Epic: Plugin extensibility phase 2 roadmap after governed MVP

[tamirdresher]

Recommendation

PR #1092 is the safe governed MVP and should merge as-is. It delivers declarative plugin manifests, provider contracts, lifecycle commands, state/audit persistence, and allowlisted Graphify artifact generation without opening arbitrary execution.

This epic tracks the next extensibility wave: distribution, more governed built-in providers, and a separately reviewed trusted executable provider runtime.

Phase plan

1. Marketplace distribution — install/search/update declarative plugins from remote sources while preserving the no-execution boundary.
2. Governed provider expansion — add more built-in approved providers such as MemPalace and Index Server using deterministic artifact generation only.
3. Trusted executable provider RFC/runtime — design and implement explicit trust tiers, permission grants, sandboxing, approval gates, provenance, and audit before any plugin-supplied execution is allowed.

Non-goals for #1092

• No arbitrary plugin-supplied code execution.
• No shell/package-manager execution.
• No live MCP startup.
• No network calls from plugin content.
• No dynamic provider assemblies.

Definition of done

• Implement declarative plugin behavior context proof (#1068) #1092 merged green as the foundation.
• Follow-up phase issues exist with clear security gates and acceptance criteria.
• Worf/Picard approval required before any executable-provider work merges.