diff --git a/scripts/check-stageable-secrets.mjs b/scripts/check-stageable-secrets.mjs
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+#!/usr/bin/env node
+// Fail if `git add -A` would stage a credential.
+//
+// On 2026-08-03 we found live keys sitting unignored in PUBLIC repo clones on
+// BOTH machines, within an hour of each other, and neither was caught by a
+// rule:
+//
+//   MacBook   config/grok.env      `config/*.json` was scoped to .json
+//   Mac mini  logs/start-all.out   `*.log` did not cover .out
+//
+// Both were fixed by adding the missing pattern. That is the wrong lesson.
+// The rules were not wrong, they were INCOMPLETE, and the same day gave us a
+// third instance of the identical shape (`*.bak.*` matched foo.bak.1 but not
+// foo.bak) and a fourth in a different repo entirely. Each time the rule that
+// existed stayed correct, so nothing looked broken — it was always the
+// sibling nobody thought to name.
+//
+// You cannot enumerate your way out of that. The next one will be .out2, or
+// .tmp, or a directory nobody has created yet. So this checks the OUTCOME
+// rather than the filenames: whatever `git add -A` would actually stage, does
+// any of it look like a credential?
+//
+// WHAT A PASS DOES AND DOES NOT MEAN. This asks git what is stageable, and
+// git honours .git/info/exclude — which is machine-local and never committed.
+// So a PASS means "nothing dangerous is stageable ON THIS MACHINE RIGHT NOW".
+// It does NOT mean the repo's ignore rules are complete: a fresh clone, a new
+// user, or CI has none of your local excludes, and if .gitignore is still
+// missing the pattern then the same file is stageable there with nothing to
+// warn them.
+//
+// Those are two different claims and conflating them is how both of today's
+// leaks survived. Closing a hole with .git/info/exclude is the tourniquet;
+// the .gitignore change is the fix. This script cannot tell you whether you
+// did the second one. (Blind spot found by claudemm, who tested exactly this
+// rather than taking the script at its word.)
+//
+// Run: node scripts/check-stageable-secrets.mjs   (exit 1 on any finding)
+
+import { execFileSync } from 'node:child_process';
+import { readFileSync, statSync } from 'node:fs';
+
+// Shapes worth stopping for. Deliberately narrow: a scanner that cries wolf
+// gets disabled, and a disabled scanner is worse than none. Every pattern
+// here is a real credential format we use or plausibly would.
+const PATTERNS = [
+  [/xfb_[a-f0-9]{32,}/i, 'GroupMind agent key'],
+  // sk-ant- BEFORE the general sk- rule: the broad one also matches an
+  // Anthropic key and would mislabel it, and a wrong label sends someone
+  // rotating the wrong credential.
+  [/sk-ant-[A-Za-z0-9_-]{20,}/, 'Anthropic API key'],
+  [/sk-[A-Za-z0-9_-]{20,}/, 'OpenAI-style secret key'],
+  [/AIza[0-9A-Za-z_-]{35}/, 'Google API key'],
+  [/gh[pousr]_[A-Za-z0-9]{36,}/, 'GitHub token'],
+  [/github_pat_[A-Za-z0-9_]{50,}/, 'GitHub fine-grained PAT'],
+  [/-----BEGIN [A-Z ]*PRIVATE KEY-----/, 'private key'],
+  [/\b(?:api[_-]?key|secret|password|token)\s*[:=]\s*['"]?[A-Za-z0-9_\-]{24,}/i,
+    'assigned secret-looking value'],
+];
+
+// Binaries and lockfiles produce noise, not credentials.
+const SKIP_EXT = /\.(png|jpe?g|gif|webp|ico|pdf|zip|gz|tgz|jar|aab|apk|keystore|jks|woff2?|ttf|mp[34]|mov|wav)$/i;
+const MAX_BYTES = 2 * 1024 * 1024;
+
+const git = (args) =>
+  execFileSync('git', args, { encoding: 'utf8', maxBuffer: 64 * 1024 * 1024 });
+
+// Exactly the set `git add -A` would stage: tracked-and-modified plus
+// untracked-and-not-ignored. Asking git rather than reimplementing its ignore
+// logic is the point — a hand-rolled matcher would inherit the same blind
+// spots as the .gitignore rules that missed these files.
+function stageableFiles() {
+  const out = git(['status', '--porcelain=v1', '--untracked-files=all']);
+  const files = [];
+  for (const line of out.split('\n')) {
+    if (!line.trim()) continue;
+    const status = line.slice(0, 2);
+    let path = line.slice(3);
+    if (status.includes('R')) path = path.split(' -> ').pop(); // renames
+    if (status === 'D ' || status === ' D') continue;          // going away
+    files.push(path.replace(/^"|"$/g, ''));
+  }
+  return files;
+}
+
+function scan(path) {
+  if (SKIP_EXT.test(path)) return null;
+  let text;
+  try {
+    if (statSync(path).size > MAX_BYTES) return null;
+    text = readFileSync(path, 'utf8');
+  } catch {
+    return null; // unreadable, gone, or a directory: not our problem
+  }
+  if (text.includes('\0')) return null; // binary
+  for (const [re, label] of PATTERNS) {
+    const m = text.match(re);
+    if (m) {
+      // Report WHERE and WHAT, never the value itself. This output ends up in
+      // CI logs and terminal scrollback, and a scanner that prints the secret
+      // it found has simply moved the leak.
+      const line = text.slice(0, m.index).split('\n').length;
+      return { label, line, hint: `${m[0].slice(0, 6)}…(${m[0].length} chars)` };
+    }
+  }
+  return null;
+}
+
+const findings = [];
+for (const f of stageableFiles()) {
+  const hit = scan(f);
+  if (hit) findings.push({ file: f, ...hit });
+}
+
+if (findings.length === 0) {
+  console.log('PASS: nothing `git add -A` would stage looks like a credential.');
+  process.exit(0);
+}
+
+console.error(`FAIL: ${findings.length} stageable file(s) contain credential-shaped data\n`);
+for (const f of findings) {
+  console.error(`  ${f.file}:${f.line}`);
+  console.error(`      ${f.label} — ${f.hint}\n`);
+}
+console.error('These are NOT committed yet, and this repo is public.');
+console.error('Fix by ignoring the file, not by deleting it — something may be using it:');
+console.error('  echo "<path>" >> .git/info/exclude     # this machine, immediate');
+console.error('  then add the pattern to .gitignore in a PR, so every user gets it.');
+process.exit(1);