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Stellaris
Stellaris
4.5|Sep 10, 2026
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Stellaris Dev Diary #432 - Yet More About 4.5 'Cygnus'

3/5 Moderate

BETAMajor AI economy overhaul improves resource management and colony specialization alongside a 50% speed buff to Biomorphosis completion.

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Key Changes

  • 1Core AI economy code rewritten to improve resource management and prevent plan stagnation.
  • 2Biomorphosis completion time reduced by 50% for better parity with other paths.
  • 3AI now regularly re-evaluates planetary designations as colonies develop.
  • 4Fixed a critical desync issue related to pop group statistics tiebreaking.
  • 5Shroud-consumed worlds now leave Zro deposits that scale with population lost.
  • 6AI now proactively buys resources from the market 6 months before depletion.
  • 7Cyber-zombies now correctly take jobs instead of remaining in a purged state.
  • 8Biological ships now consume food instead of energy, reflecting their nature.
  • 9Non-free pops like slaves and robots no longer migrate externally via Migration Pacts.
  • 10Pierce the Shroud decision now correctly creates Shrouded Worlds with proper features.

All Changes

🤖AI Behavior(7)

  • changeAI Empires: AI empires can no longer end up with no economic plan; they will now retain the last plan if they outgrow all others.
  • changeAI Empires: AI resource prioritization improved to prevent pouring all resources into one area while others hold the plan back.
  • buffBioship Empires: Bioship empires now have food targets at every stage of their economic plan to ensure continuous growth.
  • changeAI Empires: AI now settles on a small surplus above income targets and reacts to shortages while stockpiles still exist.
  • changeAI Empires: AI will now buy resources on the market before they run out rather than after.
  • changeAI Empires: AI now weighs Naval Capacity against other building needs and actual capacity provided, preventing overbuilding of Strongholds.
  • changeAI Empires: AI now regularly re-evaluates colony designations as worlds develop (e.g., switching to Research World when specialized).

⚙️Gameplay Systems(9)

  • buffBiomorphosis: Biomorphosis completion time reduced by approximately 50%.
  • buffShroud: Zro deposits left behind when the Shroud consumes a world now scale with the population lost.
  • buffBiological Ships: Biological ships are no longer affected by energy deficits.
  • nerfBiological Ships: Biological ships are now affected by food deficits.
  • fixMigration: Pops that are not free (slaves, robots, bio-trophies) no longer migrate externally under Migration Pacts or Free Migration laws.
  • fixMigration: Automigrating pops now correctly check if destination colonies are appropriate for their species.
  • fixSurveying: Resource Deposit Size survey chance now correctly applies from all sources and survey types.
  • fixAssimilation: Assimilation events no longer attempt to move 0-sized pop groups.
  • fixEnvoys: Psionic and other traits are no longer incorrectly added to envoys.

🏛️Origins & Civics(8)

  • fixEvolutionary Predators: Nomadic Evolutionary Predators now gain genetic material from pops held by temporary purge vassals.
  • fixPierce the Shroud: Pierce the Shroud now leaves a properly formed Shrouded World with correct features instead of an unknown class.
  • fixThe Great Awakening: Reaching The Great Awakening as Shroud-Forged no longer incorrectly enslaves pops lacking the Shroud-Forged trait.
  • fixShroud-Forged: Shroud-Forged origin no longer always starts with a red dwarf star.
  • fixCycle of Growth: Cycle of Growth now grants energy instead of food/pop growth to empires that do not use food.
  • fixMechromancy: Cyber-zombies created by Mechromancy now correctly take jobs instead of being stuck as purged pops.
  • fixDeath Cult: Sacrifice boon no longer stays active after an empire abandons the Death Cult civic.
  • fixEvolutionary Predators: Evolutionary Predators can no longer gain species traits from disabled DLCs.

🖥️UI/UX(7)

  • fixFactions View: Fixed supporters icon overlapping size values in the Factions view.
  • fixUI: Enforced Nemma Slavery Planet Modifier now displays the correct icon.
  • changeMultiplayer: Ban Buttons in Multiplayer now have bespoke icons.
  • changeContracts: Contract offer and completion windows now use consistent reward headings.
  • fixUI: Pierce the Shroud decision text now fits the window and displays the consumption chance.
  • fixUI: Nomad Contract button is now disabled when no contracts are available.
  • fixLocalization: Corrected the spelling of 'gases' throughout the game.

🛠️Performance & Stability(4)

  • fixStability: Fixed a tiebreak issue in pop group statistics that could cause desyncs.
  • fixGenetic Memory: Fixed error log spam caused by the Genetic Memory trait.
  • fixStability: Storm Buildings no longer generate errors when built on AI Arkships.
  • fixStability: Fixed multiple buildings generating errors on colonies with no owners.

📜Modding(4)

  • fixModding: modify_species and trait_available_for_species no longer select traits from disabled DLCs.
  • changeModding: The 'optional' flag on economic plan subplans now blocks plan completion again, reversing 4.4 guidance.
  • changeModding: Economic plan completion is now determined solely by income.
  • newModding: Added new defines for AI income target buffers and market buy cover.

Summary

AI Economy Overhaul

This update introduces a significant rewrite of the core AI economy code. AI empires will no longer get stuck without economic plans and have been improved to prioritize resources more effectively, avoiding the trap of over-investing in one resource while others lag. The AI now settles on income buffers, reacts to shortages three months before stockpiles deplete, and proactively uses the market. Additionally, AI empires will now regularly re-evaluate colony designations as they develop, ensuring worlds specialized for research actually become Research Worlds.

Gameplay & Balance

Biomorphosis has received a major buff, with its completion time halved to bring it in line with other ascension paths. Shroud-Forged empires see improvements to Shroud-consumed worlds, where Zro deposits now scale with the population lost. Biological ships have also been mechanically corrected to be affected by food deficits rather than energy deficits.

Bug Fixes & Stability

Extensive fixes address issues with Nomadic empires, Shroud-Forged origins, and Cyber-zombies. A critical desync issue related to pop group statistics has been resolved, and various UI overlaps in the Factions view have been corrected.

← OlderStellaris Dev Diary #431 - 4.5 'Cygnus' Development Continues to ContinueSep 3, 2026

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