fix(export): /export/events date range truncated to calendar date, not exact timestamp

[kristohear]

Summary

/export/events's start/end query params are silently truncated to calendar
date before being compared, so passing an exact timestamp (e.g. midnight) does
not actually bound the query to that moment — it includes the entire
calendar day instead. Additionally, a date filter is only applied at all when
both start and end are present; passing just one silently disables
date filtering entirely.

Repro

GET /export/events?projectId=<id>&event=<name>&start=2026-09-02T00:00:00Z&end=2026-09-03T00:00:00Z

Expectation: only events created on 2026-09-02 (up to, but not including,
midnight of 2026-09-03).

Actual: events created any time on 2026-09-03 are also returned — e.g. an
event created at 2026-09-03T17:56:03Z came back despite end being set to
2026-09-03T00:00:00Z.

Root cause

packages/db/src/services/event.service.ts, in both getEventList and
getEventsCount:

if (startDate && endDate) {
  sb.where.created_at = `toDate(created_at) BETWEEN toDate('${formatClickhouseDate(startDate)}') AND toDate('${formatClickhouseDate(endDate)}')`;
}

toDate() truncates a ClickHouse DateTime down to just its calendar date,
dropping hour/minute/second — on both sides of the comparison. So
end=2026-09-03T00:00:00Z becomes the literal date 2026-09-03, and
BETWEEN ... AND toDate('2026-09-03') matches the entire day, not "up to
midnight."

This also means a date filter is skipped entirely unless both startDate and
endDate are truthy (see the if (startDate && endDate) guard) — passing
only one silently falls through to whatever cursor-based default window
applies instead, with no indication to the caller that their date bound was
ignored.

Notably, packages/db/src/services/chart.service.ts already does this
correctly for /export/charts:

if (startDate) {
  sb.where.startDate = `created_at >= toDateTime('${formatClickhouseDate(startDate)}')`;
}
if (endDate) {
  sb.where.endDate = `created_at <= toDateTime('${formatClickhouseDate(endDate)}')`;
}

— full DateTime precision, and each bound applied independently. This PR
brings event.service.ts in line with that existing, correct pattern.

Fix

Replace the toDate(...) BETWEEN toDate(...) AND toDate(...) pattern with
independent toDateTime() comparisons in both getEventList and
getEventsCount, matching chart.service.ts:

if (startDate) {
  sb.where.startDate = `created_at >= toDateTime('${formatClickhouseDate(startDate)}')`;
}
if (endDate) {
  sb.where.endDate = `created_at <= toDateTime('${formatClickhouseDate(endDate)}')`;
}

Impact

• Exact timestamp filtering now works as documented — end actually means
  "up to this moment," not "up to the end of this calendar day."
• start and end can be used independently; you no longer need both to get
  any date filtering at all.
• No change to callers that already pass both params expecting whole-day
  semantics — a start/end pair spanning full calendar days (e.g.
  00:00:00 to 23:59:59 the same day) behaves identically to before.

Test plan

• Query with start/end spanning part of a single day; confirm events
  outside that exact window are excluded.
• Query with only start (no end); confirm it now filters rather than
  being silently ignored.
• Query with only end (no start); same.
• Existing whole-day-range queries return the same results as before.

Summary by CodeRabbit

• Bug Fixes
  • Event lists and event counts now correctly support filtering with only a start date or only an end date.
  • Date filters are applied inclusively and independently when provided.
  • Empty-result handling now behaves correctly when no cursor or date filters are specified.
  • These updates provide more accurate event searches across a wider range of date-filtering scenarios.
  • Searches using partial date ranges now return results consistently.

[CLAassistant]

All committers have signed the CLA.

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• packages/db/src/services/event.service.ts

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• packages/db/src/services/event.service.ts

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---

📝 Walkthrough

Walkthrough

Event list and count queries now apply independent inclusive startDate and endDate filters. Event list lookback behavior now requires no cursor or date boundary before applying the default time window.

Changes

Event date filtering

Layer / File(s)	Summary
Event query date filters packages/db/src/services/event.service.ts	getEventList and getEventsCount apply independent startDate and endDate filters to created_at. getEventList updates its empty-result lookback condition. Documentation comments describe both query behaviors.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 5293a

Event exports now honor independent start and end timestamps without truncating end-time boundaries, while preserving default cursor-window behavior when no date bounds are provided. No current merge-blocking risk is identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the primary change: preserving exact timestamp boundaries instead of truncating dates to calendar dates for /export/events filtering.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 3

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Inline comments:
In `@packages/db/src/services/event.service.ts`:
- Around line 669-672: Update the event date-filter construction around the
startDate and endDate predicates to use the shared query-builder and
query-functions helpers for ClickHouse date comparisons, replacing the raw
toDateTime fragments while preserving the existing inclusive boundaries and
formatted dates. Apply the same change to both the listing and counting paths.
- Around line 669-672: Update the startDate and endDate predicates in the event
service to preserve millisecond precision by formatting dates with milliseconds
and using toDateTime64(..., 3) for both created_at comparisons. Reuse the
existing formatClickhouseDate helper or adjust it as needed without truncating
sub-second values.
- Line 530: Update the condition in the event-list query flow to test cursor
against undefined explicitly rather than using truthiness, so cursor value 0 is
treated as present and does not trigger the default cursorWindow; preserve the
existing startDate and endDate checks.

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