{"version":"2.1.318","anchor":"repl-code-mode-opt-in-dialog-lost-eval-events-resume-ru","canonical_anchor":"repl-code-mode-opt-in-dialog-lost-eval-events-resume-ru","heading":"An experimental REPL mode, where Claude writes JavaScript to call its tools, appears","tier":"soon","area":"REPL Mode","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.318\/e\/repl-code-mode-opt-in-dialog-lost-eval-events-resume-ru","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.318","markdown":"### An experimental REPL mode, where Claude writes JavaScript to call its tools, appears\n\nAn experimental REPL mode lets Claude write JavaScript that calls its tools, with an opt-in dialog and limits on resuming and moving sessions\n\n**Unclear.** It is not clear how the mode is switched on or which environment variable controls it.\n\n**What**\n\nClaude Code has new code for a REPL mode. In it, Claude writes JavaScript that calls its tools, rather than calling each tool directly. Most of it stays switched off unless the mode is on. What it includes:\n\n- An opt-in dialog that calls the mode \"an early experiment\" that \"may change or be removed in any release\".\n\n- A session started in the mode can only be resumed with the mode on.\n\n- When you resume, code that was still running in the background when Claude Code closed shows as \"Lost: Claude Code exited before this finished\".\n\n- Moving such a session to the cloud is refused.\n\n- Asking a background agent to continue when it has no waiting results reports that there is nothing to wake for.\n\n- The mode can be turned off through a setting or a shell environment variable.\n\n**Why**\n\nIf you try the mode, the sessions you start in it are tied to it: you cannot resume them without the mode on or move them to the cloud, and background work cut short by closing Claude Code is marked as lost.\n\n- Area: REPL Mode\n- Tier: Nothing to try yet\n- Useful: 5\/5\n- Signal: 5\/5\n- Scope: individual\n- Heads-up: no\n- Present in the build but not switched on"}