[C4 HL-027] Prototype bounded collective composition and session control #37

Outcome

Let multiple participants materially change one score under explicit rules.

Placement and activation

• Circle: C4 — Performance, space, and participation
• System responsibilities: Product / Assurance
• Capability coverage: 01 Core Domain / Proprietary Engine; 02 Product Applications & Interfaces; 04 Data Platform; 05 Identity, Security & Trust; 08 Quality, Testing & Evaluation
• Planning status: Conditional; activate only when the requirement below is met.
• Activation: A selected performance needs more than one live participant.
• Parent epic: [EPIC C4] Performance, space, and participation #7; master roadmap: [MASTER EPIC] Hole-loop: concentric evolution within Persona / Visual Form Canon #2.

Dependencies

• HL-018 #28
• HL-025 #35

Acceptance evidence

• Define host/performer/audience permissions, join/leave, session lifecycle, accepted actions, order/conflict resolution, and moderation of contributed text.
• Demonstrate that participant intervention changes form/topology/score rather than merely generating decorative telemetry.
• Replay the accepted event sequence; test disconnect, duplicate/late events, divergent client state, and host recovery.
• Record consent, contributor attribution, data minimization, export/reset/deletion and retention choices before hosted participation.
• Keep local single-user execution intact and document when a synchronization service becomes a justified independent deployment.

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.