Access to ANY spell at ANY time?

[Vampireshado]

Oh nice! Chameleon with Customize Domain is sweet.

[awaken_D_M_golem]

The Magic domain part in there, can get anything 8 or lower.
The various other domains can get almost everything else.

I suppose the earliest this could happen would be level 6.
Cleric with early Miracle stuff, early entry into Cham 2.

[Vampireshado]

We'd be missing like two Wu Jen spells. That's a bummer. So close.

[awaken_D_M_golem]

And not Wish because it's Universal school.
It's a short list all those Customizes don't cover.

Alamanther's Return 9 (wtf it's called in 3.5e)
lets you duplicate any spell you've seen
up to level 8.  Magic Mantle via a 1 level dip,
would then get all psi up to level 8s.  Have to
go Ardent 2 and Dr#349 psiotheurgists feats
to get most of the psi 9s.

Expanded Spell List handbook should get a few more.

 

[Kethrian]

Divine Rank 0, 29 Cha, Alter Reality salient ability.

[Vampireshado]

Oh man I hadn't even thought of using Magic Mantle to get powers that's awesome! So theoretically you could do Ur-Priest (they still know all spells automatically right?) and Eldritch Master with an Ardent dip could get every spell and power ever at will. We could take Eldritch Master to 8th if there is a psionics class that grants all powers. Or if there is a way to make powers divine then the archivist could just learn them.

Are there rules on how to achieve divine rank?

[ClayQ]

Archivist has access to all arcane spells potentially, just have a

 arcane caster x/cleric 3/geomancer x

Scribe a divine scroll of the spell.... These would be  divine spells when recast not arcane as per methods referenced in the op.

Im afb atm but its also worth noting most of your chameleon builds may not work. Almost none of the chameleon abilities can be progressed with prcs or used for entry to prcs

However, inspired build is to stick your eldritch mastet prc on a sponaneous know itall warmage anyone, and name archivist or chameleon as both have access to all arcane and divine spells.....