Q 673 - What are some gods for a 3.5 game that have the knowledge and planning domain?
A673: According to
this website, (doesn't include some more recent sources IIRC)
Boccob N quarterstaff Knowledge, Magic, Mind, Oracle, Planning, Trickery
Chronepsis N Scythe Death, Dragon, Fate, Knowledge, Planning, Time
Gond N warhammer City, Earth, Fire, Knowledge, Metal, Planning, Sin-Pride
Siamorphe] LN light mace Knowledge, Law, Nobility, Planning, Sin-Pride
Vecna NE dagger Destiny, Evil, Knowledge, Madness, Magic, Planning, Portal, Portal (alt), Sin-Pride, Tyranny
but as Smudgyhandsman noted, you could simply go
Cloistered Cleric.