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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.221 ·

MCP policy URL predicates flag collapsible dot segments

MCP URL allowlist patterns that could be rewritten by dot segments are now flagged with fix instructions.

You'll notice Improvements
JSON All of v2.1.221
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.221,
ImprovementsSection of the release
What

Expansion safety analysis now catches allowlist patterns whose expanded path would be silently rewritten by URL parsing.

Details
  • A pattern containing $ whose expanded path carries a .. or . segment is treated as unsafe.
  • The diagnostic explains how to fix it and distinguishes patterns where the $ is not a real ${NAME} reference.
  • The variable list in the diagnostic now includes missing variables, and the analysis result exposes missingVars to callers.
  • Allowlist entries using an unsafe expansion continue to fail closed.
Evidence

the expanded entry's path carries a dot segment ('..' or '.') that URL parsing would collapse

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.221 →

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