[backnotprop]

Cause

The test hooks.json's SessionStart compact hook > PowerShell: prints only whitespace and exits 0, set or not in apps/hook/hooks/mod/inbox-reminder.test.ts started pwsh from cold three times in one test (unset, the reminder text, the hostile text). Bun's default budget for the test is 5 s. On main's unit-2 shard it already uses most of that:

Run	Sha	Result	Time
42339830014	5c6fafd	pass	3096 ms
42338872718	8c8addd	pass	2739 ms
42336706551	9ebcc8b	pass	3185 ms
42336075827	efd8239	pass	3516 ms

On PR 2776 (run 42340487682, unit-2) it hit 5008 ms and timed out. Bun then killed the leftover pwsh, so the failure reads as Expected: 0, Received: null. PR 2776 changes only packages/system/.

Change

• One test per value: unset, set to the text, set to the hostile text. Each starts pwsh once and keeps the same three assertions: exit 0, stdout is only whitespace, stderr is empty.
• The probe for whether pwsh is present still runs once, when the file is collected. It is the shared skip condition and does not count against any test's budget.
• No timeout changed. Each case should take about a third of the old 2.7 to 3.5 s.

Timing

• pwsh is not installed on the author's machine, so locally the three PowerShell cases skip: 18 pass, 3 skip, 0 fail, 115 to 144 ms over three runs (bun test apps/hook/hooks/mod/inbox-reminder.test.ts, as the unit lane runs it, without --isolate).
• The per-case times on CI are in this PR's unit shard log.
• tsc for apps/hook/hooks/mod/tsconfig.json and apps/hook/tsconfig.server.json is clean. The mod tsconfig excludes *.test.ts. Gitleaks over the range found no leaks.