diff --git a/src/plugin-sdk/root-alias.cjs b/src/plugin-sdk/root-alias.cjs
index 9c1c1b9ab61..09f4453f70c 100644
--- a/src/plugin-sdk/root-alias.cjs
+++ b/src/plugin-sdk/root-alias.cjs
@@ -76,6 +76,20 @@ function getPackageRoot() {
   return path.resolve(__dirname, "..", "..");
 }
 
+function findDistChunkByPrefix(prefix) {
+  const distRoot = path.join(getPackageRoot(), "dist");
+  try {
+    const entries = fs.readdirSync(distRoot, { withFileTypes: true });
+    const match = entries.find(
+      (entry) =>
+        entry.isFile() && entry.name.startsWith(`${prefix}-`) && entry.name.endsWith(".js"),
+    );
+    return match ? path.join(distRoot, match.name) : null;
+  } catch {
+    return null;
+  }
+}
+
 function listPluginSdkExportedSubpaths() {
   const packageRoot = getPackageRoot();
   if (pluginSdkSubpathsCache.has(packageRoot)) {
@@ -157,7 +171,7 @@ function loadDiagnosticEventsModule() {
     return diagnosticEventsModule;
   }
 
-  const distCandidate = path.resolve(
+  const directDistCandidate = path.resolve(
     __dirname,
     "..",
     "..",
@@ -165,12 +179,17 @@ function loadDiagnosticEventsModule() {
     "infra",
     "diagnostic-events.js",
   );
-  if (!shouldPreferSourceInTests && fs.existsSync(distCandidate)) {
-    try {
-      diagnosticEventsModule = getJiti(true)(distCandidate);
-      return diagnosticEventsModule;
-    } catch {
-      // Fall through to source path if dist is unavailable or stale.
+  if (!shouldPreferSourceInTests) {
+    const distCandidate =
+      (fs.existsSync(directDistCandidate) && directDistCandidate) ||
+      findDistChunkByPrefix("diagnostic-events");
+    if (distCandidate) {
+      try {
+        diagnosticEventsModule = getJiti(true)(distCandidate);
+        return diagnosticEventsModule;
+      } catch {
+        // Fall through to source path if dist is unavailable or stale.
+      }
     }
   }
 
diff --git a/src/plugin-sdk/root-alias.test.ts b/src/plugin-sdk/root-alias.test.ts
index 5705c22e9a3..cd26489740a 100644
--- a/src/plugin-sdk/root-alias.test.ts
+++ b/src/plugin-sdk/root-alias.test.ts
@@ -22,6 +22,7 @@ type EmptySchema = {
 
 function loadRootAliasWithStubs(options?: {
   distExists?: boolean;
+  distEntries?: string[];
   env?: Record<string, string | undefined>;
   monolithicExports?: Record<string | symbol, unknown>;
   aliasPath?: string;
@@ -62,7 +63,18 @@ function loadRootAliasWithStubs(options?: {
               "./plugin-sdk/group-access": { default: "./dist/plugin-sdk/group-access.js" },
             },
           }),
-        existsSync: () => options?.distExists ?? false,
+        existsSync: (targetPath: string) => {
+          if (targetPath.endsWith(path.join("dist", "infra", "diagnostic-events.js"))) {
+            return options?.distExists ?? false;
+          }
+          return options?.distExists ?? false;
+        },
+        readdirSync: () =>
+          (options?.distEntries ?? []).map((name) => ({
+            name,
+            isFile: () => true,
+            isDirectory: () => false,
+          })),
       };
     }
     if (id === "jiti") {
@@ -203,6 +215,32 @@ describe("plugin-sdk root alias", () => {
     );
   });
 
+  it("prefers hashed dist diagnostic events chunks before falling back to src", () => {
+    const packageRoot = path.dirname(path.dirname(rootAliasPath));
+    const distAliasPath = path.join(packageRoot, "dist", "plugin-sdk", "root-alias.cjs");
+    const lazyModule = loadRootAliasWithStubs({
+      aliasPath: distAliasPath,
+      distExists: false,
+      distEntries: ["diagnostic-events-W3Hz61fI.js"],
+      monolithicExports: {
+        onDiagnosticEvent: () => () => undefined,
+        slowHelper: () => "loaded",
+      },
+    });
+
+    expect(
+      typeof (lazyModule.moduleExports.onDiagnosticEvent as (listener: () => void) => () => void)(
+        () => undefined,
+      ),
+    ).toBe("function");
+    expect(lazyModule.loadedSpecifiers).toContain(
+      path.join(packageRoot, "dist", "diagnostic-events-W3Hz61fI.js"),
+    );
+    expect(lazyModule.loadedSpecifiers).not.toContain(
+      path.join(packageRoot, "src", "infra", "diagnostic-events.ts"),
+    );
+  });
+
   it("forwards delegateCompactionToRuntime through the compat-backed root alias", () => {
     const delegateCompactionToRuntime = () => "delegated";
     const lazyModule = loadRootAliasWithStubs({