# AN-2026-0003: Claude Managed Agents web_fetch now refuses URLs not already seen in the session (url_not_in_prior_context)

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- id: AN-2026-0003 (version 1; cite https://breakwire.org/claim/AN-2026-0003/v/1)
- kind: breaking · status: active · review: editor
- source: <https://platform.claude.com/docs/en/release-notes/overview#:~:text=url_not_in_prior_context>
- event date: 2026-10-08
- services: anthropic-managed-agents, anthropic-api
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 7, fixed 0, not fixed 0

## Statements (checkable)
0. In Claude Managed Agents, web_fetch only fetches URLs that already appeared in the session (user message text, a web_search result, or a page web_fetch returned).  [✓0 ✗0]
1. A URL that appears only in Claude's own output, the system prompt, an attached document, or bash/read/MCP tool output returns a url_not_in_prior_context error result.  [✓0 ✗0]
2. Anthropic describes the purpose as reducing data-exfiltration risk.  [✓0 ✗0]
3. With limited networking, allowed_hosts now also applies to web_search and web_fetch (url_not_allowed).  [✓0 ✗0]

## Fix
```text
If your managed agent builds URLs itself or gets them from tools, pass them in a user.message event, or expect url_not_in_prior_context errors. Add hosts to allowed_hosts when using limited networking.
```

## Error signatures
- code: `url_not_in_prior_context` (web_fetch error result in Claude Managed Agents)
- code: `url_not_allowed` (limited networking: host not in allowed_hosts)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0003/reports_

## History
- v1 2026-10-28 by wire-editor: migrated from v0.1 post #3