feat(showcase): load older messages + per-message permalinks - #764
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The public room told visitors older messages existed and gave them no way to reach them -- `hasMore` was tracked in state and rendered as a dead note. And there was no way to point someone at a specific exchange, which is the whole job of a read-only showcase link. Load older: the button uses the `before` cursor the showcase API already accepted. No backend change was needed. Permalinks: every message is an anchor with a hover control that copies ?m=<id>. On load, if the target is not in the current window the page walks backwards until it finds it, bounded by MAX_AUTO_PAGES so a stale link cannot page an entire room into memory, then centres it and flashes a highlight. The initial auto-scroll-to-bottom is suppressed when a target is present, or it would yank the visitor away from the message they were sent to. One trap worth naming: the 12s poll replaced the whole message list, so naively adding pagination would have made loaded history vanish on the next tick. Both paths now merge by id and re-sort. Only the initial fetch and loadOlder may write hasMore -- letting a poll write it would resurrect the button after the visitor reached the beginning. Verified in a real browser against the live room through a local proxy: 49 -> 98 messages on click with the newest retained, and ?m=50855 paged back two pages, found the target and scrolled it into view at 390px width. 310/310 frontend tests pass, including two new regression tests. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01RWkf1SuYRHosxnPqsXwaVa
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"Load older messages" worked on the anonymous showcase route but did nothing in a pod you had actually joined. Not a broken feature — it was never built there. PR #764 added paging to the showcase reader only; the authenticated path fired exactly one `?limit=50` request, kept no cursor, and exposed no way to ask for anything older, so any conversation past 50 messages was simply unreachable. The backend already supported it: messageController accepts `before`, and both readers bottom out in the same PGMessage.findByPodId. The entire gap was client-side. - useV2PodDetail gains hasMore / loadingOlder / loadOlder. End-of-history is inferred from a short page, since this endpoint returns a bare array with no envelope and changing that shape would break every existing consumer. - Pages are merged by id rather than concatenated: the socket can deliver a message while the request is in flight, and a plain concat would duplicate it. - V2PodChat renders the pager at the top of the scroll container, styled to match the showcase pill so the two reading surfaces agree. Two scroll defects had to be fixed or the feature would have looked broken: - the auto-scroll effect keyed on `messages.length`, so prepending a page threw the reader from the older message they had just asked for straight back to the bottom. It now keys on the newest message's id, so prepends are ignored. - a prepend changes scrollHeight and jumps the viewport, so the reader's position is held by restoring distance-from-bottom, which is invariant under a prepend. 6 hook tests: cursor correctness, prepend order, dedupe against an overlapping socket message, no-op on an empty pod, and hasMore surviving a failed request so the button stays retryable. Frontend suite 69/69, 316 tests. Lint at baseline. Needs a real-browser check after deploy — jsdom has no layout engine, so the scroll-anchor behaviour specifically is not covered by these tests. Claude-Session: https://claude.ai/code/session_01DMeWzgFxsfBcjoLVLewEES Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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Why
Two gaps in the public read-only room, both of which matter because that room is how we show the product to people who can't log in:
hasMorewas already tracked in state and rendered as a dead note telling visitors older messages existed — with no control to load them.What
Load older messages — a real button, using the
beforecursor the showcase API already accepted. No backend change was needed;GET /api/showcase/:podId/messages?before=&limit=was already implemented and clamped.Per-message permalinks — every message is an anchor (
#msg-<id>) with a hover control that copies?m=<id>. On load, if the target isn't in the current window, the page walks backwards until it finds it — bounded byMAX_AUTO_PAGESso a stale link can't page an entire room into memory — then centres it and flashes a highlight. The initial auto-scroll-to-bottom is suppressed when a target is present, or it would yank the visitor away from the message they were sent to.The trap this had to avoid
The 12-second poll replaced the whole message list. Naively adding pagination would have made loaded history silently vanish on the next tick.
Both paths now merge by id and re-sort chronologically. And only the initial fetch and
loadOldermay writehasMore— letting a poll write it would resurrect the button after a visitor had already reached the beginning of the room, because the flag describes the newest page's tail rather than how far back we've actually paged.Verification
Real browser against the live showcase room (via a local CORS proxy, since jsdom can't verify scroll or paging):
msg-51152→msg-50855, newestmsg-51293still present?m=50855auto-paged back two pages, found the target, scrolled it into the viewportTwo new regression tests cover the
beforecursor + prepend + merge-survives-poll path, and the permalink page-back-and-highlight path. Typecheck errors and lint warnings present are pre-existing onmainand touch none of these files.Note
zh-CN strings are included and follow the existing glossary, but 🇨🇳 a native pass is the merge gate, same as #763.
🤖 Generated with Claude Code
https://claude.ai/code/session_01RWkf1SuYRHosxnPqsXwaVa