{env:VAR} substitutions break on Windows (backslashes in paths produce InvalidEscapeCharacter) #20640

Description

{env:VAR} substitutions are broken on Windows. Paths in opencode.jsonc using {env:XDG_CONFIG_HOME} or {env:HOME} trigger InvalidEscapeCharacter errors and prevent the config from loading.

The issue is in packages/opencode/src/config/paths.ts. The substitute function performs a raw string replacement before the JSONC parser runs:

text = text.replace(/\{env:([^}]+)\}/g, (_, varName) => {
  return process.env[varName] || ""
})

On Windows, HOME contains backslashes (e.g., C:\Users\name). After substitution, the JSON contains sequences like \U, which are invalid escape characters, causing the parser to crash.

The Fix:
Swap backslashes for forward slashes after expanding the variable:

return (process.env[varName] || "").replaceAll("\\", "/")

Steps to reproduce

1. Run OpenCode on Windows.
2. Add a path using {env:HOME} in opencode.jsonc:

   "file:///{env:HOME}/opencode/plugins/myplugin.ts"

3. OpenCode reports InvalidEscapeCharacter.

Workaround

Hardcode paths with forward slashes:

"file:///C:/Users/username/.config/opencode/plugins/myplugin.ts"

Operating System

Windows 11

Terminal

Windows Terminal