This document describes the public-data source posture for urban-observatory's v0 work. It is prioritized but open-ended: it names source tiers and reliability considerations, not specific canonical datasets.
For the broader method, see methodology.md. For the v0 scope this source strategy supports, see v0-scope.md.
The project uses only publicly available data — plans, environmental reviews, agendas, permit records, progress reports, capital plans, funding records, policy documents, and other artifacts accessible to any researcher or member of the public. This is a deliberate architectural choice; see methodology.md.
The method's value comes from connecting and interpreting public sources, not from acquiring novel data.
Every claim the method produces should be inspectable to its source. Each source contributing to a finding or signal card is recorded with:
- the source document or dataset
- the retrieval date
- the relevant location within the source
- the confidence in the interpretation derived from it
- any limits or caveats the source carries
Outputs without provenance are not the same artifact class as outputs with provenance; see methodology.md.
This document's source ladder (Tier A / Tier B) is a different axis from the analytical-depth pass (Tier 1 / Tier 2) used in v0 scoping (see v0-scope.md). The source ladder describes what kind of reading a source supports — signal visibility (Tier A) versus dependency interpretation (Tier B). The depth pass describes how far v0 interprets — a shallow citywide baseline (Tier 1) versus deeper interpretation of flagged cases (Tier 2). A Tier-A source can be read at Tier-1 or Tier-2 depth; the two axes are independent.
Tier A is the signal-visibility layer: shallow, source-linked public-record signals across the systems that bear on implementation, not housing records alone. Tier A states what the record shows — signal present / absent / unclear · source found / not found · status changed · dependency flagged · public-record silence · procedural gate visible · public-record wall — and implies no causation.
Tier A is a visibility posture, not a source-collection mandate. It can surface signals across the bearing systems where those signals are shallowly visible in authorized public sources or already-pinned records:
- Housing / planning — Housing Element site inventory, APR, development pipeline, planning applications, DBI building permits, completions, zoning and parcel GIS (the sources pinned and exercised in v0)
- Infrastructure — capital plan and infrastructure-investment references
- Transportation — transportation plans and transit-access layers
- Capital / funding — affordable-housing and public funding / subsidy signals
- Environmental / resilience — environmental-constraint and resilience layers
- Public / institutional — public and institutional records
v0 operates on the housing / planning sources already pinned (see source-inventory.md); the non-housing systems are named here as the Tier-A visibility posture — surfaced where public records make them shallowly visible — not as a present collection requirement. Specific datasets within each system are not named here as v0-canonical; dataset selection is part of the prototype's own work.
Tier B is the interpretation layer, triggered when the project must read how systems interact or whether a dependency materially affects implementation: explanation, causality, delivery-risk claims, intervention priority, cross-system dependency interpretation, and higher-confidence, expert-review-facing, or public-facing claims. Tier B is gated — Tier-A visibility never implies a Tier-B interpretation on its own.
Tier B is a function, not a separate source list. It interprets deeper reads of the same public records (and, where a specific finding, claim, reviewer need, or demo concept requires it, additional sources such as capital / infrastructure references, transportation plans, funding / subsidy records, environmental-constraint layers, construction-cost / interest-rate / vacancy indicators, or policy / program documents). It is not exercised in v0 by default.
Tier C sources are used selectively for Tier-2 deeper interpretation of flagged sites. They are not expected to be exhaustively retrieved in v0's Tier-1 shallow pass.
Tier C categories include:
- Board of Supervisors and Planning Commission agendas and decision records
- CEQA notices and environmental impact reports
- public comments and meeting transcripts
- code enforcement records
- ownership fragmentation analysis
- litigation and appeals data
- utility-capacity documents
- neighborhood-specific and area plans
Tier C predates the Tier-A / Tier-B visibility-versus-interpretation reframe; its placement on the revised ladder is reserved for a separate source-taxonomy review and is left unchanged here.
The source strategy is a posture, not a manifest. New sources may emerge during prototype work, and some named categories may turn out to be less useful than expected. The category-level naming is durable; specific dataset choices remain candidate. Tier A names a visibility posture across systems, not a commitment to collect every system's data: v0 exercises the housing / planning sources, and other systems' signals enter only where public records make them shallowly visible.
No data is fetched as part of this document; retrieval is a separate, later phase.