feat(webapp): a "What's new" page anchored at your last visit (BEA-65)

[ssowonny]

TL;DR

• New What's new page per project (/<project-id>/since): everything that changed since you were last here, agent runs still folded into one card each.
• The anchor is a localStorage last-visit marker plus a five-line ?since= filter on the history API. That's the whole feature — the page below the header is HistoryView unchanged.
• The marker is frozen at mount and stamped after entries render, and only this page writes it — so it can't empty itself while you read it, and no other view marks your changes as seen.
• First visit (fresh browser, private mode, storage off) falls back to the last 7 days and says so.
• Known gap: the marker is per browser, not per account — laptop and phone keep separate last-visit times. The server-side per-account marker is the larger follow-up named in the issue's CTO gate.

Closes BEA-65.

What it looks like

Before — History, flat reverse-chron	After — What's new, anchored

Revisit, once the marker has advanced:

Server

?since=<RFC3339> on GET /api/p/<id>/history — one case in the filter switch that already handles path/prefix, and a parse next to ?n= (unparseable → 400 invalid since, same style as invalid n / invalid cursor). Absent, the response is byte-for-byte what it was.

Placement is the whole correctness story, and it is unchanged from the plan:

loadOps → journal.Sort → kinds[] classification   ← still walks ALL ops
                              ↓
                    filter: path / prefix / SINCE  ← new case here
                              ↓
                    sort.Slice(histLess) → cursor skip → n → next_cursor

Filtering after kinds[] keeps add-vs-edit labelling identical to the full feed; filtering before the sort means next_cursor is minted from the filtered list, so paging a since-feed terminates on its own oldest match instead of walking the whole project.

TestHistorySince covers: only-newer, strictly-after (an op at exactly the marker is excluded), composition with prefix= and path=, a very old marker being identical to no marker at all, cursor paging to exhaustion, and the 400.

Client

• since joins VIEW_ROUTES / ViewName — a real route, so deep link, reload, back/forward and SPA fallback all come free.
• lib/lastVisit.ts — the first localStorage in the frontend. Keyed bdrive.lastVisit.<account>.<project> (the one deviation from the spec, called out in the plan: two people on one laptop shouldn't share a last-visit time). Every access is try/caught, so private mode degrades to "always the last 7 days" rather than a white screen.
• SinceView — ~80 lines: reads the baseline from a useState initializer (frozen for the mount), renders the header line, and stamps behind a useRef guard so "Load more" can't restamp. It is the only caller of stampVisit.
• HistoryView gains three optional props (since, emptyText, onLoaded). since is part of qs, which is also the queryKey, so a revisit with a fresh baseline refetches instead of reusing the previous visit's page. With all three absent /history renders exactly as before.
• Nav row "What's new" (clock icon) above History; crumb, active state, styles.

Not done, per the issue's Out column: no unread badge, no subtree scoping, no "mark all as read", no server-side marker.

Architecture changes

architecture/webapp-frontend.md: router's VIEW_ROUTES gains since; components gains SinceView; lib gains lastVisit.ts — the one storage-touching module in a folder documented as pure, so its note says so. No class was removed and no relationship changed. webapp-server.md names no history types and overview.md no new package, so neither changes.

✅ added · ❌ removed (strikethrough) · unmarked = unchanged

flowchart TB
    Browser["<div style='text-align:left'><b>Browser</b><br/>folder listing, file view<br/>per-view routes</div>"]
    router["<div style='text-align:left'><b>router</b><br/><span style='background:#22c55e55;padding:0 4px;border-radius:3px'>✅ +VIEW_ROUTES dashboard history <b>since</b> install settings</span><br/>+LEGACY_VIEWS insights to dashboard<br/>+parseRoute(url, mode) Route<br/>+urlForView / encodePath / decodePath</div>"]
    components["<div style='text-align:left'><b>components</b><br/>FileView FolderListing FileTree<br/>HistoryView HistoryRow DiffView<br/><span style='background:#22c55e55;padding:0 4px;border-radius:3px'>✅ SinceView</span><br/>Insights ShareDialog Palette shell ...</div>"]
    lib["<div style='text-align:left'><b>lib</b><br/>+diff.ts splitLines lcsDiff diffText<br/>+runs.ts groupRuns runFileCount<br/><span style='background:#22c55e55;padding:0 4px;border-radius:3px'>✅ +lastVisit.ts lastVisit stampVisit (localStorage)</span><br/>+heat.ts / sniff.ts / utils.ts</div>"]
    Marker["lastVisit.ts is the one storage-touching<br/>module in an otherwise pure lib/ —<br/>the only localStorage in the frontend.<br/>SinceView is its only writer, so no<br/>other page can move the marker."]
    Browser --> router
    Browser --> components
    components --> lib
    lib -.- Marker
    classDef added fill:#22c55e22,stroke:#22c55e,stroke-width:2px
    classDef noteBox fill:#88888822,stroke:#888888,stroke-dasharray:2 2
    class Marker noteBox

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Verification

• go build ./..., go vet ./..., go test ./... — all pass, including the new TestHistorySince.
• npm run e2e — 109 passed, including the new e2e/since.spec.ts (first-visit 7-day fallback, a change landing then the revisit going empty, other pages not stamping, the baseline holding still while mounted, and the nav row / hard reload).
• npm run build run and internal/webapp/static committed; frontend/check-dist.sh reports fresh.
• UI checked by driving the real hub; the screenshots above are from that pass.

One note on the plan: it proposed two PRs (server, then frontend) and said one was fine — this is the one-PR version, since the e2e spec needs both halves anyway. Nothing else deviates.

Build session

cd $(git worktree list | grep bea-65-ph-idea-what-changed-while-i-was-away | awk '{print $1}') && claude --resume 8610a341-f27a-44d9-9d35-e013e37e909b

(only works on the machine this ran on)

🤖 Generated with Claude Code