diff --git a/core/archipelago/src/content_indeehub.rs b/core/archipelago/src/content_indeehub.rs
index 043c60b3..8ff96ce5 100644
--- a/core/archipelago/src/content_indeehub.rs
+++ b/core/archipelago/src/content_indeehub.rs
@@ -157,6 +157,16 @@ async fn nostr_session(client: &reqwest::Client, data_dir: &Path) -> Result<Stri
 /// a different endpoint, so they are set from the same values used to send.
 async fn sign_nip98(data_dir: &Path, url: &str, method: &str) -> Result<serde_json::Value> {
     let identity_dir = data_dir.join("identity");
+    // Prove the identity this node already has; never mint one here.
+    // `get_nostr_pubkey` goes through `load_or_create_nostr_keys`, so on a node
+    // without an identity it would GENERATE a keypair, sign with it, and write
+    // the secret to disk — an HTTP auth header quietly creating a new node
+    // identity, and authenticating to IndeeHub as a stranger with a key nobody
+    // has ever seen. The `.context("node has no Nostr identity")` below could
+    // never fire because of it.
+    if !nostr_discovery::nostr_identity_exists(&identity_dir).await {
+        anyhow::bail!("node has no Nostr identity");
+    }
     let pubkey = nostr_discovery::get_nostr_pubkey(&identity_dir)
         .await
         .context("node has no Nostr identity")?;
diff --git a/core/archipelago/src/nostr_discovery.rs b/core/archipelago/src/nostr_discovery.rs
index 13a84753..f37b89ff 100644
--- a/core/archipelago/src/nostr_discovery.rs
+++ b/core/archipelago/src/nostr_discovery.rs
@@ -26,6 +26,20 @@ const D_TAG: &str = "archipelago-node";
 /// Relays we previously published to (for one-time revocation overwrite only)
 const LEGACY_RELAYS: &[&str] = &["wss://relay.damus.io", "wss://relay.nostr.info"];
 
+/// Does this node already have a Nostr identity on disk?
+///
+/// `load_or_create_nostr_keys` mints one when it finds none. That is right at
+/// bootstrap and wrong for anything that AUTHENTICATES as this node: signing
+/// with a key generated on the spot proves nothing, presents the node as a
+/// stranger to whatever it is authenticating to, and writes a new secret to
+/// disk as a side effect of what the caller thought was a read. Callers that
+/// must prove an EXISTING identity gate on this first and fail loudly.
+pub(crate) async fn nostr_identity_exists(identity_dir: &Path) -> bool {
+    fs::try_exists(identity_dir.join(NOSTR_SECRET_FILE))
+        .await
+        .unwrap_or(false)
+}
+
 /// Load or create Nostr keys (secp256k1) for node discovery.
 pub(crate) async fn load_or_create_nostr_keys(identity_dir: &Path) -> Result<Keys> {
     let secret_path = identity_dir.join(NOSTR_SECRET_FILE);