Webwright skill is shell-unaware on Windows — bash heredocs loop/fail with code-specialist models (gpt-5-codex / gpt-5.3-codex)

Environment
Windows 11, Codex VS Code extension, Codex CLI 0.136.0-alpha.2
Detected shell (from environment_context): powershell
Webwright skill invoked via /webwright:run

Summary
The webwright skill instructs the agent to "drive the browser through one bash command at a time" and its reference (reference/playwright_patterns.md, the inline-Python example) demonstrates a bash heredoc (python - <<'PY' … PY). On Windows the shell is PowerShell, which cannot parse bash heredocs. Whether a run succeeds therefore depends entirely on the model being able to recognize this and deviate from the skill's examples.

Observed behavior (same machine, same skill, same shell)
gpt-5.5: recognizes it's on PowerShell, writes the script to a .py file and runs python file.py. Completes tasks in a few steps.
gpt-5-codex / gpt-5.3-codex: follow the skill's bash heredoc example literally, hit the PowerShell parse error, and retry the same broken syntax in a loop. A simple Wikipedia task took ~18 minutes; a moderately complex booking task looped for hours without converging.

Root cause
The skill's instructions and examples assume bash. Code-specialist models are tuned for tight, literal adherence to skill instructions, so they reproduce the bash heredoc verbatim instead of adapting to the reported powershell shell. There is no shell-awareness in the skill and no guardrail when the harness runs under a model that doesn't self-correct.

Read reference/playwright_patterns.md and the Webwright skill instructions, then reproduce the inline-Python example under PowerShell on Windows. Trace where the skill assumes bash and compare the behavior with the reported Codex models. Done means PowerShell runs no longer invoke bash heredoc syntax or repeat the resulting parse failure.