chore: resume Zcash firmware version changes

diff --git a/rust/apps/wallets/src/zcash.rs b/rust/apps/wallets/src/zcash.rs
index 4bdcdad..5663012 100644
--- a/rust/apps/wallets/src/zcash.rs
+++ b/rust/apps/wallets/src/zcash.rs
@@ -1,4 +1,4 @@
-use alloc::string::String;
+use alloc::string::{String, ToString};
 
 use alloc::vec::Vec;
 
@@ -19,6 +19,7 @@ impl_public_struct!(UFVKInfo {
 pub fn generate_sync_ur(
     key_infos: Vec<UFVKInfo>,
     seed_fingerprint: [u8; 32],
+    device_version: Option<&str>,
 ) -> URResult<ZcashAccounts> {
     let keys = key_infos
         .iter()
@@ -30,7 +31,10 @@ pub fn generate_sync_ur(
             ))
         })
         .collect::<URResult<Vec<ZcashUnifiedFullViewingKey>>>()?;
-    let accounts = ZcashAccounts::new(seed_fingerprint.to_vec(), keys);
+    let mut accounts = ZcashAccounts::new(seed_fingerprint.to_vec(), keys);
+    if let Some(version) = device_version {
+        accounts.set_device_version(version.to_string());
+    }
     Ok(accounts)
 }
 
@@ -56,7 +60,7 @@ mod tests {
             },
         ];
 
-        let result = generate_sync_ur(key_infos, seed_fingerprint);
+        let result = generate_sync_ur(key_infos, seed_fingerprint, Some("1.2.3"));
         assert!(result.is_ok());
 
         let accounts = result.unwrap();
diff --git a/rust/apps/zcash/build.rs b/rust/apps/zcash/build.rs
new file mode 100644
index 0000000..ff0e0b3
--- /dev/null
+++ b/rust/apps/zcash/build.rs
@@ -0,0 +1,48 @@
+use std::env;
+use std::fs;
+use std::io::Write;
+use std::path::Path;
+
+fn main() {
+    let version_h = Path::new("../../../src/config/version.h");
+    println!("cargo:rerun-if-changed={}", version_h.display());
+
+    let contents = fs::read_to_string(version_h).unwrap_or_else(|e| {
+        panic!(
+            "Failed to read {}: {e}. \
+             build.rs expects to run from rust/apps/zcash/ with the repo root three levels up.",
+            version_h.display()
+        )
+    });
+
+    let mut major: Option<u8> = None;
+    let mut minor: Option<u8> = None;
+    let mut build: Option<u8> = None;
+
+    for line in contents.lines() {
+        let line = line.trim();
+        if let Some(val) = line.strip_prefix("#define SOFTWARE_VERSION_MAJOR ") {
+            if !val.starts_with('(') {
+                major = Some(val.trim().parse().expect("SOFTWARE_VERSION_MAJOR is not a valid u8"));
+            }
+        } else if let Some(val) = line.strip_prefix("#define SOFTWARE_VERSION_MINOR ") {
+            minor = Some(val.trim().parse().expect("SOFTWARE_VERSION_MINOR is not a valid u8"));
+        } else if let Some(val) = line.strip_prefix("#define SOFTWARE_VERSION_BUILD ") {
+            build = Some(val.trim().parse().expect("SOFTWARE_VERSION_BUILD is not a valid u8"));
+        }
+    }
+
+    let major = major.expect("SOFTWARE_VERSION_MAJOR not found in version.h");
+    let minor = minor.expect("SOFTWARE_VERSION_MINOR not found in version.h");
+    let build = build.expect("SOFTWARE_VERSION_BUILD not found in version.h");
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let out_path = Path::new(&out_dir).join("version_generated.rs");
+    let mut f = fs::File::create(&out_path).unwrap();
+    writeln!(
+        f,
+        "/// Auto-generated from src/config/version.h — do not edit.\n\
+         pub const KEYSTONE_FW_VERSION: Version = Version({major}, {minor}, {build});"
+    )
+    .unwrap();
+}
diff --git a/rust/apps/zcash/src/lib.rs b/rust/apps/zcash/src/lib.rs
index 7dacd23..f932195 100644
--- a/rust/apps/zcash/src/lib.rs
+++ b/rust/apps/zcash/src/lib.rs
@@ -3,6 +3,7 @@ extern crate alloc;
 
 pub mod errors;
 pub mod pczt;
+pub mod version;
 
 use errors::{Result, ZcashError};
 
@@ -13,7 +14,6 @@ use alloc::{
 use pczt::structs::ParsedPczt;
 use zcash_vendor::{
     pczt::Pczt,
-    transparent::keys::{NonHardenedChildIndex, TransparentKeyScope},
     zcash_keys::keys::{UnifiedAddressRequest, UnifiedFullViewingKey},
     zcash_protocol::consensus::{self},
     zip32,
@@ -212,9 +212,9 @@ pub fn sign_pczt(pczt: &[u8], seed: &[u8]) -> Result<Vec<u8>> {
 mod tests {
     use alloc::vec::Vec;
 
+    use ::pczt::roles::creator::Creator;
     use consensus::MainNetwork;
     use keystore::algorithms::zcash::{calculate_seed_fingerprint, derive_ufvk};
-    use ::pczt::roles::creator::Creator;
     use rand_core::OsRng;
     use serde::{Deserialize, Serialize};
     use zcash_primitives::transaction::{
@@ -256,9 +256,15 @@ mod tests {
     }
 
     fn malformed_pczt_with_empty_sapling_bundle_and_nonzero_value_sum() -> Vec<u8> {
-        let mut bytes = Creator::new(BranchId::Nu6.into(), 10, MainNetwork.coin_type(), [0; 32], [0; 32])
-            .build()
-            .serialize();
+        let mut bytes = Creator::new(
+            BranchId::Nu6.into(),
+            10,
+            MainNetwork.coin_type(),
+            [0; 32],
+            [0; 32],
+        )
+        .build()
+        .serialize();
         let mut pczt: PcztMirror = postcard::from_bytes(&bytes[8..]).unwrap();
         assert!(pczt.sapling.spends.is_empty());
         assert!(pczt.sapling.outputs.is_empty());
@@ -330,13 +336,12 @@ mod tests {
         let ufvk_text = derive_ufvk(&params, &victim_seed, "m/32'/133'/0'").unwrap();
         let ufvk = UnifiedFullViewingKey::decode(&params, &ufvk_text).unwrap();
         let victim_fvk = ufvk.orchard().unwrap().clone();
-        let victim_account =
-            zcash_vendor::transparent::keys::AccountPrivKey::from_seed(
-                &params,
-                &victim_seed,
-                zip32::AccountId::ZERO,
-            )
-            .unwrap();
+        let victim_account = zcash_vendor::transparent::keys::AccountPrivKey::from_seed(
+            &params,
+            &victim_seed,
+            zip32::AccountId::ZERO,
+        )
+        .unwrap();
         let (victim_addr, address_index) = victim_account
             .to_account_pubkey()
             .derive_external_ivk()
@@ -394,8 +399,7 @@ mod tests {
         let pczt_bytes = pczt.serialize();
         let seed_fingerprint = calculate_seed_fingerprint(&victim_seed).unwrap();
 
-        let result =
-            parse_pczt_cypherpunk(&params, &pczt_bytes, &ufvk_text, &seed_fingerprint);
+        let result = parse_pczt_cypherpunk(&params, &pczt_bytes, &ufvk_text, &seed_fingerprint);
         match result {
             Err(ZcashError::InvalidPczt(_)) => {}
             Err(ZcashError::InvalidDataError(msg))
diff --git a/rust/apps/zcash/src/pczt/sign.rs b/rust/apps/zcash/src/pczt/sign.rs
index d8fadf8..ffa5d34 100644
--- a/rust/apps/zcash/src/pczt/sign.rs
+++ b/rust/apps/zcash/src/pczt/sign.rs
@@ -1,11 +1,17 @@
 use super::*;
+use crate::version::KEYSTONE_FW_VERSION;
+
+/// `global.proprietary` key stamped into every signed PCZT response.
+/// Value is 3 bytes `[major, minor, build]`. Wallets read this to check
+/// whether the device meets their minimum version requirements.
+const PROP_KEY_FW_VERSION: &str = "keystone:fw_version";
 use bitcoin::secp256k1;
 use blake2b_simd::Hash;
 use keystore::algorithms::secp256k1::get_private_key_by_seed;
 use rand_core::OsRng;
 use zcash_vendor::{
     pczt::{
-        roles::{low_level_signer, redactor::Redactor},
+        roles::{low_level_signer, redactor::Redactor, updater::Updater},
         Pczt,
     },
     pczt_ext::{self, PcztSigner},
@@ -112,11 +118,24 @@ pub fn sign_pczt(pczt: Pczt, seed: &[u8]) -> crate::Result<Vec<u8>> {
     let signer = pczt_ext::sign_orchard(signer, &SeedSigner { seed })
         .map_err(|e| ZcashError::SigningError(e.to_string()))?;
 
+    // Stamp the firmware version into `global.proprietary` so the wallet can
+    // tell exactly which version of Keystone firmware produced this signature.
+    // The Redactor below intentionally does not touch `global`, so this value
+    // survives the redaction pass into the returned bytes.
+    let stamped_pczt = Updater::new(signer.finish())
+        .update_global_with(|mut g| {
+            g.set_proprietary(
+                PROP_KEY_FW_VERSION.into(),
+                KEYSTONE_FW_VERSION.encode().to_vec(),
+            );
+        })
+        .finish();
+
     // Now that we've created the signature, remove the other optional fields from the
     // PCZT, to reduce its size for the return trip and make the QR code scanning more
     // reliable. The wallet that provided the unsigned PCZT can retain it for combining if
     // these fields are needed.
-    let signed_pczt = Redactor::new(signer.finish())
+    let signed_pczt = Redactor::new(stamped_pczt)
         .redact_orchard_with(|mut r| {
             r.redact_actions(|mut ar| {
                 ar.clear_spend_recipient();
@@ -204,11 +223,104 @@ mod tests {
         let result = sign_pczt(pczt, &seed);
         assert!(result.is_ok());
 
-        let signed_pczt = result.unwrap();
+        let signed_pczt_bytes = result.unwrap();
         // Verify result is a valid PCZT
-        assert!(Pczt::parse(&signed_pczt).is_ok());
+        let parsed = Pczt::parse(&signed_pczt_bytes).expect("signed PCZT must parse");
 
         // Verify redaction occurred (size should be smaller as witness data is removed)
-        assert!(signed_pczt.len() < pczt_bytes.len());
+        // (The updater stamp adds only a few dozen bytes; redaction strips kilobytes.)
+        assert!(signed_pczt_bytes.len() < pczt_bytes.len());
+
+        // The firmware version stamp must be present in every signed response,
+        // even when the request carried no explicit minimum version.
+        let stamp = parsed
+            .global()
+            .proprietary()
+            .get(PROP_KEY_FW_VERSION)
+            .expect("firmware version stamp must be present");
+        assert_eq!(stamp, &KEYSTONE_FW_VERSION.encode().to_vec());
+    }
+
+    /// Reusable helper: parse the bundled test PCZT and inject a
+    /// test proprietary entry at the global level to verify round-trip.
+    fn pczt_with_min_version(min_version: &[u8]) -> Pczt {
+        // Same real Orchard→transparent PCZT used by `test_sign_pczt_invalid_seed_fingerprint`.
+        let pczt_hex = "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";
+        let pczt_bytes = hex::decode(pczt_hex).unwrap();
+        let base = Pczt::parse(&pczt_bytes).unwrap();
+        let min_version = min_version.to_vec();
+        Updater::new(base)
+            .update_global_with(|mut g| {
+                g.set_proprietary("test:min_fw_version".to_string(), min_version);
+            })
+            .finish()
+    }
+
+    fn test_seed() -> Vec<u8> {
+        hex::decode("d561f5aba9db8b100a9a84197322e522f952171a388ad74eaab1ab9db815be3335c3099a0a2bb0fee57e630db5ed7251412b6bd4b905cf518627411fee3f32dd").unwrap()
+    }
+
+    #[test]
+    fn firmware_equal_version_stamps_response() {
+        // Demand the exact running version. Must pass and stamp the response.
+        let pczt = pczt_with_min_version(&KEYSTONE_FW_VERSION.encode());
+        let signed = sign_pczt(pczt, &test_seed()).expect("equal-version PCZT should sign");
+        let parsed = Pczt::parse(&signed).expect("signed PCZT must parse");
+
+        let stamp = parsed
+            .global()
+            .proprietary()
+            .get(PROP_KEY_FW_VERSION)
+            .expect("firmware version stamp must be present");
+        assert_eq!(stamp, &KEYSTONE_FW_VERSION.encode().to_vec());
+
+        // The min-version request key the wallet set should survive unchanged
+        // so the wallet can correlate response to request if it wants to.
+        let request_min = parsed
+            .global()
+            .proprietary()
+            .get("test:min_fw_version")
+            .expect("request min-version should round-trip");
+        assert_eq!(request_min, &KEYSTONE_FW_VERSION.encode().to_vec());
+    }
+
+    #[test]
+    fn firmware_older_min_version_still_stamps_response() {
+        // Wallet demands 1.0.0 — older than firmware. Must pass and stamp.
+        let pczt = pczt_with_min_version(&[1, 0, 0]);
+        let signed = sign_pczt(pczt, &test_seed()).expect("older-min PCZT should sign");
+        let parsed = Pczt::parse(&signed).expect("signed PCZT must parse");
+
+        let stamp = parsed
+            .global()
+            .proprietary()
+            .get(PROP_KEY_FW_VERSION)
+            .expect("firmware version stamp must be present");
+        assert_eq!(stamp, &KEYSTONE_FW_VERSION.encode().to_vec());
+    }
+
+    #[test]
+    fn malformed_min_version_round_trips_and_stamps() {
+        // The wallet is the authority on min-version; firmware does not
+        // validate the shape of wallet-set proprietary keys on the way in.
+        // A short/malformed value from the wallet should still round-trip,
+        // and the response must still carry the firmware stamp.
+        let pczt = pczt_with_min_version(&[1, 2]);
+        let signed = sign_pczt(pczt, &test_seed()).expect("malformed min bytes must not block signing");
+        let parsed = Pczt::parse(&signed).expect("signed PCZT must parse");
+
+        let stamp = parsed
+            .global()
+            .proprietary()
+            .get(PROP_KEY_FW_VERSION)
+            .expect("firmware version stamp must be present");
+        assert_eq!(stamp, &KEYSTONE_FW_VERSION.encode().to_vec());
+
+        let request_min = parsed
+            .global()
+            .proprietary()
+            .get("test:min_fw_version")
+            .expect("wallet-set min key must survive round trip");
+        assert_eq!(request_min.as_slice(), &[1u8, 2][..]);
     }
 }
diff --git a/rust/apps/zcash/src/version.rs b/rust/apps/zcash/src/version.rs
new file mode 100644
index 0000000..59479e1
--- /dev/null
+++ b/rust/apps/zcash/src/version.rs
@@ -0,0 +1,78 @@
+//! Firmware version stamped into every signed PCZT response via
+//! `global.proprietary["keystone:fw_version"]`.
+//!
+//! Wallets read this stamp to decide whether the device meets their
+//! minimum version requirements. The firmware itself does not enforce
+//! any minimum, it just reports its own version.
+//!
+//! Version encoding is three raw bytes `[major, minor, build]`, matching the
+//! `SOFTWARE_VERSION_MAJOR / MINOR / BUILD` triple in `src/config/version.h`.
+//!
+//! `KEYSTONE_FW_VERSION` is generated at compile time by `build.rs` from
+//! `src/config/version.h` — no manual sync needed.
+
+use crate::errors::ZcashError;
+use alloc::string::ToString;
+
+// Generated by build.rs from src/config/version.h.
+include!(concat!(env!("OUT_DIR"), "/version_generated.rs"));
+
+/// A `[major, minor, build]` firmware version triple.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Version(pub u8, pub u8, pub u8);
+
+impl Version {
+    /// Raw 3-byte encoding used in `global.proprietary` values.
+    pub fn encode(&self) -> [u8; 3] {
+        [self.0, self.1, self.2]
+    }
+
+    /// Parses the 3-byte encoding.
+    pub fn parse(bytes: &[u8]) -> Result<Self, ZcashError> {
+        if bytes.len() != 3 {
+            return Err(ZcashError::InvalidPczt(
+                "firmware version must be 3 bytes [major, minor, build]".to_string(),
+            ));
+        }
+        Ok(Version(bytes[0], bytes[1], bytes[2]))
+    }
+
+    pub fn major(&self) -> u8 {
+        self.0
+    }
+    pub fn minor(&self) -> u8 {
+        self.1
+    }
+    pub fn build(&self) -> u8 {
+        self.2
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    extern crate std;
+
+    #[test]
+    fn encode_round_trip() {
+        let v = KEYSTONE_FW_VERSION;
+        let encoded = v.encode();
+        assert_eq!(encoded, [v.major(), v.minor(), v.build()]);
+        assert_eq!(Version::parse(&encoded).unwrap(), v);
+    }
+
+    #[test]
+    fn parse_rejects_wrong_length() {
+        assert!(Version::parse(&[]).is_err());
+        assert!(Version::parse(&[1, 2]).is_err());
+        assert!(Version::parse(&[1, 2, 3, 4]).is_err());
+    }
+
+    #[test]
+    fn ordering_is_lexicographic() {
+        assert!(Version(12, 4, 0) < Version(12, 4, 1));
+        assert!(Version(12, 4, 0) < Version(12, 5, 0));
+        assert!(Version(12, 4, 0) < Version(13, 0, 0));
+        assert!(Version(12, 4, 0) == Version(12, 4, 0));
+    }
+}
diff --git a/rust/rust_c/src/wallet/cypherpunk_wallet/zcash.rs b/rust/rust_c/src/wallet/cypherpunk_wallet/zcash.rs
index 32752b6..22d94ce 100644
--- a/rust/rust_c/src/wallet/cypherpunk_wallet/zcash.rs
+++ b/rust/rust_c/src/wallet/cypherpunk_wallet/zcash.rs
@@ -18,6 +18,7 @@ pub unsafe extern "C" fn get_connect_zcash_wallet_ur(
     seed_fingerprint: PtrBytes,
     seed_fingerprint_len: u32,
     zcash_keys: Ptr<CSliceFFI<ZcashKey>>,
+    device_version: PtrString,
 ) -> *mut UREncodeResult {
     if seed_fingerprint_len != 32 {
         return UREncodeResult::from(URError::UrEncodeError(format!(
@@ -41,7 +42,12 @@ pub unsafe extern "C" fn get_connect_zcash_wallet_ur(
             )
         })
         .collect();
-    let result = generate_sync_ur(ufvks, seed_fingerprint);
+    let version = if device_version.is_null() {
+        None
+    } else {
+        Some(recover_c_char(device_version))
+    };
+    let result = generate_sync_ur(ufvks, seed_fingerprint, version.as_deref());
     match result.map(|v| v.try_into()) {
         Ok(v) => match v {
             Ok(data) => UREncodeResult::encode(
diff --git a/src/ui/gui_components/gui_keyboard.c b/src/ui/gui_components/gui_keyboard.c
index b50875e..59b0caa 100644
--- a/src/ui/gui_components/gui_keyboard.c
+++ b/src/ui/gui_components/gui_keyboard.c
@@ -1200,6 +1200,13 @@ char *GuiGetTrueWord(const lv_obj_t *obj, uint16_t btn_id)
 void KbTextAreaHandler(lv_event_t * e)
 {
     lv_event_code_t code = lv_event_get_code(e);
+#ifdef COMPILE_SIMULATOR
+    // Skip events this handler doesn't process. During view teardown the
+    // text area may already be freed, and the strlen below would crash.
+    if (code != LV_EVENT_VALUE_CHANGED && code != LV_EVENT_READY && code != LV_EVENT_CANCEL) {
+        return;
+    }
+#endif
     lv_obj_t *ta = lv_event_get_target(e);
     uint8_t taLen = strlen(lv_textarea_get_text(ta));
     KeyBoard_t *keyBoard = lv_event_get_user_data(e);
diff --git a/src/ui/gui_model/gui_model.c b/src/ui/gui_model/gui_model.c
index 1b2dc70..9caad95 100644
--- a/src/ui/gui_model/gui_model.c
+++ b/src/ui/gui_model/gui_model.c
@@ -116,15 +116,110 @@ static PasswordVerifyResult_t g_passwordVerifyResult;
 static bool g_stopCalChecksum = false;
 
 #ifdef COMPILE_SIMULATOR
+// On the real device, AsyncExecute posts to a FreeRTOS background task
+// (FIFO). On the simulator we approximate this with a FIFO queue drained
+// by a 1ms lv_timer — model functions run on the next main-loop tick,
+// after the current event chain unwinds. Using lv_async_call directly
+// doesn't work because lv_timer_create inserts at the list head (LIFO).
+// inData is deep-copied because callers often pass stack buffers.
+#include "lvgl.h"
+
+typedef enum {
+    ASYNC_KIND_FUNC,
+    ASYNC_KIND_FUNC_WITH_RUNNABLE,
+} AsyncKind_t;
+
+typedef struct AsyncQueueNode {
+    AsyncKind_t kind;
+    union {
+        BackgroundAsyncFunc_t func;
+        BackgroundAsyncFuncWithRunnable_t funcWithRunnable;
+    } u;
+    BackgroundAsyncRunnable_t runnable;
+    uint32_t dataLen;
+    struct AsyncQueueNode *next;
+    uint8_t data[];
+} AsyncQueueNode_t;
+
+static AsyncQueueNode_t *g_asyncQueueHead = NULL;
+static AsyncQueueNode_t *g_asyncQueueTail = NULL;
+static lv_timer_t *g_asyncDrainTimer = NULL;
+
+static void AsyncDrainTimerCb(lv_timer_t *timer)
+{
+    (void)timer;
+    // Snapshot the head so that any new enqueues from inside the callbacks
+    // (e.g. a model function that schedules another AsyncExecute) go at the
+    // tail and run on the next drain, not inside this one. This keeps each
+    // drain iteration bounded and mirrors the real device's "process the
+    // current batch, let signals unwind, handle next batch" semantics.
+    AsyncQueueNode_t *current = g_asyncQueueHead;
+    g_asyncQueueHead = NULL;
+    g_asyncQueueTail = NULL;
+    while (current != NULL) {
+        AsyncQueueNode_t *node = current;
+        current = current->next;
+        const void *data = node->dataLen > 0 ? node->data : NULL;
+        if (node->kind == ASYNC_KIND_FUNC) {
+            node->u.func(data, node->dataLen);
+        } else {
+            node->u.funcWithRunnable(data, node->dataLen, node->runnable);
+        }
+        free(node);
+    }
+}
+
+static void EnsureAsyncDrainTimer(void)
+{
+    if (g_asyncDrainTimer == NULL) {
+        // Period 1ms: effectively "run every lv_timer_handler iteration".
+        g_asyncDrainTimer = lv_timer_create(AsyncDrainTimerCb, 1, NULL);
+    }
+}
+
+static void EnqueueAsync(AsyncQueueNode_t *node)
+{
+    node->next = NULL;
+    if (g_asyncQueueTail != NULL) {
+        g_asyncQueueTail->next = node;
+    } else {
+        g_asyncQueueHead = node;
+    }
+    g_asyncQueueTail = node;
+    EnsureAsyncDrainTimer();
+}
+
 int32_t AsyncExecute(BackgroundAsyncFunc_t func, const void *inData, uint32_t inDataLen)
 {
-    func(inData, inDataLen);
+    AsyncQueueNode_t *node = malloc(sizeof(*node) + inDataLen);
+    if (node == NULL) {
+        return ERR_GENERAL_FAIL;
+    }
+    node->kind = ASYNC_KIND_FUNC;
+    node->u.func = func;
+    node->runnable = NULL;
+    node->dataLen = inDataLen;
+    if (inData != NULL && inDataLen > 0) {
+        memcpy(node->data, inData, inDataLen);
+    }
+    EnqueueAsync(node);
     return SUCCESS_CODE;
 }
 
 int32_t AsyncExecuteRunnable(BackgroundAsyncFuncWithRunnable_t func, const void *inData, uint32_t inDataLen, BackgroundAsyncRunnable_t runnable)
 {
-    func(inData, inDataLen, runnable);
+    AsyncQueueNode_t *node = malloc(sizeof(*node) + inDataLen);
+    if (node == NULL) {
+        return ERR_GENERAL_FAIL;
+    }
+    node->kind = ASYNC_KIND_FUNC_WITH_RUNNABLE;
+    node->u.funcWithRunnable = func;
+    node->runnable = runnable;
+    node->dataLen = inDataLen;
+    if (inData != NULL && inDataLen > 0) {
+        memcpy(node->data, inData, inDataLen);
+    }
+    EnqueueAsync(node);
     return SUCCESS_CODE;
 }
 #endif
diff --git a/src/ui/gui_widgets/multi/cypherpunk/gui_connect_wallet_widgets.c b/src/ui/gui_widgets/multi/cypherpunk/gui_connect_wallet_widgets.c
index b0fc21e..8d30390 100644
--- a/src/ui/gui_widgets/multi/cypherpunk/gui_connect_wallet_widgets.c
+++ b/src/ui/gui_widgets/multi/cypherpunk/gui_connect_wallet_widgets.c
@@ -1,5 +1,6 @@
 #include "gui_connect_wallet_widgets.h"
 #include "account_public_info.h"
+#include "version.h"
 #include "gui.h"
 #include "gui_button.h"
 #include "gui_hintbox.h"
@@ -358,7 +359,10 @@ UREncodeResult *GuiGetZecData(void)
     data[0].key_text = ufvk;
     data[0].key_name = GetWalletName();
     data[0].index = 0;
-    return get_connect_zcash_wallet_ur(sfp, 32, keys);
+    char firmwareVersion[32];
+    snprintf(firmwareVersion, sizeof(firmwareVersion), "%d.%d.%d",
+             SOFTWARE_VERSION_MAJOR, SOFTWARE_VERSION_MINOR, SOFTWARE_VERSION_BUILD);
+    return get_connect_zcash_wallet_ur(sfp, 32, keys, firmwareVersion);
 }
 
 void GuiPrepareArConnectWalletView(void)