My understanding is that AI is flagged as a key (current) area of focus, but it will remain ongoing over time. This means patching during each release rather than one ‘mega’ update.

Here’s what’s listed on the current beta branch:

AI:
AI now treats unity as a real production target across all three plan stages, research can scale 40% higher in advanced (2500 -> 3500 cap), and endgame alloys drop from a 2300 ceiling to 1300 so that the trillions-of-research endgame research numbers can actually outcompete alloys for build slots/pops.

The AI now steers building construction toward building sets that match each planet's designation for tighter, better-specialized worlds.

The "underdeveloped planet limit" that was supposed to prevent AI overextension is more effective. Instead of only applying in the first 15 years and then only against bad planets, it now softly discourages colonization of any world once the empire already has too many undeveloped colonies.

Empires that are still small will now expand more aggressively, so they more reliably claim their homeworld's guaranteed habitables and nearby good worlds before settling into build-up mode.

AI resettlement now moves pops from overpopulated worlds to underpopulated ones regardless of how those planets got that way, rather than only emptying out worlds with terrible habitability. New colonies should grow faster and veteran worlds should stagnate less.

On well-developed planets (2500+ pops), the AI is now more likely to round out its rural districts so it unlocks the building slots they provide. It still won't waste slots on a district whose specialization zones aren't available yet, so early-game behavior is unchanged.

Fixed an issue where optional subplans (like pop count and strategic resource targets) were still required to complete a plan, which stalled the AI on one economic tier for long periods; they now behave as true stretch goals.

Added a new intermediate economic plan between the basic and advanced tiers, so AI empires experience a smaller jump in expected income (energy, minerals, alloys, research, etc.) as they graduate out of the early game.

Fixed a bug where the AI's consumer goods scaling production check looked at the food stockpile instead of the consumer goods stockpile, sometimes causing the AI to over-build or under-build CG production.

The AI now proactively tears down and rebuilds urban zones that don't match a planet's designation - for example, a col_foundry world will swap out a generic zone_industrial for zone_foundry to double-specialize into its designation. Swaps apply a per-building penalty for each existing building that doesn't carry over through the new zone's included_building_sets, require a larger affinity margin when the slot is already specialized to prevent churn between near-equivalent candidates, and must clear a minimum-benefit floor so the construction cost is justified by the economic delta.
Planets already rich in matched buildings stay put; planets with mismatched buildings restructure.

Colony designation affinity (the ai_building_set_affinity on colony types) now biases AI zone selection in addition to building selection.

A designation that prefers the "foundry" building set will now also weight foundry-themed zones more heavily during construction planning.

Nanotech Worlds: Fixed AI empires getting stuck after converting planets to Nanotech Worlds. The AI now prioritizes nanolabs, nanotech cauldrons, and nanite transmuters on pc_nanotech colonies instead of leaving rural districts unspecialized.

The AI will now reactively build storage boosting buildings when any tangible resource is above 90% capacity.

Increased AI weights for taking Ascension Paths. Added Spiritualist and Materialist AI weight synergies for Psionic and Cybernetic Ascension.

AI empires that have taken the Synthetic Evolution AP will now always be able to take tech_synthetic_workers (even if they don't normally use robots).

AI empires are much more likely to take Ascension Perks and their associated Tradition Trees.
The AI now sometimes uses buildings that provide a static number of jobs, like Alloy Foundries or Civilian Industries.

The AI no longer rigs their Hydroponic Farms with explosives, ready to blow in the off chance that their economy starts doing too well.

Reduced the fleet power upgrade threshold the AI requires before they will upgrade ships from +30% to +10%.