The mocked process.send consumed vitest's own fork-pool IPC messages and immediately ran the post callback, whose disconnect() severed the test worker's channel (process.connected is true under forks) — the whole spec's results vanished and win32-dialog-bindings.ts/win32-dialog-worker.ts fell to near-zero coverage on CI. The mock now records without invoking the callback or disconnecting; the real close lifecycle stays with built-worker.e2e.ts. Verified under both the threads and forks pools.
The win32 tier is exactly the koffi IFileOpenDialog child process; any failure surfaces as-is. The pwsh -> Windows PowerShell 5.1 cascade, the shared WinForms script, and the triple-miss AggregateError are deleted: koffi is a packaged dependency whose availability the install guarantees, so no mechanism fallback exists (the browse backend remains the fallback at the composition level). The pwsh-first DPI picker-fix note is consolidated into a new simplification note recording the reversal.
The koffi IFileOpenDialog conversation runs in a spawned child process instead of a worker thread: the dialog is the child's first window, so Windows activates it without a foreground call, and a native fault stays contained to the child. The driver maps the child's message protocol onto a promise and services aborts by posting WM_CLOSE to the dialog thread's windows, killing the child when the close budget is exhausted. The built worker ships as lib/worker.cjs (the ./worker export) under plain node, and win32-dialog.spec.ts returns to the thread-safe pool.
The koffi redesign moved the dialog from a spawned child process (which
inherits a foreground-activation right from the spawning app) onto a worker
thread of the same process, so Windows shows the dialog without activating
it — it opens behind the app with a taskbar flash. The app has no native
HWND to hand the seam, so raise from the driver: on the 'showing' notice
(the worker posts it right before Show, before the dialog window exists),
attach this thread's input queue to the dialog thread's, call
SetForegroundWindow on its top-level window, and detach — retried on the
close cadence until the window appears, stopped on settle/abort/success,
never blocking the pick. Injectable seam mirrors closeThreadWindows; driver
tests pin the raise and its retry; the in-process note records the
mechanism (both languages, pairing re-recorded).
The Description paragraph attributed the modern dialog's bottom-strip
rendering to '.NET 10', an unverifiable version the code comment
deliberately avoids (the same invented-version class flagged in round one).
Say 'the modern FolderBrowserDialog' on both language sides; pairing
re-recorded. Round-five review finding.
The driver's switch over Win32DialogWorkerMessage handled all three current
kinds but had no default, so a fourth kind added to the worker protocol
would compile cleanly and silently no-op — settle() never called and the
pick dangles until worker exit. Add the local assertNever backstop (the
command-compact shape; this package does not depend on dsh-llm for the
helper) and the return the error case needs to avoid falling into it.
Round-five review finding.
The round-four review's v6 pass found three factual gaps and the v5 pass two
nits. Correct them before merge:
- The in-process note claimed a koffi signature mistake is 'contained to
the worker thread' — worker_threads share the process, so a native access
violation takes down the whole Node process with no PowerShell fallback.
State the real blast radius and record the deferred pkg-VFS worker-spawn
arm in Consequences (both languages, pairing re-recorded).
- The 2026-07-27 picker note claimed unconditional 'per-monitor-v2 DPI';
PMv2-less hosts (Server 2016 / Win10 1607) cascade to per-monitor or
system-aware. Say 'the best thread DPI awareness the host accepts'
(both languages, pairing re-recorded).
- built-worker.e2e.ts was not in any keyless gate (vitest.e2e config is
not part of the default unit run and builtBinSmokeGate's explicit list
missed it), so lib/worker.cjs load regressions passed keyless CI. Add it
to builtBinSmokeGate alongside the workflow-workerthread sibling.
- Remove the dead trailing 'void bindings' in win32-dialog-logic.spec.ts
and give native-picker.spec.ts the sibling module header it lacked.
The @module header still described the Windows adapter as the pre-PR 'STA
PowerShell FolderBrowserDialog' while the README and Agent Notes document
the koffi IFileOpenDialog primary with the PowerShell chain as fallback;
mirror the README's platform summary.
- setThreadDpiAwareness checks SetThreadDpiAwarenessContext's return value
and cascades per-monitor-v2 -> per-monitor -> system-aware; DPI stays a
deliberate cosmetic best-effort - a host accepting none (or lacking the
API, pre-1607) still gets the modern dialog instead of a downgrade to the
legacy fallback chain over a cosmetic concern.
- The mocked-koffi world now uses a distinctive 4-byte pointer width and
rejects mis-sized out-buffers and mis-divided vtable offsets, so a
regression to hardcoded 8s fails the suite (the ia32 bug class).
- A keyless built-worker e2e guard loads lib/worker.cjs under plain
worker_threads on POSIX (the workflow-workerthread shape).
- The 'loaded lazily' module claims are reworded to attribute laziness to
the dynamic import('koffi') calls, and the discarded close-attempt
rejection is named at its catch.
Review round two on the in-process dialog:
- Vtable slots and out-pointers use koffi.sizeof('void *') instead of a
hardcoded 8 - win32-ia32 (which Node and koffi both ship) would have read
method pointers from the wrong address and crashed in-process before any
fallback could run.
- runFolderDialog pairs every successful (incl. S_FALSE) CoInitializeEx
with CoUninitialize in the outermost finally, releasing the dialog first;
a failed init is deliberately unpaired. Pinned across fake-bindings and
mocked-koffi suites.
- The abort close budget starts unconditionally: a worker hung before the
showing notice (koffi import or COM init) now ends in terminate instead
of a dangling promise; WM_CLOSE posting still waits for the thread id.
- A triple miss (dialog + pwsh + 5.1) surfaces an AggregateError carrying
all three causes - the in-process tier's reason was previously
unrecoverable from the final PowerShell error.
- The stray '=>{ ' formatter artifacts are normalized to real blocks.
Both stale note claims from the review are fixed: the DPI note's
Consequences no longer claims an ENOENT classification or zero new
dependencies, and the 2026-07-27 picker note's Windows bullet now names
the in-process primary and keeps the PowerShell chain as fallback (both
languages, pairings re-recorded).
The workspace files constraint keys worker bundles on the ./worker export
(lib/worker.cjs, the workflow-workerthread shape); the descriptive source
entry stays win32-dialog-worker.ts and tsdown renames the bundle.
On a fast host the 1ms close budget can exhaust and reject between waitFor
ticks; a rejection with no listener yet counted as an unhandled error in the
Linux run.
The modern IFileOpenDialog becomes the primary win32 tier: a koffi-driven
COM conversation on a worker_threads worker (the modal Show never blocks
the host event loop), per-monitor-v2 DPI via SetThreadDpiAwarenessContext,
and abort service by re-posting WM_CLOSE to the dialog thread's windows,
with terminate+unref as the last resort (Node cannot interrupt a thread
blocked in native code, and such a worker must never hold the process open).
The PowerShell chain stays as the fallback tier with its trigger widened
from ENOENT to any pwsh failure, closing the review-flagged PowerShell 6
regression (no WinForms: exit 1, not ENOENT, so 5.1 never ran).
Layering keeps per-file coverage honest on every host: pure sequencing and
the driver test against fakes anywhere; the bindings run against a mocked
koffi COM world (the session-persistence-jsonl technique); POSIX hosts
drive the real spawn plumbing to its koffi-load rejection; win32 hosts run
a real open-and-abort-close smoke. The smoke joins processBoundTests: a
worker blocked in a native modal wedges the threads pool's teardown, while
a fork contains it. The worker bundles as its own CJS tsdown entry
(workflow-workerthread's pattern; no TLA), and the host module is imported
statically so the node-half bundle stays chunk-free.
Built-plane and real-COM behavior verified on native Windows: standalone
probes for the source worker, the built CJS worker, and the driver's abort
path all open and close the real dialog.
Agent Notes: new implemented/feature/2026-08-02-win32-in-process-folder-dialog
(bilingual) owns the decision; the DPI note is re-scoped to the fallback tier
it now describes and its AutoUpgradeEnabled attribution corrected (.NET Core
3.0 rewrote FolderBrowserDialog; the opt-out arrived in .NET 6).
.NET 10's modern FolderBrowserDialog renders Description as a bottom
strip above the folder input, and the 5.1 classic dialog as an unthemed
white box; the property is dropped entirely and a regression assertion
pins its absence.
README pairs document the pwsh-preferred adapter and the PowerShell 7
requirement for the modern dialog; the 2026-07-27 picker note's Windows
adapter fact is updated in place, and a new bug-fix note records the
defect, the fallback decision, and the DPI awareness rationale.
The win32 branch now spawns pwsh.exe (PowerShell 7) first and falls back
to powershell.exe (Windows PowerShell 5.1) only when pwsh is missing
(ENOENT), mirroring the Zenity-KDialog fallback. PowerShell 7 renders the
modern IFileDialog folder picker; the 5.1 fallback keeps the legacy tree
functional. Both runtimes execute the identical script, which opts the
process into system DPI awareness (SetProcessDPIAware) before any window
exists, fixing the blurry bitmap-stretched dialog on scaled displays.
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Huanqi Cao
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