@@ -0,0 +1,85 @@
+import type { Request } from '@playwright/test';
+
+/**
+ * Which browser requests WRITE the records of one object, named route by route.
+ *
+ * "Every non-GET under `/api/v1/data/:object` is a write" stopped being true
+ * when the record page began loading through `POST /api/v1/data/:object/:id/page`:
+ * a read with a request body, so a detector built on the HTTP method alone
+ * counted a member's own page load as two writes. The write set is therefore
+ * NAMED here, so a future read-shaped POST cannot be mistaken for a write,
+ * and a real write still is.
+ *
+ * Source: the route ledgers, `packages/rest/src/rest-route-ledger.ts` (the
+ * `crud`, `data-actions`, `record-shares` and `batch` families) and
+ * `packages/runtime/src/route-ledger.ts` (the `/actions` domain). The rows were
+ * transcribed from them once; nothing re-derives this list, so a write route
+ * added to a ledger is not watched here until it is added below.
+ *
+ *   - PATCH, PUT and DELETE anywhere under `/data/:object` are writes by method.
+ *   - A POST is a write only on a route named in `WRITE_POSTS`. The two
+ *     read-shaped POSTs in the ledger, `POST /data/:object/query` and
+ *     `POST /data/:object/:id/page`, are deliberately absent.
+ *   - `POST /batch`, the cross-object transaction, names its objects in the
+ *     body; it writes `object` when one of its operations names it, or when
+ *     the body cannot be read.
+ *
+ * Each route also matches under the environment-scoped mirror
+ * (`/api/v1/environments/:environmentId/...`).
+ */
+const WRITE_POSTS = [
+  'POST /api/v1/data/:object',
+  'POST /api/v1/data/:object/:id/clone',
+  'POST /api/v1/data/:object/:id/shares',
+  'POST /api/v1/data/:object/import',
+  'POST /api/v1/data/:object/import/jobs',
+  'POST /api/v1/data/:object/batch',
+  'POST /api/v1/data/:object/createMany',
+  'POST /api/v1/data/:object/updateMany',
+  'POST /api/v1/data/:object/deleteMany',
+  'POST /api/v1/actions/:object/:action',
+  'POST /api/v1/actions/:object/:action/:recordId',
+  'POST /api/v1/actions/_activation/:object/:action',
+] as const;
+
+const WRITE_METHODS = new Set(['PATCH', 'PUT', 'DELETE']);
+const ENV_MIRROR = '(?:/environments/[^/]+)?';
+
+const escape = (s: string) => s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+
+/** `/api/v1/data/:object/:id` → a pathname regex, `:object` bound to `object`. */
+function routePattern(path: string, object: string): RegExp {
+  const rest = path
+    .replace(/^\/api\/v1/, '')
+    .split('/')
+    .map((seg) => (seg === ':object' ? escape(object) : seg.startsWith(':') ? '[^/]+' : escape(seg)))
+    .join('/');
+  return new RegExp(`^/api/v1${ENV_MIRROR}${rest}/?$`);
+}
+
+function batchNames(request: Request, object: string): boolean {
+  let body: unknown;
+  try {
+    body = request.postDataJSON();
+  } catch {
+    return true;
+  }
+  const operations = (body as { operations?: unknown } | null)?.operations;
+  if (!Array.isArray(operations)) return true;
+  return operations.some((op) => (op as { object?: unknown } | null)?.object === object);
+}
+
+/** A predicate over browser requests: does this one write a record of `object`? */
+export function writesRecordsOf(object: string): (request: Request) => boolean {
+  const dataPrefix = new RegExp(`^/api/v1${ENV_MIRROR}/data/${escape(object)}(?:/|$)`);
+  const posts = WRITE_POSTS.map((row) => routePattern(row.slice('POST '.length), object));
+  const crossObjectBatch = new RegExp(`^/api/v1${ENV_MIRROR}/batch/?$`);
+  return (request) => {
+    const method = request.method();
+    const path = new URL(request.url()).pathname;
+    if (WRITE_METHODS.has(method)) return dataPrefix.test(path);
+    if (method !== 'POST') return false;
+    if (posts.some((p) => p.test(path))) return true;
+    return crossObjectBatch.test(path) && batchNames(request, object);
+  };
+}
@@ -1,5 +1,6 @@
 import { test, expect, type Page } from '@playwright/test';
 import { signInMember } from './member';
+import { writesRecordsOf } from './data-writes';
 
 /**
  * objectstack#27552 — a member who may READ a record but not WRITE it is
@@ -32,6 +33,9 @@ const API = process.env.LIVE_API_URL || 'http://localhost:3000';
 const OBJECT = 'showcase_inquiry';
 const recordPath = (id: string) => `/apps/showcase_app/${OBJECT}/record/${id}`;
 const formPath = (id: string) => `${recordPath(id)}?form=${encodeURIComponent(id)}`;
+// Named write routes, not "any non-GET": the record page itself loads through
+// the read `POST /api/v1/data/:object/:id/page` (see `./data-writes`).
+const writesInquiry = writesRecordsOf(OBJECT);
 
 // The record header's Edit CTA and the record body's inline-edit pencils carry
 // no test id; their accessible names are the `detail.edit` and
@@ -84,7 +88,7 @@ test('a member who may read but not write an inquiry gets a read-only form and n
       const memberPage = await context.newPage();
       const writes: string[] = [];
       memberPage.on('request', (r) => {
-        if (r.method() !== 'GET' && r.url().includes(`/api/v1/data/${OBJECT}`)) writes.push(`${r.method()} ${r.url()}`);
+        if (writesInquiry(r)) writes.push(`${r.method()} ${r.url()}`);
       });
 
       await memberPage.goto(formPath(id));
@@ -124,9 +128,7 @@ test('a member who may read but not write an inquiry gets a read-only form and n
 
     const value = `Admin edit ${Date.now()}`;
     await company.fill(value);
-    const saved = page.waitForResponse(
-      (r) => r.request().method() !== 'GET' && r.url().includes(`/api/v1/data/${OBJECT}/${id}`),
-    );
+    const saved = page.waitForResponse((r) => writesInquiry(r.request()));
     await dialog.getByTestId('modal-form-footer').locator('button[type="submit"]').click();
     expect((await saved).ok(), 'the admin save answered 2xx').toBe(true);