Claude Code hangs with zero token consumption for 25-30 minutes, requires force-exit

Description

Claude Code repeatedly hangs mid-session with zero token consumption for 25-30 minutes. The process stays running but produces no output and consumes no tokens. Requires force-exit (Ctrl+C or kill), losing all in-context work.

Environment

• OS: Ubuntu on NVIDIA DGX Spark (ARM64)
• Model: claude-opus-4-6
• Session: Running inside tmux (not a terminal/network issue — process is local)
• Claude Code version: Latest as of 2026-04-07

Frequency

4-5 occurrences over 3 days. Roughly 1-2 hangs per working session. Each hang wastes 25-30 minutes of wall time before the user notices and force-exits.

Reproduction pattern

Hangs have occurred:

1. After tool calls that return large results (e.g., Glob returning 90+ file paths from ~/.claude/)
2. After a Read tool call that returns an internal error
3. Seemingly at random during normal edit/grep workflows

In all cases, the session shows zero token consumption — the model never runs. This suggests the client is stalling before sending the API request, or the API request fails silently with no retry or error surfaced to the user.

Impact

• Each hang loses all uncommitted in-context work
• User has spent ~1.5 hours in a single day waiting on hangs
• Significantly degrades trust in the tool for sustained development sessions
• Workaround of switching to Sonnet shouldn't be necessary if this is a client issue

Expected behavior

• If the API request times out, surface an error and retry
• If context assembly stalls, time out and report
• Never silently hang with no feedback for 25+ minutes

Additional context

• The user accesses the tmux session via SSH from a laptop. WiFi interruptions affect the terminal view only, not the Claude Code process itself.
• The hang is not network-related on the user's side — the process is local on the server.
• Previously, curling SPA routes (returning 41KB HTML into context) caused similar hangs, but those have been eliminated. Recent hangs occur without any curl activity.