ci(portability): spell the Windows test TEMP by its short name (#487)

The runner's own TEMP was C:\Users\RUNNER~1\..., so tests met 8.3 short
names in every temp path. The folder on D: keeps that when the disk has
short names, and the step logs which spelling it got. TESTING.md notes
that the slowest list is not printed when a job is cancelled.

.github/workflows/portability.yml

@@ -54,14 +54,19 @@ jobs:
       # The runner's TEMP is on C:, the OS disk, where a flush took about 6 ms
       # and a test database's create-to-delete about 111 ms; on the D: work
       # disk the same took 0.5 ms and 23 ms (macOS: 19 ms). Tests write their
-      # databases under TEMP, so it moves to the runner's temp folder on D:
-      # (measured in #487, run 40915866444).
+      # databases under TEMP, so it moves to a folder on D: (measured in #487,
+      # run 40915866444). The runner's TEMP was an 8.3 short name
+      # (C:\Users\RUNNER~1\...), so the new one is spelled by its short name too
+      # when the disk has them, and paths still have to be resolved.
       - name: Keep test files on the work disk (Windows)
         if: runner.os == 'Windows'
         shell: pwsh
         run: |
-          "TEMP=$env:RUNNER_TEMP" >> $env:GITHUB_ENV
-          "TMP=$env:RUNNER_TEMP" >> $env:GITHUB_ENV
+          $folder = New-Item -ItemType Directory -Force -Path (Join-Path $env:RUNNER_TEMP "PromptManagerTests")
+          $short = (New-Object -ComObject Scripting.FileSystemObject).GetFolder($folder.FullName).ShortPath
+          Write-Output "test TEMP: $short (long name $($folder.FullName))"
+          "TEMP=$short" >> $env:GITHUB_ENV
+          "TMP=$short" >> $env:GITHUB_ENV
 
       - name: Run tests
         env:

TESTING.md

@@ -254,14 +254,17 @@ the process exits non-zero.
 - `PM_TEST_SLOWEST=N` (off by default) lists the N slowest tests after the
   summary, each timed from its `start:` line to the next one like the hang
   limit. The Windows and macOS jobs (`portability.yml`) set it to 40, so every
-  run shows where its time went (#487).
+  run shows where its time went (#487). The list prints only when the run
+  ends: a job GitHub cancels or a watchdog exit prints none, so read the
+  timestamps between `start:` lines instead.
 - On the Windows runners `TEMP` sits on the OS disk C:, where a flush took about
   6 ms and a test database's create-to-delete about 111 ms (D: 0.5 ms and 23 ms,
-  macOS 19 ms). `portability.yml` points `TEMP`/`TMP` at `RUNNER_TEMP` on D:
-  before the suite. A test that waits on a fixed busy timeout, a network name
-  (`\\server\share`: use `\\localhost\<missing share>`) or a default TLS
-  context (it reads the Windows certificate store) costs seconds there; the
-  slowest list shows it.
+  macOS 19 ms). `portability.yml` points `TEMP`/`TMP` at a folder under
+  `RUNNER_TEMP` on D: before the suite, spelled by its 8.3 short name when D:
+  has them (the runner's own TEMP was `C:\Users\RUNNER~1\...`), and logs it.
+  A test that waits on a fixed busy timeout, a network name (`\\server\share`:
+  use `\\localhost\<missing share>`) or a default TLS context (it reads the
+  Windows certificate store) costs seconds there; the slowest list shows it.
 
 Every job in `test.yml`, `code-quality.yml` and `viewerjs-check.yml` has
 `timeout-minutes` (`tests/vendor/ci-workflow.test.mjs` checks it). The rule is