What
When Claude Code relaunches itself, starting a new copy of itself without being given explicit arguments, it now sets CLAUDE_CODE_RELAUNCH_RESUME_HINT_FLAGS for the new copy. This environment variable holds the command-line options (flags) you originally started Claude Code with, cleaned up first:
- Removed options: resume, continue, session-id, worktree, prefill and some others, plus teammate and agent options
- Character check: an option is kept only if it uses a strict set of characters
- System paths: anything touching /dev/ or /proc/ is dropped
The new copy reads the variable, clears it, and uses it only if cleaning it again gives exactly the same result.
Why
The hint shown after a relaunch, telling you how to resume, can then include the options you first started with.
Names in the bundleCLAUDE_CODE_RELAUNCH_RESUME_HINT_FLAGS
One source agreesOne thing we can check says the same as this entry.
The name it cites is new in this build
New in this build: CLAUDE_CODE_RELAUNCH_RESUME_HINT_FLAGS