diff --git a/relay/github.js b/relay/github.js
index 23c9bb38c..8cab594f4 100644
--- a/relay/github.js
+++ b/relay/github.js
@@ -123,6 +123,12 @@ export function createGitHubClient({ clientId, clientSecret, callbackURL, oauthB
         url = next;
         continue;
       }
+      // GitHub uses 403 for rate limits too; do not cache those as lost repository access.
+      if (response.status === 403 && (response.headers.get('x-ratelimit-remaining') === '0'
+        || /^\d+$/u.test(response.headers.get('retry-after') ?? ''))) {
+        await response.body?.cancel();
+        throw new Refused('GITHUB_UNAVAILABLE', 'GitHub is rate limited; wait before retrying');
+      }
       if ([401, 403, 404].includes(response.status)) {
         await response.body?.cancel();
         throw new Refused('NO_REPO_ACCESS', 'GitHub cannot confirm access with this sign-in; sign in again or ask for repository access');
diff --git a/src/api-http.js b/src/api-http.js
index 04aeca835..29f21c00c 100644
--- a/src/api-http.js
+++ b/src/api-http.js
@@ -373,7 +373,7 @@ export function applyStateDelta(state, delta) {
 /** Choose the same HTTP refusal class for local and sealed relay adapters. */
 export function apiStatus(error) {
   if (error instanceof Refused && error.code === 'ACCOUNT_STORAGE_LIMIT') return 507;
-  return { RELAY_BOARD_DELETED: 410, AUTH_REQUIRED: 401, DEVICE_REVOKED: 403, TOKEN_BOARD: 403, API_ORIGIN: 403, BAD_ORIGIN: 403, WRITE_REQUIRED: 403, HUMAN_REQUIRED: 403, NO_REPO_ACCESS: 403, NO_BOARD: 404, NO_SHOUT: 404, BOARD_NOT_LINKED: 404, NO_SNAPSHOT: 404, BASELINE_EXISTS: 412, SNAPSHOT_REQUIRED: 409, SEQUENCE_REPEAT: 409, SEQUENCE_GAP: 409 }[error.code] ?? (error instanceof Refused ? 400 : 500);
+  return { GITHUB_UNAVAILABLE: 503, RELAY_BOARD_DELETED: 410, AUTH_REQUIRED: 401, DEVICE_REVOKED: 403, TOKEN_BOARD: 403, API_ORIGIN: 403, BAD_ORIGIN: 403, WRITE_REQUIRED: 403, HUMAN_REQUIRED: 403, NO_REPO_ACCESS: 403, NO_BOARD: 404, NO_SHOUT: 404, BOARD_NOT_LINKED: 404, NO_SNAPSHOT: 404, BASELINE_EXISTS: 412, SNAPSHOT_REQUIRED: 409, SEQUENCE_REPEAT: 409, SEQUENCE_GAP: 409 }[error.code] ?? (error instanceof Refused ? 400 : 500);
 }
 
 // Relay-only snapshot/delete routes reuse the exact shared bounded-body and refusal boundary.
diff --git a/test/relay-fixture.js b/test/relay-fixture.js
index 9af901769..c73755c51 100644
--- a/test/relay-fixture.js
+++ b/test/relay-fixture.js
@@ -51,6 +51,10 @@ export async function githubFixture(t) {
     for await (const chunk of req) raw += chunk;
     const form = new URLSearchParams(raw);
     calls.push({ method: req.method, path: url.pathname, user: isUser, app: isApp, installation: isInstallation, apiVersion: req.headers['x-github-api-version'], formKeys: [...form.keys()] });
+    if (state.providerFailure?.path === url.pathname) {
+      res.writeHead(state.providerFailure.status, { 'Content-Type': 'application/json', ...state.providerFailure.headers });
+      return res.end(JSON.stringify({ message: 'fixture provider refusal' }));
+    }
     if (url.pathname === '/login/oauth/authorize') {
       assert.equal(url.searchParams.get('scope'), null);
       assert.equal(url.searchParams.get('client_id'), 'fixture-app');
diff --git a/test/relay-github.test.js b/test/relay-github.test.js
index 910051bb2..6d596d975 100644
--- a/test/relay-github.test.js
+++ b/test/relay-github.test.js
@@ -72,6 +72,28 @@ test('GitHub credentials never follow a redirect to a different origin [H8, H1]'
   assert.equal(foreignRequests, 0);
 });
 
+test('GitHub rate limits are unavailable, not access denials [H8]', async (t) => {
+  const provider = await githubFixture(t);
+  const client = createGitHubClient(provider.config);
+  const repository = '/repos/fixture/repository';
+  const permission = repository + '/collaborators/fixture-user/permission';
+  const user = { id: '7', login: 'fixture-user' };
+  for (const [headers, code] of [
+    [{ 'x-ratelimit-remaining': '0' }, 'GITHUB_UNAVAILABLE'],
+    [{ 'retry-after': '60', 'x-ratelimit-remaining': '17' }, 'GITHUB_UNAVAILABLE'],
+    [{ 'x-ratelimit-remaining': '17' }, 'NO_REPO_ACCESS'],
+    [{ 'retry-after': 'invalid' }, 'NO_REPO_ACCESS'],
+  ]) {
+    provider.state.providerFailure = { path: permission, status: 403, headers };
+    await assert.rejects(client.access(user, 'fixture/repository'), { code }, JSON.stringify(headers));
+  }
+  // Neither public-repository fallback may turn an outage into permission 'none'.
+  provider.state.public = true;
+  for (const path of [repository + '/installation', permission]) {
+    provider.state.providerFailure = { path, status: 403, headers: { 'retry-after': '60' } };
+    await assert.rejects(client.access(user, 'fixture/repository'), { code: 'GITHUB_UNAVAILABLE' }, path);
+  }
+});
 
 test('GitHub roles use role_name, custom-role flags and legacy fallback [H13,H14,H8]', async (t) => {
   const fixture = await githubFixture(t);
diff --git a/test/relay-outbox.test.js b/test/relay-outbox.test.js
index d44973598..e6cdc3196 100644
--- a/test/relay-outbox.test.js
+++ b/test/relay-outbox.test.js
@@ -108,6 +108,37 @@ test('a move on an accepted relay link waits in the ordered outbox while the rel
   assert.equal(item(there.document).item_status, 'withdrawn');
 });
 
+test('an opted-in outbox retains a move through a GitHub permission outage and replays it once [H8,H16,H21]', async (t) => {
+  const box = await relayClientFixture(t);
+  enableOutbox(box);
+  await box.link();
+  await box.cli('status');
+  assert.equal(JSON.parse(readFileSync(box.linkFile, 'utf8')).baselineAccepted, true);
+  const text = 'queued during the provider outage';
+  box.providerState.providerFailure = {
+    path: '/repos/fixture/repository/collaborators/fixture-user/permission',
+    status: 403, headers: { 'x-ratelimit-remaining': '0' },
+  };
+  const queued = await box.cli('shout', 'all', text);
+  assert.equal(queued.code, 0, queued.failure);
+  const waiting = await box.cli('status');
+  assert.equal(waiting.document.relay.outbox.length, 1);
+  assert.equal(waiting.document.relay.outbox[0].operation, 'shout');
+  const id = waiting.document.relay.outbox[0].id;
+  assert.ok(id);
+  const again = await box.cli('status');
+  assert.equal(again.document.relay.outbox[0].id, id, 'another failed sync retains the original move identity');
+  delete box.providerState.providerFailure;
+  const replayed = await box.cli('status');
+  assert.equal(replayed.code, 0, replayed.failure);
+  assert.equal(replayed.document.relay.outbox, undefined);
+  assert.equal(replayed.document.relay.outboxRefusals, undefined);
+  assert.equal((await box.cli('status')).document.relay.outbox, undefined);
+  const exported = await box.cli('export');
+  assert.equal(shoutTexts(exported.document).filter(value => value === text).length, 1,
+    'repeated syncs after recovery do not apply the queued move twice');
+});
+
 test('an item added while the relay is down keeps its queued moves when another machine adds one first [B26,H16,H17]', async (t) => {
   const { box, other } = await twoMachines(t, 'Added before the outage');
   await box.stopRelay();
diff --git a/test/relay.test.js b/test/relay.test.js
index 65a8e3f03..e65abaf70 100644
--- a/test/relay.test.js
+++ b/test/relay.test.js
@@ -731,6 +731,35 @@ test('lost GitHub read access takes effect at ten minutes and before every board
   assert.deepEqual(await box.auth.boardsFor(signed.token), [], 'a denied write invalidates an earlier allowed read');
 });
 
+test('a provider outage returns 503 without caching a denial or storing the move [H8,H16]', async (t) => {
+  const box = await fixture(t);
+  const person = await login(box);
+  const board = 'b'.repeat(32);
+  await box.auth.linkBoard(person.token, board, 'fixture/repository');
+  const service = await serveRelay({ directory: join(dirname(box.database), 'journal'), auth: box.auth, port: 0, maintenanceMs: 0 });
+  t.after(() => service.close());
+  const origin = `http://127.0.0.1:${service.port}/api/v1/boards/${board}`;
+  const headers = { authorization: `Bearer ${person.token}`, 'x-pullboard-engine': String(ENGINE_VERSION), 'content-type': 'application/json' };
+  const baseline = await fetch(origin + '/state', { method: 'PUT', headers, body: JSON.stringify({ sequence: 0, sealed: 'AQ' }) });
+  assert.equal(baseline.status, 200);
+  await baseline.arrayBuffer();
+  box.state.providerFailure = { path: '/repos/fixture/repository/collaborators/fixture-user/permission',
+    status: 403, headers: { 'x-ratelimit-remaining': '0' } };
+  const move = { method: 'POST', headers, body: JSON.stringify({ sequence: 1, sealed: 'Ag' }) };
+  const refused = await fetch(origin + '/moves', move);
+  assert.equal(refused.status, 503);
+  assert.equal((await refused.json()).error.code, 'GITHUB_UNAVAILABLE');
+  assert.equal((await box.auth.authenticate(person.token, { board })).permission, 'write', 'the valid read cache survives');
+  delete box.state.providerFailure;
+  box.advance(ACCESS_WINDOW_MS);
+  const events = await fetch(origin + '/events?after=0', { headers });
+  assert.equal(events.status, 200, 'recovery is not delayed by a cached denial');
+  assert.deepEqual((await events.json()).events, [], 'the refused move was not stored');
+  const sent = await fetch(origin + '/moves', move);
+  assert.equal(sent.status, 200);
+  await sent.arrayBuffer();
+});
+
 test('person token management lists only owned scoped metadata and preserves independent revocation [H2,H9]', async (t) => {
   const box = await fixture(t);
   const person = await login(box);