diff --git a/apps/api/src/collectives/matrix-provisioner.ts b/apps/api/src/collectives/matrix-provisioner.ts
index 7b216b4..3947ade 100644
--- a/apps/api/src/collectives/matrix-provisioner.ts
+++ b/apps/api/src/collectives/matrix-provisioner.ts
@@ -186,7 +186,23 @@ export class MatrixProvisioner implements ProvisionerPort {
       power_level_content_override: this.powerLevels(input),
     });
     for (const [index, text] of onboardingSequence(input.language).entries()) {
-      await this.post(roomId, index, { msgtype: "m.text", body: text });
+      // A brand-new room can reject the first posts until its initial events
+      // settle ("no forward extremities"); retry rather than fail the whole
+      // collective for a race measured in milliseconds.
+      let lastError: unknown = null;
+      for (const delayMs of [0, 1000, 2500, 5000]) {
+        if (delayMs > 0) await new Promise((r) => setTimeout(r, delayMs));
+        try {
+          await this.post(roomId, index, { msgtype: "m.text", body: text });
+          lastError = null;
+          break;
+        } catch (err) {
+          lastError = err;
+        }
+      }
+      if (lastError !== null) {
+        this.logger.warn(`onboarding guide post ${index} failed after retries in ${roomId}: ${errorText(lastError)}`);
+      }
     }
     if (input.founderMxid !== null) await this.inviteUser(roomId, input.founderMxid);
     return { roomId };