From 1e08d1e0014c5c51cf807c529cc409874da2823e Mon Sep 17 00:00:00 2001
From: Oscar Beaumont <oscar@otbeaumont.me>
Date: Fri, 8 May 2026 08:32:59 +0800
Subject: [PATCH] allow reuse of channels

---
 example/src/lib/bindings.ts |  4 +++-
 taurpc/src/export.rs        | 24 +++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/example/src/lib/bindings.ts b/example/src/lib/bindings.ts
index f22b023..e22109c 100644
--- a/example/src/lib/bindings.ts
+++ b/example/src/lib/bindings.ts
@@ -1,6 +1,8 @@
 // My header
 // This file has been generated by TauRPC. Do not edit this file manually.
 
+import { Channel } from '@tauri-apps/api/core';
+
 export type Error = string;
 
 export type PhaseSpecificRename = PhaseSpecificRename_Serialize | PhaseSpecificRename_Deserialize;
@@ -73,7 +75,7 @@ export const RESULT_MAP = {
   }
 };
 
-export const TRANSFORM_MAP = { "": { "semantic_types_event": { args: [(v) => ({...v,bytes:[...v.bytes]})], eventArgs: [(v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)})], result: null }, "semantic_types": { args: [(v) => ({...v,bytes:[...v.bytes]}), (v) => { const transform = (response) => ({...response,date:new Date(response.date),bytes:new Uint8Array(response.bytes),url:new URL(response.url)}); if (typeof v === "function") return (response) => v(transform(response)); const onmessage = v.onmessage; v.onmessage = (response) => onmessage(transform(response)); return v }], eventArgs: [(v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)}), null], result: (v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)}) } } };
+export const TRANSFORM_MAP = { "": { "semantic_types_event": { args: [(v) => ({...v,bytes:[...v.bytes]})], eventArgs: [(v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)})], result: null }, "semantic_types": { args: [(v) => ({...v,bytes:[...v.bytes]}), (v) => { const transform = (response) => ({...response,date:new Date(response.date),bytes:new Uint8Array(response.bytes),url:new URL(response.url)}); if (typeof v === "function") return (response) => v(transform(response)); return new Channel((response) => v.onmessage(transform(response))) }], eventArgs: [(v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)}), null], result: (v) => ({...v,date:new Date(v.date),bytes:new Uint8Array(v.bytes),url:new URL(v.url)}) } } };
 
 export type Router = {
 	"": {
diff --git a/taurpc/src/export.rs b/taurpc/src/export.rs
index 1d968fc..2dfa95c 100644
--- a/taurpc/src/export.rs
+++ b/taurpc/src/export.rs
@@ -49,6 +49,10 @@ pub(super) fn export_types(
         .framework_runtime(move |mut exporter| {
             let mut out = String::new();
 
+            if requires_channel_transform(&functions, &exporter, &export_runtime_for_runtime) {
+                out.push_str("import { Channel } from '@tauri-apps/api/core';\n\n");
+            }
+
             out.push_str(&exporter.render_types()?);
 
             out.push_str(
@@ -379,6 +383,24 @@ fn apply_semantic_type_for_phase(
     }
 }
 
+fn requires_channel_transform(
+    functions: &BTreeMap<String, Vec<Function>>,
+    exporter: &FrameworkExporter,
+    export_runtime: &ExportRuntimeConfig,
+) -> bool {
+    if export_runtime.semantic_types.is_none() {
+        return false;
+    }
+
+    functions.values().flatten().any(|function| {
+        function.args().iter().any(|(_, arg_dt)| {
+            tauri_channel_reference(arg_dt, exporter.types)
+                .and_then(|channel| named_reference_generics(channel).first())
+                .is_some()
+        })
+    })
+}
+
 fn generate_transform_map(
     functions: &BTreeMap<String, Vec<Function>>,
     exporter: &FrameworkExporter,
@@ -418,7 +440,7 @@ fn generate_transform_map(
                     .filter(|runtime| runtime != "response")
                     .map(|runtime| {
                         format!(
-                            "{{ const transform = (response) => {runtime}; if (typeof v === \"function\") return (response) => v(transform(response)); const onmessage = v.onmessage; v.onmessage = (response) => onmessage(transform(response)); return v }}"
+                            "{{ const transform = (response) => {runtime}; if (typeof v === \"function\") return (response) => v(transform(response)); return new Channel((response) => v.onmessage(transform(response))) }}"
                         )
                     })
                 } else {