Add 3DGS domain adapter strategy plan

Author: AdaWorldAPI

.claude/plans/3DGS-domain-adapter-strategy-plan.md

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+# 3DGS Domain Adapter Strategy Plan — lance-graph
+
+## Goal
+
+Define how the wider 3DGS / HHTL / certified-field substrate should support many domains without collapsing into a single domain-spaghetti crate.
+
+The rule:
+
+```text
+core substrate stays domain-neutral
+adapters carry domain semantics
+certificates cross the boundary through stable DTOs
+```
+
+## Core substrate
+
+The core should know only about:
+
+```text
+hierarchical blocks
+block metadata
+kernel summaries
+error certificates
+skip/refine/hydrate actions
+reason codes
+storage references
+query/render budgets
+```
+
+It should not know what a gene, neuron, ultrasound probe, asset, or customer ticket means.
+
+## Adapter shape
+
+Every domain adapter should implement the same conceptual flow:
+
+```text
+source payload
+  -> domain metadata extraction
+  -> block hierarchy
+  -> kernel summary
+  -> certificate request
+  -> query/render/hydrate action
+```
+
+Candidate trait shape:
+
+```rust
+pub trait CertifiedFieldAdapter {
+    type Source;
+    type Block;
+    type Query;
+    type Output;
+
+    fn describe_source(&self, source: &Self::Source) -> SourceDescriptor;
+    fn build_blocks(&self, source: &Self::Source) -> Vec<Self::Block>;
+    fn summarize_block(&self, block: &Self::Block) -> KernelSummary;
+    fn plan(&self, query: &Self::Query, blocks: &[Self::Block]) -> Vec<BlockDecision>;
+    fn execute(&self, decisions: &[BlockDecision]) -> Self::Output;
+}
+```
+
+This should remain plan-level until at least two concrete adapters exist.
+
+## Shared DTOs
+
+Keep common DTOs narrow:
+
+```text
+SourceDescriptor
+BlockDescriptor
+KernelSummary
+ErrorCertificateSummary
+BlockDecision
+DecisionReason
+ExecutionBudget
+ProvenanceRef
+```
+
+Do not put domain-specific fields directly in these DTOs. Use typed extension payloads or adapter-owned tables.
+
+## Adapter candidates
+
+### Datalake adapter
+
+```text
+source: Lance / Parquet / Iceberg dataset
+block: fragment / row group / page
+query: SQL / DataFusion logical plan / vector query
+output: selected fragments / exact scan / approximate aggregate
+```
+
+### Geospatial adapter
+
+```text
+source: 3D Tiles / ArcGIS / Cesium / GeoJSON
+block: tile / content / splat block
+query: camera / spatial predicate / feature query
+output: render schedule / selected features / tile decision report
+```
+
+### RAG memory adapter
+
+```text
+source: document corpus / embedding index
+block: document / section / chunk family
+query: user question / semantic vector / filters
+output: grounded chunks + confidence report
+```
+
+### Observability adapter
+
+```text
+source: logs / traces / metrics / deploy events
+block: service / time window / trace family
+query: incident question / anomaly signature
+output: root-cause candidates + hydrate traces
+```
+
+### Ultrasound adapter
+
+```text
+source: RF / IQ / Doppler / IMU frames
+block: frame / scanline group / splat volume block
+query: pose / atlas / anatomical region / time
+output: fused volume / registration report
+```
+
+### Genetics adapter
+
+```text
+source: FASTA / FASTQ / expression matrix / variant set
+block: sequence window / motif / gene / pathway
+query: motif / variant / pathway / sample state
+output: matched blocks + confidence envelope
+```
+
+### Neuronal adapter
+
+```text
+source: activation traces / connectome / model attention graph
+block: neuron / synapse / microcircuit / region
+query: state / activation / subgraph pattern
+output: state comparison / selected subgraph
+```
+
+## Promotion criteria
+
+A domain adapter should not become implementation work until it has:
+
+```text
+one small public or synthetic fixture
+one concrete query type
+one block hierarchy
+one measurable certificate
+one useful output
+one acceptance test
+```
+
+## Repository placement
+
+Keep Ring-1 adapters close:
+
+```text
+crates/adapter-datalake
+crates/adapter-geospatial
+```
+
+Keep exploratory adapters either in docs or separate experimental crates:
+
+```text
+crates/adapter-ultrasound-experimental
+crates/adapter-genetics-experimental
+crates/adapter-neuronal-experimental
+```
+
+Names are placeholders.
+
+## Certificate discipline
+
+A certificate must affect behavior:
+
+```text
+skip
+refine
+hydrate exact
+fallback
+warn
+reject
+```
+
+If it is only logged and never changes the decision, it is telemetry, not a certificate.
+
+## Acceptance criteria
+
+- Core DTOs remain domain-neutral.
+- Two adapters can share the same decision/report machinery.
+- Domain-specific tables do not pollute common schemas.
+- Certificates are behavior-affecting.
+- Exploratory domains cannot block Ring-1 datalake/geospatial progress.
+
+## Implementation priority
+
+```text
+1. datalake adapter
+2. geospatial adapter
+3. RAG / observability adapter
+4. ultrasound research adapter
+5. genetics / neuronal exploratory adapters
+```