[Bug] PreToolUse hook with additionalContext causes model turn to terminate on tool error

Bug Description

When a PreToolUse hook outputs additionalContext via hookSpecificOutput, and the subsequent tool call returns a non-zero exit code, the model's turn terminates immediately without responding to the error. The model never gets a chance to process the failure and continue.

Repro:

1. Add a PreToolUse hook in .claude/settings.local.json:

  {
    "hooks": {
      "PreToolUse": [
        {
          "hooks": [
            {
              "type": "command",
              "command": "echo '{\"hookSpecificOutput\":{\"hookEventName\":\"PreToolUse\",\"additionalContext\":\"Current
   time: 2026-01-01\"}}'"
            }
          ]
        }
      ]
    }
  }

1. Start a conversation and ask the agent to run: bash -c 'exit 1'
2. Observe: the model's turn ends immediately after the error. It does not respond or attempt recovery.

Expected: The model receives the error result and continues its turn (responds to the error, tries alternatives, etc.) — same as when no PreToolUse hook is configured.

Actual: The turn silently terminates. In longer autonomous workflows, this manifests as the model stopping without being able to respond to the failed tool call, and requires user prompting to continue.

Workaround: Remove the PreToolUse hook.

Environment: Claude Code CLI, claude-opus-4-6, macOS Darwin 24.5.0

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.69
• Feedback ID: 5677cd3e-ed07-4620-a851-3ac75698a58e

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/$USER/.local/share/claude/versions/2.1.69 (expected in multi-process scenarios)\n    at NS_ (/$bunfs/root/src/entrypoints/cli.js:2397:2066)\n    at zpR (/$bunfs/root/src/entrypoints/cli.js:2397:1210)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-05T01:46:44.267Z"}]