feat: detect subscriber-only tweets via tweetInterstitial (#33)

Extract visibility metadata from TweetWithVisibilityResults wrapper
before unwrapping. Adds is_subscriber_only field to Tweet model,
with full serialization roundtrip and test coverage.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

twitter_cli/models.py

@@ -52,6 +52,7 @@ class Tweet:
     score: Optional[float] = None
     article_title: Optional[str] = None
     article_text: Optional[str] = None
+    is_subscriber_only: bool = False
 
 
 @dataclass

twitter_cli/parser.py

@@ -241,15 +241,21 @@ def parse_user_result(user_data):
 # ── Tweet parsing ────────────────────────────────────────────────────────
 
 
+def _unwrap_visibility(result):
+    # type: (Dict[str, Any]) -> Tuple[Dict[str, Any], bool]
+    """Unwrap TweetWithVisibilityResults, returning (inner_data, is_subscriber_only)."""
+    if result.get("__typename") == "TweetWithVisibilityResults" and result.get("tweet"):
+        return result["tweet"], bool(result.get("tweetInterstitial"))
+    return result, False
+
+
 def parse_tweet_result(result, depth=0):
     # type: (Dict[str, Any], int) -> Optional[Tweet]
     """Parse a single TweetResult into a Tweet dataclass."""
     if depth > 2:
         return None
 
-    tweet_data = result
-    if result.get("__typename") == "TweetWithVisibilityResults" and result.get("tweet"):
-        tweet_data = result["tweet"]
+    tweet_data, is_subscriber_only = _unwrap_visibility(result)
     if tweet_data.get("__typename") == "TweetTombstone":
         return None
 
@@ -270,8 +276,7 @@ def parse_tweet_result(result, depth=0):
 
     if is_retweet:
         retweet_result = _deep_get(legacy, "retweeted_status_result", "result") or {}
-        if retweet_result.get("__typename") == "TweetWithVisibilityResults" and retweet_result.get("tweet"):
-            retweet_result = retweet_result["tweet"]
+        retweet_result, retweet_subscriber_only = _unwrap_visibility(retweet_result)
         rt_legacy = retweet_result.get("legacy")
         rt_core = retweet_result.get("core")
         if isinstance(rt_legacy, dict) and isinstance(rt_core, dict):
@@ -312,6 +317,7 @@ def parse_tweet_result(result, depth=0):
         retweeted_by=retweeted_by,
         quoted_tweet=quoted_tweet,
         lang=actual_legacy.get("lang", ""),
+        is_subscriber_only=retweet_subscriber_only if is_retweet else is_subscriber_only,
         **_parse_article(actual_data),
     )
 

twitter_cli/serialization.py

@@ -46,6 +46,7 @@ def tweet_to_dict(tweet: Tweet) -> Dict[str, Any]:
         "retweetedBy": tweet.retweeted_by,
         "lang": tweet.lang,
         "score": tweet.score,
+        "isSubscriberOnly": tweet.is_subscriber_only,
     }
     if tweet.article_title is not None:
         data["articleTitle"] = tweet.article_title
@@ -122,6 +123,7 @@ def tweet_from_dict(data: Dict[str, Any]) -> Tweet:
         score=float(data["score"]) if data.get("score") is not None else None,
         article_title=_optional_str(data.get("articleTitle")),
         article_text=_optional_str(data.get("articleText")),
+        is_subscriber_only=bool(data.get("isSubscriberOnly", False)),
     )