[Tsuki-hash]

Resolves the configured shell for session terminals created without an explicit command, instead of falling back to $SHELL.

Previously persistentPty.create passed only ctx.payload.command through, so a terminal opened without a command (for example ctrl+x t in the web UI) fell back to ShellSelect.environment(), which ignores the configured shell. This is the root cause of #51051, and it resurfaced in 2.2.5 when #60346 moved the desktop terminal to persistent PTYs, since that path resolves the shell the same way.

Fixes #51051.
Supersedes #51052 (closed by the automated cleanup, not on its merits; its fork branch is gone, so this is a fresh resubmission of the same fix against current dev).

Test plan

• Added a smoke test: a terminal created without a command uses the configured shell and prints its output.

Visual

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[opencodejr]

Thanks for coming back to this, and for the original fix in #51052. I think this duplicates #61353, which fixes the same issue (#51051) in the same persistentPty.create handler and is still open and being worked on.

One thing to know: #61353 started with the same approach as this PR, yielding ShellSelect.Service directly in the handler. A reviewer found that this made every terminal create fail with a 500, because the experimental persistent-pty routes don't run the location middleware that provides that service. It now resolves the shell in the session's location instead (sessionInfo → instances.provide, after awaitPlugins).

You clearly know this code well, so reviewing or testing #61353 (especially on Windows, where the bug shows up most) would be really helpful. If you think it's missing something, please comment there.