Three issues flagged by the Copilot review on this PR:
1. Double JSON emit on stage failure (Copilot #1, #2). When -Stage <name>
ran a worker that threw, Invoke-Stage's finally emitted a JSON result
frame AND the entry-point catch emitted a second error frame --
producing two concatenated JSON objects on stdout and breaking the
one-line-per-invocation contract that drivers parse against. Same
issue applied to -Json mode on a full install (every stage's finally
plus a final error frame missing duration_ms/skipped).
Fix: Invoke-Stage's finally now sets $script:_StageEmittedErrorFrame
when it emits a failure frame; the entry-point catch checks the flag
and skips its own emit, still exit 1.
2. $prevEAP uninitialized on early try-block throw (Copilot #3). In
Install-Uv, Test-Python, Test-Node's winget fallback,
_Run-NpmInstall, and the playwright block, '$prevEAP =
$ErrorActionPreference' lived as the first statement INSIDE the
try. If anything between 'try {' and that line threw (Write-Info on
an unusual host, the npx-finding loop, etc.), the catch's
'if ($prevEAP) { ... }' restore was a no-op and EAP could remain
relaxed.
Fix: hoist '$prevEAP = $ErrorActionPreference' to the line
immediately before 'try {' in all five sites. Catch's restore is
now always meaningful regardless of where in the try the throw
originated.
No change to Invoke-Stage's success path or to the four lint-clean EAP
sites (Test-Node was the only winget-related catch). All 19 metadata
smoke tests still pass.
c0b64f0877