multica-ai/multica · warning

unsupported platform: %s

Error message

unsupported platform: %s

What it means

openBrowser maps runtime.GOOS to an opener command: open (darwin), xgk-open... specifically xdg-open (linux), rundll32 (windows). Any other GOOS (freebsd, openbsd, plan9, js/wasm...) has no mapping and returns this error. Note: in the browser-login flow the caller catches this and merely prints 'Could not open browser automatically', so it is not fatal there.

Source

Thrown at server/cmd/multica/cmd_auth.go:119

	os.Exit(1)
	return "" // unreachable
}

func openBrowser(url string) error {
	var cmd string
	var args []string
	switch runtime.GOOS {
	case "darwin":
		cmd = "open"
		args = []string{url}
	case "linux":
		cmd = "xdg-open"
		args = []string{url}
	case "windows":
		cmd = "rundll32"
		args = []string{"url.dll,FileProtocolHandler", url}
	default:
		return fmt.Errorf("unsupported platform: %s", runtime.GOOS)
	}
	return exec.Command(cmd, args...).Start()
}

func runAuthLogin(cmd *cobra.Command, args []string) error {
	if err := requireHumanLocalCommand("login"); err != nil {
		return err
	}
	if cmd.Flags().Changed("token") {
		tokenFlag, _ := cmd.Flags().GetString("token")
		// `--token mul_xxx` (space form) is what users actually type — that's
		// the form from the docs and from #1994. NoOptDefVal prevents pflag
		// from consuming the next arg as the flag value, so it lands here as
		// a positional. Promote it to the token value.
		if tokenFlag == tokenPromptSentinel && len(args) == 1 {
			tokenFlag = args[0]
		}
		return runAuthLoginToken(cmd, tokenFlag)

View on GitHub (pinned to 2c0912b6ec)

Solutions

1. Copy the printed login URL and open it manually in any browser — the callback server still receives the token
2. Use token-based login instead: `multica login --token <PAT>`
3. On unsupported platforms, run the login flow on a supported machine and copy the saved profile/config over

Example fix

# instead of browser flow on an unsupported OS
multica login --token mul_ABCdef123...

uname=$(uname -s 2>/dev/null || echo unknown)
case "$uname" in Darwin|Linux) browser_ok=1;; *) browser_ok=0;; esac
[ "$browser_ok" = 1 ] || MULTICA_LOGIN_MODE=token   # your own dispatch convention

When it happens

Trigger: Building/running the CLI on an OS outside darwin/linux/windows and triggering a flow that calls openBrowser (login). With BROWSER-less environments the error is downgraded to a message with a manual URL.

Common situations: Running the CLI on BSD variants; cross-compiling and running under an emulator reporting an unusual GOOS; login over SSH where the browser cannot open anyway.

Related errors

• local server error: %w
• timed out waiting for authentication
• get source agent: %w
• invalid token format: must start with %s
• could not start the local login callback server (used to rec

AI-assisted analysis of multica-ai/multica@2c0912b6ec (2026-08-15). Data as JSON: /api/errors/9576200b4091925d. Report an issue: GitHub.