New macOS-only Bash tool behaviour for heredocs, on by default

On macOS with /bin/bash, the Bash tool now checks a remote switch that defaults to on for a change involving heredocs on input

You'll noticeTier: how much it should matter to you

2Useful: my rating, 1 to 5

2Signal: worth watching, 1 to 5

Bash ToolArea: what it touches

ImprovementsKind: in v2.1.318, 03 Nov 26

ImprovementsSection of the release

Unclear It is not clear what the Bash tool does differently when this check is true.

What

Claude Code now has a check that the Bash tool uses. The Bash tool is how Claude runs shell commands. The check is true only when all of these hold:

You are on macOS.
Your shell is /bin/bash.
A remote switch is on. It counts as on unless it is switched off remotely.

The check concerns heredocs, a way of passing several lines of text into a command as its input.

Why

This looks like macOS-only Bash tool behaviour that is on by default, so Mac users running /bin/bash are the ones it can affect.

Read from

Feature flag

tengu_mossy_anvil Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.318: on

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.318. It isn't a statement about your account. What a flag value here can and cannot tell you

How sure we are

Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.

The writer flagged doubtIt is not clear what the Bash tool does differently when this check is true.

Anthropic's release notes agreeImproved the reliability of git commits and pull request creation when the Bash tool runs macOS's built-in /bin/bash

The name it cites is new in this buildNew in this build: tengu_mossy_anvil

See this entry in the whole of v2.1.318 →

The build it came inv2.1.318

3 Nov 2026 · 425 entries, this one is #137.

Use it now23
You'll notice215
Nothing to try yet27
Under the hood160

Either side of it

v2.1.317Older

Open the release →

Anthropic's note

Upstream's own release notes for v2.1.318 name something this entry names, so the two are probably about the same change. Probably: the pairing is made on a shared name rather than on the words around it.

Improved the reliability of git commits and pull request creation when the Bash tool runs macOS's built-in /bin/bash

Is this right?