# reasoning models insights

Rangoon Insights reporting and guides tagged reasoning models.

Canonical: https://rangoon.ai/insights/tags/reasoning-models/

## Topics
- [Agent systems](https://rangoon.ai/insights/topics/agents/): Agent runtimes, handoffs, tools, and the boundaries that make them reviewable.
- [Governance](https://rangoon.ai/insights/topics/governance/): Policy, identity, authorization, approvals, and evidence for consequential work.
- [Infrastructure](https://rangoon.ai/insights/topics/infrastructure/): Model serving, sandboxes, tool services, and deployment boundaries.
- [Models](https://rangoon.ai/insights/topics/models/): Inference choices, local serving, compatibility, and operational tradeoffs.

## Stories
- [Grok 4 Fast combined quick and reasoning responses while xAI split API access into two models](https://rangoon.ai/insights/archive-xai-grok-4-fast-september-2025/)
  xAI announced Grok 4 Fast on September 19, 2025, combining reasoning and non-reasoning behavior in one model family and releasing two API endpoints.
- [Grok 4’s July launch put tool use, subscriber access and an API on the same release record](https://rangoon.ai/insights/archive-xai-grok-4-native-tools-july-2025/)
  xAI announced Grok 4 on July 9, 2025, offering it to SuperGrok and Premium+ subscribers and through its API, with Grok 4 Heavy as a separate tier.
- [xAI introduced Grok 3 as an early preview, with Think variants in beta while training continued](https://rangoon.ai/insights/archive-xai-grok-3-beta-february-2025/)
  xAI announced Grok 3 and Grok 3 mini on February 19, 2025, calling Grok 3 an early preview and its named Think variants beta reasoning models.
- [GPT-5.1 turned model-family updates into a release-management problem](https://rangoon.ai/insights/archive-openai-gpt-5-1-november-2025/)
  OpenAI released GPT-5.1 on November 12, 2025, introducing Instant and Thinking variants as an update to the GPT-5 family.
- [GPT-5 made routing part of a flagship-model release](https://rangoon.ai/insights/archive-openai-gpt-5-august-2025/)
  OpenAI introduced GPT-5 on August 7, 2025, describing a unified model system that combined fast responses, deeper reasoning, and a routing layer.
- [Phi-4 reasoning releases made inference-time work a route policy](https://rangoon.ai/insights/archive-microsoft-phi-4-reasoning-april-2025/)
  Microsoft introduced Phi-4-reasoning, Phi-4-reasoning-plus and Phi-4-mini-reasoning on April 30, 2025, making reasoning budget and evaluation policy explicit deployment choices.


## More information

- [Documentation index](https://rangoon.ai/llms.txt)
- [AI access and policies](https://rangoon.ai/ai/)
- [Source repository](https://github.com/hypler-dev/rangoon)