Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.269 ·

Ambient child-session detection via marker probe, and native GetProcessTimes on Windows

Claude Code can now detect when it's running nested inside another Claude Code session, plus faster process-start-time checks on Windows

TierUnder the hoodhow much it should matter to you
Useful2my rating, 1 to 5
Signal2worth watching, 1 to 5
AreaSessionswhat it touches
KindInternal Changesin v2.1.269,
Under the hood

Claude Code can now detect when it's running nested inside another Claude Code session, plus faster process-start-time checks on Windows

What

New helper code detects whether the current Claude Code process is running nested inside another Claude Code session (a "child session"), so it can decide whether to skip loading prompt history in that case. Separately, on Windows, Claude Code now queries a process's real start time using direct bindings (via bun:ffi) to Windows system functions (OpenProcess/GetProcessTimes), falling back to the previous spawn-based detection method if those bindings aren't available.

Why

Detecting nested sessions avoids unnecessary or incorrect prompt-history loading when Claude Code is run from within another Claude Code session. The Windows process-time change makes that particular check faster and more direct when the native bindings are available, with a safe fallback if not.

See this entry in the whole of v2.1.269 →