diff --git a/packages/core/src/nostr/bootstrap.ts b/packages/core/src/nostr/bootstrap.ts
index e0ca999..be1d685 100644
--- a/packages/core/src/nostr/bootstrap.ts
+++ b/packages/core/src/nostr/bootstrap.ts
@@ -23,9 +23,56 @@ export const MAINTAINER_PUBLIC_KEY_HEX: string | null = null;
 // comfortably -- a 3-relay list has zero margin the moment one relay is
 // unreachable, which is exactly what "add more vault relays" (the
 // registration failure message) is telling operators to fix.
-export const BUILTIN_VAULT_RELAYS: readonly string[] = ["wss://relay.damus.io", "wss://nos.lol", "wss://relay.nostr.band", "wss://nostr.wine", "wss://relay.snort.social"];
+/**
+ * Relays that CANNOT accept an ordinary user's capsule, by their own policy.
+ *
+ * Measured 2026-08-05 from each relay's NIP-11 document, not from reputation:
+ * `nostr.wine` advertises `payment_required: true` and
+ * `restricted_writes: true`, so a free user's write is refused there no matter
+ * how healthy the socket looks. It sat in the vault list below occupying one
+ * of five write slots it could never fill.
+ *
+ * A relay here may still be perfectly good for READING. This list exists so
+ * the test suite can refuse to let one back into a write path.
+ */
+export const WRITE_HOSTILE_RELAYS: readonly string[] = ["wss://nostr.wine", "wss://nostr21.com", "wss://nostr.land"];
 
-export const BUILTIN_DISCOVERY_RELAYS: readonly string[] = ["wss://purplepag.es", "wss://relay.nostr.band", "wss://nostr-pub.wellorder.net"];
+/**
+ * Vault relays: where capsules are PUBLISHED, so every entry must accept
+ * anonymous writes.
+ *
+ * Widened 2026-08-05 after measuring the old five. Only two could actually
+ * take a write from a fresh client: nostr.wine refuses by policy (above), and
+ * relay.damus.io and relay.nostr.band were unreachable across three runs from
+ * the machine under test. Two usable relays against a floor of two
+ * acknowledgements is zero margin -- one hiccup and registration or a
+ * password rotation fails outright.
+ *
+ * damus stays: it is the most widely used relay on the network and the
+ * failure may be datacenter-IP filtering rather than downtime. The point of
+ * widening is that quorum no longer DEPENDS on it.
+ */
+export const BUILTIN_VAULT_RELAYS: readonly string[] = [
+  "wss://nos.lol",
+  "wss://offchain.pub",
+  "wss://nostr.bitcoiner.social",
+  "wss://relay.mostr.pub",
+  "wss://nostr-pub.wellorder.net",
+  "wss://relay.primal.net",
+  "wss://relay.snort.social",
+  "wss://relay.damus.io",
+];
+
+/**
+ * Discovery relays: read-only lookups (profiles, relay lists), so a
+ * search-oriented or write-restricted relay is appropriate here.
+ */
+export const BUILTIN_DISCOVERY_RELAYS: readonly string[] = [
+  "wss://purplepag.es",
+  "wss://relay.nostr.band",
+  "wss://nostr-pub.wellorder.net",
+  "wss://relay.primal.net",
+];
 
 /** Well-known static HTTPS fallback URLs for the signed relay-list document (§19.1). */
 export const BOOTSTRAP_HTTPS_FALLBACK_URLS: readonly string[] = [];
diff --git a/packages/core/src/nostr/nostr.test.ts b/packages/core/src/nostr/nostr.test.ts
index 9298a96..20a3599 100644
--- a/packages/core/src/nostr/nostr.test.ts
+++ b/packages/core/src/nostr/nostr.test.ts
@@ -16,7 +16,10 @@ import {
 import { RelayPool } from "./pool.js";
 import { MockRelay } from "../test-support/mockRelay.js";
 import {
+  BUILTIN_DISCOVERY_RELAYS,
+  BUILTIN_VAULT_RELAYS,
   MAINTAINER_PUBLIC_KEY_HEX,
+  WRITE_HOSTILE_RELAYS,
   mergeRelayLists,
   parseAndVerifyBootstrapList,
   type BootstrapRelayList,
@@ -427,3 +430,38 @@ describe("RelayPool quorum", () => {
     pool.closeAll();
   });
 });
+
+/*
+ * The built-in relay lists are a shipped configuration that decides whether a
+ * user can create an account at all, so they get the same treatment as any
+ * other invariant: pinned, with the reasoning attached.
+ *
+ * Hermetic on purpose -- no relay is contacted here. Reachability is a
+ * property of the network the user is on and cannot be asserted in CI;
+ * WRITE POLICY is a property of the relay and can.
+ */
+describe("built-in relay lists", () => {
+  it("keeps write-hostile relays out of the vault (publish) list", () => {
+    // nostr.wine advertises payment_required + restricted_writes in its own
+    // NIP-11 document, so it can never accept a free user's capsule. It sat
+    // in this list occupying one of five write slots it could not fill.
+    for (const hostile of WRITE_HOSTILE_RELAYS) {
+      expect(BUILTIN_VAULT_RELAYS).not.toContain(hostile);
+    }
+  });
+
+  it("leaves enough margin over the publish floor to lose relays", () => {
+    // publishAndVerify enforces minAcks/minReadbacks = 2 regardless of list
+    // size. Two usable relays against a floor of two is zero margin: one
+    // unreachable relay fails registration outright. Require room to lose
+    // several and still clear the floor.
+    expect(BUILTIN_VAULT_RELAYS.length).toBeGreaterThanOrEqual(6);
+  });
+
+  it("ships no duplicates and only secure websocket URLs", () => {
+    for (const list of [BUILTIN_VAULT_RELAYS, BUILTIN_DISCOVERY_RELAYS]) {
+      expect(new Set(list).size).toBe(list.length);
+      for (const url of list) expect(url.startsWith("wss://")).toBe(true);
+    }
+  });
+});