Put invoke timing logs behind VITE_LOG_INVOKE_TIMINGS

They flooded the dev console and test logs; perf work can turn them on.

CLAUDE.md

@@ -28,6 +28,9 @@ npm run tauri dev       # full Tauri dev build with hot reload
 npm run start:http      # Vite dev server backed by test-http-api (no Tauri runtime)
 ```
 
+Set `VITE_LOG_INVOKE_TIMINGS=true` to log each command's duration
+(`[invoke] <command> <ms>ms`) to the browser console. It is off by default.
+
 ### Checks and linting (tsc, svelte-check, eslint, prettier)
 
 ```sh

README.md

@@ -40,6 +40,14 @@ To start the app in development mode with hot reload:
 npm run dev
 ```
 
+To log how long every backend command takes, for performance work, set
+`VITE_LOG_INVOKE_TIMINGS=true`. Each call then prints `[invoke] <command> <ms>ms`
+to the browser console (visible at debug level):
+
+```
+VITE_LOG_INVOKE_TIMINGS=true npm run dev
+```
+
 ## Releasing
 
 Releases are driven by an interactive, phased script. Start one with:

src/lib/invoke.ts

@@ -16,7 +16,7 @@ export async function invoke<T = null>(
   args?: tauri.InvokeArgs,
   options?: tauri.InvokeOptions,
 ): Promise<T> {
-  if (import.meta.env.DEV) {
+  if (import.meta.env.VITE_LOG_INVOKE_TIMINGS === "true") {
     const start = performance.now();
     try {
       return await withTestBackend<T>(tauri.invoke, cmd, args, options);

src/vite-env.d.ts

@@ -1,2 +1,7 @@
 /// <reference types="svelte" />
 /// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  // eslint-disable-next-line @typescript-eslint/naming-convention
+  readonly VITE_LOG_INVOKE_TIMINGS?: string;
+}