Interactive TUI crashes: screen width spirals unboundedly (100% write ratio)

Environment

• Claude Code version: 2.1.63 (Homebrew cask, macOS)
• OS: macOS (Apple Silicon, Ghostty terminal)
• Shell: zsh
• Auth: OAuth (Claude Max subscription)
• Permission mode: --dangerously-skip-permissions (bypass)

Description

Claude Code crashes consistently in interactive mode while print mode (-p) works perfectly every time. The process hard-crashes mid-stream with no clean Stop event, no signal, no OOM kill, and no macOS crash report.

Root Cause Evidence

Debug logs show the internal render surface width growing unboundedly every render cycle while height stays constant:

[DEBUG] High write ratio: blit=0, write=12279 (100.0% writes), screen=167x81
[DEBUG] High write ratio: blit=0, write=12482 (100.0% writes), screen=171x81
[DEBUG] High write ratio: blit=0, write=12840 (100.0% writes), screen=182x81
[DEBUG] High write ratio: blit=0, write=13075 (100.0% writes), screen=188x81

In longer sessions, this spirals to screen=507x81 and screen=431x103 before the process dies.

Key observations:

• 100% write ratio, 0% blits — the entire screen is redrawn from scratch every frame because the render surface dimensions keep changing
• Width grows, height stays fixed — not consistent with actual terminal resizing
• No clean shutdown — the debug log ends abruptly mid-API-stream with no Stop event, no Stopped caffeinate, no cleanup
• No OS-level crash signal — no macOS crash report, no Jetsam/OOM kill, no SIGTERM/SIGKILL in system logs

Reproduction

1. Run claude --dangerously-skip-permissions interactively in Ghostty terminal
2. Send any prompt that triggers tool use (Glob, Bash, Read, subagents)
3. Watch the debug log (~/.claude/debug/<session>.txt) — screen width increases on every High write ratio line
4. Process crashes within 30-120 seconds of active tool use

What does NOT cause it

Extensive elimination testing was performed:

• Print mode (claude -p "say ok"): Never crashes. Confirmed across dozens of runs.
• OAuth token: Re-authenticated with fresh token (all scopes: user:profile, user:inference, user:mcp_servers). Still crashes.
• MCP servers: Disabled all MCPs (google, playwright, memory, gitnexus). Only grepai remaining. Still crashes.
• Hooks: Disabled all project hooks and global hooks. Still crashes.
• Plugins: All plugins disabled (enabledPlugins: {}). Still crashes.
• Claude.ai MCP connectors: Disabled gate (tengu_claudeai_mcp_connectors: false). Still crashes.
• Shell wrapper: Tested with raw /opt/homebrew/bin/claude binary directly. Still crashes.
• Terminal size locking: Attempted stty cols 120 rows 40 + trap '' WINCH. Still crashes.

Debug Log (clean session, minimal config)

Session e5d93d29-6072-4505-bccc-16ac8596388d.txt:

• Start: 22:43:21 — clean startup, only grepai MCP, 0 plugins, 0 hooks
• 22:43:22 — REPL mounted, session active
• 22:44:16 — User prompt submitted, API streaming begins
• 22:44:16 — First High write ratio at screen=167x81
• 22:44:26 — Subagent (Explore) launched, tools executing (Glob, Bash, Read)
• 22:44:29 — Screen width at 188x81, still growing
• 22:44:40 — Log ends abruptly mid-stream — no Stop, no cleanup

Total session duration: 79 seconds before hard crash.

Expected Behavior

The screen width should remain fixed at the terminal's actual column count. The render path should use blitting (partial updates) instead of full-screen rewrites when the terminal dimensions haven't changed.

Workaround

Use print/pipe mode (claude -p "prompt") or non-interactive mode. Interactive TUI is currently unstable.