Telegram: find the token in pasted text, no password autofill, clear error

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/api.rs

@@ -349,7 +349,8 @@ struct TelegramBody {
 
 /// Connect a bot: check the token, start polling and create a pairing code.
 async fn put_telegram(Extension(user): Extension<User>, State(app): State<AppState>, Json(b): Json<TelegramBody>) -> ApiResult {
-    let token = b.token.trim().to_string();
+    let token = crate::telegram::extract_token(&b.token)
+        .ok_or_else(|| ApiError(StatusCode::BAD_REQUEST, "that is not a bot token – it looks like 123456789:AAH… (paste only the token from @BotFather)".into()))?;
     let bot = crate::telegram::check_token(&token).await.map_err(|e| ApiError(StatusCode::BAD_REQUEST, format!("token rejected by Telegram: {e:#}")))?;
     let s = crate::telegram::Settings { token, bot, pair_code: crate::telegram::new_pair_code(), ..Default::default() };
     app.store.set_user_setting(&user.id, "telegram", &s)?;

server/src/telegram.rs

@@ -149,6 +149,12 @@ impl Bot {
     }
 }
 
+/// Find the bot token in what the user pasted (also the whole BotFather message).
+pub fn extract_token(input: &str) -> Option<String> {
+    let re = regex::Regex::new(r"\b(\d{5,}:[A-Za-z0-9_-]{30,})\b").unwrap();
+    re.captures(input).map(|c| c[1].to_string())
+}
+
 /// Check a token and return the bot's username.
 pub async fn check_token(token: &str) -> Result<String> {
     let me = Bot { token: token.to_string() }.call("getMe", json!({})).await?;
@@ -1145,6 +1151,14 @@ mod tests {
         }
     }
 
+    #[test]
+    fn finds_the_token_in_pasted_text() {
+        let msg = "Done! Congratulations on your new bot.\nUse this token to access the HTTP API:\n7123456789:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw4\nKeep your token secure";
+        assert_eq!(extract_token(msg).as_deref(), Some("7123456789:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw4"));
+        assert_eq!(extract_token(" 7123456789:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw4 ").as_deref(), Some("7123456789:AAHdqTcvCH1vGWJxfSeofSAs0K5PALDsaw4"));
+        assert_eq!(extract_token("my-password-123"), None);
+    }
+
     #[test]
     fn step_lines() {
         assert_eq!(step_line("bash", &json!({"command": "cargo test\nmore"})), "bash: cargo test");