I'll head towards that, then.
Edit: build so far
Next level I'll get Cooperative Metamagic, and so can Persist your guys' spells. I'll take Item Familiar at 9th to help with the Spellcraft checks. At 9th level, I'll also finally be able to Persist my own spells...
Hmm... would it be OK to start out with different metamagic feats that are actually usable right now, and retrain them later to Extend and Persist? I'm thinking something like Sculpt and Invisible Spell.
I'm assuming I can have the level of spellthief count as my free "martial" level (instead of taking a LA +1 race). I'd rather take it at 2nd, due to the difficulty in meeting feat prereqs, though. If this is a problem, let me know.
And how are those Foci going to work, exactly? How many are we going to have starting out? I'm a little fuzzy on that.