diff --git a/craft/src/main.tsx b/craft/src/main.tsx
index 695fa33..e0da316 100644
--- a/craft/src/main.tsx
+++ b/craft/src/main.tsx
@@ -3,12 +3,19 @@ import ReactDOM from 'react-dom/client';
 import { App } from './App';
 import { WhpConfig } from './types';
 import { installConsoleErrorBuffer } from './utils/console-buffer';
+import { editorBuild } from './utils/build-stamp';
 import './styles/editor.css';
 
 // Installed before React mounts so errors thrown during the first render are
 // captured too.
 installConsoleErrorBuffer();
 
+// Logged so the build that produced a given session is visible in the
+// browser console; also the only current reference to `editorBuild()`,
+// which keeps the __EDITOR_BUILD__-reading module from being tree-shaken
+// out of the bundle before Task 19 wires it into the report payload.
+console.log(`[site-builder] build ${editorBuild()}`);
+
 // Read WHP_CONFIG injected by PHP wrapper (or null for standalone dev)
 const whpConfig: WhpConfig | null = (window as any).WHP_CONFIG || null;
 
diff --git a/craft/src/utils/build-stamp.ts b/craft/src/utils/build-stamp.ts
new file mode 100644
index 0000000..2fd273f
--- /dev/null
+++ b/craft/src/utils/build-stamp.ts
@@ -0,0 +1,10 @@
+/**
+ * Reads the compile-time `__EDITOR_BUILD__` define.
+ *
+ * vitest does not apply Vite's `define`, and `npm run dev` in a non-git
+ * checkout may not either, so every read goes through here. `typeof` on an
+ * undeclared identifier is safe in JS -- it does not throw.
+ */
+export function editorBuild(): string {
+  return typeof __EDITOR_BUILD__ !== 'undefined' ? __EDITOR_BUILD__ : 'dev';
+}
diff --git a/craft/src/vite-env.d.ts b/craft/src/vite-env.d.ts
new file mode 100644
index 0000000..a3024a5
--- /dev/null
+++ b/craft/src/vite-env.d.ts
@@ -0,0 +1,5 @@
+/// <reference types="vite/client" />
+
+/** Injected by vite.config.ts `define`. Absent under vitest -- always read
+ *  it through `utils/build-stamp.ts`'s `editorBuild()`, never directly. */
+declare const __EDITOR_BUILD__: string;
diff --git a/craft/vite.config.ts b/craft/vite.config.ts
index 516589b..de42c20 100644
--- a/craft/vite.config.ts
+++ b/craft/vite.config.ts
@@ -1,6 +1,20 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 import path from 'path'
+import { execSync } from 'child_process'
+
+/** Short git SHA + build date, injected as __EDITOR_BUILD__ so an issue
+ *  report identifies exactly which bundle produced it. package.json's
+ *  version is hand-maintained and never changes between builds. */
+const editorBuild = (() => {
+  let sha = 'nogit'
+  try {
+    sha = execSync('git rev-parse --short HEAD', { cwd: __dirname }).toString().trim()
+  } catch {
+    // Building outside a git checkout (release tarball) -- keep 'nogit'.
+  }
+  return `${sha}-${new Date().toISOString().slice(0, 10)}`
+})()
 
 export default defineConfig({
   plugins: [react()],
@@ -10,6 +24,9 @@ export default defineConfig({
       '@': path.resolve(__dirname, './src'),
     },
   },
+  define: {
+    __EDITOR_BUILD__: JSON.stringify(editorBuild),
+  },
   build: {
     outDir: 'dist',
     rollupOptions: {