couchbase: Add ttl support to caches & chat_message_history (#26214)

**Description:** Add support to delete documents automatically from the
caches & chat message history by adding a new optional parameter, `ttl`.


- [x] **Add tests and docs**: If you're adding a new integration, please
include
1. a test for the integration, preferably unit tests that do not rely on
network access,
2. an example notebook showing its use. It lives in
`docs/docs/integrations` directory.


- [x] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/

---------

Co-authored-by: Nithish Raghunandanan <nithishr@users.noreply.github.com>
Co-authored-by: Erick Friis <erick@langchain.dev>

libs/partners/couchbase/langchain_couchbase/vectorstores.py

@@ -377,6 +377,9 @@ class CouchbaseVectorStore(VectorStore):
         if metadatas is None:
             metadatas = [{} for _ in texts]
 
+        # Check if TTL is provided
+        ttl = kwargs.get("ttl", None)
+
         embedded_texts = self._embedding_function.embed_documents(list(texts))
 
         documents_to_insert = [
@@ -396,7 +399,11 @@ class CouchbaseVectorStore(VectorStore):
         for i in range(0, len(documents_to_insert), batch_size):
             batch = documents_to_insert[i : i + batch_size]
             try:
-                result = self._collection.upsert_multi(batch[0])
+                # Insert with TTL if provided
+                if ttl:
+                    result = self._collection.upsert_multi(batch[0], expiry=ttl)
+                else:
+                    result = self._collection.upsert_multi(batch[0])
                 if result.all_ok:
                     doc_ids.extend(batch[0].keys())
             except DocumentExistsException as e: