--- 0604d91fc/packages/cli/tests/case1-accept.test.mjs
+++ scratch/packages/cli/tests/case1-accept.test.mjs
@@ -262,6 +262,8 @@
   };
   for(const [name,fault] of Object.entries(faults)){
     const h=host(t);fault(h);const r=run(h);
+    const diagnosticP10 = r.lines.filter(line => line.startsWith('P10 '));
+    writeFileSync(process.env.ROW253_P10_DIAG, JSON.stringify({fault:name, p10:diagnosticP10, reason:/\breason=([^ ]+)/.exec(diagnosticP10.join('\n'))?.[1] ?? null, status:r.status})+'\n', {flag:'a'});
     assert.equal(r.status,name==='peer-uid-fields'?1:0,`${name}: ${r.out}${r.err}`);
     assert.match(r.out,/P10 tester-socket-squat unnamed boundary=failed/,name);
     assert.doesNotMatch(r.out,/boundary=observed/,name);