feat: support API key authentication via environment variable

README.md

@@ -31,6 +31,12 @@ You'll be prompted for your Client ID and Client Secret. The CLI opens your brow
 
 > **Note:** Splitwise ignores `redirect_uri` in OAuth requests and always uses the registered callback URL. If you hit `ERR_CONNECTION_REFUSED` after authorizing, do a manual token exchange with `curl` using the `code` from the URL.
 
+Alternatively, you can skip the OAuth flow by setting the `SPLITWISE_API_KEY` environment variable with an API key generated from [secure.splitwise.com/apps](https://secure.splitwise.com/apps):
+
+```bash
+export SPLITWISE_API_KEY="your_api_key_here"
+```
+
 ## Usage
 
 ```bash
@@ -82,8 +88,9 @@ This CLI ships with an [OpenClaw](https://github.com/openclaw/openclaw) / [Gemin
 
 ## Configuration
 
-| File | Purpose |
-|------|---------|
+| File/Variable | Purpose |
+|---------------|---------|
+| `SPLITWISE_API_KEY` | Environment variable for API key (bypasses OAuth) |
 | `~/.config/splitwise-cli/auth.json` | OAuth token |
 | `~/.config/splitwise-cli/config.json` | User preferences |
 

internal/api/client.go

@@ -77,7 +77,7 @@ func (c *Client) do(req *http.Request) ([]byte, error) {
 	}
 
 	if resp.StatusCode == 401 {
-		return nil, fmt.Errorf("unauthorized — run `splitwise auth` to re-authenticate")
+		return nil, fmt.Errorf("unauthorized — run `splitwise auth` to re-authenticate or set SPLITWISE_API_KEY")
 	}
 	if resp.StatusCode == 403 {
 		return nil, fmt.Errorf("forbidden — you don't have access to this resource")

internal/auth/auth.go

@@ -114,9 +114,13 @@ func Login(clientID, clientSecret string) error {
 
 // LoadToken returns a valid token, refreshing if needed.
 func LoadToken() (string, error) {
+	if apiKey := os.Getenv("SPLITWISE_API_KEY"); apiKey != "" {
+		return apiKey, nil
+	}
+
 	stored, err := loadAuth()
 	if err != nil {
-		return "", fmt.Errorf("not logged in — run `splitwise auth` first")
+		return "", fmt.Errorf("not logged in — run `splitwise auth` first or set SPLITWISE_API_KEY")
 	}
 
 	if stored.Token.Valid() {
@@ -128,7 +132,7 @@ func LoadToken() (string, error) {
 	src := cfg.TokenSource(context.Background(), stored.Token)
 	newToken, err := src.Token()
 	if err != nil {
-		return "", fmt.Errorf("token expired and refresh failed — run `splitwise auth` again: %w", err)
+		return "", fmt.Errorf("token expired and refresh failed — run `splitwise auth` again or set SPLITWISE_API_KEY: %w", err)
 	}
 
 	stored.Token = newToken
@@ -141,6 +145,9 @@ func LoadToken() (string, error) {
 
 // IsLoggedIn checks if credentials exist.
 func IsLoggedIn() bool {
+	if os.Getenv("SPLITWISE_API_KEY") != "" {
+		return true
+	}
 	_, err := loadAuth()
 	return err == nil
 }