New CLAUDE_CODE_SIMPLE environment variable for enabling a simplified mode.
Details
Activated by setting CLAUDE_CODE_SIMPLE=1 in the environment or by passing the --bare CLI flag; both paths go through cf(), which returns true for either.
When active, the following subsystems are disabled: CLAUDE.md reading, skills discovery, plugins, syntax-highlight language packs (hljsLanguages), hooks, MCP agent frontmatter, agent definitions, and LSP servers.
The following subsystems remain enabled in simple mode: workflows, themes, status line, file suggestions, auto-discovered MCP, Claude.ai MCP, output styles, and keybindings.
Authentication is narrowed to the minimum: OAuth (Claude.ai login) is bypassed entirely; only ANTHROPIC_API_KEY or an apiKeyHelper-sourced key is accepted. The normal managed-key and OAuth token paths return null.
Auto-memory (persistent write-after-turn memory) is unconditionally disabled regardless of other memory settings or the CLAUDE_CODE_DISABLE_AUTO_MEMORY env var.
Several background startup jobs are skipped: plugin hook setup and hot-reload, session file access hooks, release-notes prefetch, and memory extraction after turns.
In coordinator/multi-agent mode, worker tool guidance is abbreviated: workers are described as having access only to bash, computer-use, read/write tools, and connected MCP tools — the Skill and Workflow tools are omitted from the listing.
Forking is refused: /fork exits with "Cannot fork — this session was started with launch flags (safe or bare mode, a custom system prompt, a tool allowlist, or restricted settings) that the copy wouldn't inherit…"
Evidence
function cf() { return qt(process.env.CLAUDE_CODE_SIMPLE) || fsi("--bare"); } and the Ffg feature-disable map at ZT initialization (search for "CLAUDE_CODE_SIMPLE" and "Ffg")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agree/fork now copies your conversation into a new background session (its own row in claude agents) while you keep working; the in-session…
