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LongCat-2.5: Native Multimodality for Agentic Tasks
longcat.aiarticle

LongCat-2.5: Native Multimodality for Agentic Tasks

LongCat-2.5 is a native multimodal mixture-of-experts model with 1.6 trillion total and about 48 billion activated parameters, built on LongCat-2.0 for long-horizon agentic coding. The post describes discrete RVQ visual tokens, large-scale asynchronous agentic RL with synthesized F2P/P2P-tested environments, on-policy distillation, train-inference numerical alignment, and W4A4 inference on domestic accelerators. A table compares it with GPT-5.5, Claude-Opus-5, GLM-5.3, Kimi K3 and DeepSeek-V4.1-Flash.

TL;DR Announces LongCat-2.5, a 1.6T-parameter multimodal MoE agent model, with details on its RL pipeline, discrete visual tokens, infrastructure and benchmarks.

Organisations named here

  • DeepSeek
  • THUDM
  • Meituan
  • LongCat

Technologies named here

  • LongCat-2.0
  • gpt-5.5
  • Mooncake
  • Muon
  • GPT-5.6 Sol
  • Claude Opus 4.8
  • Claude Opus 5
  • GLM-5.3
  • Kimi K3
  • DeepSeek V4.1 Flash
  • LLM
  • Opus 5
  • Terminal-Bench
  • DeepSWE
  • AutomationBench
  • HLE
  • BrowseComp
  • CharXiv
  • GDPval-AA
  • Vision2Web
  • 3DCodeBench
  • Claw-Eval
  • FinSearchComp
  • FlatQuant
  • FrontierScience
  • FSDP
  • HiCache
  • IsoExec
  • JobBench
  • LongCat-2.5
  • LongCat-Next
  • MathVision
  • MCP Atlas
  • MoonEP
  • NL2Repo
  • PaperBench
  • PosterBench
  • Program Bench
  • ResearchRubrics
  • SkillsBench
  • SpreadsheetBench 2
  • SWE Atlas
  • Tree Attention
  • VideoMME

Techniques named here

  • Agentic reinforcement learning
  • Multi-teacher on-policy distillation
  • Prefill-Decode disaggregation
  • Asynchronous partial rollouts
  • Batch-invariant kernels
  • Expert parallelism with dynamic expert replication
  • FlatQuant
  • Residual Vector Quantization (RVQ)
  • Tree Attention
  • W4A4 quantization

Concepts named here

  • Mixed training across scaffolds
  • Native multimodality
  • Policy staleness
  • Train-inference numerical consistency

Also named here

  • Mixture of Experts
  • Residual Vector Quantization