Add 3DGS ArcGIS Cesium ingestion plan

Author: AdaWorldAPI

.claude/plans/3DGS-ArcGIS-Cesium-ingestion-plan.md

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+# 3DGS ArcGIS and Cesium Ingestion Plan — lance-graph
+
+## Goal
+
+Define how `lance-graph` ingests external geospatial sources into the 3DGS runtime model.
+
+This plan focuses on source acquisition and normalization, not rendering.
+
+## Source classes
+
+### 1. 3D Tiles / Cesium-compatible packages
+
+Inputs:
+
+- `tileset.json`
+- subtree files
+- glTF / GLB payloads
+- SPZ / Gaussian splat glTF extensions where available
+- metadata and batch/property tables
+
+Outputs:
+
+- `tiles` table
+- `contents` table
+- `subtrees` table
+- `features` table where metadata exists
+- raw content resource references
+
+### 2. ArcGIS REST services
+
+Inputs:
+
+- FeatureServer metadata and query output
+- MapServer metadata and query output
+- VectorTileServer metadata, styles, and tiles
+- Scene/3D layer references where available
+- service directory JSON / PJSON
+
+Outputs:
+
+- vector overlays
+- semantic features
+- basemap/vector-tile references
+- optional source provenance rows
+
+### 3. glTF / GLB content
+
+Inputs:
+
+- mesh payloads
+- splat-related extensions
+- metadata extensions
+
+Outputs:
+
+- content refs
+- derived bounds
+- feature metadata where available
+- optional conversion to 3DGS blocks if supported
+
+### 4. GeoJSON / MVT overlays
+
+Inputs:
+
+- GeoJSON feature collections
+- Mapbox Vector Tile payloads
+- ArcGIS query output converted to GeoJSON
+
+Outputs:
+
+- `features` table
+- overlay content refs
+- queryable geometry metadata
+
+### 5. Native 3DGS payloads
+
+Inputs:
+
+- splat point records
+- SPZ-like compressed payloads
+- custom columnar splat blocks
+
+Outputs:
+
+- `contents` rows with kind `GaussianSplat3d`
+- `splat_blocks` rows
+- optional raw payload files or Lance column chunks
+
+## Normalization stages
+
+```text
+source fetch/read
+  -> source manifest
+  -> bounds and CRS detection
+  -> content kind classification
+  -> normalized tile/content rows
+  -> optional feature extraction
+  -> optional certificate preflight
+  -> Lance/Arrow write
+```
+
+## Coordinate policy
+
+Every ingest path must record coordinate assumptions:
+
+- CRS / spatial reference if known
+- local origin if converted
+- ECEF / ENU / projected frame where applicable
+- transform applied
+- uncertainty if unknown
+
+Do not silently treat unknown coordinates as WGS84.
+
+## Provenance
+
+Add a provenance row/table or metadata object:
+
+```text
+source_id
+source_kind
+source_uri
+retrieved_at
+source_version
+license_hint
+crs_hint
+conversion_notes
+```
+
+This matters for debugging and for later ArcGIS/Cesium export.
+
+## Ingestion crate layout
+
+```text
+crates/ada-geo-ingest
+  mod.rs
+  source_manifest.rs
+  arcgis.rs
+  cesium_3dtiles.rs
+  gltf.rs
+  geojson.rs
+  mvt.rs
+  native_3dgs.rs
+  provenance.rs
+```
+
+## ArcGIS-first test endpoints
+
+Use public/sample services for tests that do not require credentials:
+
+- sample service directory root
+- FeatureServer query result
+- MapServer layer query result
+- VectorTile metadata if available without secrets
+
+Credentialed services should be integration-test optional and skipped by default.
+
+## Acceptance criteria
+
+- A 3D Tiles tileset can be ingested into tile/content tables without loading all payload bytes.
+- ArcGIS FeatureServer query output can become features/overlay rows.
+- GeoJSON can become features rows.
+- Every ingested source records provenance.
+- Unknown CRS is explicit, not guessed.
+- 3DGS payloads become first-class content rows.