Threaded discussion

Problem Context

• Users are discussing one topic, question, announcement, channel message, support issue, forum post, design proposal, or community thread.
• Replies may be top-level, nested under another reply, marked as an answer, collapsed, hidden, moderated, unread, followed, muted, paginated, or broadcast back to a main channel.
• The same activity may also appear in feeds or notifications, but the discussion surface owns the parent topic, branch context, reply relationships, and participation state.
• The conversation may continue over hours or days and users may return through unread lists, direct reply links, search, or notification center.

Selection Rules

• Choose threaded discussion when the core unit is a topic or parent message with replies that need branch context and participation state.
• Use comments when feedback is anchored to a specific object, selection, file line, record, or task rather than a navigable topic conversation.
• Use feed when users primarily browse a stream of many independent posts, not one open discussion with reply hierarchy.
• Use notification center when users need cross-object unread triage, retention, and preference controls rather than the thread's full reply context.
• Use activity log when entries are system facts or audit events, not authored replies that can branch, react, or be marked as answers.
• Use review queue when many threads need moderation, assignment, bulk triage, or SLA processing.
• Avoid deep visual indentation beyond a readable mobile depth; switch to branch cards, quoted parent snippets, or collapse controls.
• Keep answer, resolved, unread, followed, muted, and hidden states attached to the exact branch or reply they describe.

Required States

• Parent topic or parent message with author, timestamp, title or body, category, and reply count.
• Top-level reply, nested reply, quoted parent snippet, and collapsed branch states.
• Unread reply, last-read marker, followed, muted, mentioned, and notification-deep-linked reply states.
• Reply composer, draft reply, saving reply, failed reply, retry, and recovered draft states.
• Accepted answer, unmarked answer, resolved branch, reopened branch, hidden or moderated reply, and deleted reply states.
• Load newer, load older, has more replies, empty branch, access-limited branch, and outdated or moved parent states.
• Mobile stacked state where parent context and reply target remain visible without excessive indentation.
• Direct-linked reply state that scrolls and focuses the target while keeping parent topic context visible.

Interaction Contract

• Starting a reply records the exact parent topic or parent reply being answered and shows that target while composing.
• Submitting a reply appends it to the correct branch, updates reply count, unread state, subscribed state, and any notification or broadcast behavior.
• Following or muting a thread changes notifications for that thread without changing channel, feed, or global notification preferences by accident.
• Marking an answer or resolving a branch updates the thread summary and keeps the marked reply findable when the branch is collapsed or paginated.
• Direct links, unread lists, and notifications open the exact reply or branch, highlight it, and preserve parent context.
• Loading more replies preserves the user's position and announces the new reply boundary rather than shifting focus unexpectedly.
• Moderation actions such as hide, delete, lock, or report remain scoped to the selected reply or branch and leave appropriate reason or history evidence.

Implementation Checklist

• Model parent discussion, reply id, parent reply id, branch path, author, timestamp, body, answer state, unread state, subscription state, moderation state, and pagination cursor separately.
• Design parent context, reply cards, nested branch affordance, composer target, branch collapse, load controls, and last-read marker before adding reactions or badges.
• Provide follow, mute, mark read, reply, quote, mark answer, copy link, collapse, load more, report, hide, delete, and lock behavior only where product rules support them.
• Preserve drafts, scroll position, focused branch, and reply target across reload, route return, failed save, offline retry, and permission changes.
• Keep mobile layouts readable by limiting visual indentation and using quoted parent context or branch headers for deep replies.
• Test direct links, unread return, answer marking, collapsed branches, pagination, hidden replies, deleted parent replies, permission-limited threads, and long nested conversations.

Common Generated-UI Mistakes

• Flattening every reply into a chronological stream and losing who replied to whom.
• Using a threaded discussion for simple object comments where the anchor matters more than topic navigation.
• Letting nested indentation consume the viewport on mobile.
• Showing unread count for the whole thread without identifying which branch changed.
• Hiding accepted answers, resolved replies, or moderation state inside collapsed branches.
• Broadcasting every thread reply back to a main channel and recreating the noise threading was meant to reduce.
• Using feed ranking inside a thread so reply order and branch context become unpredictable.
• Treating a thread as an audit log and allowing edited or deleted replies to erase decision evidence.

Critique Questions

• What parent topic or message owns this thread?
• Can users tell which reply each nested reply is answering?
• What happens when a notification points to a reply that is collapsed, hidden, paginated, or deleted?
• How do follow, mute, mention, unread, and last-read states interact?
• Can answer, resolved, hidden, or deleted state be found from the thread summary?
• Does the mobile layout preserve branch context without deep indentation?