[BUG] managed-settings sandbox.enabled: true causes all Bash tool output to be empty on macOS

Bug Description

When sandbox.enabled: true is set in managed-settings.json (/Library/Application Support/ClaudeCode/managed-settings.json), all Bash tool commands return "(Bash completed with no output)" even though the commands actually execute successfully.

Setting sandbox.enabled: false immediately resolves the issue.

Environment

• OS: macOS (Darwin 25.3.0)
• Claude Code: Latest version (as of 2026-04-10)
• Shell: zsh

Steps to Reproduce

1. Create /Library/Application Support/ClaudeCode/managed-settings.json with sandbox enabled:

{
  "permissions": {
    "ask": ["Bash(*)"],
    "allow": ["Bash(ls*)", "Bash(find*)", "Bash(echo*)"]
  },
  "sandbox": {
    "enabled": true,
    "autoAllowBashIfSandboxed": false
  }
}

1. Start a new Claude Code session
2. Run any Bash command (e.g., echo hello, pwd, ls)
3. All commands return "(Bash completed with no output)"

Observed Behavior

• All Bash commands return empty output — including echo, pwd, ls, git status
• Commands do execute (verified by writing to a file and reading it with the Read tool)
• Only stdout/stderr capture is broken
• Read, Write, Edit, Glob, Grep tools all work normally
• Sub-agents also affected (Bash denied or no output)

Expected Behavior

Bash commands should return their stdout/stderr output normally when sandbox is enabled via managed-settings.

Verification

| Setting | Bash Output |
|---------|------------|
| sandbox.enabled: true | Empty (broken) |
| sandbox.enabled: false | Normal (working) |

Toggling autoAllowBashIfSandboxed between true/false made no difference — only sandbox.enabled itself matters.

Workaround

Set sandbox.enabled: false in managed-settings.json.

Related Issues

• #19663 — Bash Tool Returns No Output on macOS (most active related issue)
• #43122 — Bash mode commands produce no output
• #16305 — Sandbox Bash tool loses pipe data
• #41722 — Bash Commands do not execute, Return No Output

This issue differs from the above in that it is specifically reproducible by toggling sandbox.enabled in managed-settings.json, suggesting the root cause is in the macOS Seatbelt sandbox initialization or stdio redirect, not shell config or environment variables.