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Claude 4 and Claude Code

Anthropic releases Opus 4 and Sonnet 4, models that work autonomously on code for hours, and its terminal agent Claude Code reaches general availability; the coding agent becomes a category.

category
product
significance
3 of 5
people
Dario Amodei, Boris Cherny
organisations
Anthropic

what had to happen · 55 events back to 1943

Every event this one built on, transitively, in order. The organism has the same path lit. Direct influences are marked.

00 · One neuron · 1

  1. 1943A logical calculus of nervous activity

I · Foundations · 9

  1. 1948A mathematical theory of communication
  2. 1949Cells that fire together wire together
  3. 1950Programming a computer for playing chess
  4. 1958The perceptron learns
  5. 1959Samuel's checkers program coins 'machine learning'
  6. 1960ADALINE and the least-mean-squares rule
  7. 1965Moore's law
  8. 1969Perceptrons
  9. 1970Reverse-mode automatic differentiation

W1 · The first winter · 2

  1. 1974Werbos applies backpropagation to neural networks
  2. 1980The Neocognitron

II · Connection · 3

  1. 1982The Hopfield network
  2. 1985The Boltzmann machine
  3. 1986Backpropagation

W2 · The second winter · 6

  1. 1988Temporal-difference learning
  2. 1989Q-learning
  3. 1989LeNet reads handwritten postcodes
  4. 1990Finding structure in time
  5. 1991The vanishing gradient problem
  6. 1992TD-Gammon reaches world-class backgammon

III · Statistics and data · 10

  1. 1997Long short-term memory
  2. 1998MNIST and LeNet-5
  3. 1999The first GPU
  4. 2003A neural probabilistic language model
  5. 2006Deep belief networks and the word 'deep'
  6. 2007CUDA
  7. 2009Deep learning moves to GPUs
  8. 2009ImageNet
  9. 2010Rectified linear units
  10. 2010DeepMind is founded

IV · Deep learning · 11

  1. 2012Google Brain's network discovers cats
  2. 2012Dropout
  3. 2012AlexNet wins ImageNet
  4. 2013Deep Q-networks play Atari
  5. 2014Google buys DeepMind
  6. 2014Superintelligence
  7. 2014Attention
  8. 2014Sequence to sequence learning
  9. 2015Batch normalisation
  10. 2015Residual networks
  11. 2015OpenAI is founded

V · Transformers · 9

  1. 2017Attention is all you need
  2. 2017Deep reinforcement learning from human preferences
  3. 2018GPT: generative pre-training
  4. 2019GPT-2 and the model too dangerous to release
  5. 2020Scaling laws for neural language models
  6. 2020GPT-3
  7. 2020Learning to summarise from human feedback
  8. 2021Anthropic is founded
  9. 2021GitHub Copilot writes codedirect

VI · Everyone · 4

  1. 2022InstructGPT
  2. 2023Claude
  3. 2024Claude 3 catches GPT-4direct
  4. 2024Claude learns to use a computerdirect

On 22 May 2025 Anthropic released Claude Opus 4 and Claude Sonnet 4, and with them made Claude Code, a command-line agent that had been in preview since February, generally available. The models scored 72.5 percent on SWE-bench Verified, a test of resolving real GitHub issues, and the company reported customers running them on a single task for seven hours. Claude Code lived in the terminal: given a goal, it read the repository, planned, wrote, ran the tests, fixed what failed and opened a pull request, asking permission at the steps that mattered.

Copilot in 2021 had completed lines. The agents of 2025 completed work. OpenAI's Codex agent launched the same month, Google's Jules and Gemini CLI in the summer, and Cursor, which wrapped the same models in an editor, became the fastest-growing software company in history. By 2026 the laboratories were reporting that most of their own code was written this way, and the question of what it meant for the profession that had adopted the technology first was no longer hypothetical.

The release is on this timeline as the point at which "agent" stopped meaning a demo. The system card also documented Opus 4 attempting, in a contrived test, to blackmail an engineer to avoid being shut down, and the company's decision to publish that was as discussed as the model.

what it led to · 2 events downstream, through 2026

Built on it directly:

  1. 2026Claude Fable 5 and the Mythos classVII

And, through them, by era:

VII · Agents · 1
  1. 2026Claude Fable 5.1

sources · 1

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