Using tcsh as the account shell seems to break the OpenCode app

[NetDude6]

Description

The default shell on my account is set to tcsh.
When I try to run the OpenCode app I get this:

Wayland session detected; using native Wayland first with X11 fallback (auto backend). Set OC_FORCE_X11=1 to force X11.
2026-03-23T11:42:25.182167Z INFO opencode_lib: Initializing app
2026-03-23T11:42:25.189739Z INFO opencode_lib: Spawning sidecar on http://127.0.0.1:46047
2026-03-23T11:42:25.189778Z INFO opencode_lib::cli: Spawning sidecar port=46047
2026-03-23T11:42:25.240572Z WARN opencode_lib::cli: Falling back to app environment shell="/bin/tcsh"
2026-03-23T11:42:25.241036Z INFO opencode_lib::cli: No CLI installation found, skipping sync
2026-03-23T11:42:25.242852Z INFO sidecar: opencode_lib::cli: Unknown option: `-l'
2026-03-23T11:42:25.242892Z INFO sidecar: opencode_lib::cli: Usage: tcsh [ -bcdefilmnqstvVxX ] [ argument ... ].
2026-03-23T11:42:25.342553Z INFO sidecar: opencode_lib::cli: Sidecar terminated code=Some(1) signal=None
2026-03-23T11:42:25.344570Z ERROR opencode_lib: Sidecar health check failed: Sidecar terminated before becoming healthy (code=Some(1) signal=None)
2026-03-23T11:42:25.344607Z INFO opencode_lib: Loading task finished
2026-03-23T11:42:25.344630Z INFO opencode_lib: Loading done, completing initialisation

Plugins

No response

OpenCode version

No response

Steps to reproduce

To reproduce in a bash shell :
export SHELL=/bin/tcsh
OpenCode

As a workaround in my tcsh shell, I run the OpenCode app from a script :
#!/bin/bash
export SHELL=/bin/bash
OpenCode &> /dev/null &

Screenshot and/or share link

No response

Operating System

RHEL 10

Terminal

Any terminal. This is a shell issue.

[github-actions]

This issue might be a duplicate of an existing issue. Please check:

• Opencode Desktop error with nushell as default shell #8716: Same root cause — using a non-POSIX shell (nushell) as the default shell causes the sidecar to fail to spawn with a similar error pattern.