Certify GeoArrow producer conformance and portability #802

Parent

Native close-gate slice of #797, dependent on #799-#801.

Objective

Certify GraphForge as a standards-based GeoArrow producer and query engine without making any particular visualization consumer part of GraphForge's implementation or close gate.

Scope

• Publish producer-neutral golden fixtures for every initial geometry, certified CRS/edge profile, preserved-only metadata case, null/offset/nesting boundary, IPC, and Parquet.
• Validate those fixtures with independent standards-aware readers where practical.
• Freeze compatibility, schema/metadata, fingerprint, resource-limit, and unsupported-operation expectations.
• Reconcile ontology/value, Arrow, storage/project, query, Python, Node, CLI/export, and compatibility documentation.
• Correct stale point()/distance() claims unless direct executable Rust evidence exists.
• Document the consumer boundary: downstream projects consume the public fixtures and own their own integration/rendering tests.

Acceptance Criteria

• Golden fixtures cover every initial geometry, certified CRS/edge profile, preserved-only metadata case, nulls, offsets, IPC, and Parquet.
• Independent parsing proves the fixtures are standards-conformant and do not require field renaming or WKB/WKT/GeoJSON reconstruction.
• GraphForge documentation describes producer/query semantics, compatibility, limits, and errors without renderer instructions.
• XYG and other consumers can reference the published fixtures, but their execution is not required to merge or close GraphForge work.
• Stale spatial completeness claims are corrected unless backed by direct executable evidence.
• No visualization, map, scene, tile, or XYG dependency is introduced.
• Relevant exact-head CI Gate is green.

BDD Completion Scenario

Scenario: Any compliant consumer can read the fixture

Given a GraphForge-produced canonical GeoArrow fixture
When an independent standards-aware consumer reads it
Then geometry type, CRS/edge metadata, buffers, offsets, nulls, and values agree
And no GraphForge- or XYG-specific reconstruction is required.

Documentation

GraphForge owns the producer contract and fixture catalog. Consumer-specific projection, rendering, interaction, and integration documentation belongs in the consumer repository.

Non-Goals

Executing XYG in GraphForge CI, renderer certification, map screenshots, viewport/LOD tests, or consumer release gates.

Related Issues

• XYG consumes these fixtures under Build scalable geospatial projections, layers, interaction, and temporal-spatial analysis xyg#39.
• GraphForge visualization completeness across every XYG host (epic) xyg#31 tracks visualization completeness independently.

Completion

Blocks #797; the parent remains the close gate.