With resize rendering now synchronous, no PTY test depends on wall-clock
timing, so concurrent execution is safe. Enable sequence.concurrent: true.
Each test already spawns its own isolated PTY subprocess (or in-process app)
with no shared state.
Verified stable: 12/12 runs green under sequence.concurrent with forks capped
to 4 (mimicking a 4-core CI runner) — the configuration that reliably flaked
before the resize fix. No it.sequential opt-outs are needed.
Yunfei He
a07fc889c4