Worker IPC fails when $TMPDIR is long (macOS Shortcuts), scan reports 0 pages with no error

[rqahmad]

Summary

NAPS2 creates its worker IPC socket inside $TMPDIR. On macOS, unix domain socket paths are
limited to 104 bytes, so when $TMPDIR is long the worker cannot start and the scan silently
returns 0 pages. Anything launching NAPS2 from macOS Shortcuts hits this, because Shortcuts
sets TMPDIR to a per-helper subdirectory.

Failure is silent from the user's perspective: NAPS2 prints "0 page(s) scanned" and exits 0.
The underlying exception only appears on stderr.

Environment

Same as Issue 1 (NAPS2 8.3.2, macOS 26.5.2, Apple Silicon).

Steps to reproduce

1. Create a Shortcut in the macOS Shortcuts app with a "Run Shell Script" action calling
   NAPS2 console -a -p "Some Profile".
2. Assign a keyboard shortcut and run it with a document in the feeder.

Or reproduce directly:

export TMPDIR=/var/folders/nd/cf4pd31x6816khp2xf97kxxm0000gn/T/com.apple.shortcuts.mac-helper/
NAPS2 console -a -p "Some Profile" -v

Actual

Beginning scan...
Starting scan 1 of 1...
ArgumentOutOfRange_PathLengthInvalid, /var/folders/nd/cf4pd31x6816khp2xf97kxxm0000gn/T/com.apple.shortcuts.mac-helper//CoreFxPipe_NAPS2.Worker.5928, 104 Arg_ParamName_Name, path
ArgumentOutOfRange_ActualValue, /var/folders/nd/cf4pd31x6816khp2xf97kxxm0000gn/T/com.apple.shortcuts.mac-helper//CoreFxPipe_NAPS2.Worker.5928
0 page(s) scanned.

Exit code is 0. The same command with the default TMPDIR scans normally.

Note the doubled slash in the socket path (.../mac-helper//CoreFxPipe_...), which suggests a
trailing separator is not being normalized when the pipe path is composed.

Expected

Either the worker socket is placed somewhere path-length-safe regardless of $TMPDIR, or the
failure is reported as an error with a non-zero exit code instead of "0 page(s) scanned".

Background

This is the .NET named-pipe-on-unix path limit: see
dotnet/runtime#79503 — PipeStream composes
$TMPDIR/CoreFxPipe_<name> and the total must fit in sockaddr_un.sun_path (104 bytes on
macOS). The default macOS TMPDIR (~49 chars) leaves room; Shortcuts' helper subdirectory
does not.

Workaround

Set a short TMPDIR before invoking NAPS2:

export TMPDIR=/tmp/