> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flumes.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Conflict Keys & Supersession

> Keep one current truth per fact and audit prior values.

## Why keys matter

Keys ensure only one active fact per logical slot (e.g., a user's city).

Example key: `"ent:user_123|likes_city"` for subject+predicate.

## Writing facts with keys

```bash theme={null}
curl -s "https://api.flumes.ai/v0/memories:batch_upsert" \
  -H "Authorization: Bearer $FLUMES_API_KEY" \
  -H "Content-Type": "application/json" \
  -d '{
    "items": [
      {"type":"fact","subject":"ent:user_123","predicate":"likes_city","object_text":"Rome","keys":["ent:user_123|likes_city"]}
    ],
    "upsert_conflicts":"smart"
  }'
```

When a new fact arrives with the same key, prior rows become `status: superseded` and get `valid_to` set to now.

## Query current truth

Filter by `status=active`, your `namespace`, and `entity_id`.