ADR-A71: Platform Licence (MPL-2.0) and SPI Seam

Status: Proposed Date: 2026-09-23 Related: Architecture Review §5.11, G-14 Drafted by: Agent, autonomous session (P0.1.12). Pending human ratification — see phase-0-status.md.

Context

The platform needs a stated open-source/commercial boundary before third-party or commercial adapters are written against any SPI, so the boundary is not discovered by accident during an engagement (a named risk in the review).

Decision

• Platform code is licensed MPL-2.0 (file-level copyleft): a commercial adapter implemented in a new file carries no obligation to open its own source.
• SPI interface modules are the sanctioned extension boundary, documented explicitly as the seam where OSS and commercial implementations meet.

• The OSS/commercial seam is published as an inventory of every extension point:

  ScopedDataset, ChangeFeedSource, ReasonerProvider, ShaclEngine, LlmProvider, IdentityProvider, ArtifactStore, SecretProvider, UsageSink, PackSigner/TrustStore, PartitionedWorkQueue, DocumentExtractor, NotificationSink.

LATTICE does not force a choice of backend for any of these; each SPI ships at least one reference (often in-process) implementation under MPL-2.0.

Consequences

• Every new SPI module introduced by Phase 0 (graph-spi, coordination-spi, partitioned-queue-spi) is added to this inventory as it lands.
• P1.11.2 publishes the SPI inventory table with TCK coverage per SPI and the OSS/commercial boundary document, cross-referencing this ADR.
• File headers across platform/ carry the MPL-2.0 SPDX identifier from this point forward; this is a lint-enforced convention (G9-adjacent), not just documentation.