Chart syncs per day over the last 30 days

[DimitriKwihangana]

Closes #5.

What changes for the user

A new Trend page at /trend answers whether device activity is rising or falling. It shows the last 30 days: a bar per day for the number of syncs, a line for the resources those syncs carried (submissions, org units and entities added together), and three numbers above the chart — total syncs, total resources, and the change against the previous 30 days.

Days with no sync are drawn as zero rather than skipped, which is the point of the ticket: a line that jumps a silent day hides exactly the event the page exists to show.

The tooltip writes the day out in full, with how long ago it was: 4 September 2026 (14 days ago).

How it works

• listDailyActivity builds the 30 days with Postgres generate_series and left-joins the syncs onto it, so a silent day arrives as a real row of zeros. Enforcing that in SQL is what makes it testable in one place.
• getActivityTotals returns the current and previous window in one pass, split with count(...) filter (where ...).
• now is set by the tRPC procedure and never sent by the client, so the window cannot be moved from the browser and a test can still choose its own date. Days are bucketed in UTC.
• Every count and sum carries an ::int cast: Postgres returns bigint, which the pg driver hands back as a string.
• The chart is Mantine's CompositeChart. Its stylesheet was missing from the root route — that is what lays out the chart tooltip and legend — so @mantine/charts/styles.css is now loaded next to the core one.

The dual axis, on purpose

The two series are about fifteen times apart, so the chart uses two y-axes. This goes against the usual advice: where the line sits against the bars is set by how the two scales are picked, not by the data, so the crossing point means nothing. Two stacked plots and a single shared axis were both mocked up and looked at; the single axis flattens the syncs series against the floor and cannot answer the ticket's question, and density won over the stacked plots because this page is read at a glance. There is a comment saying so in ActivityChart.tsx.

An ADR was drafted for this decision and deliberately left out at the author's request.

Tests

61 pass. Query tests on in-process Postgres cover the zero-filled days, the three counters, and both window boundaries. ActivitySummary and formatDay have their own tests — formatDay counts whole UTC days rather than elapsed hours, so a day does not become "yesterday" partway through the afternoon.

ActivityChart has no test: jsdom computes no layout, so a chart draws nothing there.

Worth a reviewer's eye

• Today's bar is a partial day. The window includes today by choice, so the last bar is always low until the day is over. On the current seed it reads as zero.
• A missing stylesheet is invisible to CI. Nothing in pnpm test or pnpm build could have caught the bug above — only looking at the page did. Fits issue Add an end-to-end smoke test #9.
• relativeDays in SyncTable overlaps formatDay. Four duplicated lines, left alone so this branch does not edit another feature's file.

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Project	Deployment	Actions	Updated
wee-app	Ready	Preview	Sep 18, 2026 10:00am UTC