fix(graph): key checkpoints on graph shape and expose the LLM retry budget

- checkpoint resume keyed only by ticker+date silently continued the old graph
  under a different analyst selection / depth / asset mode; fold a run signature
  into the thread id #1089
- add llm_max_retries + TRADINGAGENTS_LLM_MAX_RETRIES, forwarded to every provider
  when set (int-coerced, rejects negatives/booleans), so a 429 burst can't abort
  a run #1091

tradingagents/graph/checkpointer.py

@@ -25,9 +25,17 @@ def _db_path(data_dir: str | Path, ticker: str) -> Path:
     return p / f"{safe}.db"
 
 
-def thread_id(ticker: str, date: str) -> str:
-    """Deterministic thread ID for a ticker+date pair."""
-    return hashlib.sha256(f"{ticker.upper()}:{date}".encode()).hexdigest()[:16]
+def thread_id(ticker: str, date: str, signature: str = "") -> str:
+    """Deterministic thread ID for a ticker+date pair.
+
+    ``signature`` folds in graph-shape-affecting run choices so a resume under a
+    different graph can't reuse this checkpoint (#1089); omitting it keeps the
+    legacy ID.
+    """
+    base = f"{ticker.upper()}:{date}"
+    if signature:
+        base = f"{base}:{signature}"
+    return hashlib.sha256(base.encode()).hexdigest()[:16]
 
 
 @contextmanager
@@ -43,17 +51,17 @@ def get_checkpointer(data_dir: str | Path, ticker: str) -> Generator[SqliteSaver
         conn.close()
 
 
-def has_checkpoint(data_dir: str | Path, ticker: str, date: str) -> bool:
+def has_checkpoint(data_dir: str | Path, ticker: str, date: str, signature: str = "") -> bool:
     """Check whether a resumable checkpoint exists for ticker+date."""
-    return checkpoint_step(data_dir, ticker, date) is not None
+    return checkpoint_step(data_dir, ticker, date, signature) is not None
 
 
-def checkpoint_step(data_dir: str | Path, ticker: str, date: str) -> int | None:
+def checkpoint_step(data_dir: str | Path, ticker: str, date: str, signature: str = "") -> int | None:
     """Return the step number of the latest checkpoint, or None if none exists."""
     db = _db_path(data_dir, ticker)
     if not db.exists():
         return None
-    tid = thread_id(ticker, date)
+    tid = thread_id(ticker, date, signature)
     with get_checkpointer(data_dir, ticker) as saver:
         config = {"configurable": {"thread_id": tid}}
         cp = saver.get_tuple(config)
@@ -73,12 +81,12 @@ def clear_all_checkpoints(data_dir: str | Path) -> int:
     return len(dbs)
 
 
-def clear_checkpoint(data_dir: str | Path, ticker: str, date: str) -> None:
+def clear_checkpoint(data_dir: str | Path, ticker: str, date: str, signature: str = "") -> None:
     """Remove checkpoint for a specific ticker+date by deleting the thread's rows."""
     db = _db_path(data_dir, ticker)
     if not db.exists():
         return
-    tid = thread_id(ticker, date)
+    tid = thread_id(ticker, date, signature)
     conn = sqlite3.connect(str(db))
     try:
         for table in ("writes", "checkpoints"):