feat(services): add window.nostr fallback for hashtag preference decryption

This commit updates `HashtagPreferencesService.decryptEvent` to register and utilize decryption methods from `window.nostr` (NIP-04 and NIP-44) as a fallback mechanism. This ensures that users without an active internal signer (e.g., read-only or extension-only users) can still decrypt their preferences if they have granted permission to the extension.

- Mirrors the decryption logic from `UserBlockListManager` (`js/userBlocks.js`).
- Adds logging for fallback attempts and failures.
- Preserves existing scheme selection logic (`determineDecryptionOrder`).
- Adds new test cases to `tests/hashtag-preferences.test.mjs` verifying fallback behavior when the active signer is missing or incapable.

Co-authored-by: PR0M3TH3AN <[email protected]>

js/services/hashtagPreferencesService.js

@@ -726,22 +726,76 @@ class HashtagPreferencesService {
     }
 
     const decryptors = new Map();
-    const registerDecryptor = (scheme, handler) => {
+    const sources = new Map();
+    const registerDecryptor = (scheme, handler, source = "unknown") => {
       if (!scheme || typeof handler !== "function" || decryptors.has(scheme)) {
         return;
       }
       decryptors.set(scheme, handler);
+      sources.set(scheme, source);
     };
 
     if (signerHasNip44) {
-      registerDecryptor("nip44", (payload) => signer.nip44Decrypt(userPubkey, payload));
-      registerDecryptor("nip44_v2", (payload) =>
-        signer.nip44Decrypt(userPubkey, payload),
+      registerDecryptor(
+        "nip44",
+        (payload) => signer.nip44Decrypt(userPubkey, payload),
+        "active-signer",
+      );
+      registerDecryptor(
+        "nip44_v2",
+        (payload) => signer.nip44Decrypt(userPubkey, payload),
+        "active-signer",
       );
     }
 
     if (signerHasNip04) {
-      registerDecryptor("nip04", (payload) => signer.nip04Decrypt(userPubkey, payload));
+      registerDecryptor(
+        "nip04",
+        (payload) => signer.nip04Decrypt(userPubkey, payload),
+        "active-signer",
+      );
+    }
+
+    const nostrApi = typeof window !== "undefined" ? window?.nostr : null;
+    if (nostrApi) {
+      if (typeof nostrApi.nip04?.decrypt === "function") {
+        registerDecryptor(
+          "nip04",
+          (payload) => nostrApi.nip04.decrypt(userPubkey, payload),
+          "extension",
+        );
+      }
+
+      const nip44 =
+        nostrApi.nip44 && typeof nostrApi.nip44 === "object"
+          ? nostrApi.nip44
+          : null;
+      if (nip44) {
+        if (typeof nip44.decrypt === "function") {
+          registerDecryptor(
+            "nip44",
+            (payload) => nip44.decrypt(userPubkey, payload),
+            "extension",
+          );
+        }
+
+        const nip44v2 =
+          nip44.v2 && typeof nip44.v2 === "object" ? nip44.v2 : null;
+        if (nip44v2 && typeof nip44v2.decrypt === "function") {
+          registerDecryptor(
+            "nip44_v2",
+            (payload) => nip44v2.decrypt(userPubkey, payload),
+            "extension",
+          );
+          if (!decryptors.has("nip44")) {
+            registerDecryptor(
+              "nip44",
+              (payload) => nip44v2.decrypt(userPubkey, payload),
+              "extension",
+            );
+          }
+        }
+      }
     }
 
     if (!decryptors.size) {
@@ -760,6 +814,14 @@ class HashtagPreferencesService {
       if (!decryptFn) {
         continue;
       }
+      const source = sources.get(scheme);
+
+      if (source === "extension") {
+        userLogger.info(
+          `${LOG_PREFIX} Attempting decryption via window.nostr fallback (${scheme})`,
+        );
+      }
+
       try {
         const plaintext = await decryptFn(ciphertext);
         if (typeof plaintext !== "string") {
@@ -771,6 +833,12 @@ class HashtagPreferencesService {
         }
         return { ok: true, plaintext, scheme };
       } catch (error) {
+        if (source === "extension") {
+          userLogger.warn(
+            `${LOG_PREFIX} window.nostr fallback decryption failed (${scheme})`,
+            error,
+          );
+        }
         attemptErrors.push({ scheme, error });
       }
     }

tests/hashtag-preferences.test.mjs

@@ -463,3 +463,95 @@ test(
   },
 );
 
+test(
+  "load falls back to window.nostr when active signer is missing",
+  { concurrency: false },
+  async (t) => {
+    const pubkey = "abcdef".repeat(10) + "1234";
+
+    // Ensure no active signer (override beforeEach)
+    clearActiveSigner();
+
+    // Mock window.nostr
+    window.nostr = {
+        nip04: {
+            decrypt: async (pk, ciphertext) => {
+                if (pk !== pubkey) throw new Error("Wrong pubkey");
+                if (ciphertext === "window-encrypted") {
+                    return JSON.stringify({
+                        version: 1,
+                        interests: ["WindowSuccess"],
+                        disinterests: []
+                    });
+                }
+                throw new Error("Decrypt failed");
+            }
+        }
+    };
+
+    // Mock pool list to return an event
+    nostrClient.pool = {
+        list: async () => [{
+            id: "evt1",
+            created_at: 1000,
+            pubkey,
+            content: "window-encrypted",
+            tags: [["encrypted", "nip04"]]
+        }]
+    };
+
+    relayManager.setEntries([{ url: "wss://relay.fallback", mode: "both" }], { allowEmpty: false, updateClient: false });
+
+    await hashtagPreferences.load(pubkey);
+
+    assert.deepEqual(hashtagPreferences.getInterests(), ["windowsuccess"]);
+  }
+);
+
+test(
+    "load falls back to window.nostr when active signer lacks decrypt capabilities",
+    { concurrency: false },
+    async (t) => {
+      const pubkey = "abcdef".repeat(10) + "5678";
+
+      // Set a signer that can sign but NOT decrypt (override beforeEach)
+      setActiveSigner({
+          signEvent: async (e) => ({ ...e, id: "fake" }),
+          // No nip04Decrypt or nip44Decrypt
+      });
+
+      // Mock window.nostr
+      window.nostr = {
+          nip04: {
+              decrypt: async (pk, ciphertext) => {
+                  if (pk !== pubkey) throw new Error("Wrong pubkey");
+                  if (ciphertext === "window-encrypted-2") {
+                      return JSON.stringify({
+                          version: 1,
+                          interests: ["SignerFallback"],
+                          disinterests: []
+                      });
+                  }
+                  throw new Error("Decrypt failed");
+              }
+          }
+      };
+
+      // Mock pool list to return an event
+      nostrClient.pool = {
+          list: async () => [{
+              id: "evt2",
+              created_at: 1000,
+              pubkey,
+              content: "window-encrypted-2",
+              tags: [["encrypted", "nip04"]]
+          }]
+      };
+
+      relayManager.setEntries([{ url: "wss://relay.fallback", mode: "both" }], { allowEmpty: false, updateClient: false });
+
+      await hashtagPreferences.load(pubkey);
+
+      assert.deepEqual(hashtagPreferences.getInterests(), ["signerfallback"]);
+    }
+  );