Claude Code v2.1.257 · 1 Sep 2026
New system prompt snapshot plumbed into MCP/tool context
The tool and agent context now exposes a snapshot of the system prompt in effect alongside the appended one.
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All of v2.1.257
Under the hood Tier: how much it should matter to you
3 Useful: my rating, 1 to 5
3 Signal: worth watching, 1 to 5
System Prompt Area: what it touches
Internal Changes Kind: in v2.1.257, 01 Sep 26
Internal Changes Section of the release
1 Sep 2026 · 505 entries, this one is #363.
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Names in this entry
setting systemPromptSnapshot A new --system-prompt-snapshot option makes a session record its system prompt once and reuse it on resume.
setting appendSystemPrompt Forked background sessions are told to stay in their own worktree and never touch the original session's branch.
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Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.
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New wait condition can hold background-task shutdown for armed monitors
Under the hood Background Tasks
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Under the hood Web Research
