Report firmware version in Zcash batch results

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3654bbb..6a8fe13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,8 @@
 
 ### What's new
 
-1. Added support for Zcash batch PCZT signing
+1. Added support for Zcash batch PCZT signing with compact signature results
+   that report the signing firmware version
 
 ### Bug Fixes
 
diff --git a/docs/protocols/ur_registrys/zcash.md b/docs/protocols/ur_registrys/zcash.md
index 6a2f71e..52bf878 100644
--- a/docs/protocols/ur_registrys/zcash.md
+++ b/docs/protocols/ur_registrys/zcash.md
@@ -59,7 +59,8 @@ zcash-pczt {
 The outer UR registry envelope carries a request id for response correlation and
 an opaque `data` field containing the PCZT-owned batch request. The matching
 compact response uses `zcash-batch-sig-result`, echoes the request id, and
-carries the PCZT-owned response in its own opaque `data` field.
+carries the PCZT-owned response in its own opaque `data` field. It also reports
+the signing firmware version once for the entire response.
 
 Batch version 1 is supported by cypherpunk firmware and currently accepts up to
 50 PCZTs. The encoded batch data and request id together, and the canonical PCZT
@@ -72,10 +73,11 @@ are rejected.
 
 #### Outer UR/CBOR envelopes
 
-Both registry types use definite-length CBOR maps with the same integer keys.
-Firmware requires `request-id` to be non-empty. Key `1` follows `zcash-pczt` by
-carrying opaque transaction data, and key `2` follows `zcash-sign-result` by
-carrying the request id.
+Both registry types use definite-length CBOR maps. Firmware requires
+`request-id` to be non-empty. Key `1` follows `zcash-pczt` by carrying opaque
+transaction data, and key `2` follows `zcash-sign-result` by carrying the
+request id. The result's required key `3` is the three-byte firmware version
+`[major, minor, build]` that produced the signatures.
 
 ```cddl
 zcash-sign-batch = {
@@ -86,6 +88,7 @@ zcash-sign-batch = {
 zcash-batch-sig-result = {
     1: bytes, ; BatchSignResponse::serialize output
     2: bytes, ; echoed request-id
+    3: bytes, ; firmware version [major, minor, build]
 }
 ```
 
diff --git a/rust/Cargo.lock b/rust/Cargo.lock
index e41bca9..59b6bf0 100644
--- a/rust/Cargo.lock
+++ b/rust/Cargo.lock
@@ -4814,7 +4814,7 @@ dependencies = [
 [[package]]
 name = "ur-registry"
 version = "1.0.5"
-source = "git+https://github.com/KeystoneHQ/keystone-sdk-rust.git?rev=bf5b6e4b5c533e8934c4611837db2b6567ae837e#bf5b6e4b5c533e8934c4611837db2b6567ae837e"
+source = "git+https://github.com/KeystoneHQ/keystone-sdk-rust.git?rev=f6b688eb9b6eb928f400b4cd7d2d623fdbc3b34d#f6b688eb9b6eb928f400b4cd7d2d623fdbc3b34d"
 dependencies = [
  "bs58",
  "hex",
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 3886a33..86bb8b6 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -131,6 +131,6 @@ zcash_protocol = { git = "https://github.com/zcash/librustzcash", rev = "878db20
 zcash_transparent = { git = "https://github.com/zcash/librustzcash", rev = "878db2074ae8ac2682d3e6c61c00f7018b6adc0c" }
 # Keep `orchard` aligned with the pinned PCZT/librustzcash revision.
 orchard = { git = "https://github.com/zcash/orchard", rev = "8995ee7e26f8b654a5457d05c95ee5b3132b3edd" }
-# Use the SDK rev that wraps PCZT-owned Postcard messages as opaque UR data and
-# correlates each request and result through the outer registry envelope.
-ur-registry = { git = "https://github.com/KeystoneHQ/keystone-sdk-rust.git", rev = "bf5b6e4b5c533e8934c4611837db2b6567ae837e" }
+# Use the SDK rev that wraps PCZT-owned Postcard messages as opaque UR data,
+# correlates requests and results, and reports one firmware version per batch result.
+ur-registry = { git = "https://github.com/KeystoneHQ/keystone-sdk-rust.git", rev = "f6b688eb9b6eb928f400b4cd7d2d623fdbc3b34d" }
diff --git a/rust/apps/zcash/src/version.rs b/rust/apps/zcash/src/version.rs
index 59479e1..7489b8d 100644
--- a/rust/apps/zcash/src/version.rs
+++ b/rust/apps/zcash/src/version.rs
@@ -1,9 +1,12 @@
-//! Firmware version stamped into every signed PCZT response via
-//! `global.proprietary["keystone:fw_version"]`.
+//! Firmware version reported by Zcash signing responses.
 //!
-//! 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.
+//! Single-PCZT responses stamp it into
+//! `global.proprietary["keystone:fw_version"]`. Compact batch responses carry
+//! the same encoding once in the outer `zcash-batch-sig-result` envelope.
+//!
+//! Wallets read this stamp to identify the firmware that produced a signature.
+//! The firmware does not interpret it as a minimum requirement; it only 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`.
diff --git a/rust/rust_c/src/zcash/mod.rs b/rust/rust_c/src/zcash/mod.rs
index 3105909..5573d9d 100644
--- a/rust/rust_c/src/zcash/mod.rs
+++ b/rust/rust_c/src/zcash/mod.rs
@@ -14,6 +14,8 @@ use alloc::{boxed::Box, format, string::String, string::ToString, vec::Vec};
 use app_zcash::get_address;
 #[cfg(feature = "cypherpunk")]
 use app_zcash::pczt::{sign::SpendAuthCache, structs::ParsedPczt};
+#[cfg(feature = "cypherpunk")]
+use app_zcash::version::KEYSTONE_FW_VERSION;
 use core::slice;
 use cryptoxide::hashing::sha256;
 use cty::c_char;
@@ -350,13 +352,14 @@ fn encode_checked_zcash_batch(request_id: &[u8], data: Vec<u8>) -> Result<Vec<u8
         })
 }
 
-/// Wraps the PCZT crate's signature response with its echoed request id.
+/// Wraps the PCZT crate's signature response with its echoed request id and
+/// the firmware version that produced the signatures.
 #[cfg(feature = "cypherpunk")]
 fn encode_zcash_batch_sig_result(
     request_id: Vec<u8>,
     data: Vec<u8>,
 ) -> Result<Vec<u8>, RustCError> {
-    ZcashBatchSigResult::new(request_id, data)
+    ZcashBatchSigResult::new(request_id, data, KEYSTONE_FW_VERSION.encode().to_vec())
         .try_into()
         .map_err(|e| RustCError::InvalidData(format!("encode Zcash batch result envelope: {e:?}")))
 }
@@ -1047,7 +1050,7 @@ mod tests {
 
     #[cfg(feature = "cypherpunk")]
     #[test]
-    fn test_encode_zcash_batch_sig_result_wraps_pczt_response() {
+    fn test_encode_zcash_batch_sig_result_wraps_response_with_firmware_version() {
         use zcash_vendor::{orchard::ValuePool, pczt::roles::signer::SpendAuthSignature};
 
         let request_id = vec![0xaa, 0xbb];
@@ -1071,6 +1074,7 @@ mod tests {
 
         assert_eq!(decoded.get_request_id(), request_id);
         assert_eq!(decoded.get_data(), response_bytes);
+        assert_eq!(decoded.get_firmware_version(), KEYSTONE_FW_VERSION.encode());
         assert_eq!(
             BatchSignResponse::parse(decoded.get_data()).unwrap(),
             response