diff --git a/docs/TROUBLESHOOTING.md b/docs/TROUBLESHOOTING.md
index fbde23d..d01d86e 100644
--- a/docs/TROUBLESHOOTING.md
+++ b/docs/TROUBLESHOOTING.md
@@ -163,9 +163,9 @@ LaunchServices now opens `http`, `https` and `mailto` links on the Linux desktop
 
 ## Riot client shows "Not Found" instead of its UI
 
-The client window opens but only shows `Not Found`, and its log has `ENOENT, dist/renderer/index.html not found in …/app.asar` although the archive contains that file. Electron cannot hand out a descriptor into `app.asar`, so its asynchronous `fs.open` copies the file to a temporary file first (`copyFileOut`) and reports a failed copy as "not found". Chromium on macOS takes its temporary directory from `NSTemporaryDirectory()`, not `TMPDIR`, and that directory is unusable here, so every copy fails. Synchronous reads such as `fs.readFileSync` do not copy and keep working, which is why the rest of the client starts.
+On affected setups, including the reported NixOS installation, the client window opens but only shows `Not Found`, and its log has `ENOENT, dist/renderer/index.html not found in …/app.asar` although the archive contains that file. Electron's asynchronous file opening can copy an archive entry to a temporary file first (`copyFileOut`), and a failed copy can be reported as "not found". Chromium checks `MAC_CHROMIUM_TMPDIR` before falling back to `NSTemporaryDirectory()`; an unusable default temporary directory can therefore produce this symptom even while synchronous archive reads work.
 
-The launcher sets `MAC_CHROMIUM_TMPDIR=/private/tmp`, which Chromium checks first; `scripts/install-runtime.sh` already creates that guest directory with mode `1777`. To check the archive outside the client, run the client binary as Node (`ELECTRON_RUN_AS_NODE=1`) with a script that calls `fs.createReadStream` on a file inside `app.asar`: it fails without the variable and reads the file with it.
+The launcher defaults `MAC_CHROMIUM_TMPDIR` to `/private/tmp`, preserving a non-empty override. `scripts/install-runtime.sh` creates that guest directory with mode `1777`. Verify directory creation and temporary-file writes with a standalone guest probe, then launch the client normally and check whether its UI loads. Do not run diagnostic scripts through Riot's executable. This workaround addresses temporary-file failures; an actually missing or damaged archive needs separate investigation.
 
 ## Language dropdown closes Riot, or client resize leaves a clipped UI
 
diff --git a/tools/run-riot-client.sh b/tools/run-riot-client.sh
index 21fc89f..770568d 100755
--- a/tools/run-riot-client.sh
+++ b/tools/run-riot-client.sh
@@ -98,11 +98,9 @@ export __GL_YIELD="${__GL_YIELD:-NOTHING}"
 if [ -w /proc/self/timerslack_ns ]; then
   echo 1 > /proc/self/timerslack_ns 2>/dev/null || true
 fi
-# Chromium takes its temp directory from NSTemporaryDirectory(), which is unusable
-# under Darling, so every temp file fails. Electron opens files in app.asar
-# asynchronously by copying them to a temp file and reports the failed copy as
-# "not found": the Riot client then shows a "Not Found" page instead of its UI.
-# MAC_CHROMIUM_TMPDIR overrides the directory.
+# On affected setups Chromium's default temp directory is unusable. Electron
+# can copy app.asar entries to temporary files for async reads and report a
+# failed copy as "not found". Use a writable guest directory by default.
 exec env -u ELECTRON_RUN_AS_NODE -u DYLD_INSERT_LIBRARIES EGL_PLATFORM=x11 \
   MAC_CHROMIUM_TMPDIR="${MAC_CHROMIUM_TMPDIR:-/private/tmp}" \
   LANG="${RCLOL_GUEST_LOCALE:-en_US.UTF-8}" LC_ALL="${RCLOL_GUEST_LOCALE:-en_US.UTF-8}" \