🐛 Describe the Bug

When using Qdrant with local path storage, all data is silently deleted on every program restart if on_disk is not explicitly set to True.

🔍 Root Cause

In mem0/vector_stores/qdrant.py lines 62-67:

if not params:          # Local path mode
    params["path"] = path
    self.is_local = True
    if not on_disk:     # Defaults to False!
        if os.path.exists(path) and os.path.isdir(path):
            shutil.rmtree(path)   # ← Deletes all persisted data!

When on_disk is False (the default), the code unconditionally calls shutil.rmtree(path) to wipe the entire storage directory on every initialization. This means any data saved in a previous session is silently destroyed.

✅ Expected Behavior

Local storage should persist across restarts by default, or at minimum warn users clearly about this destructive behavior before deleting data.

❌ Actual Behavior

All memories are silently deleted every time Memory.from_config() is called without on_disk: True.

🔄 Steps to Reproduce

from mem0 import Memory

config = {
    "vector_store": {
        "provider": "qdrant",
        "config": {
            "collection_name": "memories",
            "path": "./qdrant_storage",
            "embedding_model_dims": 1024,
            # "on_disk": True  # ← Not specified, defaults to False!
        }
    }
}

# First run
m = Memory.from_config(config)
m.add("My name is Alice", user_id="alice")
print(m.get_all(user_id="alice"))  # Shows 1 memory

# Restart program...

# Second run - data is gone!
m = Memory.from_config(config)  # ← Silently deletes ./qdrant_storage/
print(m.get_all(user_id="alice"))  # Empty!

💡 Proposed Solutions

Option A (Recommended): Change default on_disk to True when path is specified:

# In qdrant.py __init__
if not on_disk and path:
    on_disk = True  # Auto-enable persistence for local storage

Option B: Never auto-delete existing directories; only create a fresh collection if explicitly requested via a new reset=True parameter:

if reset and os.path.exists(path) and os.path.isdir(path):
    shutil.rmtree(path)

Option C: At minimum, add a prominent warning log before deletion so users are not caught off guard.

📋 Environment

• Mem0 version: 0.1.0+
• Python: 3.8+
• OS: Any (tested on Windows 11, Linux)

🔗 Related Issues

• How to save and load a database from local in mem0？ #1643 (local storage confusion)
• [qdrant]: Error in new_memories_with_actions while using QdrantLocal #1989 (uses on_disk: True as workaround)