diff --git a/app/user/page.tsx b/app/user/page.tsx
index b86cde31..7351638b 100644
--- a/app/user/page.tsx
+++ b/app/user/page.tsx
@@ -802,6 +802,8 @@ function UserProfileContent() {
         author: reply.author,
         content: reply.content,
         createdAt: reply.createdAt,
+        updatedAt: reply.updatedAt,
+        isEdited: reply.isEdited,
         likes: reply.likes,
         reposts: reply.reposts,
         replies: reply.replies,
diff --git a/components/post/edit-post-modal.tsx b/components/post/edit-post-modal.tsx
new file mode 100644
index 00000000..90f01acd
--- /dev/null
+++ b/components/post/edit-post-modal.tsx
@@ -0,0 +1,199 @@
+'use client'
+
+import { logger } from '@/lib/logger'
+import { useEffect, useRef, useState } from 'react'
+import * as Dialog from '@radix-ui/react-dialog'
+import { XMarkIcon } from '@heroicons/react/24/outline'
+import { motion, AnimatePresence } from 'framer-motion'
+import toast from 'react-hot-toast'
+import { Button } from '@/components/ui/button'
+import { IconButton } from '@/components/ui/icon-button'
+import { Spinner } from '@/components/ui/spinner'
+import { UserAvatar } from '@/components/ui/avatar-image'
+import { CharacterCounter } from '@/components/compose/compose-sub-components'
+import { useEditPostModal } from '@/hooks/use-edit-post-modal'
+import { useRequireAuth } from '@/hooks/use-require-auth'
+import { useAuth } from '@/contexts/auth-context'
+import { useSettingsStore } from '@/lib/store'
+import { categorizeError } from '@/lib/error-utils'
+import { CHARACTER_LIMIT } from '@/components/compose/thread-post-editor'
+
+/**
+ * Modal for editing the content of an existing post or reply.
+ *
+ * Uses document replacement on Dash Platform: only the content field changes,
+ * all other stored fields are preserved by the service layer. The platform
+ * bumps $revision on replacement, which drives the "(edited)" indicator.
+ */
+export function EditPostModal() {
+  const { isOpen, post, close } = useEditPostModal()
+  const { requireAuth } = useRequireAuth()
+  const { user } = useAuth()
+  const potatoMode = useSettingsStore((s) => s.potatoMode)
+  const [content, setContent] = useState('')
+  const [isSaving, setIsSaving] = useState(false)
+  const textareaRef = useRef<HTMLTextAreaElement>(null)
+
+  // Pre-populate content when the modal opens
+  useEffect(() => {
+    if (isOpen && post) {
+      setContent(post.content)
+      // Small delay so the modal animation has mounted the textarea
+      const timeoutId = setTimeout(() => {
+        const textarea = textareaRef.current
+        if (textarea) {
+          textarea.focus()
+          textarea.setSelectionRange(textarea.value.length, textarea.value.length)
+        }
+      }, 50)
+      return () => clearTimeout(timeoutId)
+    }
+  }, [isOpen, post])
+
+  // Auto-resize the textarea to fit its content, like the thread composer
+  useEffect(() => {
+    const textarea = textareaRef.current
+    if (!textarea) return
+    textarea.style.height = 'auto'
+    textarea.style.height = `${Math.max(120, textarea.scrollHeight)}px`
+  }, [content, isOpen])
+
+  const trimmed = content.trim()
+  const isUnchanged = !!post && trimmed === post.content.trim()
+  const canSave = !!post && trimmed.length > 0 && content.length <= CHARACTER_LIMIT && !isUnchanged && !isSaving
+  const isReply = Boolean(post?.parentId)
+
+  const handleSave = async () => {
+    if (!post || !canSave) return
+    const authedUser = requireAuth('post')
+    if (!authedUser) return
+
+    setIsSaving(true)
+    try {
+      if (isReply) {
+        const { replyService } = await import('@/lib/services/reply-service')
+        await replyService.updateReply(post.id, authedUser.identityId, trimmed)
+      } else {
+        const { postService } = await import('@/lib/services/post-service')
+        await postService.updatePost(post.id, authedUser.identityId, trimmed)
+      }
+
+      toast.success(isReply ? 'Reply updated' : 'Post updated')
+
+      // Let mounted cards/pages refresh their displayed content
+      window.dispatchEvent(new CustomEvent('post-updated', {
+        detail: { postId: post.id, content: trimmed, isReply }
+      }))
+
+      close()
+    } catch (error) {
+      logger.error('Failed to update post:', error)
+      toast.error(categorizeError(error))
+    } finally {
+      setIsSaving(false)
+    }
+  }
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if ((e.ctrlKey || e.metaKey) && e.key === 'Enter') {
+      e.preventDefault()
+      handleSave().catch(err => logger.error('Failed to save edit:', err))
+    }
+  }
+
+  return (
+    <Dialog.Root open={isOpen} onOpenChange={(open) => !open && !isSaving && close()}>
+      <AnimatePresence>
+        {isOpen && (
+          <Dialog.Portal forceMount>
+            <Dialog.Overlay asChild>
+              <motion.div
+                initial={{ opacity: 0 }}
+                animate={{ opacity: 1 }}
+                exit={{ opacity: 0 }}
+                className={`fixed inset-0 bg-black/60 z-50 flex items-start justify-center pt-12 sm:pt-20 px-4 overflow-y-auto pb-12 ${potatoMode ? '' : 'backdrop-blur-sm'}`}
+              >
+                <Dialog.Content asChild>
+                  <motion.div
+                    initial={{ opacity: 0, scale: 0.95, y: 20 }}
+                    animate={{ opacity: 1, scale: 1, y: 0 }}
+                    exit={{ opacity: 0, scale: 0.95, y: 20 }}
+                    transition={{ duration: 0.2, ease: 'easeOut' }}
+                    className="w-full max-w-2xl bg-white dark:bg-neutral-900 rounded-2xl shadow-2xl overflow-hidden"
+                    onClick={(e) => e.stopPropagation()}
+                    onKeyDown={handleKeyDown}
+                  >
+                    {/* Accessibility */}
+                    <Dialog.Title className="sr-only">
+                      Edit {isReply ? 'reply' : 'post'}
+                    </Dialog.Title>
+                    <Dialog.Description className="sr-only">
+                      Your changes replace the original content. The {isReply ? 'reply' : 'post'} will be marked as edited.
+                    </Dialog.Description>
+
+                    {/* Header */}
+                    <div className="flex items-center justify-between px-5 py-3 border-b border-gray-100 dark:border-gray-800">
+                      <div className="flex items-center gap-3">
+                        <IconButton
+                          onClick={() => !isSaving && close()}
+                          className="hover:bg-gray-200 dark:hover:bg-gray-800"
+                        >
+                          <XMarkIcon className="h-5 w-5" />
+                        </IconButton>
+                        {user && (
+                          <UserAvatar userId={user.identityId} size="sm" alt="Your avatar" />
+                        )}
+                        <span className="text-sm font-semibold text-gray-900 dark:text-gray-100">
+                          Edit {isReply ? 'reply' : 'post'}
+                        </span>
+                      </div>
+
+                      <Button
+                        onClick={() => { handleSave().catch(err => logger.error('Failed to save edit:', err)) }}
+                        disabled={!canSave}
+                        className={`min-w-[100px] h-10 px-5 text-sm font-semibold transition-all ${
+                          canSave
+                            ? 'bg-yappr-500 hover:bg-yappr-600 shadow-lg shadow-yappr-500/25 hover:shadow-xl hover:shadow-yappr-500/30 hover:scale-[1.02]'
+                            : 'bg-gray-300 dark:bg-gray-700 text-gray-500 dark:text-gray-400 cursor-not-allowed'
+                        }`}
+                      >
+                        {isSaving ? (
+                          <span className="flex items-center gap-2">
+                            <Spinner size="xs" className="border-current" />
+                            Saving...
+                          </span>
+                        ) : (
+                          'Save'
+                        )}
+                      </Button>
+                    </div>
+
+                    {/* Main content area */}
+                    <div className="px-5 py-4 max-h-[60vh] overflow-y-auto">
+                      <textarea
+                        ref={textareaRef}
+                        value={content}
+                        onChange={(e) => setContent(e.target.value)}
+                        placeholder={isReply ? 'Edit your reply' : 'Edit your post'}
+                        disabled={isSaving}
+                        className="w-full min-h-[120px] text-base resize-none outline-none bg-transparent placeholder:text-gray-400 dark:placeholder:text-gray-600 disabled:opacity-60"
+                      />
+
+                      {/* Footer with edit note and character count */}
+                      <div className="flex items-center justify-between mt-3 pt-2 border-t border-gray-100 dark:border-gray-800">
+                        <span className="text-xs text-gray-400">
+                          Replaces the original — will be marked as edited
+                        </span>
+                        <CharacterCounter current={content.length} limit={CHARACTER_LIMIT} />
+                      </div>
+                    </div>
+                  </motion.div>
+                </Dialog.Content>
+              </motion.div>
+            </Dialog.Overlay>
+          </Dialog.Portal>
+        )}
+      </AnimatePresence>
+    </Dialog.Root>
+  )
+}
diff --git a/components/post/post-card.tsx b/components/post/post-card.tsx
index 25e2cc4e..57615c58 100644
--- a/components/post/post-card.tsx
+++ b/components/post/post-card.tsx
@@ -45,6 +45,7 @@ import { useHashtagRecoveryModal } from '@/hooks/use-hashtag-recovery-modal'
 import { useMentionValidation } from '@/hooks/use-mention-validation'
 import { useMentionRecoveryModal } from '@/hooks/use-mention-recovery-modal'
 import { useDeleteConfirmationModal } from '@/hooks/use-delete-confirmation-modal'
+import { useEditPostModal } from '@/hooks/use-edit-post-modal'
 import { tipService } from '@/lib/services/tip-service'
 import { useCanReplyToPrivate } from '@/hooks/use-can-reply-to-private'
 
@@ -172,10 +173,18 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
   const initialBookmarked = progressiveEnrichment?.interactions?.bookmarked ?? post.bookmarked ?? false
 
 
+  // Local override applied when this post is edited while mounted
+  // (set from the global 'post-updated' event dispatched by the edit modal)
+  const [editedContent, setEditedContent] = useState<string | null>(null)
+  const displayContent = editedContent ?? post.content
+  const isEdited = Boolean(post.isEdited) || editedContent !== null
+
   // Memoize enriched post for use in compose/tip modals and caching
   // Includes all resolved values so cached posts display correctly
   const enrichedPost = useMemo(() => ({
     ...post,
+    content: displayContent,
+    isEdited,
     author: {
       ...post.author,
       username: usernameState || post.author.username,
@@ -185,7 +194,7 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
       // undefined = still loading, true = has DPNS, false = no DPNS
       hasDpns: usernameState !== undefined ? (usernameState !== null) : post.author.hasDpns
     }
-  }), [post, usernameState, displayName, avatarUrl])
+  }), [post, displayContent, isEdited, usernameState, displayName, avatarUrl])
 
   // Render username/identity display based on state
   const renderUsernameOrIdentity = useCallback(() => {
@@ -271,6 +280,7 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
   const { open: openHashtagRecoveryModal } = useHashtagRecoveryModal()
   const { open: openMentionRecoveryModal } = useMentionRecoveryModal()
   const { open: openDeleteModal } = useDeleteConfirmationModal()
+  const { open: openEditModal } = useEditPostModal()
 
   // Validate hashtags for all posts (checks if hashtag documents exist on platform)
   const { validations: hashtagValidations, revalidate: revalidateHashtags } = useHashtagValidation(post)
@@ -327,8 +337,22 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
     }
   }, [post.id, revalidateMentions])
 
+  // Listen for edit events so the displayed content refreshes without a refetch
+  useEffect(() => {
+    const handlePostUpdated = (event: CustomEvent<{ postId: string; content: string }>) => {
+      if (event.detail.postId === post.id) {
+        setEditedContent(event.detail.content)
+      }
+    }
+
+    window.addEventListener('post-updated', handlePostUpdated as EventListener)
+    return () => {
+      window.removeEventListener('post-updated', handlePostUpdated as EventListener)
+    }
+  }, [post.id])
+
   // Check if this post is a tip and parse tip info
-  const tipInfo = useMemo(() => tipService.parseTipContent(post.content), [post.content])
+  const tipInfo = useMemo(() => tipService.parseTipContent(displayContent), [displayContent])
   const isTipPost = !!tipInfo
   const createdAtLabel = useRelativeTime(post.createdAt)
 
@@ -469,6 +493,12 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
     openMentionRecoveryModal(post, username)
   }
 
+  const handleEdit = () => {
+    if (!requireAuth('post')) return
+    // enrichedPost carries the latest displayed content so the modal pre-fills correctly
+    openEditModal(enrichedPost)
+  }
+
   const handleDelete = () => {
     const authedUser = requireAuth('delete')
     if (!authedUser) return
@@ -617,6 +647,13 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
                 </span>
               )}
               <span className="text-gray-500 text-sm">{createdAtLabel}</span>
+              {isEdited && (
+                <Tooltip.Provider>
+                  <ActionTooltip label={post.updatedAt ? `Edited ${post.updatedAt.toLocaleString()}` : 'This post was edited'}>
+                    <span className="text-gray-400 text-sm cursor-help">(edited)</span>
+                  </ActionTooltip>
+                </Tooltip.Provider>
+              )}
               <DropdownMenu.Root>
               <DropdownMenu.Trigger asChild>
                 <IconButton onClick={(e: React.MouseEvent) => e.stopPropagation()}>
@@ -645,6 +682,15 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
                   >
                     View post engagements
                   </DropdownMenu.Item>
+                  {isOwnPost && !isPrivatePost(post) && (
+                    <DropdownMenu.Item
+                      onClick={(e) => { e.stopPropagation(); handleEdit(); }}
+                      className="flex items-center gap-2 px-4 py-2 text-sm hover:bg-gray-100 dark:hover:bg-gray-900 cursor-pointer outline-none"
+                    >
+                      <PencilSquareIcon className="h-4 w-4" />
+                      Edit {post.parentId ? 'reply' : 'post'}
+                    </DropdownMenu.Item>
+                  )}
                   {isOwnPost && (
                     <DropdownMenu.Item
                       onClick={(e) => { e.stopPropagation(); handleDelete(); }}
@@ -704,9 +750,9 @@ export function PostCard({ post, hideAvatar = false, isOwnPost: isOwnPostProp, e
               mentionValidations={mentionValidations}
               onFailedMentionClick={handleFailedMentionClick}
             />
-          ) : post.content ? (
+          ) : displayContent ? (
             <PostContent
-              content={post.content}
+              content={displayContent}
               className="mt-1"
               hashtagValidations={hashtagValidations}
               onFailedHashtagClick={handleFailedHashtagClick}
diff --git a/components/post/reply-thread.tsx b/components/post/reply-thread.tsx
index 6236f846..9004c89a 100644
--- a/components/post/reply-thread.tsx
+++ b/components/post/reply-thread.tsx
@@ -15,6 +15,8 @@ function replyToPostLike(reply: Reply): Post {
     author: reply.author,
     content: reply.content,
     createdAt: reply.createdAt,
+    updatedAt: reply.updatedAt,
+    isEdited: reply.isEdited,
     likes: reply.likes,
     reposts: reply.reposts,
     replies: reply.replies,
diff --git a/components/providers.tsx b/components/providers.tsx
index cbec400d..0df9a1f9 100644
--- a/components/providers.tsx
+++ b/components/providers.tsx
@@ -9,6 +9,7 @@ import { TipModal } from '@/components/post/tip-modal'
 import { HashtagRecoveryModal } from '@/components/post/hashtag-recovery-modal'
 import { MentionRecoveryModal } from '@/components/post/mention-recovery-modal'
 import { DeleteConfirmationModal } from '@/components/post/delete-confirmation-modal'
+import { EditPostModal } from '@/components/post/edit-post-modal'
 import { DashPayContactsModal } from '@/components/contacts/dashpay-contacts-modal'
 import { EncryptionKeyModal } from '@/components/auth/encryption-key-modal'
 
@@ -29,6 +30,7 @@ export function Providers({ children }: { children: React.ReactNode }) {
           <HashtagRecoveryModal />
           <MentionRecoveryModal />
           <DeleteConfirmationModal />
+          <EditPostModal />
           <DashPayContactsModal />
           <EncryptionKeyModal />
         </AuthProvider>
diff --git a/hooks/use-edit-post-modal.ts b/hooks/use-edit-post-modal.ts
new file mode 100644
index 00000000..65583541
--- /dev/null
+++ b/hooks/use-edit-post-modal.ts
@@ -0,0 +1,22 @@
+'use client'
+
+import { create } from 'zustand'
+import { Post } from '@/lib/types'
+
+interface EditPostModalStore {
+  isOpen: boolean
+  post: Post | null
+  open: (post: Post) => void
+  close: () => void
+}
+
+/**
+ * Global store for the edit post modal.
+ * Use this to let users edit the content of their own posts and replies.
+ */
+export const useEditPostModal = create<EditPostModalStore>((set) => ({
+  isOpen: false,
+  post: null,
+  open: (post) => set({ isOpen: true, post }),
+  close: () => set({ isOpen: false, post: null }),
+}))
diff --git a/hooks/use-yappr-post-reference.ts b/hooks/use-yappr-post-reference.ts
index 29c87f50..2a7dc591 100644
--- a/hooks/use-yappr-post-reference.ts
+++ b/hooks/use-yappr-post-reference.ts
@@ -25,6 +25,8 @@ function convertReplyToPost(reply: Reply): Post {
     author: reply.author,
     content: reply.content,
     createdAt: reply.createdAt,
+    updatedAt: reply.updatedAt,
+    isEdited: reply.isEdited,
     likes: reply.likes,
     reposts: reply.reposts,
     replies: reply.replies,
diff --git a/lib/services/post-service.ts b/lib/services/post-service.ts
index 4acc3c87..05e92732 100644
--- a/lib/services/post-service.ts
+++ b/lib/services/post-service.ts
@@ -2,7 +2,7 @@ import { logger } from '@/lib/logger';
 import { BaseDocumentService, QueryOptions, DocumentResult } from './document-service';
 import { Post, PostQueryOptions } from '../../types';
 import type { BlogPost } from '@/lib/types';
-import { identifierToBase58, RequestDeduplicator, identifierStringToDocumentBytes, normalizeBytes, getCurrentUserId as getSessionUserId, createDefaultUser } from './sdk-helpers';
+import { identifierToBase58, RequestDeduplicator, identifierStringToDocumentBytes, normalizeBytes, getCurrentUserId as getSessionUserId, createDefaultUser, documentToPlainObject } from './sdk-helpers';
 import { paginateCount } from './pagination-utils';
 import { fetchBatchPostStats, fetchBatchUserInteractions, fetchPostStats, fetchUserInteractions } from './post-stats-helpers';
 import { enrichPostFull as enrichPostFullHelper, enrichPostsBatch as enrichPostsBatchHelper, resolvePostAuthor as resolvePostAuthorHelper } from './post-enrichment-helpers';
@@ -79,6 +79,8 @@ class PostService extends BaseDocumentService<Post> {
     const id = (doc.$id || doc.id) as string;
     const ownerId = (doc.$ownerId || doc.ownerId) as string;
     const createdAt = (doc.$createdAt || doc.createdAt) as number;
+    const updatedAt = (doc.$updatedAt || doc.updatedAt) as number | undefined;
+    const revision = (doc.$revision || doc.revision) as number | undefined;
 
     // Content and other fields may be in data or at root level
     const content = (data.content || doc.content || '') as string;
@@ -107,6 +109,8 @@ class PostService extends BaseDocumentService<Post> {
       author: createDefaultUser(ownerId),
       content,
       createdAt: new Date(createdAt),
+      updatedAt: updatedAt ? new Date(updatedAt) : undefined,
+      isEdited: typeof revision === 'number' && revision > 1, // Base revision is 1 on Dash Platform
       likes: 0,
       reposts: 0,
       replies: 0,
@@ -268,6 +272,83 @@ class PostService extends BaseDocumentService<Post> {
     return this.create(ownerId, data);
   }
 
+  /**
+   * Update an existing post's content.
+   *
+   * Only the content field changes — language, mediaUrl, quotedPostId and other
+   * stored fields are preserved from the current document, since Dash Platform
+   * document replacement requires the full document payload.
+   *
+   * Encrypted (private) posts cannot be edited: a content-only replacement would
+   * desync the stored ciphertext from the public teaser/placeholder.
+   */
+  async updatePost(postId: string, ownerId: string, content: string): Promise<Post> {
+    const trimmed = content.trim();
+    if (!trimmed) {
+      throw new Error('Post content cannot be empty');
+    }
+    if (trimmed.length > 500) {
+      throw new Error('Post content exceeds 500 character limit');
+    }
+
+    // Fetch the raw document (bypassing the lossy Post transform) so the
+    // replacement payload preserves every stored field and the current revision.
+    const { getEvoSdk } = await import('./evo-sdk-service');
+    const sdk = await getEvoSdk();
+    const response = await sdk.documents.get(this.contractId, this.documentType, postId);
+    if (!response) {
+      throw new Error('Post not found');
+    }
+    const raw = documentToPlainObject(response);
+
+    if (raw.encryptedContent) {
+      throw new Error('Encrypted posts cannot be edited');
+    }
+
+    const data: Record<string, unknown> = {
+      content: trimmed,
+      // language is required by the contract — preserve the stored value
+      language: (raw.language as string) || 'en',
+    };
+    if (raw.mediaUrl != null) data.mediaUrl = raw.mediaUrl;
+    if (raw.sensitive != null) data.sensitive = raw.sensitive;
+    // Abort rather than silently drop a stored quote reference the replacement must preserve
+    for (const field of ['quotedPostId', 'quotedPostOwnerId'] as const) {
+      if (raw[field] == null) continue;
+      const base58 = identifierToBase58(raw[field]);
+      if (!base58) {
+        logger.error(`updatePost: could not convert stored ${field} for post ${postId}`);
+        throw new Error('Post could not be edited: stored quote reference is unreadable');
+      }
+      data[field] = identifierStringToDocumentBytes(base58);
+    }
+
+    const revision = Number(raw.$revision ?? raw.revision);
+    if (!Number.isFinite(revision) || revision < 1) {
+      throw new Error('Post could not be edited: current document revision is unavailable');
+    }
+
+    const { stateTransitionService } = await import('./state-transition-service');
+    const result = await stateTransitionService.updateDocument(
+      this.contractId,
+      this.documentType,
+      postId,
+      ownerId,
+      data,
+      revision
+    );
+
+    if (!result.success || !result.document) {
+      throw new Error(result.error || 'Failed to update post');
+    }
+
+    // Drop any cached copy so subsequent reads see the new content and revision
+    this.clearCache(postId);
+
+    // The update result has no $createdAt — carry it over from the fetched document
+    return this.transformDocument({ $createdAt: raw.$createdAt, ...result.document });
+  }
+
   /**
    * Get timeline posts.
    * Uses the languageTimeline index: [language, $createdAt].
@@ -618,6 +699,8 @@ class PostService extends BaseDocumentService<Post> {
       author: reply.author,
       content: reply.content,
       createdAt: reply.createdAt,
+      updatedAt: reply.updatedAt,
+      isEdited: reply.isEdited,
       likes: reply.likes,
       reposts: reply.reposts,
       replies: reply.replies,
diff --git a/lib/services/reply-service.ts b/lib/services/reply-service.ts
index 7fa78ad8..ff9756f5 100644
--- a/lib/services/reply-service.ts
+++ b/lib/services/reply-service.ts
@@ -3,7 +3,7 @@ import { BaseDocumentService, QueryOptions, DocumentResult } from './document-se
 import { Reply, PostQueryOptions } from '../../types';
 import { dpnsService } from './dpns-service';
 import { unifiedProfileService } from './unified-profile-service';
-import { identifierToBase58, normalizeSDKResponse, RequestDeduplicator, identifierStringToDocumentBytes, normalizeBytes, createDefaultUser } from './sdk-helpers';
+import { identifierToBase58, normalizeSDKResponse, RequestDeduplicator, identifierStringToDocumentBytes, normalizeBytes, createDefaultUser, documentToPlainObject } from './sdk-helpers';
 import type { EncryptionOptions } from './post-service';
 
 export interface ReplyDocument {
@@ -52,6 +52,8 @@ class ReplyService extends BaseDocumentService<Reply> {
     const id = (doc.$id || doc.id) as string;
     const ownerId = (doc.$ownerId || doc.ownerId) as string;
     const createdAt = (doc.$createdAt || doc.createdAt) as number;
+    const updatedAt = (doc.$updatedAt || doc.updatedAt) as number | undefined;
+    const revision = (doc.$revision || doc.revision) as number | undefined;
 
     // Content and other fields may be in data or at root level
     const content = (data.content || doc.content || '') as string;
@@ -79,6 +81,8 @@ class ReplyService extends BaseDocumentService<Reply> {
       author: createDefaultUser(ownerId),
       content,
       createdAt: new Date(createdAt),
+      updatedAt: updatedAt ? new Date(updatedAt) : undefined,
+      isEdited: typeof revision === 'number' && revision > 1, // Base revision is 1 on Dash Platform
       likes: 0,
       reposts: 0,
       replies: 0,
@@ -190,6 +194,80 @@ class ReplyService extends BaseDocumentService<Reply> {
     return this.create(ownerId, data);
   }
 
+  /**
+   * Update an existing reply's content.
+   *
+   * Only the content field changes — parentId, parentOwnerId, mediaUrl and other
+   * stored fields are preserved from the current document, since Dash Platform
+   * document replacement requires the full document payload.
+   *
+   * Encrypted (private) replies cannot be edited: a content-only replacement
+   * would desync the stored ciphertext from the public placeholder.
+   */
+  async updateReply(replyId: string, ownerId: string, content: string): Promise<Reply> {
+    const trimmed = content.trim();
+    if (!trimmed) {
+      throw new Error('Reply content cannot be empty');
+    }
+    if (trimmed.length > 500) {
+      throw new Error('Reply content exceeds 500 character limit');
+    }
+
+    // Fetch the raw document (bypassing the lossy Reply transform) so the
+    // replacement payload preserves every stored field and the current revision.
+    const { getEvoSdk } = await import('./evo-sdk-service');
+    const sdk = await getEvoSdk();
+    const response = await sdk.documents.get(this.contractId, this.documentType, replyId);
+    if (!response) {
+      throw new Error('Reply not found');
+    }
+    const raw = documentToPlainObject(response);
+
+    if (raw.encryptedContent) {
+      throw new Error('Encrypted replies cannot be edited');
+    }
+
+    // parentId and parentOwnerId are required by the contract — preserve them
+    const parentId = identifierToBase58(raw.parentId);
+    const parentOwnerId = identifierToBase58(raw.parentOwnerId);
+    if (!parentId || !parentOwnerId) {
+      throw new Error('Reply document is missing parent references');
+    }
+
+    const data: Record<string, unknown> = {
+      content: trimmed,
+      parentId: identifierStringToDocumentBytes(parentId),
+      parentOwnerId: identifierStringToDocumentBytes(parentOwnerId),
+    };
+    if (raw.mediaUrl != null) data.mediaUrl = raw.mediaUrl;
+    if (raw.sensitive != null) data.sensitive = raw.sensitive;
+
+    const revision = Number(raw.$revision ?? raw.revision);
+    if (!Number.isFinite(revision) || revision < 1) {
+      throw new Error('Reply could not be edited: current document revision is unavailable');
+    }
+
+    const { stateTransitionService } = await import('./state-transition-service');
+    const result = await stateTransitionService.updateDocument(
+      this.contractId,
+      this.documentType,
+      replyId,
+      ownerId,
+      data,
+      revision
+    );
+
+    if (!result.success || !result.document) {
+      throw new Error(result.error || 'Failed to update reply');
+    }
+
+    // Drop any cached copy so subsequent reads see the new content and revision
+    this.clearCache(replyId);
+
+    // The update result has no $createdAt — carry it over from the fetched document
+    return this.transformDocument({ $createdAt: raw.$createdAt, ...result.document });
+  }
+
   /**
    * Get replies to a post or reply.
    * Uses the parentAndTime index: [parentId, $createdAt]
diff --git a/types/post.ts b/types/post.ts
index f190a279..e821435a 100644
--- a/types/post.ts
+++ b/types/post.ts
@@ -32,6 +32,8 @@ export interface Post {
   author: User
   content: string
   createdAt: Date
+  updatedAt?: Date      // When post was last edited ($updatedAt from platform, if stored)
+  isEdited?: boolean    // True if $revision > 1 (base revision is 1 on Dash Platform)
   likes: number
   reposts: number
   replies: number
@@ -72,6 +74,8 @@ export interface Reply {
   author: User
   content: string
   createdAt: Date
+  updatedAt?: Date      // When reply was last edited ($updatedAt from platform, if stored)
+  isEdited?: boolean    // True if $revision > 1 (base revision is 1 on Dash Platform)
   likes: number
   reposts: number
   replies: number