A microblog timeline is a receipt-bound sequence of stable post placements, not an array of rendered cards. The browser must preserve post, conversation, viewer-action, policy, and reading identity while pages, counters, labels, and live inventory change independently.
A short post looks simple until it becomes part of a timeline. The same record may appear because its author was followed, because another account reposted it, because it belongs to a thread, or because an algorithm recommended it. A reply needs conversation context. A quote post contains new speech and a reference to older speech. An edit, deletion, block, moderation label, or changed handle may alter what the viewer is allowed to see without changing every other timeline entry.
The frontend therefore needs several small, explicit contracts. The server owns eligible inventory and authoritative order. Content records have stable IDs and revisions. Placements explain why a record appears. Viewer actions reconcile through operation IDs. The browser owns the current reading anchor, local draft state, focus, and bounded media work.
Clarify the timeline contract
Ask whether the product offers a following timeline, a ranked home timeline, custom feeds, lists, or all of them. Define whether replies are included, collapsed, or shown only when accounts in the conversation are followed. Clarify repost, quote, pin, edit, delete, block, mute, sensitive-content, and regional-policy behavior.
Determine the consistency promise. Does refresh produce a new snapshot? Can the user return from a detail route to the exact post and offset? Are handles mutable while account IDs remain stable? Can a post be edited, and does its public record ID remain constant? Define live arrival, offline draft, optimistic publish, media upload, and accessibility expectations before drawing components.
The useful promise is narrow: accepted pages belong to one timeline receipt, visible cards keep stable identity, and newer inventory never steals the reader's position.
The public interview prompt
Design a browser-based microblog timeline. It supports following and ranked feeds, text and media posts, replies, reposts, quote posts, reactions, bookmarks, deletes, moderation labels, live arrivals, and continuous loading. Users can compose while offline or on an unreliable network.
Explain:
- stable account, record, placement, session, and operation identity;
- timeline snapshots, opaque cursors, deduplication, and refresh;
- reply roots, parents, reposts, quotes, and deleted records;
- normalized projections and revision-aware hydration;
- optimistic publishing, reactions, retries, and draft recovery;
- live inventory, counter events, moderation changes, and scroll anchoring;
- media upload, rendering, prefetch, and playback budgets;
- accessible feed semantics, focus, routing, and restoration;
- caching, security, telemetry, testing, and rollout.
What the premium solution covers
The full solution builds the timeline from identity and receipts upward. It models conversations without recursive card state, separates a repost action from quoted speech, and traces a first page through skeleton selection, hydration, policy labeling, merge, and presentation. It includes a frame-checked animation, three high-resolution decision diagrams, and a deterministic six-input timeline-pressure lab.