Stop the suite failing on things that are not test failures

Two sources of random red on WSL, neither of them a test.

A launch that never happened. The Godot binary is a Windows executable
started across the interop boundary, and with six going at once that start
occasionally just fails: exit 127, an empty log, no engine banner, nothing
run. It was indistinguishable from a failure and moved between tests from
run to run. Anything that actually ran got as far as printing the banner, so
the two are easy to tell apart; a start that produced no banner is retried
up to three times and reported as NOSTART if it never comes up. Retries are
printed, never hidden - a test that needed one is saying the machine is
struggling even where it went on to pass.

The working tree as a run directory. WSL ran the suite in place, so six
Godot processes wrote .godot and created and deleted files under
PlanetSetups/ inside the live repo, alongside git and whatever else was
using it. Single tests failed at random under that - a delete that did not
take, a scene that would not instantiate - never the same one twice. WSL now
copies to %LOCALAPPDATA% first, the same isolation Termux already gets from
its own copy, on a native NTFS path so the Windows Godot still reads it at
full speed. Costs about 10s a run and leaves the repo untouched.

Four consecutive clean 124/124 runs since.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/_run_inside.sh

@@ -22,6 +22,15 @@ VERBOSE="$1"; shift
 # complete in seconds, even on a busy phone, so make that failure explicit
 # rather than making the suite look hung. Override for deliberate long runs.
 TEST_TIMEOUT_SECONDS="${TEST_TIMEOUT_SECONDS:-120}"
+# How many times to start a test whose process never came up at all. Under
+# WSL the Godot binary is a Windows executable started across the interop
+# boundary, and with six of them going at once that start occasionally just
+# fails - exit 127, an empty log, no engine banner, nothing run. It looked
+# exactly like a test failure while being a property of the launch, and it
+# moved from test to test between runs. A test that genuinely fails always
+# gets far enough to print the banner, so the two are easy to tell apart and
+# only the launch is worth retrying.
+LAUNCH_ATTEMPTS="${LAUNCH_ATTEMPTS:-3}"
 
 cd "$PROJECT_DIR" || exit 2
 
@@ -56,18 +65,37 @@ run_one() {
   # 3 parallel runs. Pinned, a test simulates the same 60fps whatever else
   # the phone is doing, and its result no longer depends on how busy the
   # machine was.
-  timeout "$TEST_TIMEOUT_SECONDS" "$GODOT_BIN" --headless --fixed-fps 60 \
-    -s "res://tests/$name" >"$log" 2>&1
-  local rc=$?
+  local rc=0
+  local attempt=1
+  while true; do
+    timeout "$TEST_TIMEOUT_SECONDS" "$GODOT_BIN" --headless --fixed-fps 60 \
+      -s "res://tests/$name" >"$log" 2>&1
+    rc=$?
+    # "Never started" is rc != 0 with no banner in the log. Anything that
+    # ran - passed, failed, crashed mid-way - printed the banner first.
+    if (( rc == 0 )) || grep -q "Godot Engine" "$log" \
+        || (( attempt >= LAUNCH_ATTEMPTS )); then
+      break
+    fi
+    attempt=$(( attempt + 1 ))
+    sleep 1
+  done
   end=$(date +%s%N)
   local ms=$(( (end - start) / 1000000 ))
 
+  # Retries are reported, never hidden: a test that needed one is telling
+  # you the machine is struggling, even where it went on to pass.
+  local retried=""
+  if (( attempt > 1 )); then
+    retried=" (started on attempt $attempt)"
+  fi
+
   # Two independent criteria, because either one alone can lie: a test that
   # crashes before reaching its verdict exits non-zero without ever printing
   # FAIL, and a hypothetical `quit(0)` on a failing path would exit clean
   # while the log says otherwise.
   if (( rc == 0 )) && grep -q ": PASS" "$log"; then
-    printf 'PASS %6dms  %s\n' "$ms" "$name" > "$outdir/$name.status"
+    printf 'PASS %6dms  %s%s\n' "$ms" "$name" "$retried" > "$outdir/$name.status"
   elif (( rc == 124 )); then
     printf 'TIMEOUT %4dms  %s (limit %ss)\n' \
       "$ms" "$name" "$TEST_TIMEOUT_SECONDS" > "$outdir/$name.status"
@@ -78,8 +106,11 @@ run_one() {
     # indistinguishable from a hang.
     printf 'KILLED %4dms  %s (signal %d - out of memory? try JOBS=1)\n' \
       "$ms" "$name" "$(( rc - 128 ))" > "$outdir/$name.status"
+  elif (( rc != 0 )) && ! grep -q "Godot Engine" "$log"; then
+    printf 'NOSTART %3dms  %s (exit %d after %d attempts - the process never came up)\n' \
+      "$ms" "$name" "$rc" "$attempt" > "$outdir/$name.status"
   else
-    printf 'FAIL %6dms  %s (exit %d)\n' "$ms" "$name" "$rc" > "$outdir/$name.status"
+    printf 'FAIL %6dms  %s (exit %d)%s\n' "$ms" "$name" "$rc" "$retried" > "$outdir/$name.status"
   fi
   cat "$outdir/$name.status"
 }