0.4.0

OAP becomes the runtime source of truth for UI templates, the 5-theme system lands, and the app supports being served behind a gateway prefix.

Five reserved template families now live on OAP’s UI-template REST surface (/ui-management/templates* on the admin port): overview dashboards, per-layer dashboards, alert page setup, theme selection, time-defaults. Bundled JSON ships as the seed + read-only fallback.
One-shot seed on BFF boot pushes any missing bundled template to OAP; runtime sync is read-only with a 30-second single-flight cache.
New admin endpoints: GET /api/admin/templates/sync-status, POST /api/admin/templates/save, POST /api/admin/templates/resync, POST /api/admin/templates/:name/push-bundled.
When the admin port is unreachable, every admin page goes read-only with a red banner; Save / Create / Delete are disabled; render falls back to bundled.
Diverged rows surface a “Show diff & reset” Monaco modal with a destructive-confirm (type the template key to arm reset).

Five bundled themes — Horizon (default), Meridian, Obsidian, Daybreak, Aurora — each shipping a complete token set (bg, fg, accent, info/ok/warn/err, font, radius, density).
New /admin/global-defaults admin page replaces the old “Setup” link. Theme picker uses preview cards lifted from the design (hero strip, mini-app mockup with Primary/Tonal/Ghost buttons, KPI tiles, sparkline, density/font/radius badges).
Per-user theme override via a labelled topbar chip — three-tier resolution localStorage user → OAP org default → bundled, written to <html data-theme> / <html data-appearance> synchronously on boot so the pre-auth login page already respects the local override.
Sidebar SkyWalking logo swaps to the official brand blue (#1368B3) on light-appearance themes.
Widget series colors (Zipkin trace palette, AlarmSnapshotChart, AlarmsTimeline) track the active theme’s --sw-accent via a shared readAccent() util.
Sign-in button gradient derives both stops from the theme accent.

/admin/global-defaults also owns the global picker’s default window (60 minutes shipped). OAP step precision is derived from window size — ≤ 4 h MINUTE, 6 h–14 d HOUR, ≥ 30 d DAY — and surfaced inline on the page.
Per-user override in the topbar time picker: “Save as my default” / “Reset to org default”.

Topology cluster boundary now grows to encompass dragged nodes; the chip moved inside the cluster header so it stays visible at any drag position.
Alarms page gains an Other KPI tile that surfaces the residual count between Active and the sum of pinned-layer chips — Active = General + Mesh + Other reconciles even when alarms land in unmapped layers.
Overview “Active alarms” widget now reads the admin’s configured defaultWindowMs from /admin/alert-page-setup; all three alarm surfaces (overview widget, alarms page, topbar badge) share one window.
Every backend call failure (network throw or non-2xx) writes a pushEvent('api', 'err', …) into the debug event log with the BFF’s code / message envelope inlined when present.
Dashboards with more than 40 widgets (e.g. the General/instance page, 56 widgets) now succeed: the UI splits oversize requests into ≤40-widget chunks fired in parallel, then merges results.

Gateway-prefix support: BffClient.request() prepends import.meta.env.BASE_URL to every API path. Build with vite build --base=/horizon/ and a gateway that strips the prefix and the SPA + every API call resolves cleanly under the sub-path.
Cluster Status route corrected from /admin/cluster → /operate/cluster (the prior default 404’d because no route by that name existed).

Documentation rewritten as an orientation map; the left-side menu is the canonical navigation now. All SWIP-* references removed from user-visible text and docs.
“Coming in Phase 6 / 7” placeholder strip on Cluster Status removed.
Dead code dropped — LandingView.vue, LayerTabPlaceholder.vue, the orphaned disk-write template routes (POST /api/admin/overview-templates/:id + POST /api/admin/layer-templates/:key), and stale Phase X markers across BFF + UI + docs.
The OAP UTC-offset chip is gone from the topbar; the health dot stays.