Make rich messages editable via InstantPage↔markdown round-trip

Reconstruct markdown source from a stored InstantPage to populate the edit
field, then re-classify on save (the inverse of the send path). Adds the
InstantPageToMarkdown converter, edit-field population and save-time
re-classification in ChatControllerLoadDisplayNode, and a shared InstantPage
previewText surfaced through MessageContentKind for reply/pinned/forward
previews. Documented in CLAUDE.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

submodules/BrowserUI/Sources/InstantPageToMarkdown.swift

@@ -0,0 +1,249 @@
+import Foundation
+import TelegramCore
+
+/// Reconstructs a markdown source string from an `InstantPage`.
+///
+/// This is the inverse of the markdown→`InstantPage` conversion used when
+/// sending rich messages. It is best-effort and never fails: media blocks
+/// (images/videos/audio/embeds/maps) are skipped, and any block or inline node
+/// without a CommonMark representation falls back to its plain text.
+///
+/// Inline formatting is emitted as CommonMark (`**bold**`, `*italic*`,
+/// `` `code` ``, `~~strike~~`, `[text](url)`) because the send-time classifier
+/// re-parses the text through the rich (Apple CommonMark) path, not the entity
+/// regex.
+public func markdownStringFromInstantPage(_ instantPage: InstantPage) -> String {
+    return markdownString(from: instantPage.blocks)
+}
+
+private func markdownString(from blocks: [InstantPageBlock]) -> String {
+    var pieces: [String] = []
+    for block in blocks {
+        if let piece = markdownString(from: block) {
+            pieces.append(piece)
+        }
+    }
+    return pieces.joined(separator: "\n\n")
+}
+
+private func markdownString(from block: InstantPageBlock) -> String? {
+    switch block {
+    case let .heading(text, level):
+        let hashes = String(repeating: "#", count: max(1, min(6, Int(level))))
+        return "\(hashes) \(markdownInline(from: text))"
+    case let .title(text):
+        return "# \(markdownInline(from: text))"
+    case let .paragraph(text):
+        let rendered = markdownInline(from: text)
+        return rendered.isEmpty ? nil : escapeLeadingBlockMarker(rendered)
+    case let .preformatted(text, language):
+        let language = language ?? ""
+        return "```\(language)\n\(markdownInline(from: text))\n```"
+    case let .blockQuote(text, _):
+        return markdownBlockQuote(text)
+    case let .pullQuote(text, _):
+        return markdownBlockQuote(text)
+    case let .list(items, ordered):
+        return markdownList(items: items, ordered: ordered, indent: 0)
+    case let .table(_, rows, _, _):
+        return markdownTable(rows: rows)
+    case .divider:
+        return "---"
+    case let .formula(latex):
+        return "$\(latex)$"
+    case .anchor:
+        // Chat send already strips generated heading anchors; drop them here too.
+        return nil
+    case let .subtitle(text), let .header(text), let .subheader(text), let .footer(text), let .kicker(text):
+        let rendered = markdownInline(from: text)
+        return rendered.isEmpty ? nil : escapeLeadingBlockMarker(rendered)
+    default:
+        // Media and other structural blocks are skipped (out of scope).
+        return nil
+    }
+}
+
+private func markdownBlockQuote(_ text: RichText) -> String {
+    let body = markdownInline(from: text)
+    let lines = body.split(separator: "\n", omittingEmptySubsequences: false)
+    return lines.map { "> \($0)" }.joined(separator: "\n")
+}
+
+private func markdownInline(from richText: RichText) -> String {
+    switch richText {
+    case .empty:
+        return ""
+    case let .plain(string):
+        return escapeMarkdown(string)
+    case let .bold(text):
+        return "**\(markdownInline(from: text))**"
+    case let .italic(text):
+        return "*\(markdownInline(from: text))*"
+    case let .fixed(text):
+        return "`\(markdownInline(from: text))`"
+    case let .strikethrough(text):
+        return "~~\(markdownInline(from: text))~~"
+    case let .url(text, url, _):
+        return "[\(markdownInline(from: text))](\(url))"
+    case let .email(text, email):
+        return "[\(markdownInline(from: text))](mailto:\(email))"
+    case let .phone(text, phone):
+        return "[\(markdownInline(from: text))](tel:\(phone))"
+    case let .concat(parts):
+        return parts.map { markdownInline(from: $0) }.joined()
+    case let .anchor(text, _):
+        return markdownInline(from: text)
+    case let .formula(latex):
+        return "$\(latex)$"
+    // No CommonMark equivalent; emit inner text. These cannot arise from a
+    // markdown-composed message (Apple's markdown parser never produces them),
+    // so this is purely defensive.
+    case let .underline(text):
+        return markdownInline(from: text)
+    case let .marked(text):
+        return markdownInline(from: text)
+    case let .superscript(text):
+        return markdownInline(from: text)
+    case let .`subscript`(text):
+        return markdownInline(from: text)
+    default:
+        // .image, .textCustomEmoji, and the entity cases (.textMention,
+        // .textHashtag, …): fall back to plain text.
+        return escapeMarkdown(richText.plainText)
+    }
+}
+
+/// Backslash-escapes inline markdown-significant characters so literal text
+/// does not re-parse as formatting. Pragmatic set, not full CommonMark.
+private func escapeMarkdown(_ string: String) -> String {
+    var result = ""
+    result.reserveCapacity(string.count)
+    for character in string {
+        switch character {
+        case "\\", "*", "_", "`", "[", "]", "~", "|":
+            result.append("\\")
+            result.append(character)
+        default:
+            result.append(character)
+        }
+    }
+    return result
+}
+
+/// Escapes a line-leading character that would otherwise be read as a block
+/// marker (ATX heading, blockquote, or list item) when the text starts a line.
+private func escapeLeadingBlockMarker(_ string: String) -> String {
+    guard let first = string.first else {
+        return string
+    }
+    if first == "#" || first == ">" || first == "-" || first == "+" {
+        return "\\" + string
+    }
+    // Ordered-list marker: one or more digits followed by '.' or ')'.
+    if first.isNumber {
+        var index = string.startIndex
+        while index < string.endIndex, string[index].isNumber {
+            index = string.index(after: index)
+        }
+        if index < string.endIndex, string[index] == "." || string[index] == ")" {
+            let prefix = string[string.startIndex ..< index]
+            let delimiter = string[index]
+            let rest = string[string.index(after: index)...]
+            return "\(prefix)\\\(delimiter)\(rest)"
+        }
+    }
+    return string
+}
+
+/// Collapses newlines for a single-line GFM table cell. The `|` character is
+/// already escaped by `escapeMarkdown` for `.plain` runs.
+private func escapeTableCell(_ string: String) -> String {
+    return string.replacingOccurrences(of: "\n", with: " ")
+}
+
+private func markdownList(items: [InstantPageListItem], ordered: Bool, indent: Int) -> String {
+    let indentString = String(repeating: " ", count: indent * 2)
+    var lines: [String] = []
+    var index = 1
+    for item in items {
+        // The stored per-item marker string (`InstantPageListItem`'s `String?`) is
+        // intentionally ignored: ordered markers are regenerated from the running
+        // index (CommonMark renumbers anyway) and the unordered marker is fixed.
+        let marker = ordered ? "\(index). " : "- "
+        switch item {
+        case let .text(text, _):
+            lines.append("\(indentString)\(marker)\(markdownInline(from: text))")
+        case let .blocks(blocks, _):
+            var remainder = blocks
+            var markerLineText = ""
+            if case let .paragraph(text)? = remainder.first {
+                markerLineText = markdownInline(from: text)
+                remainder = Array(remainder.dropFirst())
+            }
+            lines.append("\(indentString)\(marker)\(markerLineText)")
+            let childIndentString = String(repeating: " ", count: (indent + 1) * 2)
+            for block in remainder {
+                if case let .list(nestedItems, nestedOrdered) = block {
+                    lines.append(markdownList(items: nestedItems, ordered: nestedOrdered, indent: indent + 1))
+                } else if let rendered = markdownString(from: block) {
+                    for line in rendered.split(separator: "\n", omittingEmptySubsequences: false) {
+                        lines.append("\(childIndentString)\(line)")
+                    }
+                }
+            }
+        case .unknown:
+            break
+        }
+        index += 1
+    }
+    return lines.joined(separator: "\n")
+}
+
+private func markdownTable(rows: [InstantPageTableRow]) -> String? {
+    guard !rows.isEmpty else {
+        return nil
+    }
+    let columnCount = rows.map { $0.cells.count }.max() ?? 0
+    guard columnCount > 0 else {
+        return nil
+    }
+
+    func renderRow(_ row: InstantPageTableRow) -> String {
+        var cellStrings: [String] = []
+        for columnIndex in 0 ..< columnCount {
+            if columnIndex < row.cells.count, let text = row.cells[columnIndex].text {
+                cellStrings.append(escapeTableCell(markdownInline(from: text)))
+            } else {
+                cellStrings.append("")
+            }
+        }
+        return "| " + cellStrings.joined(separator: " | ") + " |"
+    }
+
+    var lines: [String] = []
+    lines.append(renderRow(rows[0]))
+
+    var separators: [String] = []
+    for columnIndex in 0 ..< columnCount {
+        let alignment: TableHorizontalAlignment
+        if columnIndex < rows[0].cells.count {
+            alignment = rows[0].cells[columnIndex].alignment
+        } else {
+            alignment = .left
+        }
+        switch alignment {
+        case .left:
+            separators.append("---")
+        case .center:
+            separators.append(":---:")
+        case .right:
+            separators.append("---:")
+        }
+    }
+    lines.append("| " + separators.joined(separator: " | ") + " |")
+
+    for row in rows.dropFirst() {
+        lines.append(renderRow(row))
+    }
+    return lines.joined(separator: "\n")
+}

submodules/ChatListUI/Sources/Node/ChatListItemStrings.swift

@@ -77,181 +77,6 @@ private func paidContentGroupType(paidContent: TelegramMediaPaidContent) -> Mess
     return currentType
 }
 
-extension RichText {
-    func previewText() -> String {
-        switch self {
-        case .empty:
-            return ""
-        case let .plain(value):
-            return value
-        case let .bold(value):
-            return value.previewText()
-        case let .italic(value):
-            return value.previewText()
-        case let .underline(value):
-            return value.previewText()
-        case let .strikethrough(value):
-            return value.previewText()
-        case let .fixed(value):
-            return value.previewText()
-        case let .url(value, _, _):
-            return value.previewText()
-        case let .email(value, _):
-            return value.previewText()
-        case let .concat(values):
-            var result = ""
-            for value in values {
-                result.append(value.previewText())
-            }
-            return result
-        case let .`subscript`(value):
-            return value.previewText()
-        case let .superscript(value):
-            return value.previewText()
-        case let .marked(value):
-            return value.previewText()
-        case let .phone(value, _):
-            return value.previewText()
-        case .image:
-            //TODO:localize
-            return "Photo"
-        case let .anchor(value, _):
-            return value.previewText()
-        case .formula:
-            //TODO:localize
-            return "Fx"
-        case let .textCustomEmoji(_, alt):
-            return alt
-        case let .textAutoEmail(value), let .textAutoPhone(value), let .textAutoUrl(value), let .textBankCard(value), let .textBotCommand(value), let .textCashtag(value), let .textHashtag(value), let .textMention(value), let .textMentionName(value, _), let .textSpoiler(value):
-            return value.previewText()
-        }
-    }
-}
-
-extension InstantPageListItem {
-    func previewText() -> String {
-        switch self {
-        case .unknown:
-            return ""
-        case let .text(text, num):
-            if let num, !num.isEmpty {
-                return "\(num). \(text.previewText())"
-            } else {
-                return text.previewText()
-            }
-        case let .blocks(blocks, num):
-            var blocksText = ""
-            for block in blocks {
-                if !blocksText.isEmpty {
-                    blocksText.append("\n")
-                }
-                blocksText.append(block.previewText())
-            }
-            if let num {
-                return "\(num). \(blocksText)"
-            } else {
-                return blocksText
-            }
-        }
-    }
-}
-
-extension InstantPageBlock {
-    func previewText() -> String {
-        switch self {
-        case .unsupported:
-            return ""
-        case let .title(text):
-            return text.previewText()
-        case let .subtitle(text):
-            return text.previewText()
-        case let .authorDate(author, _):
-            return author.previewText()
-        case let .header(text):
-            return text.previewText()
-        case let .subheader(text):
-            return text.previewText()
-        case let .heading(text, _):
-            return text.previewText()
-        case .formula:
-            return "Fx"
-        case let .paragraph(text):
-            return text.previewText()
-        case let .preformatted(text, _):
-            return text.previewText()
-        case let .footer(text):
-            return text.previewText()
-        case .divider:
-            return "\n"
-        case .anchor:
-            return ""
-        case let .list(items, _):
-            var result = ""
-            for item in items {
-                if !result.isEmpty {
-                    result.append("\n")
-                }
-                result.append(item.previewText())
-            }
-            return result
-        case let .blockQuote(text, caption):
-            return text.previewText() + caption.previewText()
-        case let .pullQuote(text, caption):
-            return text.previewText() + caption.previewText()
-        case .image(_, _, _, _):
-            //TODO:localize
-            return "Photo"
-        case .video(_, _, _, _):
-            //TODO:localize
-            return "Video"
-        case .audio:
-            //TODO:localize
-            return "Audio"
-        case .cover:
-            return ""
-        case .webEmbed:
-            return ""
-        case .postEmbed:
-            return ""
-        case .collage:
-            return ""
-        case .slideshow:
-            return ""
-        case .channelBanner:
-            return ""
-        case .kicker:
-            return ""
-        case .table:
-            //TODO:localize
-            return "Table"
-        case .details:
-            return ""
-        case .relatedArticles:
-            return ""
-        case .map:
-            //TODO:localize
-            return "Map"
-        }
-    }
-}
-
-extension InstantPage {
-    func previewText() -> String {
-        let maxLength: Int = 200
-        var result = ""
-        for block in self.blocks {
-            if !result.isEmpty {
-                result.append("\n")
-            }
-            result.append(block.previewText())
-            if result.count > maxLength {
-                break
-            }
-        }
-        return result
-    }
-}
-
 public func chatListItemStrings(strings: PresentationStrings, nameDisplayOrder: PresentationPersonNameOrder, dateTimeFormat: PresentationDateTimeFormat, contentSettings: ContentSettings, messages: [EngineMessage], chatPeer: EngineRenderedPeer, accountPeerId: EnginePeer.Id, enableMediaEmoji: Bool = true, isPeerGroup: Bool = false) -> (peer: EnginePeer?, hideAuthor: Bool, messageText: String, messageEntities: [MessageTextEntity], spoilers: [NSRange]?, customEmojiRanges: [(NSRange, ChatTextInputTextCustomEmojiAttribute)]?) {
     let peer: EnginePeer?
     

submodules/TelegramStringFormatting/Sources/InstantPagePreviewText.swift

@@ -0,0 +1,177 @@
+import Foundation
+import TelegramCore
+
+extension RichText {
+    public func previewText() -> String {
+        switch self {
+        case .empty:
+            return ""
+        case let .plain(value):
+            return value
+        case let .bold(value):
+            return value.previewText()
+        case let .italic(value):
+            return value.previewText()
+        case let .underline(value):
+            return value.previewText()
+        case let .strikethrough(value):
+            return value.previewText()
+        case let .fixed(value):
+            return value.previewText()
+        case let .url(value, _, _):
+            return value.previewText()
+        case let .email(value, _):
+            return value.previewText()
+        case let .concat(values):
+            var result = ""
+            for value in values {
+                result.append(value.previewText())
+            }
+            return result
+        case let .`subscript`(value):
+            return value.previewText()
+        case let .superscript(value):
+            return value.previewText()
+        case let .marked(value):
+            return value.previewText()
+        case let .phone(value, _):
+            return value.previewText()
+        case .image:
+            //TODO:localize
+            return "Photo"
+        case let .anchor(value, _):
+            return value.previewText()
+        case .formula:
+            //TODO:localize
+            return "Fx"
+        case let .textCustomEmoji(_, alt):
+            return alt
+        case let .textAutoEmail(value), let .textAutoPhone(value), let .textAutoUrl(value), let .textBankCard(value), let .textBotCommand(value), let .textCashtag(value), let .textHashtag(value), let .textMention(value), let .textMentionName(value, _), let .textSpoiler(value):
+            return value.previewText()
+        }
+    }
+}
+
+extension InstantPageListItem {
+    public func previewText() -> String {
+        switch self {
+        case .unknown:
+            return ""
+        case let .text(text, num):
+            if let num, !num.isEmpty {
+                return "\(num). \(text.previewText())"
+            } else {
+                return text.previewText()
+            }
+        case let .blocks(blocks, num):
+            var blocksText = ""
+            for block in blocks {
+                if !blocksText.isEmpty {
+                    blocksText.append("\n")
+                }
+                blocksText.append(block.previewText())
+            }
+            if let num {
+                return "\(num). \(blocksText)"
+            } else {
+                return blocksText
+            }
+        }
+    }
+}
+
+extension InstantPageBlock {
+    public func previewText() -> String {
+        switch self {
+        case .unsupported:
+            return ""
+        case let .title(text):
+            return text.previewText()
+        case let .subtitle(text):
+            return text.previewText()
+        case let .authorDate(author, _):
+            return author.previewText()
+        case let .header(text):
+            return text.previewText()
+        case let .subheader(text):
+            return text.previewText()
+        case let .heading(text, _):
+            return text.previewText()
+        case .formula:
+            return "Fx"
+        case let .paragraph(text):
+            return text.previewText()
+        case let .preformatted(text, _):
+            return text.previewText()
+        case let .footer(text):
+            return text.previewText()
+        case .divider:
+            return "\n"
+        case .anchor:
+            return ""
+        case let .list(items, _):
+            var result = ""
+            for item in items {
+                if !result.isEmpty {
+                    result.append("\n")
+                }
+                result.append(item.previewText())
+            }
+            return result
+        case let .blockQuote(text, caption):
+            return text.previewText() + caption.previewText()
+        case let .pullQuote(text, caption):
+            return text.previewText() + caption.previewText()
+        case .image(_, _, _, _):
+            //TODO:localize
+            return "Photo"
+        case .video(_, _, _, _):
+            //TODO:localize
+            return "Video"
+        case .audio:
+            //TODO:localize
+            return "Audio"
+        case .cover:
+            return ""
+        case .webEmbed:
+            return ""
+        case .postEmbed:
+            return ""
+        case .collage:
+            return ""
+        case .slideshow:
+            return ""
+        case .channelBanner:
+            return ""
+        case .kicker:
+            return ""
+        case .table:
+            //TODO:localize
+            return "Table"
+        case .details:
+            return ""
+        case .relatedArticles:
+            return ""
+        case .map:
+            //TODO:localize
+            return "Map"
+        }
+    }
+}
+
+extension InstantPage {
+    public func previewText() -> String {
+        let maxLength: Int = 200
+        var result = ""
+        for block in self.blocks {
+            if !result.isEmpty {
+                result.append("\n")
+            }
+            result.append(block.previewText())
+            if result.count > maxLength {
+                break
+            }
+        }
+        return result
+    }
+}

submodules/TelegramStringFormatting/Sources/MessageContentKind.swift

@@ -309,6 +309,11 @@ public func messageContentKind(contentSettings: ContentSettings, message: Engine
             return kind
         }
     }
+    for attribute in message.attributes {
+        if let attribute = attribute as? RichTextMessageAttribute {
+            return .text(NSAttributedString(string: attribute.instantPage.previewText()))
+        }
+    }
     return .text(messageTextWithAttributes(message: message))
 }
 

submodules/TelegramUI/Sources/Chat/ChatControllerLoadDisplayNode.swift

@@ -15,6 +15,7 @@ import DeviceAccess
 import TextFormat
 import TelegramBaseController
 import AccountContext
+import BrowserUI
 import TelegramStringFormatting
 import OverlayStatusController
 import DeviceLocationManager
@@ -1779,7 +1780,12 @@ extension ChatControllerImpl {
                                 }
                             }
                             
-                            let inputText = chatInputStateStringWithAppliedEntities(message.text, entities: entities)
+                            let inputText: NSAttributedString
+                            if let richTextAttribute = message.attributes.first(where: { $0 is RichTextMessageAttribute }) as? RichTextMessageAttribute {
+                                inputText = NSAttributedString(string: markdownStringFromInstantPage(richTextAttribute.instantPage))
+                            } else {
+                                inputText = chatInputStateStringWithAppliedEntities(message.text, entities: entities)
+                            }
                             var disableUrlPreviews: [String] = []
                             if webpageUrl == nil {
                                 disableUrlPreviews = detectUrls(inputText)
@@ -2208,7 +2214,17 @@ extension ChatControllerImpl {
                 }
                 
                 let text = trimChatInputText(convertMarkdownToAttributes(expandedInputStateAttributedString(editMessage.inputState.inputText)))
-                
+
+                let rawEditText = expandedInputStateAttributedString(editMessage.inputState.inputText).string
+                var isSpecialChatContents = false
+                if case .customChatContents = strongSelf.presentationInterfaceState.subject {
+                    isSpecialChatContents = true
+                }
+                var richTextAttribute: RichTextMessageAttribute?
+                if !isSpecialChatContents {
+                    richTextAttribute = richMarkdownAttributeIfNeeded(context: strongSelf.context, text: rawEditText)
+                }
+
                 let entities = generateTextEntities(text.string, enabledTypes: .all, currentEntities: generateChatInputTextEntities(text))
                 var entitiesAttribute: TextEntitiesMessageAttribute?
                 if !entities.isEmpty {
@@ -2290,9 +2306,17 @@ extension ChatControllerImpl {
                         if let currentMessage = currentMessage {
                             let currentEntities = currentMessage.textEntitiesAttribute?.entities ?? []
                             let currentWebpagePreviewAttribute = currentMessage.webpagePreviewAttribute ?? WebpagePreviewMessageAttribute(leadingPreview: false, forceLargeMedia: nil, isManuallyAdded: true, isSafe: false)
-                            
-                            if currentMessage.text != text.string || currentEntities != entities || updatingMedia || webpagePreviewAttribute != currentWebpagePreviewAttribute || disableUrlPreview {
-                                strongSelf.context.account.pendingUpdateMessageManager.add(messageId: editMessage.messageId, text: text.string, media: media, entities: entitiesAttribute, richText: nil, inlineStickers: inlineStickers, webpagePreviewAttribute: webpagePreviewAttribute, invertMediaAttribute: invertedMediaAttribute, disableUrlPreview: disableUrlPreview)
+                            let currentRichText = currentMessage.attributes.first(where: { $0 is RichTextMessageAttribute }) as? RichTextMessageAttribute
+
+                            if let richTextAttribute = richTextAttribute {
+                                // Rich edit: empty text, no entities, carry the rich attribute.
+                                if currentRichText != richTextAttribute || !currentMessage.text.isEmpty || updatingMedia {
+                                    strongSelf.context.account.pendingUpdateMessageManager.add(messageId: editMessage.messageId, text: "", media: media, entities: nil, richText: richTextAttribute, inlineStickers: inlineStickers, webpagePreviewAttribute: webpagePreviewAttribute, invertMediaAttribute: invertedMediaAttribute, disableUrlPreview: disableUrlPreview)
+                                }
+                            } else {
+                                if currentMessage.text != text.string || currentEntities != entities || currentRichText != nil || updatingMedia || webpagePreviewAttribute != currentWebpagePreviewAttribute || disableUrlPreview {
+                                    strongSelf.context.account.pendingUpdateMessageManager.add(messageId: editMessage.messageId, text: text.string, media: media, entities: entitiesAttribute, richText: nil, inlineStickers: inlineStickers, webpagePreviewAttribute: webpagePreviewAttribute, invertMediaAttribute: invertedMediaAttribute, disableUrlPreview: disableUrlPreview)
+                                }
                             }
                         }