So the text regarding summoning a pact weapon, along with specific instructions on dismissing it, seems clear:

You can use your action to create a pact weapon in your empty hand. You can choose the form that this melee weapon takes each time you create it (see the Weapons section for weapon options). You are proficient with it while you wield it. This weapon counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Your pact weapon disappears if it is more than 5 feet away from you for 1 minute or more. It also disappears if you use this feature again, if you dismiss the weapon (no action required), or if you die.

Does this mean if a warlock summons a pact weapon, the weapon can then be stowed on the warlock's person for easy retrieval (meaning not requiring a full action) indefinitely? 

I'm asking specifically because requiring an action to summon the weapon can cost the warlock a round/turn in combat; the RAW don't seem to prevent a warlock from summoning the weapon and keeping it on their person indefinitely (as long as the conditions for it being dismissed aren't met) but I'm wondering about the RAI. 

Thoughts?

That's correct, assuming it's a weapon that can be stowed in the first place.

Yes. The summoning/dismissing part is mostly for hiding it or if you get disarmed/captured.

There's no time limit on how long a Warlock's Pact Weapon stays with them once summoned.

They could summon it exactly once and decide never to dismiss at all, carrying it around forever.

But the ability to dismiss a Pact Weapon and recall it later is too useful not to use.