Billing aggregate tiles lack tooltips and use an inconsistent "credits" definition vs. the per-user column

[muminkoykiran]

Describe the bug

Two related problems on the Billing (per-user credits) view:

1. No tooltips / no source explanation. The three aggregate tiles — "Total credits", "Gross cost (USD)", "Net cost (USD)" — carry only a plain caption with no explanation of source, gross-vs-net meaning, or time window. This is inconsistent with the My Usage page, which documents the exact same concepts carefully with mdi-information-outline tooltips and a tab-level info alert.

2. "Credits" is computed two different ways on the same screen. The "Total credits" tile sums grossQuantity, whereas the per-user "Credits" column sums netQuantity + discountQuantity. On discounted plans these two definitions diverge, so the tile total and the sum of the per-user column disagree, with nothing in the UI explaining why.

Environment

• copilot-metrics-viewer v3.11.3
• Enterprise scope, per-user billing (CSV export ingested), admin-gated Billing tab
• Reproducible on plans with per-credit discounts (gross ≠ net)

Steps to reproduce

1. Open the Billing tab as an admin on an enterprise with discounted credit pricing.
2. Note the "Total credits" tile value.
3. Load per-user rows and sum the "Credits" column.
4. Observe the two totals do not reconcile; hover the tiles and note there is no tooltip explaining the difference.

Expected behavior

• Each aggregate tile explains its source, gross/net meaning, and time window (mirroring My Usage).
• "Credits" means the same thing in the tile and in the per-user column, or the two are relabeled so the difference is explicit.

Actual behavior

• Tiles have no tooltips or explanatory text.
• The tile "credits" (gross quantity) and the per-user "credits" (net + discount quantity) silently disagree on discounted plans.

Root cause (code references)

• app/components/BillingCreditsViewer.vue:114-135 — the three tiles are plain v-card captions with no tooltip.
• app/components/BillingCreditsViewer.vue:511-512 — "Total credits" tile is SUM(grossQuantity):

const totalGrossQty = computed(() =>
  items.value.reduce((s, i) => s + (i.grossQuantity || 0), 0)
);

• app/components/BillingCreditsViewer.vue:455-456 — per-user "Credits" column is netQuantity + discountQuantity:

prev.credits += Number.isFinite(it.netQuantity) ? it.netQuantity : 0;
prev.credits += Number.isFinite(it.discountQuantity) ? it.discountQuantity : 0;

• app/components/MyUsageViewer.vue:73-88 (tab-level "two sources" info alert) and :131-141 (per-tile mdi-information-outline tooltip) — the well-documented pattern this view should mirror.

Suggested fix

• Add info tooltips to the three billing tiles describing source (Billing API / CSV export), gross-vs-net, and the applicable time window, mirroring MyUsageViewer.vue.
• Reconcile the two "credits" definitions, or relabel them explicitly (e.g. "Gross credits" on the tile vs. "Net credits" on the per-user column) so tile and table no longer appear contradictory on discounted plans.

[karpikpl]

thanks for reporting - #415 may address this already

[muminkoykiran]

Thanks @karpikpl! #415's per-section Source · Range labels do address the first half here (the missing source/window context — nice improvement).

The second half still stands on main though: the "Total credits" tile is SUM(grossQuantity) (app/components/BillingCreditsViewer.vue:616-617) while the per-user "Credits" column is netQuantity + discountQuantity (:560-561), so on discounted plans the tile total and the sum of that column still don't reconcile — with nothing marking them as different metrics. Could these be reconciled (or relabeled, e.g. "Gross credits" vs "Net credits")? Happy to keep this issue scoped to just that discrepancy.