Add reply support to Comments v2

Modules/Sources/WordPressComments/Models/CommentChangeEvent.swift

@@ -6,6 +6,11 @@ import Foundation
 enum CommentChangeEvent: Equatable, Sendable {
     case statusChanged(id: Int64, to: CommentListItem.Status)
     case deleted(id: Int64)
+    /// A reply was created under `parentID`. Carries the reply's own status
+    /// (not the parent's) so loaded tabs can decide whether it belongs to
+    /// them; stales rather than inserts because a paged list cannot know the
+    /// reply's correct position.
+    case replyCreated(parentID: Int64, replyStatus: CommentListItem.Status)
 }
 
 extension CommentChangeEvent {
@@ -15,6 +20,7 @@ extension CommentChangeEvent {
         switch self {
         case .statusChanged(let id, _): id
         case .deleted(let id): id
+        case .replyCreated(let parentID, _): parentID
         }
     }
 }

Modules/Sources/WordPressComments/Services/CommentDraftStore.swift

@@ -0,0 +1,58 @@
+import Foundation
+
+/// Persists in-progress reply drafts per (site, user, comment), matching the
+/// legacy composer's behavior so a half-written reply survives cancel and
+/// process death. Edit mode deliberately has no drafts (legacy parity).
+@MainActor
+public protocol CommentDraftStoring {
+    func loadDraft(commentID: Int64) -> String?
+    func saveDraft(_ text: String, commentID: Int64)
+    func deleteDraft(commentID: Int64)
+}
+
+@MainActor
+public final class UserDefaultsCommentDraftStore: CommentDraftStoring {
+    private let namespace: String
+    private let defaults: UserDefaults
+
+    /// `namespace` identifies the (site, user) pair so drafts never leak
+    /// across sites or accounts; see `namespace(siteURL:username:)`.
+    init(namespace: String, defaults: UserDefaults = .standard) {
+        self.namespace = namespace
+        self.defaults = defaults
+    }
+
+    public convenience init(siteURL: URL, username: String, defaults: UserDefaults = .standard) {
+        self.init(namespace: Self.namespace(siteURL: siteURL, username: username), defaults: defaults)
+    }
+
+    /// Keys drafts per (site, user): same person different site, or same
+    /// site different account, must never see each other's drafts. Only the
+    /// case-insensitive URL parts (scheme, host) are normalized; the path is
+    /// case-sensitive, so lowercasing the whole URL would collapse distinct
+    /// sites like /Blog and /blog and leak drafts between them.
+    static func namespace(siteURL: URL, username: String) -> String {
+        guard var components = URLComponents(url: siteURL, resolvingAgainstBaseURL: false) else {
+            return "\(siteURL.absoluteString)|\(username)"
+        }
+        components.scheme = components.scheme?.lowercased()
+        components.host = components.host?.lowercased()
+        return "\(components.string ?? siteURL.absoluteString)|\(username)"
+    }
+
+    private func key(_ commentID: Int64) -> String {
+        "CommentsV2Draft.\(namespace).\(commentID)"
+    }
+
+    public func loadDraft(commentID: Int64) -> String? {
+        defaults.string(forKey: key(commentID))
+    }
+
+    public func saveDraft(_ text: String, commentID: Int64) {
+        defaults.set(text, forKey: key(commentID))
+    }
+
+    public func deleteDraft(commentID: Int64) {
+        defaults.removeObject(forKey: key(commentID))
+    }
+}

Modules/Sources/WordPressComments/Services/CommentsDetailRouter.swift

@@ -14,6 +14,7 @@ final class CommentsDetailRouter {
     /// while the list loads and later screens read it synchronously.
     private let capabilities: CommentsCapabilityResolver
     private let coordinator: CommentsModerationCoordinator
+    private let draftStore: any CommentDraftStoring
     private let titleResolver: PostTitleResolver
     private let tracker: (any CommentsTracker)?
     private let noticePresenter: any NoticePresenting
@@ -23,6 +24,7 @@ final class CommentsDetailRouter {
         service: any CommentsServiceProtocol,
         capabilities: any CommentsCapabilitiesProtocol,
         coordinator: CommentsModerationCoordinator,
+        draftStore: any CommentDraftStoring,
         titleResolver: PostTitleResolver,
         tracker: (any CommentsTracker)?,
         noticePresenter: any NoticePresenting,
@@ -31,6 +33,7 @@ final class CommentsDetailRouter {
         self.service = service
         self.capabilities = CommentsCapabilityResolver(capabilities: capabilities)
         self.coordinator = coordinator
+        self.draftStore = draftStore
         self.titleResolver = titleResolver
         self.tracker = tracker
         self.noticePresenter = noticePresenter
@@ -48,6 +51,7 @@ final class CommentsDetailRouter {
             service: service,
             capabilities: capabilities,
             coordinator: coordinator,
+            draftStore: draftStore,
             titleResolver: titleResolver,
             tracker: tracker,
             noticePresenter: noticePresenter

Modules/Sources/WordPressComments/Services/CommentsModerationCoordinator.swift

@@ -26,6 +26,15 @@ enum CommentModerationAction: Hashable, Sendable {
     }
 }
 
+/// The outcome of a successful `reply(to:content:)` call.
+struct ReplyOutcome: Equatable, Sendable {
+    let replyStatus: CommentListItem.Status
+    /// True when create returned comment_duplicate: the content already
+    /// existed server-side (an earlier send landed), so the composer words
+    /// its notice differently.
+    let alreadyPosted: Bool
+}
+
 /// Owns every comment mutation for the feature. All state changes flow through
 /// here so the coordinator can enforce two ordering rules the design requires:
 ///   1. One mutation in flight per comment.
@@ -51,20 +60,70 @@ final class CommentsModerationCoordinator {
 
     /// The in-flight mutation task per comment ID. Presence means "mutating";
     /// `waitForPendingMutation` awaits the stored task's value.
-    private var inFlight: [Int64: Task<Void, Never>] = [:]
+    private var inFlightMutations: [Int64: Task<Void, Never>] = [:]
 
     init(service: any CommentsServiceProtocol, tracker: (any CommentsTracker)? = nil) {
         self.service = service
         self.tracker = tracker
     }
 
     func isMutating(id: Int64) -> Bool {
-        inFlight[id] != nil
+        inFlightMutations[id] != nil
     }
 
     /// Awaits any in-flight mutation for the comment (re-entry race guard).
     func waitForPendingMutation(id: Int64) async {
-        await inFlight[id]?.value
+        await inFlightMutations[id]?.value
+    }
+
+    /// Creates a reply to `parent` and, for a pending parent, approves it
+    /// afterwards, all inside one owning task holding the parent's in-flight
+    /// slot. Pessimistic: nothing is emitted until the create outcome is
+    /// known; a failure throws back to the composer.
+    func reply(to parent: CommentDetail, content: String) async throws -> ReplyOutcome {
+        try await holdingSlot(for: parent.id, waitingForSlot: true) { [weak self] in
+            guard let self else { throw CancellationError() }
+            let created: CommentDetail?
+            do {
+                created = try await self.service.createReply(
+                    postID: parent.postID,
+                    parentID: parent.id,
+                    content: content
+                )
+            } catch {
+                // comment_duplicate proves this author already has this exact
+                // content on this post (core never accepts it twice), so an
+                // earlier send landed (timeout-after-commit). Continue the
+                // chain rather than failing, or the promised parent approval
+                // would be silently dropped on the retry path.
+                guard (error as? WpApiError)?.wpErrorCode == .CommentDuplicate else { throw error }
+                created = nil
+            }
+            self.tracker?.track(.repliedTo(commentID: parent.id, postID: parent.postID))
+            // The composer is only reachable by moderators, so a pending
+            // parent always means "approve on send" (no separate consent
+            // step). The approve runs pessimistically: its statusChanged
+            // event is emitted only after the request succeeds, so there is no
+            // optimistic emit to undo. It's possible the reply lands but the
+            // parent approval fails; the parent then remains Pending in list
+            // and detail, which is the true server state. We consider that an
+            // edge case and accept the risk; the user can approve manually.
+            if parent.status == .pending {
+                try? await self.runModeration(.approve, on: parent)
+            }
+            // Reply is moderator-gated, so core auto-approves our replies; a
+            // duplicate (unknown landed status) assumes approved on the same
+            // basis. A plugin forcing moderation is corrected by the next
+            // list refetch (the event only marks tabs stale).
+            //
+            // Emitted after the approve so its statusChanged lands first: a
+            // loaded list tab then updates the parent row in place with
+            // nothing in flight, instead of invalidating the page-one fetch
+            // that replyCreated's stale mark would already have started.
+            let replyStatus = created?.status ?? .approved
+            self.events.send(.replyCreated(parentID: parent.id, replyStatus: replyStatus))
+            return ReplyOutcome(replyStatus: replyStatus, alreadyPosted: created == nil)
+        }
     }
 
     /// Broadcasts a status change the detail screen observed on load (its seed
@@ -90,16 +149,26 @@ final class CommentsModerationCoordinator {
     /// slot, so the mutation outlives a popped screen while the caller can
     /// still await its outcome. The slot claim happens synchronously before any
     /// suspension, so no second claimant can interleave.
+    ///
+    /// With `waitingForSlot`, a busy slot is awaited instead of being the
+    /// caller's problem. The check repeats after every wait rather than
+    /// awaiting once: two callers can both be suspended on the same in-flight
+    /// task and both resume once it completes. Looping lets only the first
+    /// claimant proceed; the second waits on that new claim instead.
     private func holdingSlot<T: Sendable>(
         for id: Int64,
+        waitingForSlot: Bool = false,
         _ body: @escaping @MainActor () async throws -> T
     ) async throws -> T {
+        while waitingForSlot, isMutating(id: id) {
+            await waitForPendingMutation(id: id)
+        }
         let chain = Task { try await body() }
         let slot = Task { [weak self] in
             _ = try? await chain.value
-            self?.inFlight[id] = nil
+            self?.inFlightMutations[id] = nil
         }
-        inFlight[id] = slot
+        inFlightMutations[id] = slot
         // Await the slot first so `isMutating` is false by the time the caller
         // resumes; the chain has already settled when the slot clears.
         await slot.value

Modules/Sources/WordPressComments/Services/CommentsService.swift

@@ -56,6 +56,10 @@ protocol CommentsServiceProtocol: Sendable {
     /// Total number of replies to `id`, read from the list response's
     /// `X-WP-Total` header rather than the (unused) page of results.
     func numberOfReplies(for id: Int64) async throws -> Int
+
+    /// Creates a reply to `parentID` on `postID` and returns the created
+    /// comment's detail.
+    func createReply(postID: Int64, parentID: Int64, content: String) async throws -> CommentDetail
 }
 
 /// Errors raised by `CommentsService` that don't originate from wordpress-rs.
@@ -166,6 +170,18 @@ final class CommentsService: CommentsServiceProtocol {
         )
         return Int(response.headerMap.wpTotal() ?? 0)
     }
+
+    func createReply(postID: Int64, parentID: Int64, content: String) async throws -> CommentDetail {
+        // Core returns the create response in view context unless the caller
+        // has moderate_comments (create_item overrides any requested
+        // ?context=), and wordpress-rs decodes it as such, so the result never
+        // carries edit-only fields (`contentRaw`, email, IP). The reply chain
+        // only reads its status.
+        let response = try await client.api.comments.create(
+            params: CommentCreateParams(post: postID, content: content, parent: parentID)
+        )
+        return CommentDetail(comment: response.data)
+    }
 }
 
 extension WpApiError {

Modules/Sources/WordPressComments/Services/CommentsTracker.swift

@@ -5,6 +5,8 @@ public enum CommentsTrackedEvent: Equatable, Sendable {
     case spammed(commentID: Int64, postID: Int64)
     case trashed(commentID: Int64, postID: Int64)
     // Permanent delete: legacy has no analytics event; deliberately untracked.
+    /// A reply was successfully created, matching legacy's reply-sent event.
+    case repliedTo(commentID: Int64, postID: Int64)
 }
 
 public protocol CommentsTracker: Sendable {

Modules/Sources/WordPressComments/Strings/Strings.swift

@@ -242,4 +242,88 @@ enum Strings {
         value: "Couldn't load this comment",
         comment: "Error state title when the comment detail fails to load"
     )
+
+    static let composerReplyTitle = NSLocalizedString(
+        "commentComposer.title.reply",
+        value: "Reply",
+        comment: "Title of the compose screen for replying to a comment"
+    )
+
+    static let composerPlaceholder = NSLocalizedString(
+        "commentComposer.placeholder",
+        value: "Leave a reply…",
+        comment: "Placeholder text in the composer text input field"
+    )
+
+    static let composerSend = NSLocalizedString(
+        "commentComposer.action.send",
+        value: "Send",
+        comment: "Button label to send a new reply"
+    )
+
+    static let composerCancel = NSLocalizedString(
+        "commentComposer.action.cancel",
+        value: "Cancel",
+        comment: "Button label to cancel composing or editing a comment"
+    )
+
+    static let composerApproveNote = NSLocalizedString(
+        "commentComposer.approveNote",
+        value: "Sending will also approve this comment.",
+        comment: "Note explaining that sending a reply will also approve the pending comment"
+    )
+
+    static let composerSaveDraft = NSLocalizedString(
+        "commentComposer.action.saveDraft",
+        value: "Save Draft",
+        comment: "Button label to save the current text as a draft"
+    )
+
+    static let composerDeleteDraft = NSLocalizedString(
+        "commentComposer.action.deleteDraft",
+        value: "Delete Draft",
+        comment: "Button label to delete a saved draft"
+    )
+
+    static let composerKeepEditing = NSLocalizedString(
+        "commentComposer.action.keepEditing",
+        value: "Keep Editing",
+        comment: "Button label to continue editing instead of discarding changes"
+    )
+
+    static let composerErrorClosed = NSLocalizedString(
+        "commentComposer.error.closed",
+        value: "Comments are closed for this post.",
+        comment: "Error message shown when comments are disabled for the post"
+    )
+
+    static let composerErrorReplyFailed = NSLocalizedString(
+        "commentComposer.error.replyFailed",
+        value: "Failed to send reply.",
+        comment: "Error message shown when sending a reply fails"
+    )
+
+    static let noticeReplySent = NSLocalizedString(
+        "commentComposer.notice.replySent",
+        value: "Reply sent.",
+        comment: "Notice shown after a reply is successfully sent"
+    )
+
+    static let noticeReplyPending = NSLocalizedString(
+        "commentComposer.notice.replyPending",
+        value: "Reply submitted for moderation.",
+        comment: "Notice shown when a reply is submitted and awaiting moderation"
+    )
+
+    static let noticeReplyAlreadyPosted = NSLocalizedString(
+        "commentComposer.notice.replyAlreadyPosted",
+        value: "This reply has already been posted.",
+        comment: "Notice shown when attempting to post a reply that was already submitted"
+    )
+
+    static let detailReply = NSLocalizedString(
+        "commentDetail.action.reply",
+        value: "Reply",
+        comment: "Button label to reply to a comment on the detail screen"
+    )
 }