The resize handler painted synchronously via commit() but left the commit
scheduler's pending trailing throttle timer armed. If an update was sitting
in that timer, it fired a second doCommit() right after the resize paint —
and because shouldClearTerminalForFrame clears whenever the previous frame
overflowed the viewport, the second commit emitted a duplicate clearTerminal.
Cancel the pending trailing commit before the synchronous paint; the paint
already reflects the current tree, so the pending commit is redundant.
Regression test (test-first) in throttle.sequential.test.tsx reproduces the
double-clear (2 clears) and verifies the fix (1 clear). Closes#26 (item 1).
Enable sequence.concurrent: true in vite.config.ts so the non-PTY suite runs
concurrently like the PTY suite. Stress-verified stable (8/8 at maxForks=4);
the suite drops from ~13s to ~4-5s.
Three test patterns were incompatible with concurrency; handled per cause:
- Inline snapshots (background-color, borders): the module-level `expect`
loses snapshot test context under concurrency. Fixed in place by using the
context-local `expect` (async ({ expect }) => ...), so they stay concurrent.
- Process-global state (throttle/animation-scheduler use fake timers; leak
asserts on process exit/SIGINT listener counts and live yoga nodes): a
concurrent sibling clobbers the shared global mid-test. These genuinely
require serial execution, so they move to *.sequential.test.* files with
it.sequential / describe.sequential and a header explaining why.
`vp run ready` passes.
Yunfei He