Add backend reset and startNewConversation entry point

Author: staskus

Modules/Sources/WooAIAssistant/Backend/AssistantBackend.swift

@@ -4,6 +4,11 @@ public protocol AssistantBackend: Sendable {
     func send(turn: AssistantTurn,
               context: AssistantContext,
               session: AssistantSession?) -> AsyncThrowingStream<BackendYield, Error>
+    func reset() async
+}
+
+public extension AssistantBackend {
+    func reset() async {}
 }
 
 public protocol AssistantBackendConfirming: AssistantBackend {

Modules/Sources/WooAIAssistant/State/AssistantController.swift

@@ -47,9 +47,39 @@ public final class AssistantController {
             conversation.markCancelled(messageID: messageID)
         }
         activeAssistantMessageID = nil
+        for proposalID in pendingProposalIDs() {
+            conversation.applyConfirmationResolution(proposalID: proposalID, approved: false)
+            cancelProposal(proposalID)
+        }
         conversation.setStreaming(.idle)
     }
 
+    private func pendingProposalIDs() -> [UUID] {
+        var ids: [UUID] = []
+        for message in conversation.messages {
+            for segment in message.segments {
+                if case .confirmation(_, let proposalID, _, _, .pending) = segment {
+                    ids.append(proposalID)
+                }
+            }
+        }
+        return ids
+    }
+
+    public func startNewConversation() {
+        cancel()
+        let token = UUID()
+        activeTurnToken = token
+        activeTask = Task { [weak self] in
+            guard let self else { return }
+            await backend.reset()
+            guard activeTurnToken == token else { return }
+            conversation.reset()
+            activeTask = nil
+            activeTurnToken = nil
+        }
+    }
+
     public var canSend: Bool {
         activeTask == nil
     }

Modules/Sources/WooAIAssistant/State/AssistantConversation.swift

@@ -26,6 +26,20 @@ public final class AssistantConversation {
         self.messages = seededMessages
     }
 
+    func reset() {
+        messages = []
+        streamingState = .idle
+        outcomeUnknownObserved = false
+        session = nil
+    }
+
+    func applyConfirmationResolution(proposalID: UUID, approved: Bool) {
+        for index in messages.indices {
+            messages[index].updateConfirmation(proposalID: proposalID,
+                                               to: approved ? .confirmed : .cancelled)
+        }
+    }
+
     func appendUserMessage(_ text: String) -> ChatMessage {
         let message = ChatMessage(role: .user,
                                   segments: [.text(id: UUID(), content: text)])

Modules/Tests/WooAIAssistantTests/Mocks/MockAssistantBackend.swift

@@ -1,7 +1,8 @@
 import Foundation
 @testable import WooAIAssistant
 
-final class MockAssistantBackend: AssistantBackendConfirming, @unchecked Sendable {
+@MainActor
+final class MockAssistantBackend: AssistantBackendConfirming {
 
     private(set) var recordedTurns: [AssistantTurn] = []
     private(set) var confirmedProposalIDs: [UUID] = []