One possible solution is to make a call to CandidatesFromStoredRequest from OnFileReadyToParse:

```python
  def OnFileReadyToParse( self ):
    # Invalidate cache on buffer switch
    self.completions_cache = None
    self.SetCandidates()

    # make a snippets cache
    self.CandidatesFromStoredRequest()
```

This way we will create a required cache on buffer enter and first actual call to CandidatesFromStoredRequest will return filtered results. More thoughts?