| name | implementation-extension-plane |
| description | Implement the session-scoped extension plane that discovers, attributes, filters, names, merges, and invalidates commands, skills, output styles, plugins, hooks, MCP providers, and language servers. Use when deciding how extension contributions become reachable without weakening core runtime contracts. |
Implementation Extension Plane
Preserve compositional registries
Extensions contribute descriptors and protocol adapters; they do not acquire implicit authority. Discover contributions with source provenance, validate them at the boundary, normalize their identities, resolve deterministic precedence, apply feature/trust/policy filters, and publish immutable session registries. Invocation must return through the shared command, tool, query, permission, hook, and task contracts.
Use the architecture diagram to inspect discovery and registry composition. Read registry composition for common identity, provenance, collision, policy, cache, reload, and failure rules. Requirement identifiers EXT-* are stable implementation anchors.
Specialized workflows
- Use implementation-commands-input to implement slash-command discovery, user-input routing, references, attachments, local control, and model-bound expansion.
- Use implementation-skills-output to implement skill discovery and invocation plus output-style selection and prompt effects.
- Use implementation-plugins-hooks to implement plugin manifests, marketplaces, installation, dependencies, component loading, and lifecycle hooks.
- Use implementation-mcp-lsp to implement MCP configuration, transports, authentication, elicitation, channels, and plugin language servers.
Composition workflow
