diff --git a/apps/lsp-playground/fixtures/broken.psl b/apps/lsp-playground/fixtures/broken.psl
index 8ab2f4061f50..e83416cfcef2 100644
--- a/apps/lsp-playground/fixtures/broken.psl
+++ b/apps/lsp-playground/fixtures/broken.psl
@@ -1,3 +1,4 @@
+// use prisma-next
 model User {
   id    Int    @id
   email String
diff --git a/packages/1-framework/3-tooling/language-server/README.md b/packages/1-framework/3-tooling/language-server/README.md
index 5244d5718105..abd317de07e3 100644
--- a/packages/1-framework/3-tooling/language-server/README.md
+++ b/packages/1-framework/3-tooling/language-server/README.md
@@ -4,56 +4,8 @@
 
 The Prisma Next language server speaks the Language Server Protocol over stdio for PSL schema inputs declared in a project's `prisma.config.ts`. It is launched by the `prisma lsp` subcommand, so editor features come from the project's own Prisma Next version and stay version-matched by construction.
 
-## Scope
-
-Supported capabilities are intentionally narrow: parse diagnostics, whole-document formatting, folding ranges, full/range semantic tokens, model field type completion, descriptor-backed generic block parameter completion, and declaration keyword completion for configured PSL inputs. Formatting is only available for documents listed in `contract.source.inputs`, uses `@internal/psl-parser/format`, and applies formatter options from the project's Prisma config `formatter` block. Semantic tokens use the standard LSP token taxonomy advertised by the server; they do not introduce Prisma-specific token names or a second parser. Completion is only available for open configured PSL inputs. At model field type positions, it suggests configured scalar types plus visible model, composite type, scalar, type-alias, and namespace qualifier candidates from the current project symbol table; bare positions offer namespace segments such as `auth.`, and after a namespace qualifier the provider suggests visible model and composite type members inside that namespace. The classifier also accepts contract-space-qualified type-position syntax such as `supabase:auth.User` when the namespace data is visible in the current cached artifacts. Inside descriptor-backed generic block bodies, it suggests declared parameter keys and excludes keys already present in sibling entries. At document top-level declaration positions, it suggests native PSL block keywords `model`, `type`, `types`, and `namespace`, plus descriptor-backed generic block keywords from `pslBlockDescriptors`. Inside namespace bodies, declaration keyword completion suggests only namespace-valid native keywords `model` and `type`, plus descriptor-backed generic block keywords; it does not suggest nested `namespace` or `types`. Declaration keyword items are snippets only when the client advertises `textDocument.completion.completionItem.snippetSupport === true`; otherwise the server returns plain-text edits for the same labels. Ordinary PSL `@` / `@@` attribute completions, attribute argument completions, generic block parameter value completions, generic block value completions, relation-aware completions, and new external contract-space candidate discovery are not part of this slice. Hover, navigation, range formatting, on-type formatting, semantic-token delta requests, and editor-extension work are out of scope. A server process can manage multiple projects under the workspace root, keyed by the config file each open document belongs to.
+The server only handles documents whose first non-whitespace content is a `// use prisma-next` line comment; all other documents belong to the legacy (Prisma ≤7) language server and are ignored per request from current document content. The check must stay byte-for-byte in sync with the legacy server's copy in `prisma/language-tools`.
 
 ## Responsibilities
 
-- Resolve workspace/project configuration for open PSL documents and keep managed projects aligned with config-file changes.
-- Serve parse diagnostics (LSP 3.17 pull with push fallback) plus whole-document formatting, folding ranges, full/range semantic tokens, and model field type completion for configured PSL inputs.
-- Preserve parser artifacts per project so editor features share the same AST, source-file, and symbol-table lifecycle instead of reparsing through feature-specific paths.
-- Fail safely for unsupported documents, missing or closed buffers, config-load failures, malformed inputs, and oversized semantic-token requests.
-
-## Dependencies
-
-- `@internal/config-loader` — discovers nearest config files and loads project configuration.
-- `@internal/psl-parser` — parses PSL, builds symbol tables, exposes syntax artifacts, and formats PSL text.
-- `@internal/framework-components` — supplies control-stack input types used when resolving project configuration.
-- `@internal/errors` and `@internal/utils` — shared framework utilities used by parsing/config plumbing.
-- `vscode-languageserver` and `vscode-languageserver-textdocument` — LSP connection, request/notification types, semantic-token/folding/formatting types, and incremental document management.
-
-## How it works
-
-1. **`initialize`** — resolves the workspace root from the client's `rootUri` and registers config-file watching when the client supports it. The server advertises incremental text sync, whole-document formatting, folding ranges, and `semanticTokensProvider` with a stable standard-only legend, `full: true`, and `range: true`. When the client advertises `textDocument.diagnostic`, the server also advertises `diagnosticProvider` with `{ interFileDependencies: false, workspaceDiagnostics: false }` — flags that describe the current single-input implementation scope, not PSL itself. Configs are loaded when matching documents open, on the first read that needs them, or when watched config files change. If a config cannot be loaded, the server does not manage that project.
-2. **Document sync** — text-document sync is **incremental** (`TextDocumentSyncKind.Incremental`); the `TextDocuments` manager applies incremental edits, and each open or change is forwarded to the project's artifact store as a document-changed event. The server parses the full current buffer at most once per change, when a read (diagnostic pull, completion, semantic tokens, folding, or a push publish) next needs the document's artifacts.
-3. **Diagnostics** — served over exactly one transport per client, decided at `initialize`. For clients that advertise `textDocument.diagnostic` (pull), `didOpen` / `didChange` only invalidate — the artifact store is only told the document changed and no eager work runs; a `textDocument/diagnostic` request reads the document artifacts from the store, which parses the current buffer internally when needed (running `@internal/psl-parser`'s `parse()` and `buildSymbolTable()` once per change) and returns a full report with the merged, mapped diagnostics. Documents that are not configured inputs, or whose project cannot load, return an empty full report. On a config-file change the server reloads the project and asks the client to re-pull via `workspace/diagnostic/refresh` when the client advertises `workspace.diagnostics.refreshSupport`, instead of republishing. For clients without pull support, the previous push behavior is preserved: the server computes on `didOpen` / `didChange` and publishes via `textDocument/publishDiagnostics` (a clean document publishes an empty array, clearing markers; unconfigured documents publish nothing), and config changes republish affected open documents. The report builder is project-scoped so a future multi-input symbol table can attach `relatedDocuments`; today reports carry only the requested document's items.
-4. **Formatting** — on `textDocument/formatting`, the server formats the current in-memory document text with `@internal/psl-parser/format` when the document is a configured PSL input. It returns one whole-document edit when the formatted text differs, and returns no edits for missing or closed documents, unconfigured documents, already canonical text, malformed PSL, or invalid formatter options.
-5. **Folding ranges** — on `textDocument/foldingRange`, the server reads the current document artifacts from the project store for the configured input and returns foldable declaration/block ranges. Missing or unconfigured documents return an empty result.
-6. **Semantic tokens** — on `textDocument/semanticTokens/full` and `textDocument/semanticTokens/range`, the server reads the current preserved `DocumentAst`, `SourceFile`, project `SymbolTable`, and control-stack scalar types from the same `ProjectArtifacts` lifecycle used by diagnostics. It classifies PSL keywords, declaration names, field/property names, type references, attributes, strings, numbers, booleans, and comments into standard token types/modifiers, then encodes them as LSP five-integer relative semantic-token data. The range request filters to intersecting tokens before encoding. Unconfigured, missing, closed, config-resolution-failed, or oversized documents return `{ data: [] }` instead of throwing; the store parses the current buffer internally before returning artifacts, so tokens never derive from an out-of-date parse. Malformed PSL returns best-effort tokens from parser recovery when artifacts are available.
-7. **Completion** — on `textDocument/completion`, the server serves configured PSL model field type positions, descriptor-backed generic block parameter-key positions, and declaration keyword positions from cached parse artifacts. It classifies the cursor using the cached AST/source file, reads the current project symbol table plus project control-stack block descriptors, threads the client's snippet capability into declaration keyword item construction, and returns `[]` for missing or closed documents, unconfigured documents, unavailable artifacts, unsupported contexts, ordinary attributes or attribute arguments, generic block parameter values, generic block value positions, relation-aware scenarios, and external contract-space discovery gaps.
-8. **Project artifact store** — each project load constructs one artifact store with the config's inputs, control stack, and a text provider over the open-document mirror. The store returns the AST, `SourceFile`, and diagnostics per open configured input plus one project symbol table, parsing internally when a read needs them; document-changed/closed events (edits, closes) and store replacement on config reload are the only things that change what reads return. The artifacts are exposed through `getDocumentAst` / `getProjectSymbolTable` for future features. Filling the project table from several inputs — and reading unopened inputs from disk — is deferred cross-file work.
-
-## Module layout
-
-- `diagnostic-mapping.ts` — pure `ParseDiagnostic[] → LspDiagnostic[]` mapping. Free of any `vscode-languageserver` import; it returns plain shape objects (ranges pass through unchanged) so it stays reusable. The connection layer adapts the numeric severity to the LSP enum.
-- `schema-inputs.ts` — resolves the schema-input set (`SchemaInputSet`) from a config and answers URI membership.
-- `config-resolution.ts` — wraps `loadConfig` and resolves schema inputs, formatter options, and control-stack inputs for a config. A standalone async function so it can be re-run on a config change without rewiring the server.
-- `document-diagnostics.ts` — `computeDocumentDiagnostics(uri, text, inputs, controlStack)`, the pure seam that parses, builds the symbol table, and returns the diagnostics plus the parse artifacts.
-- `project-artifacts.ts` — `createProjectArtifacts({ inputs, controlStack, getText })`, the per-project-load store that owns document artifacts and the project symbol table, parsing on demand and responding to document-changed/closed events.
-- `folding-ranges.ts` — pure AST-to-LSP folding-range computation for declaration/block bodies.
-- `semantic-tokens.ts` — pure PSL semantic-token collection, range filtering, multiline normalization, duplicate resolution, modifier bitset encoding, and LSP semantic-token data encoding.
-- `completion-context.ts` — pure cursor classifier for PSL completion contexts, currently routing model field type positions, descriptor-backed generic block parameter-key positions, and declaration keyword positions while marking everything outside slice scope unsupported.
-- `completion-provider.ts` — pure completion item provider for supported model field type, generic block parameter, and declaration keyword contexts.
-- `server.ts` — `createServer(connection)` wires diagnostics, whole-document formatting, folding ranges, semantic-token handlers, completion, config watching, and project-artifact access onto an injected connection.
-- `start-server.ts` — `startServer()` and `startServer(streams)`, the two ways in, kept apart by overloads so neither can be awaited wrongly. With no argument it builds its own stdio connection from the process arguments and returns nothing: `vscode-languageserver/node` ends the process itself on disconnect, so there is no exit code to hand back. With the host's streams it resolves with one.
-- `stream-server.ts` — runs the server over an injected stream pair and resolves with the exit code the client's departure implies: 0 after a `shutdown`, 1 otherwise (and 1 for a frame the reader cannot make sense of, which leaves it desynchronised for good). It waits for the work in flight to finish first — end of input is not the end of the conversation — and redirects the global console to the host's stderr for the length of the run, so nothing but frames reaches the client. Nothing here ends the process; the host owns it.
-- `stdio-transport.ts` — the byte adapter between a host's streams (`AsyncIterable<Uint8Array>` in, `write(text: string)` out) and the Node streams `vscode-languageserver`'s reader and writer want. Output is decoded through a `StringDecoder`, so a body split mid-character across two writes still declares the `Content-Length` it has.
-- `guarded-connection.ts` — wraps the connection so a send the departed client cannot receive does nothing. Without it a send after the input ends throws, and a throw escaping a notification handler ends the process.
-
-## Package Location
-
-- **Domain**: framework (target-agnostic)
-- **Layer**: tooling
-- **Plane**: migration
-- **Path**: `packages/1-framework/3-tooling/language-server`
+- Serve diagnostics, whole-document formatting, folding ranges, semantic tokens, and completion for open configured PSL inputs carrying the directive.
diff --git a/packages/1-framework/3-tooling/language-server/src/document-diagnostics.ts b/packages/1-framework/3-tooling/language-server/src/document-diagnostics.ts
index 1fc10ecf9e24..611f8060b646 100644
--- a/packages/1-framework/3-tooling/language-server/src/document-diagnostics.ts
+++ b/packages/1-framework/3-tooling/language-server/src/document-diagnostics.ts
@@ -2,6 +2,7 @@ import type { SymbolTable } from '@internal/psl-parser';
 import type { DocumentAst, SourceFile } from '@internal/psl-parser/syntax';
 import type { LspDiagnostic } from './diagnostic-mapping';
 import { type PipelineInputs, runPipeline } from './pipeline';
+import { isPrismaNextSchema } from './schema-directive';
 import type { SchemaInputSet } from './schema-inputs';
 
 export interface DocumentDiagnostics {
@@ -23,7 +24,7 @@ export function computeDocumentDiagnostics(
   inputs: SchemaInputSet,
   controlStack: PipelineInputs,
 ): DocumentDiagnostics | null {
-  if (!inputs.includes(uri)) {
+  if (!inputs.includes(uri) || !isPrismaNextSchema(text)) {
     return null;
   }
   const { document, sourceFile, symbolTable, diagnostics } = runPipeline(text, controlStack);
diff --git a/packages/1-framework/3-tooling/language-server/src/project-artifacts.ts b/packages/1-framework/3-tooling/language-server/src/project-artifacts.ts
index 45cb53da045d..e69c42278957 100644
--- a/packages/1-framework/3-tooling/language-server/src/project-artifacts.ts
+++ b/packages/1-framework/3-tooling/language-server/src/project-artifacts.ts
@@ -135,7 +135,7 @@ export function createProjectArtifacts(options: ProjectArtifactsOptions): Projec
       // once its last open input closes. Throwing loudly beats serving a
       // fabricated empty symbolTable that would mask the broken invariant.
       throw new InternalError(
-        'invariant violated: project has no open configured input — the server must drop such projects',
+        'invariant violated: project has no readable configured input — callers must check document artifacts first',
       );
     },
     documentChanged: drop,
diff --git a/packages/1-framework/3-tooling/language-server/src/schema-directive.ts b/packages/1-framework/3-tooling/language-server/src/schema-directive.ts
new file mode 100644
index 000000000000..b483880c7327
--- /dev/null
+++ b/packages/1-framework/3-tooling/language-server/src/schema-directive.ts
@@ -0,0 +1,5 @@
+const PRISMA_NEXT_DIRECTIVE = /^\s*\/\/ *use +prisma-next *(?!\S)/;
+
+export function isPrismaNextSchema(text: string): boolean {
+  return PRISMA_NEXT_DIRECTIVE.test(text);
+}
diff --git a/packages/1-framework/3-tooling/language-server/src/server.ts b/packages/1-framework/3-tooling/language-server/src/server.ts
index edda326d410f..473c8e7946d7 100644
--- a/packages/1-framework/3-tooling/language-server/src/server.ts
+++ b/packages/1-framework/3-tooling/language-server/src/server.ts
@@ -42,6 +42,7 @@ import {
   type DocumentArtifacts,
   type ProjectArtifacts,
 } from './project-artifacts';
+import { isPrismaNextSchema } from './schema-directive';
 import type { SchemaInputSet } from './schema-inputs';
 import { buildSemanticTokens, semanticTokensLegend } from './semantic-tokens';
 
@@ -379,12 +380,16 @@ function createServerOn(connection: Connection): LanguageServer {
       return [];
     }
 
+    const source = document.getText();
+    if (!isPrismaNextSchema(source)) {
+      return [];
+    }
+
     const project = await resolveProjectForDocument(uri);
     if (project === undefined) {
       return [];
     }
 
-    const source = document.getText();
     let formatted: string;
     try {
       formatted = format(source, project.formatter);
@@ -652,7 +657,13 @@ function createServerOn(connection: Connection): LanguageServer {
     getDocumentAst: (uri) => artifactsForDocument(uri)?.document(uri),
     // `| undefined` only because the uri may be unmanaged (closed, non-input,
     // or projectless); a managed document's project always yields a symbolTable.
-    getProjectSymbolTable: (uri) => artifactsForDocument(uri)?.symbolTable(),
+    getProjectSymbolTable: (uri) => {
+      const artifacts = artifactsForDocument(uri);
+      if (artifacts?.document(uri) === undefined) {
+        return undefined;
+      }
+      return artifacts.symbolTable();
+    },
   };
 }
 
diff --git a/packages/1-framework/3-tooling/language-server/test/document-diagnostics.test.ts b/packages/1-framework/3-tooling/language-server/test/document-diagnostics.test.ts
index 7995615620ef..8f1ca8c2214b 100644
--- a/packages/1-framework/3-tooling/language-server/test/document-diagnostics.test.ts
+++ b/packages/1-framework/3-tooling/language-server/test/document-diagnostics.test.ts
@@ -17,7 +17,10 @@ const controlStack: PipelineInputs = {
   pslBlockDescriptors: {},
 };
 
+const directive = '// use prisma-next';
+
 const duplicateModelSource = [
+  directive,
   'model User {',
   '  id Int @id',
   '}',
@@ -29,7 +32,7 @@ const duplicateModelSource = [
 
 describe('computeDocumentDiagnostics', () => {
   it('publishes parser diagnostics for a configured PSL input with a parse error', () => {
-    const source = 'model {';
+    const source = '// use prisma-next\nmodel {';
     const result = computeDocumentDiagnostics(schemaUri, source, inputs, controlStack);
     expect(result).not.toBeNull();
     expect(result?.diagnostics).toEqual(mapParseDiagnostics(parse(source).diagnostics));
@@ -39,7 +42,7 @@ describe('computeDocumentDiagnostics', () => {
   it('publishes an empty array for a clean configured PSL input', () => {
     const result = computeDocumentDiagnostics(
       schemaUri,
-      'model User {\n  id Int @id\n}\n',
+      '// use prisma-next\nmodel User {\n  id Int @id\n}\n',
       inputs,
       controlStack,
     );
@@ -51,6 +54,12 @@ describe('computeDocumentDiagnostics', () => {
     const result = computeDocumentDiagnostics(otherUri, 'model {', inputs, controlStack);
     expect(result).toBeNull();
   });
+
+  it('returns null for a configured input without the prisma-next directive', () => {
+    const result = computeDocumentDiagnostics(schemaUri, 'model {', inputs, controlStack);
+    expect(result).toBeNull();
+  });
+
   it('runs the symbol-table tier and reports a duplicate top-level declaration', () => {
     const result = computeDocumentDiagnostics(
       schemaUri,
@@ -64,7 +73,7 @@ describe('computeDocumentDiagnostics', () => {
   });
 
   it('matches the merged parse + symbol-table diagnostics for the same inputs', () => {
-    const source = ['model Profile {', '  user a.b.c', '}'].join('\n');
+    const source = [directive, 'model Profile {', '  user a.b.c', '}'].join('\n');
     const { document, sourceFile, diagnostics: parseDiagnostics } = parse(source);
     const { diagnostics: symbolTableDiagnostics } = buildSymbolTable({
       document,
@@ -82,7 +91,7 @@ describe('computeDocumentDiagnostics', () => {
   it('exposes the parsed AST and the symbol table as artifacts', () => {
     const result = computeDocumentDiagnostics(
       schemaUri,
-      'model User {\n  id Int @id\n}\n',
+      '// use prisma-next\nmodel User {\n  id Int @id\n}\n',
       inputs,
       controlStack,
     );
@@ -100,7 +109,12 @@ describe('computeDocumentDiagnostics', () => {
 
   it('does not throw on a malformed, half-typed buffer', () => {
     expect(() =>
-      computeDocumentDiagnostics(schemaUri, 'model User {\n  id ', inputs, controlStack),
+      computeDocumentDiagnostics(
+        schemaUri,
+        '// use prisma-next\nmodel User {\n  id ',
+        inputs,
+        controlStack,
+      ),
     ).not.toThrow();
   });
 });
diff --git a/packages/1-framework/3-tooling/language-server/test/project-artifacts.test.ts b/packages/1-framework/3-tooling/language-server/test/project-artifacts.test.ts
index ee8a5d8ccc14..a1e71d19daa2 100644
--- a/packages/1-framework/3-tooling/language-server/test/project-artifacts.test.ts
+++ b/packages/1-framework/3-tooling/language-server/test/project-artifacts.test.ts
@@ -36,8 +36,10 @@ const controlStack: PipelineInputs = {
   pslBlockDescriptors: {},
 };
 
-const cleanSource = 'model User {\n  id Int @id\n}\n';
-const twoModelSource = 'model User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n';
+const directive = '// use prisma-next\n';
+const cleanSource = `${directive}model User {\n  id Int @id\n}\n`;
+const twoModelSource = `${directive}model User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n`;
+const unmarkedSource = 'model Stray {\n  id Int @id\n}\n';
 
 function projectWithMirror(interpretation?: ProjectInterpretation): {
   readonly texts: Map<string, string>;
@@ -119,6 +121,47 @@ describe('createProjectArtifacts', () => {
     expect(pipelineMock.runPipeline).not.toHaveBeenCalled();
   });
 
+  it('returns undefined for a configured input without the prisma-next directive', () => {
+    const { texts, store } = projectWithMirror();
+    texts.set(schemaUri, unmarkedSource);
+
+    expect(store.document(schemaUri)).toBeUndefined();
+    expect(pipelineMock.runPipeline).not.toHaveBeenCalled();
+  });
+
+  it('serves a configured input again once an edit adds the directive', () => {
+    const { texts, store } = projectWithMirror();
+    texts.set(schemaUri, unmarkedSource);
+    expect(store.document(schemaUri)).toBeUndefined();
+
+    texts.set(schemaUri, `${directive}${unmarkedSource}`);
+    store.documentChanged(schemaUri);
+
+    expect(store.document(schemaUri)?.document).toBeDefined();
+  });
+
+  it('excludes an unmarked sibling input from the symbol table', () => {
+    const schema2Uri = pathToFileURL('/abs/schema2.psl').toString();
+    const twoInputs = resolveSchemaInputs({
+      contract: {
+        source: { format: 'psl', inputs: ['/abs/schema.psl', '/abs/schema2.psl'] },
+      },
+    });
+    const texts = new Map<string, string>();
+    const store = createProjectArtifacts({
+      inputs: twoInputs,
+      controlStack,
+      getText: (uri) => texts.get(uri),
+    });
+    texts.set(schemaUri, unmarkedSource);
+    texts.set(schema2Uri, cleanSource);
+
+    expect(store.document(schemaUri)).toBeUndefined();
+    const models = Object.keys(store.symbolTable().topLevel.models);
+    expect(models).toContain('User');
+    expect(models).not.toContain('Stray');
+  });
+
   it('reading the symbol table on a fresh store parses the open configured input once', () => {
     const { texts, store } = projectWithMirror();
     texts.set(schemaUri, cleanSource);
@@ -163,7 +206,9 @@ describe('createProjectArtifacts', () => {
   it('throws when no configured input is open instead of fabricating a table', () => {
     const { store } = projectWithMirror();
 
-    expect(() => store.symbolTable()).toThrowError(/invariant violated.*no open configured input/i);
+    expect(() => store.symbolTable()).toThrowError(
+      /invariant violated.*no readable configured input/i,
+    );
     expect(pipelineMock.runPipeline).not.toHaveBeenCalled();
   });
 
@@ -180,7 +225,7 @@ describe('createProjectArtifacts', () => {
 
   it('returns diagnostics with parity to parse + buildSymbolTable for the same inputs', () => {
     const { texts, store } = projectWithMirror();
-    const source = ['model Profile {', '  user a.b.c', '}'].join('\n');
+    const source = [`${directive}model Profile {`, '  user a.b.c', '}'].join('\n');
     texts.set(schemaUri, source);
     const { document, sourceFile, diagnostics: parseDiagnostics } = parse(source);
     const { diagnostics: symbolTableDiagnostics } = buildSymbolTable({
@@ -196,7 +241,7 @@ describe('createProjectArtifacts', () => {
 
   it('does not throw on a malformed, half-typed buffer', () => {
     const { texts, store } = projectWithMirror();
-    texts.set(schemaUri, 'model User {\n  id ');
+    texts.set(schemaUri, `${directive}model User {\n  id `);
     expect(() => store.document(schemaUri)).not.toThrow();
   });
 });
@@ -205,7 +250,7 @@ describe('interpret slot', () => {
   const spanned = {
     code: 'PSL_UNRESOLVED_RELATION',
     message: 'relation target not found',
-    span: { start: { offset: 15, line: 2, column: 3 }, end: { offset: 21, line: 2, column: 9 } },
+    span: { start: { offset: 34, line: 3, column: 3 }, end: { offset: 40, line: 3, column: 9 } },
   };
 
   it('does not interpret on document reads, only when the slot is pulled', () => {
@@ -245,7 +290,7 @@ describe('interpret slot', () => {
 
     expect(store.document(schemaUri)?.interpretDiagnostics()).toEqual([
       {
-        range: { start: { line: 1, character: 2 }, end: { line: 1, character: 8 } },
+        range: { start: { line: 2, character: 2 }, end: { line: 2, character: 8 } },
         message: 'relation target not found',
         code: 'PSL_UNRESOLVED_RELATION',
         severity: 1,
diff --git a/packages/1-framework/3-tooling/language-server/test/schema-directive.test.ts b/packages/1-framework/3-tooling/language-server/test/schema-directive.test.ts
new file mode 100644
index 000000000000..cfde97f3da48
--- /dev/null
+++ b/packages/1-framework/3-tooling/language-server/test/schema-directive.test.ts
@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest';
+import { isPrismaNextSchema } from '../src/schema-directive';
+
+describe('isPrismaNextSchema', () => {
+  it('accepts a schema whose first line is the directive', () => {
+    expect(isPrismaNextSchema('// use prisma-next\nmodel User {\n  id Int @id\n}\n')).toBe(true);
+  });
+
+  it('accepts the directive with no schema body', () => {
+    expect(isPrismaNextSchema('// use prisma-next')).toBe(true);
+  });
+
+  it('accepts leading blank lines and indentation before the directive', () => {
+    expect(isPrismaNextSchema('\n\n  // use prisma-next\nmodel User {}\n')).toBe(true);
+  });
+
+  it('accepts trailing spaces after the directive', () => {
+    expect(isPrismaNextSchema('// use prisma-next   \n')).toBe(true);
+  });
+
+  it('accepts flexible spacing inside the comment', () => {
+    expect(isPrismaNextSchema('//use prisma-next\n')).toBe(true);
+    expect(isPrismaNextSchema('//   use   prisma-next\n')).toBe(true);
+  });
+
+  it('rejects a token attached to the directive name', () => {
+    for (const suffix of ['2', 'gen']) {
+      expect(isPrismaNextSchema(`// use prisma-next${suffix}\n`)).toBe(false);
+    }
+  });
+
+  it('rejects a directive that is not the first content of the file', () => {
+    expect(isPrismaNextSchema('model User {}\n// use prisma-next\n')).toBe(false);
+  });
+
+  it('rejects a block-comment form', () => {
+    expect(isPrismaNextSchema('/* use prisma-next */\n')).toBe(false);
+  });
+
+  it('rejects unmarked and empty documents', () => {
+    expect(isPrismaNextSchema('model User {\n  id Int @id\n}\n')).toBe(false);
+    expect(isPrismaNextSchema('')).toBe(false);
+    expect(isPrismaNextSchema('// use prisma\n')).toBe(false);
+  });
+});
diff --git a/packages/1-framework/3-tooling/language-server/test/server.test.ts b/packages/1-framework/3-tooling/language-server/test/server.test.ts
index 7a9323e5572b..2c020c0d76ae 100644
--- a/packages/1-framework/3-tooling/language-server/test/server.test.ts
+++ b/packages/1-framework/3-tooling/language-server/test/server.test.ts
@@ -97,8 +97,8 @@ const schemaPath = join(root, 'schema.psl');
 const schemaUri = pathToFileURL(schemaPath).toString();
 const configPath = join(root, 'prisma.config.ts');
 const configUri = pathToFileURL(configPath).toString();
-const unformattedPsl = 'model User {\nid Int\n}';
-const formattedPsl = 'model User {\n  id Int\n}\n';
+const unformattedPsl = '// use prisma-next\nmodel User {\nid Int\n}';
+const formattedPsl = '// use prisma-next\nmodel User {\n  id Int\n}\n';
 
 const scalarTypes = ['String', 'Int', 'Boolean', 'DateTime'] as const;
 const nameSnippetPlaceholder = '$' + '{1:Name}';
@@ -595,6 +595,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     await harness.initialize();
     const { source, position } = sourceWithCursor(
       [
+        '// use prisma-next',
         'model User {',
         '  id Int @id',
         '}',
@@ -627,9 +628,18 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('refreshes completion artifacts from the current buffer before classifying', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    const initial = ['model Post {', '  author |', '}'].join('\n');
+    const initial = ['// use prisma-next', 'model Post {', '  author |', '}'].join('\n');
     const updated = sourceWithCursor(
-      ['model User {', '  id Int @id', '}', '', 'model Post {', '  author U|', '}'].join('\n'),
+      [
+        '// use prisma-next',
+        'model User {',
+        '  id Int @id',
+        '}',
+        '',
+        'model Post {',
+        '  author U|',
+        '}',
+      ].join('\n'),
     );
     openDocument(harness, schemaUri, initial);
     await harness.waitForDiagnostics(schemaUri);
@@ -657,7 +667,16 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
     const { source, position } = sourceWithCursor(
-      ['model User {', '  id Int @id', '}', '', 'model Post {', '  author |', '}'].join('\n'),
+      [
+        '// use prisma-next',
+        'model User {',
+        '  id Int @id',
+        '}',
+        '',
+        'model Post {',
+        '  author |',
+        '}',
+      ].join('\n'),
     );
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnosticsCount(schemaUri, 2);
@@ -673,9 +692,18 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('parses once for an edit followed by an immediate completion', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    const initial = ['model Post {', '  author ', '}'].join('\n');
+    const initial = ['// use prisma-next', 'model Post {', '  author ', '}'].join('\n');
     const updated = sourceWithCursor(
-      ['model User {', '  id Int @id', '}', '', 'model Post {', '  author U|', '}'].join('\n'),
+      [
+        '// use prisma-next',
+        'model User {',
+        '  id Int @id',
+        '}',
+        '',
+        'model Post {',
+        '  author U|',
+        '}',
+      ].join('\n'),
     );
     openDocument(harness, schemaUri, initial);
     await harness.waitForDiagnosticsCount(schemaUri, 2);
@@ -703,7 +731,9 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns generic block parameter completions for configured PSL descriptors', async () => {
     harness = startHarness(resolveToSchemaWithPslBlockDescriptors);
     await harness.initialize();
-    const { source, position } = sourceWithCursor(['policy UserAccess {', '  wh|', '}'].join('\n'));
+    const { source, position } = sourceWithCursor(
+      ['// use prisma-next', 'policy UserAccess {', '  wh|', '}'].join('\n'),
+    );
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
 
@@ -714,7 +744,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns declaration keyword completions with plain-text edits by default', async () => {
     harness = startHarness(resolveToSchemaWithPslBlockDescriptors);
     await harness.initialize();
-    const { source, position } = sourceWithCursor('|');
+    const { source, position } = sourceWithCursor('// use prisma-next\n|');
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
 
@@ -757,7 +787,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns declaration keyword snippets when the client supports snippets', async () => {
     harness = startHarness(resolveToSchemaWithPslBlockDescriptors, snippetCompletionCapabilities);
     await harness.initialize();
-    const { source, position } = sourceWithCursor('|');
+    const { source, position } = sourceWithCursor('// use prisma-next\n|');
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
 
@@ -775,7 +805,9 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns namespace-body declaration keywords without document-only keywords', async () => {
     harness = startHarness(resolveToSchemaWithPslBlockDescriptors);
     await harness.initialize();
-    const { source, position } = sourceWithCursor(['namespace feature {', '  |', '}'].join('\n'));
+    const { source, position } = sourceWithCursor(
+      ['// use prisma-next', 'namespace feature {', '  |', '}'].join('\n'),
+    );
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
 
@@ -790,7 +822,16 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     await harness.initialize();
     const otherUri = pathToFileURL(join(root, 'not-a-schema.psl')).toString();
     const { source, position } = sourceWithCursor(
-      ['model User {', '  id Int @id', '}', '', 'model Post {', '  author |', '}'].join('\n'),
+      [
+        '// use prisma-next',
+        'model User {',
+        '  id Int @id',
+        '}',
+        '',
+        'model Post {',
+        '  author |',
+        '}',
+      ].join('\n'),
     );
     openDocument(harness, otherUri, source);
 
@@ -801,7 +842,9 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns no completion items for ordinary field attribute contexts', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    const { source, position } = sourceWithCursor(['model User {', '  id Int @|', '}'].join('\n'));
+    const { source, position } = sourceWithCursor(
+      ['// use prisma-next', 'model User {', '  id Int @|', '}'].join('\n'),
+    );
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
 
@@ -813,7 +856,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
     const { source, position } = sourceWithCursor(
-      ['model User {', '  id Int @id', '  @@|', '}'].join('\n'),
+      ['// use prisma-next', 'model User {', '  id Int @id', '  @@|', '}'].join('\n'),
     );
     openDocument(harness, schemaUri, source);
     await harness.waitForDiagnostics(schemaUri);
@@ -827,7 +870,12 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
 
     const diagnostics = await harness.waitForDiagnostics(schemaUri);
@@ -843,7 +891,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
         uri: schemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model User {\n  id Int @id\n}\n',
+        text: '// use prisma-next\nmodel User {\n  id Int @id\n}\n',
       },
     });
 
@@ -857,7 +905,12 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
 
     const otherUri = pathToFileURL(join(root, 'not-a-schema.psl')).toString();
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: otherUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: otherUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
 
     await settle();
@@ -870,7 +923,12 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     const broken = await harness.waitForDiagnostics(schemaUri);
     expect(broken.length).toBeGreaterThan(0);
@@ -884,7 +942,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     });
     harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, version: 2 },
-      contentChanges: [{ text: 'model User {\n  id Int @id\n}\n' }],
+      contentChanges: [{ text: '// use prisma-next\nmodel User {\n  id Int @id\n}\n' }],
     });
     expect(await cleared).toEqual([]);
   });
@@ -895,7 +953,12 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     expect(result).toBeDefined();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     await waitUntil(() => configResolutionMock.resolveConfigInputs.mock.calls.length === 1);
     await new Promise((resolve) => setTimeout(resolve, 0));
@@ -910,7 +973,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
 
     await expect(requestFormatting(harness, schemaUri)).resolves.toEqual([
       {
-        range: { start: { line: 0, character: 0 }, end: { line: 2, character: 1 } },
+        range: { start: { line: 0, character: 0 }, end: { line: 3, character: 1 } },
         newText: formattedPsl,
       },
     ]);
@@ -937,7 +1000,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns no edits for malformed PSL', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model {');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel {');
     expect((await harness.waitForDiagnostics(schemaUri)).length).toBeGreaterThan(0);
 
     await expect(requestFormatting(harness, schemaUri)).resolves.toEqual([]);
@@ -967,8 +1030,8 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
 
     await expect(requestFormatting(harness, schemaUri)).resolves.toEqual([
       {
-        range: { start: { line: 0, character: 0 }, end: { line: 2, character: 1 } },
-        newText: 'model User {\r\n\tid Int\r\n}\r\n',
+        range: { start: { line: 0, character: 0 }, end: { line: 3, character: 1 } },
+        newText: '// use prisma-next\r\nmodel User {\r\n\tid Int\r\n}\r\n',
       },
     ]);
   });
@@ -976,11 +1039,13 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns full semantic tokens for a configured open PSL input', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
 
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({
-      data: [0, 0, 5, 0, 0, 0, 6, 4, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0],
+      data: [
+        0, 0, 18, 9, 0, 1, 0, 5, 0, 0, 0, 6, 4, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0,
+      ],
     });
   });
 
@@ -990,7 +1055,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     openDocument(
       harness,
       schemaUri,
-      'model User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n',
+      '// use prisma-next\nmodel User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n',
     );
     expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
 
@@ -1000,7 +1065,9 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
         end: { line: 3, character: 0 },
       }),
     ).resolves.toEqual({
-      data: [0, 0, 5, 0, 0, 0, 6, 4, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0],
+      data: [
+        0, 0, 18, 9, 0, 1, 0, 5, 0, 0, 0, 6, 4, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0,
+      ],
     });
   });
 
@@ -1008,7 +1075,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
     const otherUri = pathToFileURL(join(root, 'not-a-schema.psl')).toString();
-    openDocument(harness, otherUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, otherUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
 
     await expect(requestSemanticTokens(harness, otherUri)).resolves.toEqual({ data: [] });
   });
@@ -1018,7 +1085,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     await harness.initialize();
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({ data: [] });
 
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
     const closed = harness.waitForDiagnosticsMatching(
       schemaUri,
@@ -1033,7 +1100,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns best-effort semantic tokens for malformed configured inputs', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n');
     expect((await harness.waitForDiagnostics(schemaUri)).length).toBeGreaterThan(0);
 
     const tokens = await requestSemanticTokens(harness, schemaUri);
@@ -1054,7 +1121,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns empty semantic tokens when config resolution fails', async () => {
     harness = startHarness(resolveFails);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     await waitUntil(() => configResolutionMock.resolveConfigInputs.mock.calls.length === 1);
 
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({ data: [] });
@@ -1063,7 +1130,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns empty semantic tokens for oversized configured inputs', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    openDocument(harness, schemaUri, `// ${'x'.repeat(100_000)}`);
+    openDocument(harness, schemaUri, `// use prisma-next\n// ${'x'.repeat(100_000)}`);
     expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
 
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({ data: [] });
@@ -1072,7 +1139,7 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
   it('returns semantic tokens for the current edit', async () => {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
 
     const cleared = harness.waitForDiagnosticsMatching(
@@ -1081,12 +1148,14 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     );
     harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, version: 2 },
-      contentChanges: [{ text: 'model Invoice {\n  id Int @id\n}\n' }],
+      contentChanges: [{ text: '// use prisma-next\nmodel Invoice {\n  id Int @id\n}\n' }],
     });
     await cleared;
 
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({
-      data: [0, 0, 5, 0, 0, 0, 6, 7, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0],
+      data: [
+        0, 0, 18, 9, 0, 1, 0, 5, 0, 0, 0, 6, 7, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0,
+      ],
     });
   });
 
@@ -1095,25 +1164,28 @@ describe('language server', { timeout: timeouts.databaseOperation }, () => {
     harness = startHarness(async () => load.promise);
     await harness.initialize();
 
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     const currentDiagnostics = harness.waitForDiagnosticsMatching(
       schemaUri,
       (diagnostics) => diagnostics.length === 0,
     );
     harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, version: 2 },
-      contentChanges: [{ text: 'model Invoice {\n  id Int @id\n}\n' }],
+      contentChanges: [{ text: '// use prisma-next\nmodel Invoice {\n  id Int @id\n}\n' }],
     });
     load.resolve(resolutionForInputs([schemaPath]));
     await currentDiagnostics;
 
     await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({
-      data: [0, 0, 5, 0, 0, 0, 6, 7, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0],
+      data: [
+        0, 0, 18, 9, 0, 1, 0, 5, 0, 0, 0, 6, 7, 2, 1, 1, 2, 2, 5, 1, 0, 3, 3, 4, 2, 0, 4, 3, 6, 0,
+      ],
     });
   });
 });
 
 const duplicateModelSource = [
+  '// use prisma-next',
   'model User {',
   '  id Int @id',
   '}',
@@ -1147,7 +1219,7 @@ describe('language server symbol-table diagnostics', {
     harness = startHarness(resolveToSchema);
     await harness.initialize();
 
-    const source = ['model Profile {', '  user a.b.c', '}'].join('\n');
+    const source = ['// use prisma-next', 'model Profile {', '  user a.b.c', '}'].join('\n');
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: source },
     });
@@ -1180,7 +1252,9 @@ describe('language server symbol-table diagnostics', {
     harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, version: 2 },
       contentChanges: [
-        { text: 'model User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n' },
+        {
+          text: '// use prisma-next\nmodel User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n',
+        },
       ],
     });
     expect(await cleared).toEqual([]);
@@ -1195,7 +1269,7 @@ describe('language server symbol-table diagnostics', {
         uri: schemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model User {\n  id Int @id\n}\n',
+        text: '// use prisma-next\nmodel User {\n  id Int @id\n}\n',
       },
     });
 
@@ -1208,6 +1282,7 @@ describe('language server symbol-table diagnostics', {
     await harness.initialize();
 
     const source = [
+      '// use prisma-next',
       'model Profile {',
       '  user a.b.c',
       '}',
@@ -1236,6 +1311,7 @@ describe('language server symbol-table diagnostics', {
     // the duplicate `model User` (a symbol-table-tier diagnostic) in the source,
     // so a stable parse-then-symbol-table merge must reorder them on publish.
     const source = [
+      '// use prisma-next',
       'model User {',
       '  id Int @id',
       '}',
@@ -1275,7 +1351,7 @@ describe('language server symbol-table diagnostics', {
         uri: schemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model User {\n  id ',
+        text: '// use prisma-next\nmodel User {\n  id ',
       },
     });
 
@@ -1382,7 +1458,7 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
         uri: projectASchemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model {',
+        text: '// use prisma-next\nmodel {',
       },
     });
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
@@ -1390,7 +1466,7 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
         uri: projectBSchemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model {',
+        text: '// use prisma-next\nmodel {',
       },
     });
 
@@ -1422,7 +1498,7 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
         uri: unseenSchemaUri,
         languageId: 'prisma',
         version: 1,
-        text: 'model {',
+        text: '// use prisma-next\nmodel {',
       },
     });
 
@@ -1445,7 +1521,12 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: otherUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: otherUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
 
     await settle();
@@ -1475,7 +1556,12 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: childSchemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: childSchemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
 
     await waitUntil(() => resolvedConfigs.length === 1);
@@ -1486,7 +1572,16 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
 
   it('serves reads during a config reload from the fresh resolution', async () => {
     const { source, position } = sourceWithCursor(
-      ['model User {', '  id Int @id', '}', '', 'model Post {', '  author |', '}'].join('\n'),
+      [
+        '// use prisma-next',
+        'model User {',
+        '  id Int @id',
+        '}',
+        '',
+        'model Post {',
+        '  author |',
+        '}',
+      ].join('\n'),
     );
     const refreshLoad = controlledPromise();
     let loadCount = 0;
@@ -1536,7 +1631,12 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     await waitUntil(() => loadCount === 1);
     harness.notifyConfigChanged(pathToFileURL(projectConfigPath).toString());
@@ -1587,10 +1687,20 @@ describe('language server project registry', { timeout: timeouts.databaseOperati
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: projectASchemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: projectASchemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: projectBSchemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: projectBSchemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     expect((await harness.waitForDiagnostics(projectASchemaUri)).length).toBeGreaterThan(0);
     expect((await harness.waitForDiagnostics(projectBSchemaUri)).length).toBeGreaterThan(0);
@@ -1652,7 +1762,12 @@ describe('language server config watching', { timeout: timeouts.databaseOperatio
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     await settle();
     expect(harness.publishCount(schemaUri)).toBe(0);
@@ -1672,7 +1787,12 @@ describe('language server config watching', { timeout: timeouts.databaseOperatio
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     expect((await harness.waitForDiagnostics(schemaUri)).length).toBeGreaterThan(0);
 
@@ -1691,7 +1811,12 @@ describe('language server config watching', { timeout: timeouts.databaseOperatio
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     await waitUntil(() => configResolutionMock.resolveConfigInputs.mock.calls.length === 1);
     await new Promise((resolve) => setTimeout(resolve, 0));
@@ -1712,7 +1837,12 @@ describe('language server config watching', { timeout: timeouts.databaseOperatio
     await harness.initialize();
 
     harness.client.sendNotification(DidOpenTextDocumentNotification.type, {
-      textDocument: { uri: schemaUri, languageId: 'prisma', version: 1, text: 'model {' },
+      textDocument: {
+        uri: schemaUri,
+        languageId: 'prisma',
+        version: 1,
+        text: '// use prisma-next\nmodel {',
+      },
     });
     const before = await harness.waitForDiagnostics(schemaUri);
     expect(before.length).toBeGreaterThan(0);
@@ -1781,7 +1911,7 @@ describe('language server pull diagnostics', { timeout: timeouts.databaseOperati
   it('parses lazily on pull after an edit and never pushes to a pull client', async () => {
     harness = startHarness(resolveToSchema, pullDiagnosticsCapabilities);
     await harness.initialize();
-    openDocument(harness, schemaUri, 'model User {\n  id Int @id\n}\n');
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
     expect(fullReportItems(await requestPullDiagnostics(harness, schemaUri))).toEqual([]);
 
     pipelineMock.runPipeline.mockClear();
@@ -1972,7 +2102,9 @@ describe('language server preserved artifacts', { timeout: timeouts.databaseOper
     harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
       textDocument: { uri: schemaUri, version: 2 },
       contentChanges: [
-        { text: 'model User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n' },
+        {
+          text: '// use prisma-next\nmodel User {\n  id Int @id\n}\n\nmodel Post {\n  id Int @id\n}\n',
+        },
       ],
     });
     await cleared;
@@ -2113,17 +2245,17 @@ describe('language server disposal', { timeout: timeouts.databaseOperation }, ()
 });
 
 describe('language server interpreter diagnostics', { timeout: timeouts.databaseOperation }, () => {
-  const cleanSchema = 'model User {\n  id Int @id\n}\n';
-  const fixedSchema = 'model User {\n  id Int @id\n}\n// fixed\n';
-  // Span covers "User" on the first line: 1-based columns 7..11 map to the
-  // 0-based LSP range {0,6}..{0,10}.
+  const cleanSchema = '// use prisma-next\nmodel User {\n  id Int @id\n}\n';
+  const fixedSchema = '// use prisma-next\nmodel User {\n  id Int @id\n}\n// fixed\n';
+  // Span covers "User" on the line after the directive: 1-based columns 7..11
+  // map to the 0-based LSP range {1,6}..{1,10}.
   const unresolvedDiagnostic = {
     code: 'PSL_UNRESOLVED_RELATION',
     message: 'relation target not found',
-    span: { start: { offset: 6, line: 1, column: 7 }, end: { offset: 10, line: 1, column: 11 } },
+    span: { start: { offset: 25, line: 2, column: 7 }, end: { offset: 29, line: 2, column: 11 } },
   };
   const expectedUnresolved: Diagnostic = {
-    range: { start: { line: 0, character: 6 }, end: { line: 0, character: 10 } },
+    range: { start: { line: 1, character: 6 }, end: { line: 1, character: 10 } },
     message: 'relation target not found',
     code: 'PSL_UNRESOLVED_RELATION',
     severity: DiagnosticSeverity.Error,
@@ -2259,7 +2391,7 @@ describe('language server interpreter diagnostics', { timeout: timeouts.database
 describe('language server config failure surfacing', {
   timeout: timeouts.databaseOperation,
 }, () => {
-  const cleanSchema = 'model User {\n  id Int @id\n}\n';
+  const cleanSchema = '// use prisma-next\nmodel User {\n  id Int @id\n}\n';
   const expectedConfigFailure = (message: string): Diagnostic => ({
     range: { start: { line: 0, character: 0 }, end: { line: 0, character: 1 } },
     message,
@@ -2487,3 +2619,122 @@ describe('language server config failure surfacing', {
     expect(harness.nonEmptyPublishCount(configUri)).toBe(0);
   });
 });
+
+describe('language server prisma-next directive gating', {
+  timeout: timeouts.databaseOperation,
+}, () => {
+  const unmarkedDuplicate = [
+    'model User {',
+    '  id Int @id',
+    '}',
+    '',
+    'model User {',
+    '  id Int @id',
+    '}',
+    '',
+  ].join('\n');
+  const markedDuplicate = `// use prisma-next\n${unmarkedDuplicate}`;
+
+  it('publishes empty diagnostics and answers no feature requests for an unmarked configured input', async () => {
+    harness = startHarness(resolveToSchemaWithPslBlockDescriptors);
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, unmarkedDuplicate);
+    expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
+    expect(harness.publishCount(schemaUri)).toBeGreaterThan(0);
+
+    const items = completionItems(
+      await requestCompletion(harness, schemaUri, { line: 0, character: 0 }),
+    );
+    expect(items).toEqual([]);
+    await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({ data: [] });
+    await expect(requestFoldingRanges(harness, schemaUri)).resolves.toEqual([]);
+    expect(harness.getDocumentAst(schemaUri)).toBeUndefined();
+    expect(harness.getProjectSymbolTable(schemaUri)).toBeUndefined();
+  });
+
+  it('returns no formatting edits for an unmarked configured input', async () => {
+    harness = startHarness(resolveToSchema);
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, 'model User {\nid Int\n}');
+    expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
+
+    await expect(requestFormatting(harness, schemaUri)).resolves.toEqual([]);
+  });
+
+  it('serves an empty pull report for an unmarked configured input', async () => {
+    harness = startHarness(resolveToSchema, pullDiagnosticsCapabilities);
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, unmarkedDuplicate);
+    expect(await requestPullDiagnostics(harness, schemaUri)).toEqual({
+      kind: DocumentDiagnosticReportKind.Full,
+      items: [],
+    });
+  });
+
+  it('publishes empty diagnostics and stops answering once an edit removes the directive', async () => {
+    harness = startHarness(resolveToSchema);
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, markedDuplicate);
+    const before = await harness.waitForDiagnostics(schemaUri);
+    expect(before.map((diagnostic) => diagnostic.code)).toContain('PSL_DUPLICATE_DECLARATION');
+
+    const cleared = harness.waitForDiagnosticsMatching(
+      schemaUri,
+      (diagnostics) => diagnostics.length === 0,
+    );
+    harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
+      textDocument: { uri: schemaUri, version: 2 },
+      contentChanges: [{ text: unmarkedDuplicate }],
+    });
+    expect(await cleared).toEqual([]);
+
+    await expect(requestSemanticTokens(harness, schemaUri)).resolves.toEqual({ data: [] });
+    await expect(requestFoldingRanges(harness, schemaUri)).resolves.toEqual([]);
+    expect(harness.getDocumentAst(schemaUri)).toBeUndefined();
+  });
+
+  it('begins diagnosing from the edited content once an edit adds the directive', async () => {
+    harness = startHarness(resolveToSchema);
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, unmarkedDuplicate);
+    expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
+
+    const diagnosed = harness.waitForDiagnosticsMatching(
+      schemaUri,
+      (diagnostics) => diagnostics.length > 0,
+    );
+    harness.client.sendNotification(DidChangeTextDocumentNotification.type, {
+      textDocument: { uri: schemaUri, version: 2 },
+      contentChanges: [{ text: markedDuplicate }],
+    });
+    expect((await diagnosed).map((diagnostic) => diagnostic.code)).toContain(
+      'PSL_DUPLICATE_DECLARATION',
+    );
+
+    const tokens = await requestSemanticTokens(harness, schemaUri);
+    expect(tokens?.data.length).toBeGreaterThan(0);
+  });
+
+  it('excludes an unmarked sibling input from schema composition', async () => {
+    const schema2Path = join(root, 'schema2.psl');
+    const schema2Uri = pathToFileURL(schema2Path).toString();
+    harness = startHarness(async () => resolutionForInputs([schemaPath, schema2Path]));
+    await harness.initialize();
+
+    openDocument(harness, schemaUri, '// use prisma-next\nmodel User {\n  id Int @id\n}\n');
+    expect(await harness.waitForDiagnostics(schemaUri)).toEqual([]);
+    openDocument(harness, schema2Uri, 'model Stray {\n  id Int @id\n}\n');
+    expect(await harness.waitForDiagnostics(schema2Uri)).toEqual([]);
+
+    const models = Object.keys(harness.getProjectSymbolTable(schemaUri)?.topLevel.models ?? {});
+    expect(models).toContain('User');
+    expect(models).not.toContain('Stray');
+    expect(harness.getDocumentAst(schema2Uri)).toBeUndefined();
+    expect(harness.getProjectSymbolTable(schema2Uri)).toBeUndefined();
+  });
+});