Migrate metrics to the user-day usage report (legacy /copilot/metrics API was sunset 2026-04-02)

[a-magdy]

Warning

The Copilot Metrics API used by main was sunset on 2026-04-02.
Without this PR, every metrics call from services/copilot-metrics-service.ts returns 404 and the dashboard renders no data on a fresh deployment today.
Tracking issue: microsoft/copilot-metrics-dashboard#87 · GitHub changelog: "Closing down notice of legacy Copilot metrics APIs" (2026-01-29).

Closes #87

What this changes

This PR rewires services/copilot-metrics-service.ts to source metrics from the user-day usage report instead of the per-day metrics endpoint, joins the result with seat assignments, and relaxes environment-variable validation so org-only deployments don't have to set GITHUB_ENTERPRISE.

The output type (CopilotUsageOutput[]) consumed by the dashboard UI is unchanged, so no UI work is required.

See #87 for the rationale and docs/metrics-ingestion.md added in this PR for an end-to-end walkthrough.

Data flow summary

GET /copilot/metrics/reports/users-28-day/latest
  -> { download_links: [...] }
  -> for each link, GET <link>
       -> JSON or NDJSON of UsageMetricsUserDayRecord rows

GET /copilot/billing/seats?per_page=100  (paginated)
  -> SeatAssignment[]
  -> derive userLogin -> teams[] map

Join, filter by date / team, aggregate by (day, language, IDE, feature),
output CopilotUsageOutput[].

Why move off the per-day endpoint?

The per-day endpoint (/orgs/{org}/copilot/metrics) returns counters already aggregated by day/IDE/language. It does not expose per-user data, so we couldn't:

• Distinguish licensed-but-inactive users from engaged ones.
• Group by team without one extra API call per team.
• Cleanly separate chat usage from completion usage.

The user-day usage report exposes the underlying per-user, per-day rows. All three become local computations; the cost is the extra download + aggregation that this PR adds.

Why touch env-service.ts?

Today the validator requires all of GITHUB_ORGANIZATION, GITHUB_ENTERPRISE, GITHUB_TOKEN, GITHUB_API_VERSION regardless of GITHUB_API_SCOPE. That contradicts the README and forces org-scope users to set a dummy GITHUB_ENTERPRISE value. This PR makes the requirement scope-aware:

• scope=organization → require GITHUB_ORGANIZATION, ignore GITHUB_ENTERPRISE.
• scope=enterprise → require GITHUB_ENTERPRISE, ignore GITHUB_ORGANIZATION.
• scope defaults to organization if unset.

Why tsconfig.json?

The new aggregation iterates over Set values. TypeScript's default target: "es5" rejects native for ... of over Set (--downlevelIteration would also work but is global noise). Setting target: "es2015" is the simplest fix and matches what every supported Node version runs natively.

Files

File	Change
src/dashboard/services/copilot-metrics-service.ts	Switch live ingestion to the user-day usage report; join with seat data; aggregate by day/team/feature. File header explains the three back-ends.
src/dashboard/services/env-service.ts	Scope-aware env validation, default scope to organization.
src/dashboard/tsconfig.json	target: "es2015".
docs/metrics-ingestion.md	End-to-end documentation of the new flow, field reference, and migration rationale.

Verification

• npm run build — lint + type-check + production build all pass.
• npm run dev — / and /seats render against a live org.

Notes for reviewers

• Each download_link may return either a JSON array or NDJSON; both are handled in parseUsageUserReport.
• All HTTP calls use cache: "no-store" because the dashboard always wants fresh data.
• A user is "engaged" on a day when any activity counter or LOC sum is > 0 (hasUsageActivity).
• Chat-vs-completion classification is feature-name based: chat_* or anything containing agent is chat; everything else is treated as completion.

Context — why now?

The user-day usage report API didn't exist when the dashboard was last updated.

Date	Event
Oct 2024	Per-day Copilot Metrics API (the one main currently uses) goes GA.
Feb 2025	Beta /usage endpoints deprecated.
2025-07-29	Last upstream commit on main (01ef37d).
2025-10-28	Copilot usage metrics dashboard + user-day usage report API enters public preview (changelog). This is the /copilot/metrics/reports/users-28-day/latest endpoint this PR adopts.

So the new endpoint is roughly three months newer than main. The motivation for switching to it (per-user granularity, native team attribution, clean chat-vs-completion split) is described in #87.

[a-magdy]

@microsoft-github-policy-service agree