New environment variables for low-resource warnings, plugin MCP servers and child sessions

What

An environment variable is a setting handed to a program from outside, usually by whatever starts it. This release adds several, mostly aimed at hosted setups and programs that embed Claude Code:

• CLAUDE_CODE_WARN_DISK_FREE_GIB and CLAUDE_CODE_WARN_MEMORY_FREE_GIB set thresholds, in GiB, for a new low-resource watchdog. It reads free memory from /proc/meminfo, container limits from cgroups and free disk space. When free space drops below a threshold it adds a critical "Low disk space" or "Low memory" reminder to the session, so Claude is told too. The disk threshold defaults to 0. Both are forced to 0, which switches them off, when an untraced check returns true. A server flag, tengu_ccr_memory_watchdog, adds reporting of memory use.
• CLAUDE_CODE_SKIP_PLUGIN_LOCAL_MCP_SERVERS drops plugin MCP servers (outside tool providers bundled with plugins) other than sse, http and ws ones, logging "only sse, http and ws servers load while CLAUDE_CODE_SKIP_PLUGIN_LOCAL_MCP_SERVERS is set".
• CLAUDE_CODE_SKIP_PLUGIN_MCP_BUNDLES and CLAUDE_CODE_SKIP_PLUGIN_MCP_SERVERS_EXCEPT were added to the list of known names; no code reading them was seen.
• CLAUDE_CODE_MCP_SERVE_ENABLED_PLUGINS is new and is passed on to child processes.
• CLAUDE_CODE_SDK_READS_STARTUP_MARKS makes Claude Code print startup_mark lines before its initialize response, for the SDK's startup() and prewarm().
• CLAUDE_CODE_BRIDGE_CHILD_PROJECTS_ENTRYPOINT is set to "1" by the bridge, the part that starts child sessions, only for a child with the projectThreadChild role when a new check (minified KOr) passes; otherwise it is left unset. The child reads and clears it at startup and, in the right host mode, records bridge_projects_entrypoint_name or host_name_kept. It appears 13 times in this build and not at all in the previous one.
• CLAUDE_CODE_ATTRIBUTION_PROJECT is new.
• CLAUDE_CODE_PERSONAL_CONFIG_FIX is read by a new function.

These names were added to the lists that decide which variables are passed to, or removed from, child processes. CLAUDE_CODE_ATTRIBUTION_PROJECT and two of the SKIP_PLUGIN variables (not the _EXCEPT one) are removed from child environments, matched regardless of upper or lower case, as CLAUDE_CODE_PLUGIN_DIRS already was. A related feature-name list gains bridge_projects_entrypoint_name and projects_reply_gate_policy.

Why

If you run Claude Code in a container or host it for others, you can now have both you and Claude warned before disk or memory runs out, and keep plugins from starting local MCP servers. The bridge and SDK variables are plumbing for host programs and do nothing unless something sets them.