I got locked out on Friday. I jiggled the key in the lock, the door handle, and the locking post and finally got it open. I removed the door panel and looked inside. Online research (DuckDuckGo) suggested that there might be a broken spring on the latch. I could not find a parts diagram which named all the rods, levers, and clips
I made a snap of the latch assembly and did not see any obvious dangling springs or vacant attachment points.
Maybe the whole assembly was toast. I called O'Reilly to inquire about availability of a replacement. Their system didn't list anything available. I needed to dig deeper.

I removed the latch on Sunday to study how the various rods and levers interact to lock and open the door. Incidentally, the "door lock rod clip" that connects outside door handle to the latch was broken. The broken piece was white plastic; the new Toyota clip is orange. When I had latch problems 10-15 years ago, I probably installed an incorrect part, which led me to problems with the linkage that might have been diagnosed as "too short," which seems to be a symptom that appears frequently.

Photos attached, with annotations: unlocked, UNlocking, and correct clip.

Unlocking occurs two ways: (1) lifting the locking post (connected to rod A) and (2) unlocking via the keylock, which pushes rod BB downward. Both actions rotate part-CC clockwise which pushes D to the right, sliding over the tab on E to connect the inside lever and the outside handle to the latch actuator (E), for lack of the correct name. The unlocked photo shows the unlocked configuration.

Two parts (D and E) were colliding inside the ellipse on the UNlocking photo. I filed the two edges at about 45 degrees. Probably due to wear and tear in the latch assembly, they were colliding and preventing unlocking. Also, I sprayed the latch with brake cleaner, which surely contributed to smoother operation. D now moves freely over E.

Back to the springs. When the key is used to unlock the door, rod BB moves downward, but there is no spring in the latch assembly or in the lock tumbler which returns that rod upward when the key is released or returns the tumbler to neutral.
Is that how it's designed to work? There is a spring on the tumbler that returns the tumbler to neutral after locking with the key(CCW), but it does return the the key to neutral after unlocking (CW).

The correct Toyota part number for the clip that connects a rod to the driver door handle is: 69293-12040. $4.15 at my local dealer.

In summary, there were two problems that locked me out. The clip connecting the outside handle to the latch was broken, and two parts on the latch were colliding that prevented movement of part D to its unlocked position over E.

 

Just replaced that clip on my passenger side lock. Bought a bag full of them in Ebay. Works great. Now have spares if the driver side goes.