🤖 This PR was written by Coder Agent on behalf of Danielle Maywood 🤖

PR 3/4 in a stack to unify agent settings pages.

What

Replaces the fixed 30-day date range on the analytics page with a URL search param–driven DateRangePicker, and extracts a shared date utility.

Why

The analytics page previously hardcoded a 30-day lookback with no way to change it. Adding the same DateRangePicker component already used on the Spend page (PR 4) lets users select custom date ranges. Persisting the selection in URL search params (startDate/endDate) means the range survives page refreshes and can be shared via URL.

The date utility extraction addresses a duplication issue: both the analytics and spend pages need to detect exclusive-midnight end dates (the date picker uses midnight of the following day as the exclusive upper bound) and adjust the display by −1 ms. This logic was duplicated inline in both view components. utils/dateRange.ts provides isMidnight and toInclusiveDateRange as a single source of truth.

Changes

AgentAnalyticsPage — parses startDate/endDate from URL search params, validates them, falls back to the default 30-day range. Passes onDateRangeChange that updates the URL params and resets to page 1.

AgentAnalyticsPageView — uses toInclusiveDateRange() from the new utility instead of inline midnight detection. Adds SectionHeader for consistent page headings.

utils/dateRange.ts — isMidnight(date) predicate and toInclusiveDateRange(dateRange, hasExplicitDateRange) helper. formatUsageDateRange will be added in PR 4 when it gains its first consumer.

Layout standardization — ChatModelAdminPanel and MCPServerAdminPanel changed from space-y-3 to space-y-6 to match the vertical rhythm used across the other settings pages. PRInsightsView gains a SectionHeader with AdminBadge for consistency.

Stack

1. CollapsibleSection + shared fixes (feat(site): add CollapsibleSection component and shared utilities #23990)
2. Behavior page CollapsibleSection cards (feat(site): wrap behavior page sections in CollapsibleSection cards #23991)
3. ➡️ This PR — Analytics DateRangePicker
4. Unified Spend page (feat: merge Limits + Usage into unified Spend page #24093)