Merge pull request 'Work around WebKitGTK EGL crash on Wayland' (#38) from fix/wayland-webkit-egl-crash into main

Review found: "nothing this app's UI depends on" is backwards — the
terminal's @xterm/addon-webgl renderer is exactly the GPU compositing path
this setting disables, it just degrades gracefully (the addon's own
construction already handles WebGL being unavailable) rather than
crashing. And the "not simply Wayland vs X11" justification for going
unconditional doesn't hold up: WAYLAND_DISPLAY is exported into an
XWayland client's environment too, so gating on it would have caught that
case as well — the real reason to go unconditional is that there's no
reliable heuristic for the thing that actually matters (which
Mesa/driver/compositor combination is affected), not that the naive gate
misses XWayland specifically.

Also noted, not changed: the env var leaks to whatever the app spawns
afterwards (a cold-launched default browser via xdg-open), and the "=0
re-enables it" parenthetical isn't verified against WebKitGTK's own
source, so softened to say what's actually guaranteed (an already-set
value is left alone) rather than assume presence-vs-boolean parsing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FGjXq6fqtAFHdbhk4f3PfZ

app/src-tauri/src/main.rs

@@ -1,6 +1,54 @@
 // Prevents additional console window on Windows in release
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
+/// WebKitGTK's DMA-BUF renderer (its default accelerated-compositing path
+/// since 2.42) fails outright on some Mesa/driver/compositor combinations
+/// under Wayland, printing `Could not create default EGL display:
+/// EGL_BAD_PARAMETER. Aborting.` straight to stderr from WebKitGTK's own C
+/// code and killing the webview before Triple-C's own logging even starts —
+/// see triple-c#34, reported on CachyOS/Arch with Wayland.
+///
+/// Set unconditionally on Linux rather than gated on `WAYLAND_DISPLAY`: that
+/// variable is exported into an XWayland client's environment too, so a
+/// gate on it wouldn't even cleanly separate "Wayland" from "X11" — and
+/// there is no reliable heuristic at all for the actual variable that
+/// matters, which Mesa/driver/compositor combination is affected. This is
+/// the blunt instrument, chosen deliberately because the fallback is a real
+/// trade, not a free one: the terminal's `@xterm/addon-webgl` renderer
+/// (`TerminalView.tsx`) is the one surface in this app actually asking for
+/// GPU compositing, and it degrades to xterm's canvas renderer under this
+/// setting — slower on very heavy output, but the addon's own construction
+/// is already wrapped in a fallback (`WebGL not available` is a handled
+/// case, not a crash), so this is a real but graceful downgrade, traded
+/// against a startup abort that has no fallback at all.
+///
+/// Must be set before `triple_c_lib::run()` — GTK/WebKitGTK reads it at
+/// their own init time, which happens inside the Tauri builder that
+/// function calls into, not at binary load.
+///
+/// A user who has already set this themselves is left alone. That includes
+/// setting it to `0`, on the assumption WebKitGTK treats it as a boolean
+/// rather than presence-only — not verified against WebKitGTK's own source,
+/// so if it turns out to be presence-only, `=0` still reads as "set" here
+/// and disables DMA-BUF the same as any other value, which is at least the
+/// safe direction to be wrong in.
+///
+/// This env var also leaks to whatever the app spawns afterwards — notably
+/// a cold-launched default browser via the `opener` plugin's `xdg-open`
+/// call. Narrow in practice (an already-running browser just receives the
+/// URL; most non-WebKitGTK browsers ignore the variable entirely), but
+/// worth knowing before chasing the "links don't open" half of triple-c#34
+/// as a separate, unrelated cause.
+#[cfg(target_os = "linux")]
+fn apply_webkit_wayland_workaround() {
+    if std::env::var_os("WEBKIT_DISABLE_DMABUF_RENDERER").is_none() {
+        std::env::set_var("WEBKIT_DISABLE_DMABUF_RENDERER", "1");
+    }
+}
+
 fn main() {
+    #[cfg(target_os = "linux")]
+    apply_webkit_wayland_workaround();
+
     triple_c_lib::run()
 }