diff --git a/js/nostr/client.js b/js/nostr/client.js
index 96cf4bba..d6b5bbaf 100644
--- a/js/nostr/client.js
+++ b/js/nostr/client.js
@@ -211,11 +211,38 @@ function attachNipMethodAliases(signer) {
   }
 }
 
+function hydrateExtensionSignerCapabilities(signer) {
+  if (!signer || typeof signer !== "object" || signer.type !== "extension") {
+    return;
+  }
+
+  const extension =
+    typeof window !== "undefined" && window && window.nostr ? window.nostr : null;
+  if (!extension) {
+    return;
+  }
+
+  if (typeof signer.signEvent !== "function" && extension.signEvent) {
+    if (typeof extension.signEvent === "function") {
+      signer.signEvent = extension.signEvent.bind(extension);
+    }
+  }
+
+  if (!signer.nip04 && extension.nip04) {
+    signer.nip04 = extension.nip04;
+  }
+
+  if (!signer.nip44 && extension.nip44) {
+    signer.nip44 = extension.nip44;
+  }
+}
+
 function setActiveSigner(signer) {
   if (!signer || typeof signer !== "object") {
     return;
   }
 
+  hydrateExtensionSignerCapabilities(signer);
   attachNipMethodAliases(signer);
 
   activeSigner = signer;
@@ -242,6 +269,7 @@ function resolveActiveSigner(pubkey) {
     const normalized = pubkey.trim().toLowerCase();
     const direct = activeSignerRegistry.get(normalized);
     if (direct) {
+      hydrateExtensionSignerCapabilities(direct);
       return direct;
     }
     if (
@@ -249,9 +277,11 @@ function resolveActiveSigner(pubkey) {
       typeof activeSigner.pubkey === "string" &&
       activeSigner.pubkey.trim().toLowerCase() === normalized
     ) {
+      hydrateExtensionSignerCapabilities(activeSigner);
       return activeSigner;
     }
   }
+  hydrateExtensionSignerCapabilities(activeSigner);
   return activeSigner;
 }
 
diff --git a/tests/nostr/signers.test.mjs b/tests/nostr/signers.test.mjs
new file mode 100644
index 00000000..a4cb2591
--- /dev/null
+++ b/tests/nostr/signers.test.mjs
@@ -0,0 +1,38 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const {
+  setActiveSigner,
+  resolveActiveSigner,
+  clearActiveSigner,
+} = await import("../../js/nostr.js");
+
+test("setActiveSigner hydrates extension capabilities from window.nostr", async () => {
+  clearActiveSigner();
+  const originalWindow = globalThis.window;
+  const signEvent = async (event) => ({ ...event, id: "signed", sig: "sig" });
+  const extension = {
+    signEvent,
+    nip04: { encrypt: () => "cipher", decrypt: () => "plain" },
+    nip44: { encrypt: () => "cipher44", decrypt: () => "plain44" },
+  };
+  globalThis.window = { nostr: extension };
+
+  try {
+    setActiveSigner({ type: "extension", pubkey: "deadbeef" });
+    const signer = resolveActiveSigner("deadbeef");
+    assert.ok(signer, "signer should be returned");
+    assert.equal(typeof signer.signEvent, "function", "signEvent should be hydrated");
+    const result = await signer.signEvent({ pubkey: "deadbeef", kind: 1, content: "" });
+    assert.equal(result.id, "signed", "hydrated signEvent should be used");
+    assert.equal(typeof signer.nip04Encrypt, "function", "nip04 alias should be attached");
+    assert.equal(typeof signer.nip44Encrypt, "function", "nip44 alias should be attached");
+  } finally {
+    clearActiveSigner();
+    if (originalWindow === undefined) {
+      delete globalThis.window;
+    } else {
+      globalThis.window = originalWindow;
+    }
+  }
+});