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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.251 Home All releases ←olderv2.1.250
Claude Code v2.1.251

Backgrounded commands record whether the move was to deliver a queued message

Under the hood
Useful1 Signal2
Bash

Backgrounded commands now record whether they moved aside to deliver a queued message.

What

Internal shell state now distinguishes a command pushed to the background so a message queued for the model could reach it from one backgrounded for other reasons, such as a plugin aborting the turn. The PowerShell command result carries this marker alongside the existing background fields. None of it surfaces in the interface while using Claude Code.

Details
  • a backgroundedToDeliverMessage field is set on the result of a backgrounded PowerShell command and passed through with the other background fields
  • the field is documented as true only when the command was moved to the background so a message queued for the model could reach it
  • commands backgrounded for any other cause leave the field unset, so the reason for backgrounding is no longer ambiguous internally
  • no flag, setting or environment variable exposes this, and there is no user-visible output change in this build
Evidence

backgroundedToDeliverMessage: b.backgroundedToDeliverMessage, True if the command was moved to the background so a message queued for the model could reach it

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.251 →