feat(language-server): flag the removed data blocks

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/language-server/test/removed-construct-diagnostics.test.ts

@@ -0,0 +1,120 @@
+import { expect, test } from "bun:test";
+import { documentDiagnostics } from "../src/index.ts";
+
+// documentDiagnostics is the language server's actual diagnostic entry point.
+// The plan's draft guessed a `diagnoseWrn` export that does not exist.
+
+// These two tests are the plan's original assertions, kept verbatim. They
+// already passed before this change — the message produced by the parser
+// named "apis" from the start — so on their own they are a false-green:
+// they would not catch a regression to the fix below. They stay as cheap
+// regression guards, not as the load-bearing coverage for this task.
+test("an ssr data block is flagged and names the replacement", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///removed-ssr.wrn",
+    text: `page P {
+  ssr { api x GET /api/x { response { return data } } }
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.length).toBeGreaterThan(0);
+  expect(diagnostics[0]!.message).toContain("apis");
+});
+
+test("client state is not flagged", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///client-state.wrn",
+    text: `page P {
+  client state { count = 0 }
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.filter((item) => item.severity === 1)).toEqual([]);
+});
+
+// --- Load-bearing tests -----------------------------------------------
+//
+// The message alone doesn't prove the diagnostic is useful: before the fix,
+// documentDiagnostics reported this error at line 0 / character 0 for every
+// input, no matter where the offending block actually was. These tests pin
+// the range to the real position of the "ssr" / "client" keyword, with the
+// block moved off line 1 so a hardcoded line number cannot pass.
+
+test("an ssr block diagnostic lands on the ssr keyword, not offset zero", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///removed-ssr-position.wrn",
+    text: `page P {
+  ssr { api x GET /api/x { response { return data } } }
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.length).toBeGreaterThan(0);
+  // "  ssr { ... }" — the keyword starts at line 1 (0-indexed), character 2.
+  expect(diagnostics[0]!.range.start).toEqual({ line: 1, character: 2 });
+});
+
+test("a client block diagnostic lands on the client keyword when it is not on line 1", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///removed-client-position.wrn",
+    text: `page P {
+  view { <main>x</main> }
+  client { api x GET /api/x { response { return data } } }
+}
+`,
+  });
+
+  expect(diagnostics.length).toBeGreaterThan(0);
+  // The client block is on line 2 (0-indexed) here, preceded by "view { ... }"
+  // on line 1 — a diagnostic hardcoded to line 1 would fail this assertion.
+  expect(diagnostics[0]!.range.start).toEqual({ line: 2, character: 2 });
+});
+
+// --- Legal `client` forms stay legal ------------------------------------
+//
+// `client` is one word with several jobs. Only the `ssr { }` / `client { }`
+// data-block form was removed; these forms must never be flagged.
+
+test("client state block produces no error-severity diagnostic", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///client-state-2.wrn",
+    text: `page P {
+  client state { count = 0 }
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.filter((item) => item.severity === 1)).toEqual([]);
+});
+
+test('runtime = "client" produces no error-severity diagnostic', () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///runtime-client.wrn",
+    text: `page P {
+  runtime = "client"
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.filter((item) => item.severity === 1)).toEqual([]);
+});
+
+test("client function inside functions { } produces no error-severity diagnostic", () => {
+  const diagnostics = documentDiagnostics({
+    uri: "file:///client-function.wrn",
+    text: `page P {
+  functions { client function go() { console.log(1) } }
+  view { <main>x</main> }
+}
+`,
+  });
+
+  expect(diagnostics.filter((item) => item.severity === 1)).toEqual([]);
+});

packages/syntax/src/parser.ts

@@ -685,7 +685,7 @@ export function parse(source: string): PageAst {
           }
           if (lx.peek().type === "lbrace") {
             throw new ParseError(
-              `"${rawMode} { … }" data blocks were removed. Declare API calls in a page-level "apis { }" block, and move mode-scoped helpers into "functions { shared function … }".`,
+              `"${rawMode} { … }" data blocks were removed. Declare API calls in a page-level "apis { }" block, and move mode-scoped helpers into "functions { shared function … }" (at offset ${kw.pos}).`,
             );
           }
           throw new ParseError(`Expected a ${rawMode} state block or hydrate assignment`);