add() returns event: ADD for memories the vector store never persisted #6911

Component

Python SDK

Description

Summary

When a batch insert into the vector store fails, _add_to_vector_store retries record-by-record. Records that also fail the retry are logged and skipped — but the returned payload, the history rows, and entity linking are all still built from the full extracted set. Callers receive {"id": ..., "event": "ADD"} for memories that were never stored, and get() on those ids later returns nothing.

Affects both Memory and AsyncMemory.

Steps to Reproduce

from mem0 import Memory

m = Memory()

# Simulate a store that rejects one record: batch insert fails,
# then one record also fails the per-record retry.
real_insert = m.vector_store.insert
POISON = "User is allergic to penicillin"

def flaky_insert(vectors, ids, payloads):
    if len(ids) > 1:
        raise RuntimeError("batch insert rejected")
    if payloads[0].get("data") == POISON:
        raise RuntimeError("record rejected by vector store")
    return real_insert(vectors=vectors, ids=ids, payloads=payloads)

m.vector_store.insert = flaky_insert

result = m.add(
    [{"role": "user", "content": f"My name is Aryan. {POISON}. I work as an engineer."}],
    user_id="u1",
)

for r in result["results"]:
    print(r["event"], r["id"], repr(r["memory"]), "| in store:", m.vector_store.get(r["id"]) is not None)

Expected Behavior

Only memories that actually persisted are returned as ADD. A record the store rejected should not appear in the results, should not get an ADD history row, and should not be referenced by linked_memory_ids in the entity store. If nothing persists at all, the call should raise VectorStoreError — which add()'s docstring already documents but nothing currently raises.

Actual Behavior

All three extracted memories are returned as successful ADDs while only two exist in the store. The failure surfaces only as a log line, at the same moment the call reports success.

ERROR mem0.memory.main: Failed to insert memory 330d01bf-...: record rejected by vector store

add() reported 3 memories as persisted:
  ADD c0196d4e "User's name is Aryan"             | in store: True
  ADD 330d01bf 'User is allergic to penicillin'   | in store: False   <-- phantom
  ADD 6d26dded 'User works as an engineer'        | in store: True

vector store actually holds 2 records

No exception is raised. The history table also gains an ADD row for the phantom id, and entity linked_memory_ids point at a memory that does not exist.

Source: mem0/memory/main.py — fallback loop at L1051 (sync) / L2704 (async); results built from the unfiltered records at L1190 / L2842.

Environment

• mem0 version: 2.0.17
• Python/Node version: Python 3.11
• OS: Windows 11