diff --git a/apps/desktop/src/backend/DesktopBackendConfiguration.test.ts b/apps/desktop/src/backend/DesktopBackendConfiguration.test.ts
index 66fffb84f10989d6b079ae20095ed04d5c445935..3b282c1c1db94c660bddf6605d55a22fc7db6d38 100644
--- a/apps/desktop/src/backend/DesktopBackendConfiguration.test.ts
+++ b/apps/desktop/src/backend/DesktopBackendConfiguration.test.ts
@@ -979,9 +979,11 @@ describe("DesktopBackendConfiguration", () => {
 
       const previousWslEnv = process.env.WSLENV;
       const previousDisabled = process.env.OTEL_SDK_DISABLED;
+      const previousTelemetry = process.env.T3CODE_TELEMETRY_ENABLED;
       try {
         delete process.env.WSLENV;
         process.env.OTEL_SDK_DISABLED = "true";
+        process.env.T3CODE_TELEMETRY_ENABLED = "false";
 
         yield* Effect.gen(function* () {
           const configuration = yield* DesktopBackendConfiguration.DesktopBackendConfiguration;
@@ -989,6 +991,8 @@ describe("DesktopBackendConfiguration", () => {
 
           assert.equal(config.env.OTEL_SDK_DISABLED, "true");
           assert.include((config.env.WSLENV ?? "").split(":"), "OTEL_SDK_DISABLED");
+          assert.equal(config.env.T3CODE_TELEMETRY_ENABLED, "false");
+          assert.include((config.env.WSLENV ?? "").split(":"), "T3CODE_TELEMETRY_ENABLED");
         }).pipe(
           Effect.provide(
             DesktopBackendConfiguration.layer.pipe(
@@ -1009,6 +1013,7 @@ describe("DesktopBackendConfiguration", () => {
       } finally {
         restoreEnv("WSLENV", previousWslEnv);
         restoreEnv("OTEL_SDK_DISABLED", previousDisabled);
+        restoreEnv("T3CODE_TELEMETRY_ENABLED", previousTelemetry);
       }
     }).pipe(Effect.scoped, Effect.provide(NodeServices.layer)),
   );
diff --git a/apps/desktop/src/backend/DesktopBackendConfiguration.ts b/apps/desktop/src/backend/DesktopBackendConfiguration.ts
index a19e4ef7179edb5d48152bf578ca2fbf9a700e07..289e3fb321f065abf7ac07956e7e15b9c2316d3d 100644
--- a/apps/desktop/src/backend/DesktopBackendConfiguration.ts
+++ b/apps/desktop/src/backend/DesktopBackendConfiguration.ts
@@ -101,6 +101,7 @@ const DESKTOP_BACKEND_ENV_NAMES = [
 const WSL_FORWARDED_ENV_NAMES = [
   "OPENAI_API_KEY",
   "ANTHROPIC_API_KEY",
+  "T3CODE_TELEMETRY_ENABLED",
   // Otherwise the WSL server keeps exporting to endpoints from the bootstrap.
   "T3CODE_OTEL_SDK_DISABLED",
   "OTEL_SDK_DISABLED",
diff --git a/apps/desktop/src/shell/DesktopShellEnvironment.test.ts b/apps/desktop/src/shell/DesktopShellEnvironment.test.ts
index 5111ea4ee53349fbb4c11d7919bbbcdc99038490..bf0fd1f6da70a13faa21cf13bbad0fc00d3e4f69 100644
--- a/apps/desktop/src/shell/DesktopShellEnvironment.test.ts
+++ b/apps/desktop/src/shell/DesktopShellEnvironment.test.ts
@@ -268,11 +268,13 @@ describe("DesktopShellEnvironment", () => {
           envOutput({
             PATH: "/home/linuxbrew/.linuxbrew/bin:/usr/bin",
             SSH_AUTH_SOCK: "/tmp/secretive.sock",
+            T3CODE_TELEMETRY_ENABLED: "false",
           }),
       });
 
       assert.equal(env.PATH, "/home/linuxbrew/.linuxbrew/bin:/usr/bin");
       assert.equal(env.SSH_AUTH_SOCK, "/tmp/secretive.sock");
+      assert.equal(env.T3CODE_TELEMETRY_ENABLED, "false");
     }),
   );
 
diff --git a/apps/desktop/src/shell/DesktopShellEnvironment.ts b/apps/desktop/src/shell/DesktopShellEnvironment.ts
index 1143ed057b2b88c3bc01096c1394fc1db739e259..01f194ea05445d9082b63c440295457b3ccbea84 100644
--- a/apps/desktop/src/shell/DesktopShellEnvironment.ts
+++ b/apps/desktop/src/shell/DesktopShellEnvironment.ts
@@ -85,6 +85,7 @@ const LOGIN_SHELL_ENV_NAMES = [
   "XDG_SESSION_DESKTOP",
   "XDG_SESSION_TYPE",
   "WAYLAND_DISPLAY",
+  "T3CODE_TELEMETRY_ENABLED",
 ] as const;
 const WINDOWS_PROFILE_ENV_NAMES = ["PATH", "FNM_DIR", "FNM_MULTISHELL_PATH"] as const;
 const LOCALE_ENV_NAMES = ["LANG", "LC_ALL", "LC_CTYPE"] as const;
@@ -450,6 +451,8 @@ const installPosixEnvironment = Effect.fn("desktop.shellEnvironment.installPosix
       "XDG_DATA_HOME",
       "XDG_RUNTIME_DIR",
       "WAYLAND_DISPLAY",
+      // The telemetry opt-out is documented as a shell variable; GUI launches never see it.
+      "T3CODE_TELEMETRY_ENABLED",
     ] as const) {
       if (!config.env[name] && shellEnvironment[name]) {
         config.env[name] = shellEnvironment[name];
diff --git a/docs/user/telemetry.md b/docs/user/telemetry.md
index 5fd4f91c9327ca2510abf83689574782afcef4f0..2f7e44825dc690ac1a3cea9f71235337aae14ce5 100644
--- a/docs/user/telemetry.md
+++ b/docs/user/telemetry.md
@@ -9,3 +9,6 @@ raw provider events, or child-agent output. Child-agent token use is excluded fr
 
 To disable collection, set `T3CODE_TELEMETRY_ENABLED=false` in the server's environment before
 starting it. This stops product events from being recorded or sent.
+
+The desktop app reads the variable from your shell profile (for example `~/.zshrc`) on macOS and
+Linux, so export it there and restart the app. On Windows, set it as a user environment variable.