The packaged Windows `orca.exe` launcher read
`ProcessStartInfo.EnvironmentVariables`, whose lazy getter copies the
case-sensitive process block into a case-insensitive dictionary via `.Add`.
An inherited block carrying both `PATH` and `Path` threw
`ArgumentException: Item has already been added. Key in dictionary: 'PATH'`,
so every `orca` invocation exited 1 before Electron started
(native/windows-cli-launcher/OrcaCliLauncher.cs:46, printed at :67).
The launcher now mutates its own environment with
`Environment.SetEnvironmentVariable` and never touches either
`ProcessStartInfo` env property, so `CreateProcess` passes a NULL environment
block and the child inherits the live one verbatim.
Orca was also minting the duplicate itself. `applyTerminalAttributionEnv`
read `baseEnv.PATH` and unconditionally wrote `baseEnv.PATH`, so a Windows
PTY that inherited `Path` got a second spelling; which one the child resolved
was non-deterministic. `createLaunchEnv` did the same and, because its read
always missed on Windows, shipped Agent Teams terminals a `PATH` containing
only the tmux shim dir.
`resolvePathEnvKey` (extracted from the existing precedent in
windows-environment-path.ts) now drives every PATH read and write in the PTY
env pipeline, and attribution collapses Windows onto the single OS-resolved
spelling. Off Windows the resolver always returns `PATH`, so POSIX behavior
is unchanged and a case-sensitive POSIX `Path` variable is never touched.
Closes#12046
Neil
OrcaWinandOrcaWin