Nested Claude Code sessions stop inheriting the parent's session…

Nested Claude Code sessions stop inheriting the parent's session id

A Claude Code started from inside another no longer takes the parent's session id, and CLAUDE_CODE_DISABLE_NESTED_SESSION_ID brings it back

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

2Useful: my rating, 1 to 5

2Signal: worth watching, 1 to 5

SessionsArea: what it touches

ImprovementsKind: in v2.1.317, 02 Nov 26

ImprovementsSection of the release

Unclear What a user sees differently when a nested session has no inherited id is not shown.

What

A session is one run of Claude Code, with its own id. Claude Code sets CLAUDE_CODE_CHILD_SESSION in programs it starts, such as commands run through its Bash tool or hooks. A Claude Code started that way no longer inherits the parent's session id when all of these hold:

CLAUDE_CODE_CHILD_SESSION is set
a parent session id exists
there is no --sdk-url argument
the command is not mcp serve

Setting CLAUDE_CODE_DISABLE_NESTED_SESSION_ID turns this off, so the child inherits the parent's id again.

Why

A Claude Code you run from inside another one no longer carries the parent's session id by default. If something you use relied on that id being passed down, the environment variable restores it.

Read from

Names in the bundleCLAUDE_CODE_CHILD_SESSION

What the documentation says

Documented inclaude-code/agent-sdk/typescript

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 doubtWhat a user sees differently when a nested session has no inherited id is not shown.

Anthropic's release notes agreeAdded CLAUDE_CODE_DISABLE_NESTED_SESSION_ID: set it to 1 on a self-hosted runner to have claude -p run inside a session use that session's…

See this entry in the whole of v2.1.317 →

The build it came inv2.1.317

2 Nov 2026 · 440 entries, this one is #127.

Use it now21
You'll notice261
Nothing to try yet13
Under the hood145

Either side of it

v2.1.316Older
v2.1.318Newer

Open the release →

Names in this entry

envCLAUDE_CODE_DISABLE_NESTED_SESSION_ID
A Claude Code started from inside another no longer takes the parent's session id, and CLAUDE_CODE_DISABLE_NESTED_SESSION_ID brings it back
envCLAUDE_CODE_CHILD_SESSION
Set to 1 in subprocesses Claude Code spawns via the Bash, PowerShell, and Monitor tools, hook commands, and status line commands. Not set for stdio MCP server subprocesses, which are long-lived and outlive the session that spawned them. Unlike CLAUDECODE, this is only set by Claude Code itself when it launches a subprocess and not by IDE extensions, so it reliably distinguishes a nested session from a top-level claude launched in an IDE-integrated terminal. A nested interactive claude TUI started this way is automatically excluded from --resume, --continue, up-arrow history, and the claude agents list. Non-interactive claude -p sessions still persist. Set CLAUDE_CODE_FORCE_SESSION_PERSISTENCE=1 to override this exclusion. Requires Claude Code v2.1.172 or later
cli--sdk-url
Startup stats now note the input format, whether --sdk-url was passed, and an experiment flag.

Anthropic's note

Upstream's own release notes for v2.1.317 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.

Added CLAUDE_CODE_DISABLE_NESTED_SESSION_ID: set it to 1 on a self-hosted runner to have claude -p run inside a session use that session's ID and transcript, as in earlier versions

Is this right?