Analyze PowerShell pipeline callback regions

[Aaronontheweb]

Summary

• type ForEach-Object Begin, Process, RemainingScripts, and End plus Where-Object FilterScript execution regions while preserving authored projection order
• analyze semantic phase order and distinguish standalone, first-stage, upstream-pipeline, and explicit InputObject cardinality
• conservatively join zero-or-more callback effects and withhold stale facts when stateful pipeline stages can interleave
• pin callback, direct dot-source and call-operator, common-parameter writer, and live PowerShell behaviors

Security model

PowerShell pipeline stages can interleave per object. When multiple stateful stages are present, callback and direct-region bodies do not publish exact variable, command-resolution, or cwd facts that a downstream stage could invalidate between upstream visits. Unsupported or unproved receiver shapes remain unknown or incomplete.

Validation

• dotnet build -c Release: 0 warnings
• dotnet test -c Release --no-build: 2,110 passed
• file-header verification passed
• strict OpenSpec validation passed
• Slopwatch strict scan passed with zero findings
• adversarial review GO on frozen staged SHA-256 a641846dc2fb282e6598056c150d2f3807a64a91322a7ed1eb4aaa7691053c62