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.
Turtle