Bridge-launched processes hand down a one-use marker and verify…

Bridge-launched processes hand down a one-use marker and verify the prompt they are piped

Processes launched by the bridge mark their marker as spent, so grandchildren are told apart.

Under the hood No documentation found Internal Changes

JSON All of v2.1.239

Under the hoodTier: how much it should matter to you

1Useful: my rating, 1 to 5

3Signal: worth watching, 1 to 5

BridgeArea: what it touches

Internal ChangesKind: in v2.1.239, 21 Aug 26

Internal ChangesSection of the release

What

A process started by the bridge is identified by an environment variable it consumes: it rewrites CLAUDE_CODE_BRIDGE_MCP_CARRIER from "1" to "spent" for anything it spawns, so a grandchild is recognisable as further removed rather than as the bridge child itself.

Details

Three variables are new: CLAUDE_CODE_BRIDGE_MCP_CARRIER, CLAUDE_CODE_BRIDGE_PROMPT_SHA256 and CLAUDE_CODE_BRIDGE_SESSION_ID.
A prompt piped to such a process is accepted only if its sha256 matches CLAUDE_CODE_BRIDGE_PROMPT_SHA256, and that variable is cleared immediately after reading.
Under CLAUDE_CODE_ENVIRONMENT_KIND of "byoc" with CLAUDE_CODE_REMOTE set, the carrier variable is deleted for children rather than marked spent.

Evidence

CLAUDE_CODE_BRIDGE_MCP_CARRIER

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

Read from

Names in the bundleCLAUDE_CODE_BRIDGE_MCP_CARRIERCLAUDE_CODE_BRIDGE_PROMPT_SHA256

How sure we are

One source agreesOne thing we can check says the same as this entry.

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

See this entry in the whole of v2.1.239 →

The build it came inv2.1.239

21 Aug 2026 · 300 entries, this one is #260.

Use it now41
You'll notice160
Nothing to try yet37
Under the hood62

Either side of it

v2.1.238Older
v2.1.240Newer

Open the release →

Names in this entry

envCLAUDE_CODE_BRIDGE_MCP_CARRIER
Processes launched by the bridge mark their marker as spent, so grandchildren are told apart.
envCLAUDE_CODE_BRIDGE_PROMPT_SHA256
Processes launched by the bridge mark their marker as spent, so grandchildren are told apart.
envCLAUDE_CODE_BRIDGE_SESSION_ID
Set automatically in Bash tool and hook command subprocesses while the session has an active Remote Control connection, and removed when the connection ends. The value is the session's ID in session_ form, the same identifier that appears in the session's claude.ai/code URL, so a script can link back to the session that ran it. Requires Claude Code v2.1.199 or later. In cloud sessions, read CLAUDE_CODE_REMOTE_SESSION_ID instead
envCLAUDE_CODE_ENVIRONMENT_KIND
Long sessions can pick up fresh credentials pushed over the live connection instead of dropping out.
envCLAUDE_CODE_REMOTE
Remote sessions started from review can skip writing some state to disk.

Is this right?

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

v2.1.224 Plugins can be installed from an HTTPS zip archive
Both mention sha256