# Claude change log

> What changed in Claude, by date: every Paralax brief about it, each linking its source where one exists.

- Canonical: https://paralax.ai/engines/claude
- Latest brief: 2026-09-23
- Change log index: https://paralax.ai/engines

## Dated briefs

### 2026-09-23 — [Claude Citation Change Log: 463 of the Top 500 Domains, a Panel the Six-Source Cap Barely Touched](https://paralax.ai/blog/claude-citation-change-log-2026)

A dated record of what Claude cites. Entry one: Claude reaches 463 of the 500 most-cited domains, second only to Perplexity among the engines measured.

- Markdown: https://paralax.ai/blog/claude-citation-change-log-2026.md

### 2026-07-28 — [Claude's Shared Chats Got Indexed by Google Search — What It Signals for AI Discovery](https://paralax.ai/blog/claude-shared-chats-indexed-google-search-2026)

Claude shared chats got indexed by Google. The real signal: AI share links are now an indexable content class.

- Markdown: https://paralax.ai/blog/claude-shared-chats-indexed-google-search-2026.md

### 2026-07-27 — [Two Answer Engines Swapped Default Models in 72 Hours — Your AI Visibility Baseline Just Expired](https://paralax.ai/blog/default-model-swap-resets-ai-visibility-baseline-2026)

Gemini 3.6 Flash and Claude Opus 5 both became default models in one week. When the model changes, so does what it cites. Here's why.

- Primary source: [blog.google](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-6-flash-3-5-flash-lite-3-5-flash-cyber/)
- Markdown: https://paralax.ai/blog/default-model-swap-resets-ai-visibility-baseline-2026.md

### 2026-07-01 — [Claude Fable 5 Returns. Model Access Is Becoming the AI Search Control Plane.](https://paralax.ai/blog/claude-fable-mythos-export-controls-ai-search-control-plane-2026)

Claude Fable 5 is back, but the real signal is model access becoming AI discovery infrastructure.

- Primary source: [platform.claude.com](https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5)
- Markdown: https://paralax.ai/blog/claude-fable-mythos-export-controls-ai-search-control-plane-2026.md

### 2026-06-30 — [Claude in Microsoft Foundry Makes Enterprise AI Retrieval Multi-Model by Default](https://paralax.ai/blog/claude-microsoft-foundry-enterprise-ai-retrieval-2026)

Claude in Microsoft Foundry turns enterprise AI retrieval into source-architecture work.

- Primary source: [learn.microsoft.com](https://learn.microsoft.com/en-us/azure/foundry/foundry-models/concepts/claude-models)
- Markdown: https://paralax.ai/blog/claude-microsoft-foundry-enterprise-ai-retrieval-2026.md

### 2026-06-24 — [Claude Tag Turns Slack Into an AI Search Surface](https://paralax.ai/blog/claude-tag-slack-ai-agent-search-surface-2026)

Claude Tag makes Slack a shared AI answer surface, forcing brands to rethink internal source architecture.

- Primary source: [anthropic.com](https://www.anthropic.com/news/introducing-claude-tag)
- Markdown: https://paralax.ai/blog/claude-tag-slack-ai-agent-search-surface-2026.md

### 2026-06-11 — [Anthropic's invisible Claude guardrail is an AI search disclosure warning](https://paralax.ai/blog/anthropic-invisible-claude-guardrail-ai-search-disclosure)

Anthropic's hidden Claude guardrail shows why AI search needs source and fallback disclosure.

- Primary source: [platform.claude.com](https://platform.claude.com/docs/en/build-with-claude/citations)
- Markdown: https://paralax.ai/blog/anthropic-invisible-claude-guardrail-ai-search-disclosure.md

## Baseline measurements

Measured citation behavior for this engine, recorded release by release: [Claude Citation Change Log: 463 of the Top 500 Domains, a Panel the Six-Source Cap Barely Touched](https://paralax.ai/blog/claude-citation-change-log-2026)