Feature Request: Respect OPENCODE_INSTALL_DIR, XDG_BIN_DIR, $HOME/bin, and Fallback for Installation Path #1124

Summary

The current OpenCode install script always installs the binary to $HOME/.opencode/bin, which does not respect common standards or user preferences for binary locations. Many modern Linux distributions and user environments prefer XDG-compliant directories or custom bin paths.

Request:
Enhance the installation script to support the following priority order for the installation path:

1. Use $OPENCODE_INSTALL_DIR if set
2. Else use $XDG_BIN_DIR if set
3. Else use $HOME/bin if it exists (or can be created)
4. Else fallback to $HOME/.opencode/bin

Motivation

• Standards compliance: The XDG Base Directory Specification is widely used and makes home directories more organized.
• User flexibility: Many users want to customize where their binaries go, either with $HOME/bin or with XDG variables.
• Better PATH defaults: Modern distros and shells often include $XDG_BIN_DIR or $HOME/bin in PATH by default.

Current Behavior

The script sets:

INSTALL_DIR=$HOME/.opencode/bin

This does not check for environment variables or user preferences.

Proposed Behavior

Update the install script to:

1. Use $OPENCODE_INSTALL_DIR if it is set
2. Else use $XDG_BIN_DIR if it is set
3. Else use $HOME/bin if it exists or can be created
4. Else fallback to $HOME/.opencode/bin

Example Implementation

if [ -n "${OPENCODE_INSTALL_DIR:-}" ]; then
    INSTALL_DIR="$OPENCODE_INSTALL_DIR"
elif [ -n "${XDG_BIN_DIR:-}" ]; then
    INSTALL_DIR="$XDG_BIN_DIR"
elif [ -d "$HOME/bin" ] || mkdir -p "$HOME/bin"; then
    INSTALL_DIR="$HOME/bin"
else
    INSTALL_DIR="$HOME/.opencode/bin"
fi

• The script should also ensure that INSTALL_DIR is added to PATH in the same way as currently, with relevant shell logic.
• If the chosen INSTALL_DIR is not present in PATH, the script should suggest or attempt to add it, as before.

Benefits

• More predictable and standards-compliant installations
• Minimal surprises for users who prefer or require custom bin locations
• Future-proofs the script for changing Linux desktop conventions

References

• XDG Base Directory Specification
• XDG_BIN_DIR notes

Additional Details

• Please document the new variables (OPENCODE_INSTALL_DIR, XDG_BIN_DIR) in the README for clarity.
• Consider echoing the chosen install location to the user at the end of the script.
• For bonus points, warn the user if the chosen path is not present in PATH.

Thank You

This change would greatly improve install experience and compliance with modern Linux standards.