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ADR 0011: Equity Layer Scaffold-First Delivery

Status

Partially Superseded by ADR-0015 (2026-02-18)

Context

Milestone 11 requires an income-overlay equity layer, but full census-tract integration depends on external StatsCan datasets that may not be immediately available during autonomous implementation.

Decision

Deliver an end-to-end scaffold first:

  1. Add a dedicated API route (/api/equity-layer) with province-aware responses.
  2. Return Ontario placeholder GeoJSON with explicit metadata that it is scaffold data.
  3. Integrate map toggle + legend + attribution rendering now.
  4. Keep unsupported provinces explicit with setup instructions in API responses.

Rationale

This keeps the product honest while unblocking UX, API contracts, and testing:

  • Enables immediate validation of map-layer plumbing and UI affordances.
  • Prevents misleading claims by labeling placeholder data clearly.
  • Reduces merge risk when replacing placeholder payloads with real StatsCan data later.

Consequences

Positive

  • Equity overlay feature path is functional and test-covered.
  • Future data replacement is isolated to the API/data layer.
  • Roadmap progress can distinguish scaffold completion from data completion.

Tradeoff

  • Current overlay does not yet represent real socioeconomic conditions.

Follow-Up

  1. Ingest real StatsCan census tract boundaries + income variables.
  2. Replace placeholder GeoJSON payload with processed provincial datasets.
  3. Keep attribution and methodology notes synchronized with final data source/version.

Supersession Notes

  • Ontario real-data integration is now governed by ADR-0015.
  • Scaffold-first behavior remains relevant for provinces not yet onboarded with real tract datasets.