[C5 HL-036] Maintain developer platform, design primitives, and compatibility evaluations #46

Outcome

Reduce duplication across proven component and repository boundaries.

Placement and activation

• Circle: C5 — Reusable and operated product platform
• System responsibilities: Platform / Assurance
• Capability coverage: 08 Quality, Testing & Evaluation; 09 Developer Platform & Tooling; 11 Documentation & Knowledge
• Planning status: Conditional; activate only when the requirement below is met.
• Activation: Multiple maintained components or real consumers demonstrate duplicated development/release work or compatibility obligations.
• Parent epic: [EPIC C5] Reusable and operated product platform #8; master roadmap: [MASTER EPIC] Hole-loop: concentric evolution within Persona / Visual Form Canon #2.

Dependencies

Required prerequisites:

• Component ownership, consumers, contracts, and compatibility/release requirements from HL-004 #13, plus evidence of duplicated work across the maintained boundaries.
• A reproducible local development and verification path for the selected components.

Conditional dependencies:

• HL-030 #40 applies if sharing an extracted composition engine or typography library; its two-real-consumer proof remains required for a new shared library.
• HL-031 #41 applies if consumers use a public API, SDK, or integration interface.
• HL-035 #45 applies if the maintained components operate services or installations with availability obligations.
• HL-022 #32 supplies AI-specific datasets and evaluations only when AI proposals or inference have been introduced.

Shared local development, CI templates, schema fixtures, and package compatibility checks can ship without a hosted service or SRE stack. Select the evaluation families that correspond to actual introduced behavior.

Acceptance evidence

• Provide reusable libraries, input/accessibility/design primitives, schemas, fixtures/synthetic data, code generators where useful, local development and documented setup.
• Share repository/CI templates and release tooling through existing estate standards where appropriate; define lintable names, metadata/tags, YAML/schema checks and automatic version/dependency updates.
• Run consumer/provider contract, integration, E2E, load/performance, security, accessibility and version compatibility checks for actual cross-repository composition.
• Keep AI golden sets/behavior/prompt/grounding/human evaluations and cost/latency benchmarks separate from ordinary CI mechanics while using release gates.
• Publish developer/API/architecture docs, ADRs, tutorials, operator runbooks, knowledge base and changelog; extract docs/evals only when lifecycle or reuse evidence exists.

Completion and scope

Attach the actual artifact or commit, relevant verification, limitations, and an artist decision where a composition changes. This issue plans authorized work; creation does not claim implementation or deployment. Preserve independent work/source identities and private source boundaries. Repository creation requires the extraction evidence in HL-004 #13 and HL-045 #14.