diff --git a/src/store/mod.rs b/src/store/mod.rs
index e6537b7..9498aef 100644
--- a/src/store/mod.rs
+++ b/src/store/mod.rs
@@ -2,8 +2,46 @@ mod id_mapping;
 pub mod persistence;
 mod id_store;
 
+use heapless::String;
 pub use id_mapping::{IDMapping, Name};
 pub use id_store::{IDStore,AttendanceDay};
 
 pub type TallyID = [u8; 6];
 pub type Date = [u8; 10];
+
+pub fn hex_string_to_tally_id(s: &str) -> Option<TallyID> {
+    let bytes = s.as_bytes();
+    if bytes.len() != 12 {
+        return None;
+    }
+
+    let mut out: TallyID = [0;6];
+    for i in 0..6 {
+        let hi = hex_val(bytes[2 * i])?;
+        let lo = hex_val(bytes[2 * i + 1])?;
+        out[i] = (hi << 4) | lo;
+    }
+    Some(out)
+}
+
+pub fn tally_id_to_hex_string(bytes: TallyID) -> Option<String<12>> {
+    const HEX_CHARS: &[u8; 16] = b"0123456789abcdef";
+    let mut s: String<12> = String::new();
+
+    for &b in &bytes {
+        s.push(HEX_CHARS[(b >> 4) as usize] as char).ok()?;
+        s.push(HEX_CHARS[(b & 0x0F) as usize] as char).ok()?;
+    }
+
+    Some(s)
+}
+
+fn hex_val(b: u8) -> Option<u8> {
+    match b {
+        b'0'..=b'9' => Some(b - b'0'),
+        b'a'..=b'f' => Some(b - b'a' + 10),
+        b'A'..=b'F' => Some(b - b'A' + 10),
+        _ => None,
+    }
+}
+
diff --git a/src/webserver/api.rs b/src/webserver/api.rs
index 3afd134..ae11e18 100644
--- a/src/webserver/api.rs
+++ b/src/webserver/api.rs
@@ -6,8 +6,8 @@ use picoserve::{
 use serde::Deserialize;
 
 use crate::{
-    store::{Name, TallyID},
-    webserver::app::AppState,
+    store::{Name, hex_string_to_tally_id},
+    webserver::{app::AppState, sse::IDEvents},
 };
 
 #[derive(Deserialize)]
@@ -16,30 +16,6 @@ pub struct NewMapping {
     name: Name,
 }
 
-pub fn hex_string_to_tally_id(s: &str) -> Option<TallyID> {
-    let bytes = s.as_bytes();
-    if bytes.len() != 24 {
-        return None;
-    }
-
-    let mut out = [0u8; 12];
-    for i in 0..12 {
-        let hi = hex_val(bytes[2 * i])?;
-        let lo = hex_val(bytes[2 * i + 1])?;
-        out[i] = (hi << 4) | lo;
-    }
-    Some(out)
-}
-
-fn hex_val(b: u8) -> Option<u8> {
-    match b {
-        b'0'..=b'9' => Some(b - b'0'),
-        b'a'..=b'f' => Some(b - b'a' + 10),
-        b'A'..=b'F' => Some(b - b'A' + 10),
-        _ => None,
-    }
-}
-
 /*
  *  #[get("/api/idevent")]
  *  #[get("/api/csv")]