Claude Code v2.1.132: SIGINT Graceful Shutdown, MCP Fixes, and Terminal Handling Overhaul

Anthropic shipped Claude Code v2.1.132 with a heavy focus on terminal reliability, MCP server robustness, and edge-case fixes that matter when you're running AI coding agents for hours on end. Here's what changed for developers and CI pipelines.

Environment Variables and Session Plumbing

• CLAUDE_CODE_SESSION_ID is now exported into the Bash tool subprocess environment, matching the session_id passed to hooks. Useful for tracking tool calls back to a session.
• CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 lets you opt out of the fullscreen alternate-screen renderer, keeping the conversation in the terminal's native scrollback.

Graceful Shutdown and Resume Fixes

• External SIGINT (e.g., IDE stop button, kill -INT) now triggers a graceful shutdown: terminal modes are restored and the --resume hint is printed instead of an abrupt exit.
• --resume no longer fails with no low surrogate in string when a tool error truncation split an emoji; pre-corrupted sessions are sanitized on load.
• --permission-mode flag is now respected when resuming a plan-mode session with -p --continue / --resume, and plan mode is re-applied after ExitPlanMode within the same session.

Terminal and Input Handling

• Fullscreen mode no longer shows a blank screen after laptop sleep/wake or Ctrl+Z/fg until the next keystroke or stream output.
• Cursor now lands correctly on Ctrl+E/A/K/U/arrow keys when an Indic conjunct or ZWJ emoji wraps across lines.
• Vim operators no longer corrupt text containing decomposed (NFD) accented characters.
• Pasting text starting with / no longer swallows input or triggers an unknown-command reply.
• Stray escape sequences from focus events or mouse-tracking reports interleaved with bracketed paste are no longer dumped into the prompt.
• Mouse wheel scrolling speed normalized in Cursor and VS Code 1.92–1.104 (upstream xterm.js bug) and in JetBrains IDE 2025.2 terminals (spurious arrow keys, wrong-direction events, runaway acceleration).
• /usage Ctrl+S no longer hangs when copying the stats screenshot to the clipboard on Linux/X11.
• /terminal-setup no longer shows a contradictory error in Windows Terminal — Shift+Enter is natively supported there.
• /effort picker now reflects the CLAUDE_CODE_EFFORT_LEVEL env var override.
• /status fixed for showing the wrong default model for some users.
• Slash command autocomplete popup now scales vertically with terminal height instead of being capped at ~3–5 visible commands.
• Statusline context_window token counts now reflect current context usage, not cumulative session totals.
• Alt+T (thinking toggle) works on macOS terminals without 'Option as Meta' enabled (iTerm2, Terminal.app defaults).
• Dead keyboard input on Windows after re-opening a background session from claude agents is fixed.

MCP Server Stability

• Unbounded memory growth (10GB+ RSS) when a stdio MCP server writes non-protocol data to stdout is fixed.
• MCP servers that connect but fail tools/list now retry once and show 'connected · tools fetch failed' in /mcp instead of silently showing 0 tools.
• Unauthorized claude.ai MCP connectors now show as 'needs auth' instead of 'failed', and headless -p mode no longer retries non-transient 4xx connection failures.

Other Improvements

• Visual consistency improved in slash command dialogs and /login, /upgrade, /extra-usage dialog spacing.
• /tui fullscreen startup banner updated to describe additional renderer benefits (lower memory usage, mouse support, auto-copy on select).
• Fixed Bedrock and Vertex 400 errors when ENABLE_PROMPT_CACHING_1H is set.

This release is particularly relevant for developers running Claude Code in headless CI environments (where graceful shutdown and session resume matter), users of IDE terminals with non-standard escape handling, and teams relying on MCP servers for custom tool integrations.