+    // Assert
+    #expect(result.isEmpty)
+    #expect(shim.recordedDeletes.count == 1)
+    #expect(try await store.loadAll().isEmpty)
+}
+
+@Test("remove 不存在的 id:集合不变、不 throw、零持久化调用")
+func removeUnknownIdIsExplicitNoOpWithoutPersisting() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+    _ = try await store.upsert(host)
+    let addsBefore = shim.recordedAdds.count
+    let updatesBefore = shim.recordedUpdates.count
+
+    // Act
+    let result = try await store.remove(id: UUID())
+
+    // Assert
+    #expect(result == [host])
+    #expect(shim.recordedAdds.count == addsBefore)
+    #expect(shim.recordedUpdates.count == updatesBefore)
+    #expect(shim.recordedDeletes.isEmpty)
+}
+
+@Test("空 keychain loadAll:errSecItemNotFound 映射为空集合而非错误")
+func loadAllMapsItemNotFoundToEmptyCollection() async throws {
+    // Arrange
+    let store = KeychainHostStore(shim: FakeSecItemShim())
+
+    // Act / Assert
+    #expect(try await store.loadAll().isEmpty)
+}
+
+@Test("delete 撞 errSecItemNotFound:视为成功(幂等删除)")
+func deleteItemNotFoundIsTreatedAsSuccess() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+    _ = try await store.upsert(host)
+    shim.forceDeleteStatus(errSecItemNotFound)
+
+    // Act
+    let result = try await store.remove(id: host.id)
+
+    // Assert
+    #expect(result.isEmpty)
+}
+
+@Test("持久化跨实例:同一 shim 上的新 store 读回全部 host")
+func persistedHostsSurviveAcrossStoreInstances() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let a = Fixtures.makeHost(name: "a")
+    let b = Fixtures.makeHost(name: "b", urlString: "https://mac.ts.net")
+    let writer = KeychainHostStore(shim: shim)
+    _ = try await writer.upsert(a)
+    _ = try await writer.upsert(b)
+
+    // Act
+    let reader = KeychainHostStore(shim: shim)
+
+    // Assert
+    #expect(try await reader.loadAll() == [a, b])
+}
+
+// MARK: - Explicit error-code mapping
+
+@Test("add 撞 -34018 errSecMissingEntitlement:映射为 .missingEntitlement")
+func addMissingEntitlementMapsToTypedError() async {
+    // Arrange
+    let shim = FakeSecItemShim()
+    shim.forceAddStatus(errSecMissingEntitlement)
+    let store = KeychainHostStore(shim: shim)
+
+    // Act / Assert
+    await #expect(throws: KeychainHostStoreError.missingEntitlement) {
+        _ = try await store.upsert(Fixtures.makeHost())
+    }
+}
+
+@Test("copyMatching 意外错误码:映射为 .unexpectedStatus(原码)")
+func copyUnexpectedStatusMapsToTypedErrorWithCode() async {
+    // Arrange
+    let shim = FakeSecItemShim()
+    shim.forceCopyStatus(errSecInteractionNotAllowed)
+    let store = KeychainHostStore(shim: shim)
+
+    // Act / Assert
+    await #expect(throws: KeychainHostStoreError.unexpectedStatus(errSecInteractionNotAllowed)) {
+        _ = try await store.loadAll()
+    }
+}
+
+@Test("update 分支失败:映射为 .unexpectedStatus(原码)")
+func updateFailureMapsToTypedErrorWithCode() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    _ = try await store.upsert(Fixtures.makeHost())
+    shim.forceUpdateStatus(errSecAuthFailed)
+
+    // Act / Assert
+    await #expect(throws: KeychainHostStoreError.unexpectedStatus(errSecAuthFailed)) {
+        _ = try await store.upsert(Fixtures.makeHost(name: "second"))
+    }
+}
+
+@Test("delete 分支意外错误码:映射为 .unexpectedStatus(原码)")
+func deleteFailureMapsToTypedErrorWithCode() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+    _ = try await store.upsert(host)
+    shim.forceDeleteStatus(errSecAuthFailed)
+
+    // Act / Assert
+    await #expect(throws: KeychainHostStoreError.unexpectedStatus(errSecAuthFailed)) {
+        _ = try await store.remove(id: host.id)
+    }
+}
+
+@Test("keychain 里的数据不是合法 [Host] JSON:映射为 .corruptedData,不 crash")
+func corruptKeychainPayloadMapsToTypedError() async {
+    // Arrange
+    let shim = FakeSecItemShim()
+    shim.forceCopyData(Data("not-json".utf8))
+    let store = KeychainHostStore(shim: shim)
+
+    // Act / Assert
+    await #expect(throws: KeychainHostStoreError.corruptedData) {
+        _ = try await store.loadAll()
+    }
+}
+
+// MARK: - §5.3 attribute dictionaries, asserted verbatim
+
+@Test("§5.3 add 属性字典逐字校验:data-protection + AfterFirstUnlockThisDeviceOnly,无 synchronizable,无多余键")
+func addAttributeDictionaryIsExactlyThePolicySet() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim, service: "svc.test", account: "acct.test")
+
+    // Act
+    _ = try await store.upsert(Fixtures.makeHost())
+
+    // Assert
+    let attrs = try #require(shim.recordedAdds.first)
+    #expect(attrs[kSecClass as String] as? String == kSecClassGenericPassword as String)
+    #expect(attrs[kSecAttrService as String] as? String == "svc.test")
+    #expect(attrs[kSecAttrAccount as String] as? String == "acct.test")
+    #expect(attrs[kSecUseDataProtectionKeychain as String] as? Bool == true)
+    #expect(attrs[kSecAttrAccessible as String] as? String
+        == kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly as String)
+    #expect(attrs[kSecAttrSynchronizable as String] == nil)
+    #expect(attrs[kSecValueData as String] is Data)
+    #expect(attrs.count == 6) // 白名单外零多余键 —— verbatim 断言
+}
+
+@Test("§5.3 update 分支字典:query 带 data-protection 不带数据;attributes 重申 accessible + 新数据")
+func updateDictionariesReassertProtectionPolicy() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    _ = try await store.upsert(Fixtures.makeHost(name: "first"))
+
+    // Act
+    _ = try await store.upsert(Fixtures.makeHost(name: "second", urlString: "http://10.1.1.1:3000"))
+
+    // Assert
+    let call = try #require(shim.recordedUpdates.first)
+    #expect(call.query[kSecClass as String] as? String == kSecClassGenericPassword as String)
+    #expect(call.query[kSecUseDataProtectionKeychain as String] as? Bool == true)
+    #expect(call.query[kSecValueData as String] == nil)
+    #expect(call.query.count == 4) // class + service + account + data-protection
+    #expect(call.attributes[kSecAttrAccessible as String] as? String
+        == kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly as String)
+    #expect(call.attributes[kSecValueData as String] is Data)
+    #expect(call.attributes.count == 2)
+}
+
+@Test("§5.3 copy 查询字典:base + returnData + matchLimitOne,共 6 键")
+func copyQueryDictionaryIsExactlyThePolicySet() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+
+    // Act
+    _ = try await store.loadAll()
+
+    // Assert
+    let query = try #require(shim.recordedCopies.first)
+    #expect(query[kSecClass as String] as? String == kSecClassGenericPassword as String)
+    #expect(query[kSecUseDataProtectionKeychain as String] as? Bool == true)
+    #expect(query[kSecReturnData as String] as? Bool == true)
+    #expect(query[kSecMatchLimit as String] as? String == kSecMatchLimitOne as String)
+    #expect(query.count == 6)
+}
+
+@Test("§5.3 delete 查询字典:带 data-protection 的 base query,共 4 键")
+func deleteQueryDictionaryIsExactlyTheBaseQuery() async throws {
+    // Arrange
+    let shim = FakeSecItemShim()
+    let store = KeychainHostStore(shim: shim)
+    let host = Fixtures.makeHost()
+    _ = try await store.upsert(host)
+
+    // Act
+    _ = try await store.remove(id: host.id)
+
+    // Assert
+    let query = try #require(shim.recordedDeletes.first)
+    #expect(query[kSecClass as String] as? String == kSecClassGenericPassword as String)
+    #expect(query[kSecUseDataProtectionKeychain as String] as? Bool == true)
+    #expect(query.count == 4)
+}

ios/Packages/HostRegistry/Tests/HostRegistryTests/LastSessionStoreTests.swift

@@ -0,0 +1,91 @@
+import Foundation
+import Testing
+import HostRegistry
+
+// UserDefaultsLastSessionStore over an injectable, per-test-unique suite
+// (plan §3.3: 非机密;lastSessionId 存取/清除)。
+
+@Test("lastSessionId 存取:set 后读回同一 UUID")
+func setThenGetReturnsSameSessionId() throws {
+    // Arrange
+    let suiteName = Fixtures.makeSuiteName()
+    let defaults = try #require(UserDefaults(suiteName: suiteName))
+    defer { defaults.removePersistentDomain(forName: suiteName) }
+    let store = UserDefaultsLastSessionStore(defaults: defaults)
+    let host = UUID()
+    let session = UUID()
+
+    // Act
+    store.setLastSessionId(session, host: host)
+
+    // Assert
+    #expect(store.lastSessionId(host: host) == session)
+}
+
+@Test("未设置过的 host:lastSessionId 返回 nil")
+func unknownHostReturnsNil() throws {
+    // Arrange
+    let suiteName = Fixtures.makeSuiteName()
+    let defaults = try #require(UserDefaults(suiteName: suiteName))
+    defer { defaults.removePersistentDomain(forName: suiteName) }
+    let store = UserDefaultsLastSessionStore(defaults: defaults)
+
+    // Act / Assert
+    #expect(store.lastSessionId(host: UUID()) == nil)
+}
+
+@Test("set nil:清除既有 lastSessionId")
+func settingNilClearsStoredSessionId() throws {
+    // Arrange
+    let suiteName = Fixtures.makeSuiteName()
+    let defaults = try #require(UserDefaults(suiteName: suiteName))
+    defer { defaults.removePersistentDomain(forName: suiteName) }
+    let store = UserDefaultsLastSessionStore(defaults: defaults)
+    let host = UUID()
+    store.setLastSessionId(UUID(), host: host)
+
+    // Act
+    store.setLastSessionId(nil, host: host)
+
+    // Assert
+    #expect(store.lastSessionId(host: host) == nil)
+}
+
+@Test("不同 host 键隔离:互不覆盖")
+func distinctHostsDoNotCollide() throws {
+    // Arrange
+    let suiteName = Fixtures.makeSuiteName()
+    let defaults = try #require(UserDefaults(suiteName: suiteName))
+    defer { defaults.removePersistentDomain(forName: suiteName) }
+    let store = UserDefaultsLastSessionStore(defaults: defaults)
+    let hostA = UUID()
+    let hostB = UUID()
+    let sessionA = UUID()
+    let sessionB = UUID()
+
+    // Act
+    store.setLastSessionId(sessionA, host: hostA)
+    store.setLastSessionId(sessionB, host: hostB)
+
+    // Assert
+    #expect(store.lastSessionId(host: hostA) == sessionA)
+    #expect(store.lastSessionId(host: hostB) == sessionB)
+}
+
+@Test("UserDefaults 中的非 UUID 垃圾值:读回 nil 而非 crash(防御性解析)")
+func garbageStoredValueReadsBackAsNil() throws {
+    // Arrange — discover the store's key via the suite's own domain, then poison it
+    let suiteName = Fixtures.makeSuiteName()
+    let defaults = try #require(UserDefaults(suiteName: suiteName))
+    defer { defaults.removePersistentDomain(forName: suiteName) }
+    let store = UserDefaultsLastSessionStore(defaults: defaults)
+    let host = UUID()
+    store.setLastSessionId(UUID(), host: host)
+    let key = try #require(defaults.persistentDomain(forName: suiteName)?.keys.first)
+
+    // Act
+    defaults.set("not-a-uuid", forKey: key)
+
+    // Assert
+    #expect(store.lastSessionId(host: host) == nil)
+}

ios/Packages/HostRegistry/Tests/HostRegistryTests/TestFixtures.swift

@@ -0,0 +1,28 @@
+import Foundation
+import WireProtocol
+import HostRegistry
+
+/// On macOS `Foundation.Host` (NSHost) shadows the package type in test
+/// files that import Foundation — pin resolution for the whole test target.
+typealias Host = HostRegistry.Host
+
+/// Shared fixtures for HostRegistryTests. Pure helpers only — no state.
+enum Fixtures {
+    /// Builds a valid Host; traps loudly if the fixture URL is malformed
+    /// (a broken fixture must fail the suite, not silently skip assertions).
+    static func makeHost(
+        name: String = "mac-studio",
+        urlString: String = "http://192.168.1.5:3000",
+        id: UUID = UUID()
+    ) -> Host {
+        guard let url = URL(string: urlString), let endpoint = HostEndpoint(baseURL: url) else {
+            fatalError("test fixture URL invalid: \(urlString)")
+        }
+        return Host(id: id, name: name, endpoint: endpoint)
+    }
+
+    /// Unique UserDefaults suite name per test — isolates parallel tests.
+    static func makeSuiteName() -> String {
+        "HostRegistryTests." + UUID().uuidString
+    }
+}