language-server.md

Language Server Architecture

Note: The language server implementation may be replaced with a new parser in the future. Focus on VS Code extension features for now.

Key Files

File	Purpose
src/server.ts	Entry point, sets up LSP connection
src/lib/MessageHandler.ts	Dispatches LSP requests
src/lib/Schema.ts	PrismaSchema class for multi-file schemas
src/lib/prisma-schema-wasm/	Wrappers around the WASM parsing module

Multi-File Schema Support

Prisma supports splitting schemas across multiple .prisma files. The PrismaSchema class handles this:

// Loading a schema (handles both single and multi-file)
const schema = await PrismaSchema.load({
  currentDocument: textDocument,
  allDocuments: documents.all(),
})

// Iterating over all lines across files
for (const line of schema.iterLines()) {
  // line.document, line.lineIndex, line.text
}

See Prisma Multi-File Schema Documentation for details.

VS Code document routing

When prisma.pinToPrisma6 is disabled, the VS Code extension routes each open Prisma document independently:

Document	Owner
No // use prisma-next directive	Legacy language server
Directive present, trusted file workspace, matching root, and Prisma Next CLI available	Prisma Next client for that workspace root
Directive present but Prisma Next execution is ineligible or unavailable	No active language-server synchronization

The directive is content-based and applies per file. A marked file does not opt sibling files or the rest of a multi-file schema into Prisma Next tooling.

For marked files, the extension uses only the Prisma CLI installed at:

<workspace-root>/node_modules/prisma/dist/prisma.js

The workspace must be trusted. The extension does not invoke a package manager, search parent directories, or fall back to a global installation. If the CLI is unavailable, the marked file has no language-server features until a suitable Prisma Next server can be started.

The extension starts at most one Prisma Next language server per workspace root. Adding or removing the directive in an open file transfers that file between the legacy and Prisma Next servers without requiring a save or restart. Prisma Next servers do not restart automatically after a failure; use Prisma: Restart Language Server to retry. Pinning the workspace to Prisma 6 routes every Prisma document to the legacy Prisma 6 server.