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+# ADR-0010: runtime/content composition over a new umbrella schema
+
+Date: 2026-04-24  
+Status: Proposed
+
+## Context
+
+Recent architecture work across the workspace introduced useful language around phase-relative orchestration, governed execution posture, content-addressed curation, and deployment envelopes.
+
+However, the SourceOS typed-contract layer already contains most of the primitives needed to express that model:
+
+- `WorkloadSpec`
+- `DataSphere`
+- `ExecutionSurface`
+- `ExecutionDecision`
+- `RunRecord`
+- `ContentRef`
+- control-plane tranche wrappers for isolation/release posture where required
+
+Creating a new umbrella schema that re-declares those fields would introduce a rival constitutional surface, increase duplication, and make it harder for downstream repos to know which type family is canonical.
+
+## Decision
+
+For runtime/content/orchestration alignment, this repository will prefer **composition from existing schema families** over creating a new top-level umbrella schema.
+
+The rule is:
+
+1. First express the concern using existing typed contracts and references.
+2. If a true gap remains, add the smallest additive schema necessary.
+3. Any additive schema must reference existing types rather than re-declaring their fields.
+4. Vendor-specific names such as OpenShift, Giant Swarm, Docker, Podman, or Kubernetes should remain realization/adaptation concerns unless a generic contract cannot express the required semantics.
+
+### Composition guidance
+
+- Runnable unit identity and entrypoint → `WorkloadSpec`
+- Execution boundary / trust posture → `DataSphere` and `ExecutionSurface`
+- Allow/deny/ask/defer/rewrite control → `ExecutionDecision`
+- Run/evidence linkage → `RunRecord`
+- Content-addressed input/output references → `ContentRef`
+- Release/isolation control-plane posture → control-plane tranche wrappers where appropriate
+
+## Consequences
+
+### Positive
+
+- Preserves a single canonical contract layer.
+- Keeps downstream repos aligned on existing `schemas.srcos.ai/v2/...` identities.
+- Avoids needless field duplication and version drift.
+- Keeps orchestrator/vendor names out of the stable schema identity unless truly necessary.
+
+### Negative
+
+- Some higher-level concepts may be less immediately convenient to describe in one document.
+- Composition may require better guidance notes or examples for downstream implementers.
+- If a real gap exists, we still need disciplined additive work rather than pretending composition solves everything.
+
+## References
+
+- Issue: #51
+- Workspace placement anchor: SocioProphet/sociosphere#158
+- Workspace codification PR: SocioProphet/sociosphere#159
diff --git a/docs/adr/README.md b/docs/adr/README.md
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+++ b/docs/adr/README.md
@@ -24,3 +24,4 @@ This directory contains Architecture Decision Records for the SourceOS/SociOS ty
 - `ADR-0007-local-first-control-node-and-image-promotion-seam.md`
 - `ADR-0008-local-first-release-and-enrollment-contract-family.md`
 - `0009-truth-surfaces-b11-delta.md`
+- `0010-runtime-content-composition-over-new-umbrella-schema.md`