Oleg Isonen
98d5c607ee
## Summary This combines the three reported MCP improvements into one release-ready change: - Safer mutation planning and confirmation for destructive operations. - Much smaller MCP handshake and default discovery responses. - Better agent workflows for checkpoints, multi-project work, and page duplication. ## Safer destructive operations - Exposes `dryRun` in MCP schemas for every local-capable mutation. - Returns planned transactions through `meta.session.transaction`. - Requires a two-step confirmation flow for destructive semantic operations. - Returns a short-lived token bound to the project, build version, input, and exact generated patch plan. - Rejects expired tokens, altered inputs, changed versions, and changed plans. - Sets `destructiveHint: true` only for operations that actually require confirmation. - Explicitly protects destructive operations whose names do not begin with delete or replace, including replacing all redirects and clearing all styles from a style source. ## Smaller, focused MCP context - Defers oversized tool input schemas from the initial MCP handshake. - Keeps complete focused schemas available through `meta.get_more_tools` and CLI schema inspection. - Makes template registry lists compact while preserving complete payloads through focused get calls. - Makes component summaries compact by default and supports paginated component details. - Replaces placeholder operation descriptions with useful command descriptions. - Constrains previously untyped JSON schema fields so clients can validate inputs earlier. - Keeps runtime output schemas compatible with strict MCP clients. ## Better agent workflows - Allows read-only discovery and inspection while a workflow checkpoint is awaiting acknowledgement. - Continues blocking mutations until the checkpoint is acknowledged. - Checks persisted checkpoints before every workflow call rather than only the first call. - Adds `--project` support so saved projects can be selected without relinking the current directory. - Isolates project sessions and checkpoints by selected project. - Adds atomic `duplicate-page` substitutions for copied fixed text and copied variable values. - Prevents substitutions from modifying source content or global root state. - Rejects ambiguous or missing copied variables without leaving a partial duplicate. ## Realistic agent verification Minimal-context tests used a weak agent against the local packaged CLI and stdio MCP: - Planned a page deletion, stopped for explicit user confirmation, committed the unchanged plan, and verified the page was absent. - Tried to reuse a confirmation token with altered input; Webstudio returned `DESTRUCTIVE_CONFIRMATION_INVALID` and preserved both pages. - Verified compact handshake schemas and focused retrieval of the complete oversized schema. - Verified compact template and component discovery responses. - Selected a saved project explicitly without relying on the directory link. - Verified checkpointed workflows permit reads but block mutations. - Duplicated a London page into a Paris page with atomic text and variable substitutions. - Verified source content remained London, copied content became Paris, and temporary pages were removed. ## Validation - Project-build focused suites: 188 tests passed. - CLI focused suites: 183 tests passed. - Protocol focused suites: 21 tests passed. - CLI, project-build, and protocol typechecks passed. - Repository lint passed with zero warnings. - Package-boundary validation passed. - Generated runtime operation contracts were regenerated from source. - Real local CLI/MCP tests passed against a running Builder server. Closes #5887 Closes #5888 Closes #5889
Protocol
@webstudio-is/protocol owns Webstudio data exchange protocols.
The project bundle is the external export/import artifact used by sync, local
.webstudio/data.json, project import, transferred asset files, and prebuild.
This package owns the assembled bundle schemas, transfer RPC payloads, and
bundle compatibility/version helpers.
Domain models such as pages, assets, and serialized builds remain owned by their domain packages and are composed here through schema-only entrypoints. Do not copy those schemas into this package.
Terminology
Project bundle is the authoritative external project artifact. It is used by
sync, .webstudio/data.json, project import, transferred asset files, and
prebuild.
Data envelope is a serialized single-key object whose key is a versioned
Webstudio marker, for example { "@webstudio/instance/v0.1": data }. The
envelope identifies the payload version and lets consumers detect malformed
Webstudio-owned data before falling back to other formats.
Transfer data is the domain payload inside a data envelope. Examples include
InstanceTransferData, InstancesTransferData, and PageTransferData.
Transfer data is portable and detached from a project; insertion/import remaps
ids and merges it into authoritative project state. Runtime-owned transfer
formats live in @webstudio-is/project-build/transfer.
Clipboard data is a UI transport concern. Builder copy/paste may serialize transfer data into a data envelope and place it on the browser clipboard, but runtime and protocol code should name the reusable format as data envelope or transfer data, not clipboard.