PowerShell completion generator: correctness bugs and feature parity gaps

[stalep]

Summary

The PowerShellCompletionGenerator has several correctness bugs and is missing features that all other generators (bash, zsh, fish) support. Test coverage is also significantly weaker than the other shells.

Correctness Bugs

1. Dynamic generator tokenization breaks on quoted arguments

$commandAst.ToString().Split(' ') splits on spaces, which breaks quoted arguments:

# User types: mycli --message "hello world"
# Split produces: mycli, --message, "hello, world"  (WRONG)

Fix: Use $commandAst.CommandElements which provides proper tokenization.

2. Program name not quoted in dynamic generator

& programName --aesh-complete breaks if the program name contains spaces. Should be & 'programName'.

3. Missing property option filtering

isProperty() is never checked. @OptionGroup properties are emitted as regular options. All other generators skip property options.

4. Error messages omit pwsh

AeshRuntimeRunner.java lines 508, 519, 652 say "Supported: bash, zsh, fish" but omit pwsh.

5. System.lineSeparator() vs "\n"

The generator uses System.lineSeparator() which produces \r\n on Windows. All other generators use "\n". Can cause issues when script is generated on Windows but used on Linux pwsh.

Feature Parity Gaps

All of the following are supported by bash, zsh, and fish generators but missing from PowerShell:

Feature	Impact
Option aliases (getAliases())	--config not suggested if only --configuration emitted
Short names (shortName())	-v never offered alongside --verbose
Negatable options (isNegatable())	--no-verbose never emitted
Value completion (allowedValues/defaultValues)	Enum values not listed as candidates
File options (isTypeAssignableByResourcesOrFile())	No Get-ChildItem fallback for file-type options
Arguments (@Argument/@Arguments)	Positional arguments completely ignored

Test Coverage Gaps

What	Bash	Zsh	Fish	PowerShell
Option aliases	Yes	Yes	Yes	No
Negatable options	Yes	Yes	Yes	No
Value completion	Yes	Yes	Yes	No
File options	Yes	Yes	implicit	No
Multi-arguments	Yes	Yes	Yes	No
--aesh-completion --static	Yes	Yes	Yes	No
detectShell() unit tests	—	—	—	No
Integration (run actual shell)	No	No	No	No

Related

• detectShell() returns BASH when invoked from PowerShell via bash wrapper scripts #537 — detectShell() ordering fix (PSModulePath before BASH_VERSION)
• support powershell for completions #525 — Original PowerShell completion support
• feat: improve completion command with shell auto-detection, pwsh support, and usage hints jbangdev/jbang#2552 — jbang PR that hit pwsh completion issues