diff --git a/packages/bus/src/runtime.mjs b/packages/bus/src/runtime.mjs
index ec5e4d509..01f13c139 100644
--- a/packages/bus/src/runtime.mjs
+++ b/packages/bus/src/runtime.mjs
@@ -1,7 +1,7 @@
 import { createRequirementsHost } from '../../tasks/src/builtin.mjs';
 import { createRequirementCatalog } from './requirement-catalog.mjs';
 import { readPrdMaterial } from '../../project/src/prd.mjs';
-import { lstatSync, readdirSync, readFileSync } from 'node:fs';
+import { lstatSync, mkdirSync, readdirSync, readFileSync } from 'node:fs';
 import { join } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { Store } from './store.mjs';
@@ -360,6 +360,11 @@ export async function startBroker({
     // Row 236 (#1742, #436b r5 section 5): each gitea grant record gives its agent a store reference to
     // gitea, and `held` names the files memory must not load until reconcile or a revoke.
     const { held } = storeRoot ? giteaStart(store, storeRoot, businesses, references) : { held: [] };
+    // #1886 (F3 defect l): a store reference with no file yet reads as no key (design D3a), but Credentials
+    // refuses a missing store root, and only issue() made it. Start makes it the same way issue() does when
+    // any reference names the store. A root that exists with loose modes or as a symlink still refuses.
+    if (storeRoot && Object.values(references).some(refs => Object.values(refs ?? {}).some(ref => ref?.store === true)))
+      mkdirSync(storeRoot, { recursive: true, mode: 0o700 });
     credentials = new Credentials({ references, repoRoots: protectedRoots, dataRoot, storeRoot, held,
       modelAgents: proxy ? Object.entries(businesses).flatMap(([id, b]) => Object.keys(b.roles).map(role => id + '/' + role)) : [] });
     if (proxy) {
diff --git a/packages/bus/tests/credential-verbs.test.mjs b/packages/bus/tests/credential-verbs.test.mjs
index 3adfc3a40..7b30f2368 100644
--- a/packages/bus/tests/credential-verbs.test.mjs
+++ b/packages/bus/tests/credential-verbs.test.mjs
@@ -4,7 +4,7 @@
 // scratch root only.
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { existsSync, mkdirSync, mkdtempSync, readdirSync, readFileSync, rmSync, statSync } from 'node:fs';
+import { chmodSync, existsSync, mkdirSync, mkdtempSync, readdirSync, readFileSync, rmSync, statSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { startBroker } from '../src/runtime.mjs';
@@ -18,7 +18,7 @@ const OTHER = 'fake_other_token_5555555555';
 const DATE = '2099-01-01';
 const role = { authority: { withinRole: ['message.send'], crossRole: [] } };
 
-async function setup(t) {
+async function setup(t, { storeRoot = true } = {}) {
   const root = mkdtempSync(join(tmpdir(), 'bus-cred-verbs-'));
   t.after(() => rmSync(root, { recursive: true, force: true }));
   const rolesDir = rolesCopy(root);
@@ -26,7 +26,7 @@ async function setup(t) {
   doc.roles.coder.credentials.gitea = { store: true, rotateBy: DATE };
   writeJson(join(root, 'businesses/demo.json'), doc);
   mkdirSync(join(root, 'data'), { mode: 0o700 });
-  mkdirSync(join(root, 'secrets', 'agents'), { mode: 0o700 });
+  if (storeRoot) mkdirSync(join(root, 'secrets', 'agents'), { mode: 0o700 });
   const store = (agent, service) => join(root, 'secrets', 'agents', 'demo', agent, service);
   // The bus's resolved business carries the same references; a store one names its derived file.
   const demo = {
@@ -161,3 +161,29 @@ test('T5: issue, rotate, revoke and delete are live, rewrite the business file a
   for (const path of walk(c.root))
     for (const token of [TOKEN, ROTATED, OTHER]) assert.equal(readFileSync(path).includes(token), false, path);
 });
+
+test('#1886: a store reference with no store root yet starts the bus, makes the root private and issues', async (t) => {
+  const c = await setup(t, { storeRoot: false });
+  const dir = join(c.root, 'secrets', 'agents');
+  assert.equal(statSync(dir).mode & 0o777, 0o700);
+  assert.equal(statSync(join(c.root, 'secrets')).mode & 0o077, 0);
+  assert.deepEqual(c.status('coder'), { gitea: 'not-issued', vikunja: 'valid' });
+  const issued = c.ask(c.human, 'credentials.issue', { agent: 'coder', service: 'gitea', token: TOKEN + '\n', date: DATE });
+  assert.deepEqual(issued, { agent: 'coder', verb: 'issue', service: 'gitea', date: DATE, state: 'valid' });
+  assert.equal(statSync(c.store('coder', 'gitea')).mode & 0o777, 0o600);
+});
+
+test('#1886: a store root that exists with loose modes still refuses start', async (t) => {
+  const root = mkdtempSync(join(tmpdir(), 'bus-cred-loose-'));
+  t.after(() => rmSync(root, { recursive: true, force: true }));
+  const rolesDir = rolesCopy(root);
+  writeJson(join(root, 'businesses/demo.json'), { ...businessDoc(root, 'demo'), plugins: { harness: ['pi'] } });
+  mkdirSync(join(root, 'data'), { mode: 0o700 });
+  mkdirSync(join(root, 'secrets', 'agents'), { recursive: true, mode: 0o750 });
+  chmodSync(join(root, 'secrets', 'agents'), 0o750);
+  const demo = {
+    id: 'demo', human: 'jason', arbiters: { technical: 'coder', delivery: 'coder' }, vars: {},
+    roles: { coder: { ...role, credentials: { gitea: { store: true, file: join(root, 'secrets', 'agents', 'demo', 'coder', 'gitea'), rotateBy: DATE } } } },
+  };
+  await assert.rejects(startBroker({ dataRoot: join(root, 'data'), businesses: { demo }, organization: { dir: root, rolesDir, system: systemFor(root) } }), /credential-file/);
+});