fix(desktop): make Linux AppImage GStreamer work on non-Debian distros (#2176)

.github/workflows/release.yml

@@ -629,7 +629,7 @@ jobs:
           TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY }}
           TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY_PASSWORD }}
 
-      - name: Fix AppImage (remove infra libs, symlink system GStreamer)
+      - name: Fix AppImage (remove infra libs, shim host GStreamer)
         run: |
           mapfile -t APPIMAGES < <(find desktop/src-tauri/target/release/bundle/appimage -name '*.AppImage' -type f)
           if [[ ${#APPIMAGES[@]} -eq 0 ]]; then

desktop/scripts/fix-appimage.sh

@@ -19,12 +19,19 @@
 #     skew causes eglGetDisplay to return EGL_BAD_PARAMETER under Wayland, which
 #     WebKitWebProcess treats as fatal and aborts before the window ever appears.
 #
-#  2. GStreamer crash: linuxdeploy also bundles libgst*.so* (GStreamer core libs).
-#     AppRun unconditionally sets GST_PLUGIN_SYSTEM_PATH_1_0 to a dir inside the
-#     AppImage that the bundler never populates (bundleMediaFramework is false by
-#     default), so GStreamer's plugin discovery yields an empty registry. The
-#     "GStreamer element appsink not found" error kills the render process; as a
-#     side effect the broken run poisons ~/.cache/gstreamer-1.0/registry.x86_64.bin.
+#  2. GStreamer crash: linuxdeploy's compiled AppRun.wrapped force-sets
+#     GST_PLUGIN_SYSTEM_PATH_1_0 to $APPDIR/usr/lib/gstreamer-1.0 -- a dir the
+#     bundler never populates (bundleMediaFramework is off, and we strip the
+#     bundled libgst* core below to use the host's). Crucially, once that variable
+#     is set it *replaces* GStreamer's compiled-in default search path rather than
+#     adding to it, so the app finds ZERO plugins on every distro:
+#     "GStreamer element appsink not found" kills the WebKitWebProcess and the
+#     window never paints. An earlier revision of this script hid the failure on
+#     Debian only by symlinking usr/lib/gstreamer-1.0 to the Debian multiarch dir
+#     (/usr/lib/x86_64-linux-gnu/gstreamer-1.0); that symlink dangles on Arch and
+#     Fedora, and the "safe fallback to default discovery" it assumed does not
+#     exist -- a set GST_PLUGIN_SYSTEM_PATH_1_0 disables the default. A broken run
+#     also poisons ~/.cache/gstreamer-1.0/registry.x86_64.bin.
 #
 #  3. WebKit helper mismatch (latent): the bundled WebKit helpers
 #     (WebKitNetworkProcess/WebKitWebProcess) have RUNPATH=$ORIGIN only, and
@@ -35,11 +42,17 @@
 #     wrong -- spawning nothing, dying on unresolved bundled libs, or spawning
 #     the system helpers -- and the window never appears.
 #
-# Fix: remove the offending libs so the app uses the system copies (which are
-# newer and ABI-compatible on any distro shipping glib >= 2.72 / Ubuntu 22.04+),
-# and symlink the system GStreamer plugin directory so discovery works correctly.
-# No tauri.conf.json knob can do this — bundle.linux.appimage only exposes
-# bundleMediaFramework, files (copy-only, no remove/symlink), and bundleXdgOpen.
+# Fix: (a) remove the offending libs so the app uses the system copies (newer and
+# ABI-compatible on any distro shipping glib >= 2.72 / Ubuntu 22.04+), and
+# (b) install a launcher shim in front of the app binary that strips the
+# bundle-pointing GST_PLUGIN_* overrides AppRun.wrapped injects, letting the host
+# GStreamer resolve plugins via its own default path (correct on Debian, Arch, and
+# Fedora alike). The shim has to run *after* AppRun.wrapped: the wrapper rewrites
+# the variable last -- after every apprun-hook -- so any value set before it is
+# discarded (verified empirically; a runtime GST_PLUGIN_SYSTEM_PATH_1_0 passed
+# into the AppImage does not survive). No tauri.conf.json knob can do this --
+# bundle.linux.appimage only exposes bundleMediaFramework, files (copy-only, no
+# remove/symlink), and bundleXdgOpen.
 
 set -euo pipefail
 
@@ -61,16 +74,6 @@ APPIMAGE_NAME="$(basename "$APPIMAGE_ABS")"
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 DESKTOP_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
 
-# Detect multiarch triplet for GStreamer plugin path.
-case "$(uname -m)" in
-  x86_64)  MULTIARCH="x86_64-linux-gnu" ;;
-  aarch64) MULTIARCH="aarch64-linux-gnu" ;;
-  *)
-    echo "Error: unsupported architecture: $(uname -m)" >&2
-    exit 1
-    ;;
-esac
-
 WORKDIR="$(mktemp -d)"
 trap 'rm -rf "$WORKDIR"' EXIT
 
@@ -107,12 +110,58 @@ rm -f \
   "$LIBDIR"/libelf.so* \
   "$LIBDIR"/libffi.so*
 
-echo "==> Symlinking system GStreamer plugin directory"
-# On distros without the Debian multiarch layout (e.g. Arch), this symlink
-# dangles — GStreamer then falls back to its default plugin discovery, which
-# is a safe degradation (unlike the original empty in-bundle dir).
-rm -rf "$LIBDIR/gstreamer-1.0"
-ln -s "/usr/lib/$MULTIARCH/gstreamer-1.0" "$LIBDIR/gstreamer-1.0"
+echo "==> Installing GStreamer launcher shim on the app binary"
+# AppRun.wrapped force-sets GST_PLUGIN_SYSTEM_PATH_1_0 (and the 0.10-era
+# GST_PLUGIN_SYSTEM_PATH) to $APPDIR/usr/lib/gstreamer-1.0 — a dir we bundle no
+# plugins into. Because a set path *replaces* GStreamer's default instead of
+# extending it, the app finds zero plugins on any distro and WebKit aborts. The
+# wrapper rewrites the variable after every apprun-hook, so the only place to undo
+# it is a shim between AppRun.wrapped and the real binary. First confirm the
+# wrapper still injects the override; if a tauri/linuxdeploy bump drops it, the
+# shim becomes a harmless no-op, but we want a human to re-verify rather than
+# silently ship — so fail loudly (mirrors the libwayland guard above).
+APPRUN_WRAPPED="$WORKDIR/squashfs-root/AppRun.wrapped"
+if ! grep -aq "GST_PLUGIN_SYSTEM_PATH_1_0" "$APPRUN_WRAPPED"; then
+  echo "Error: AppRun.wrapped is missing or no longer references GST_PLUGIN_SYSTEM_PATH_1_0 — GStreamer path injection changed; re-verify fix-appimage.sh" >&2
+  exit 1
+fi
+
+APP_BIN="$WORKDIR/squashfs-root/usr/bin/buzz-desktop"
+if [[ ! -f "$APP_BIN" ]]; then
+  echo "Error: app binary usr/bin/buzz-desktop not found — bundler layout changed; update fix-appimage.sh" >&2
+  exit 1
+fi
+if [[ -e "$APP_BIN.bin" ]]; then
+  echo "Error: usr/bin/buzz-desktop.bin already exists — shim already installed?" >&2
+  exit 1
+fi
+
+# The real binary moves aside; buzz-desktop becomes a shim AppRun.wrapped execs.
+mv "$APP_BIN" "$APP_BIN.bin"
+cat > "$APP_BIN" <<'SHIM'
+#!/usr/bin/env bash
+# GStreamer shim installed by desktop/scripts/fix-appimage.sh.
+#
+# linuxdeploy's AppRun.wrapped force-sets GST_PLUGIN_SYSTEM_PATH_1_0 to an empty
+# in-bundle dir ($APPDIR/usr/lib/gstreamer-1.0). A set path *replaces* the host's
+# default GStreamer search path, so the app finds zero plugins and WebKit aborts
+# (blank window). Drop the bundle-pointing GST_PLUGIN_* overrides so the system
+# GStreamer — which we use, having removed the bundled core libs — resolves
+# plugins via its own default path on any distro. Values that don't point into
+# this AppImage are the user's own and are preserved.
+here="$(dirname "$(readlink -f "$0")")"
+appdir="$(readlink -f "$here/../..")"
+for var in GST_PLUGIN_SYSTEM_PATH_1_0 GST_PLUGIN_SYSTEM_PATH \
+           GST_PLUGIN_PATH_1_0 GST_PLUGIN_PATH \
+           GST_PLUGIN_SCANNER GST_PLUGIN_SCANNER_1_0; do
+  val="${!var-}"
+  if [[ -n "$val" && "$val" == *"$appdir/"* ]]; then
+    unset "$var"
+  fi
+done
+exec -a "buzz-desktop" "$here/buzz-desktop.bin" "$@"
+SHIM
+chmod +x "$APP_BIN"
 
 echo "==> Repacking AppImage"
 # Pass a pinned type2 runtime when provided (CI sets APPIMAGETOOL_RUNTIME_FILE);

desktop/src-tauri/src/managed_agents/runtime.rs

@@ -855,7 +855,14 @@ pub(crate) fn collect_same_instance_orphans(
 
 /// Binary names for the Buzz desktop/Tauri process. Used by dead-instance
 /// detection to confirm the owning desktop is still alive.
-const DESKTOP_BINARY_NAMES: &[&str] = &["Buzz", "buzz-desktop", "buzz_desktop"];
+const DESKTOP_BINARY_NAMES: &[&str] = &[
+    "Buzz",
+    "buzz-desktop",
+    "buzz_desktop",
+    // Linux limits /proc/<pid>/comm to 15 visible bytes, truncating the
+    // AppImage shim's real executable name, `buzz-desktop.bin`.
+    "buzz-desktop.bi",
+];
 
 /// Check if a process name matches a known Buzz desktop binary.
 fn is_desktop_binary(name: &str) -> bool {

desktop/src-tauri/src/managed_agents/runtime/tests.rs

@@ -1,5 +1,12 @@
 use crate::managed_agents::known_acp_runtime;
 
+// ── desktop binary name tests ───────────────────────────────────────────
+
+#[test]
+fn appimage_binary_matches_truncated_linux_comm_name() {
+    assert!(super::is_desktop_binary("buzz-desktop.bi"));
+}
+
 // ── buffer_contains_identifier tests ────────────────────────────────────
 
 #[test]