diff --git a/CHECKPOINT-encryption.md b/CHECKPOINT-encryption.md
index eaf1f1b..0e9c4ab 100644
--- a/CHECKPOINT-encryption.md
+++ b/CHECKPOINT-encryption.md
@@ -1,4 +1,4 @@
-# Checkpoint — Profile rename + card-click selection + button wrap (2026-08-23)
+# Checkpoint — Responsive backend (concurrent IPC) + rename (2026-08-23)
 
 **App renamed to Keynectr (2026-08-23).** A stopping point you can return to if this session is closed. Everything below was
 verified green at the moment this file was written.
@@ -7,38 +7,57 @@ verified green at the moment this file was written.
 
 - Project: `/home/avi/Projects/Nostr_Keynctr` (renamed from `0_Nostr` after commit `1116dfd`;
   folder itself renamed from `Nostr-Keynectr` — see `2e4005d`)
-- Git repo: `master` @ `d618a5a` ("Add profile rename with metadata republish (GUI +
-  CLI)"). Before it: `64502c1` (button wrap), `653945a` (card-click selection),
-  `2e4005d` (folder-rename checkpoint), `24b34b6`, `6ead6f4`, `31ef305` (Keynectr
-  rebrand), `a6329d5` (metadata publishing), `db81f8d` (delete + undo).
+- Git repo: `master` @ `4d70b25` ("Make IPC concurrent so relay checks and feeds never
+  block the UI"). Before it: `d618a5a` (rename), `64502c1` (button wrap), `653945a`
+  (card-click selection), `2e4005d` (folder-rename checkpoint), `24b34b6`, `6ead6f4`,
+  `31ef305` (Keynectr rebrand), `a6329d5` (metadata publishing), `db81f8d`
+  (delete + undo).
 - Working tree is **clean** apart from this checkpoint update, which is committed right after.
 
 ## What was completed
 
-1. **Rename a profile (2026-08-23)** — new "Edit name" button on every Profiles card
+1. **Backend made responsive (2026-08-23, `4d70b25`)** — user-visible lag fixed:
+   Selecting a profile took ~10 s and renaming ~30 s. Root causes: the IPC server
+   processed requests strictly one-at-a-time; the Home screen fires a relay test per
+   enabled relay on mount (a dead relay burns the full 8 s timeout each), and
+   `feed_get` held the shared lock during multi-second relay fetches — so Select queued
+   behind them; metadata publishing also waited 10 s for connections and sent to relays
+   one-by-one with 15 s timeouts each (~30 s with one dead relay).
+   Changes:
+   - IPC server now handles requests **concurrently** (task per request; replies are
+     id-correlated so out-of-order is fine). Mutations stay serialized via the shared
+     mutex, which moved from `std::sync` to `tokio::sync` (`App`, `Signer::connect`,
+     `run_sign_task`, CLI `signer connect`).
+   - `relay_test` and `feed_get` no longer hold the shared lock during network I/O
+     (they copy settings / active-npub under a short lock first).
+   - Metadata publish now sends to all relays **in parallel** with shorter timeouts
+     (connect 5 s, send 8 s) → worst case ~13 s instead of ~100 s; typical rename is a
+     few seconds.
+2. **Rename a profile (2026-08-23)** — new "Edit name" button on every Profiles card
    opens a modal (prefilled with the current name); saving stores the new label and
    republishes kind 0 metadata to enabled relays (`d618a5a`). Wired end-to-end:
    `profiles::rename_profile` (Rust), `rename_profile` IPC request, Electron
    RENDERER_METHODS allowlist, `api.renameProfile`, AppProvider `renameProfile`,
-   RenameModal UI, fake-backend support + test. CLI: `keynectr rename <npub>
+   RenameModal UI, fake-backend support + test.    CLI: `keynectr rename <npub>
    <new-name>`. Empty names rejected; whitespace trimmed; works offline (change saved,
    publish retried later via "Publish name").
-2. **Click anywhere on a profile card to select it (2026-08-23)** — on the Profiles
+3. **Click anywhere on a profile card to select it (2026-08-23)** — on the Profiles
    screen, clicking an inactive profile's card now does the same as pressing its
    "Select" button (`653945a`). Clicks on buttons inside the card (Copy / Publish name /
    Picture / Edit name / Delete / Secret key / Select) do not trigger selection. The
    active card is not clickable and shows a hover highlight on inactive cards.
-3. **Action buttons wrap on narrow windows (2026-08-23)** — `.profile-card-actions` now
+4. **Action buttons wrap on narrow windows (2026-08-23)** — `.profile-card-actions` now
    uses `flex-wrap: wrap`, so at half-screen width the action buttons wrap onto extra
    rows inside the card instead of spilling past its border (`64502c1`).
-4. **Project folder renamed** to `Nostr_Keynctr` (`2e4005d`) — old path
+5. **Project folder renamed** to `Nostr_Keynctr` (`2e4005d`) — old path
    `Nostr-Keynectr` no longer exists; same project, new name.
-5. Earlier in the session: Keynectr rebrand across UI/package/binary (`31ef305`,
+6. Earlier in the session: Keynectr rebrand across UI/package/binary (`31ef305`,
    `6ead6f4`, `24b34b6`), metadata/picture publishing (`a6329d5`) — see previous
    checkpoint notes below for details.
 
 ## Commits added most recently
 
+- `4d70b25` Make IPC concurrent so relay checks and feeds never block the UI
 - `d618a5a` Add profile rename with metadata republish (GUI + CLI)
 - `64502c1` Wrap profile card action buttons on narrow windows
 - `653945a` Select a profile by clicking anywhere on its card
@@ -51,7 +70,7 @@ Rust (repo root):
 ```
 cargo test            # 99 passed; 0 failed
 cargo clippy --all-targets   # finishes; 2 pre-existing warnings in src/profiles.rs
-                              # (drop of reference at :170 area, unused delete_profile)
+                              # (drop of reference, unused delete_profile)
 cargo fmt --check     # clean
 cargo build --release # success
 ```
@@ -96,6 +115,12 @@ $B rename <npub> <new-name>               # rename + publish the new name
 
 ## Notes & next steps
 
+- **Architecture note (2026-08-23):** the shared `App` state mutex is now
+  `tokio::sync::Mutex` (`Arc<Mutex<App>>` in ipc.rs/signer.rs). Guards are held across
+  awaits by design; new handlers that touch vault/settings must lock it, while pure
+  network requests should copy inputs under a short lock and run lock-free.
+- If rename/publish latency still feels long, next step would be background
+  publishing (return immediately, report via notice later) instead of shorter timeouts.
 - Pre-existing clippy warnings in `src/profiles.rs` (drop of a reference, unused
   `delete_profile`) are untouched — worth cleaning up in a future pass.
 - Nostr has no relay-to-relay sync: names/pictures are only visible on relays they were