Feature: Display script output in client via CLAUDE_DISPLAY_SCRIPT_OUTPUT environment variable

Summary

When Claude runs scripts via the CLI, the output is not currently visible in the client UI. This feature proposes an opt-in mechanism to surface script output directly in the client.

Proposed Solution

Introduce a new environment variable: CLAUDE_DISPLAY_SCRIPT_OUTPUT=1

When this variable is set, the stdout/stderr of any scripts executed by Claude via the Bash tool would be streamed and displayed in the client interface — not just consumed internally by Claude.

Usage Patterns

Always-on (user sets in shell profile):

export CLAUDE_DISPLAY_SCRIPT_OUTPUT=1

Per-script (user instructs Claude to set it conditionally):

The user can tell Claude: "Set CLAUDE_DISPLAY_SCRIPT_OUTPUT=1 before running the build script so I can see the output."

Claude would then prepend the variable to that specific invocation:

CLAUDE_DISPLAY_SCRIPT_OUTPUT=1 ./build.sh

This gives users fine-grained control over which script outputs are surfaced without permanently enabling verbose output for every command.

Motivation

• Users often want visibility into what a script is doing, especially for long-running processes (builds, tests, data pipelines).
• Currently, Claude sees the output but the user does not — creating an information asymmetry.
• An environment variable is a familiar, low-friction mechanism that fits naturally into existing shell workflows.
• The opt-in design avoids cluttering the client with output the user doesn't care about.

Acceptance Criteria

• [ ] When CLAUDE_DISPLAY_SCRIPT_OUTPUT=1 is set, script output (stdout + stderr) is displayed in the client in real time or upon completion.
• [ ] When the variable is unset or 0, behavior is unchanged from today.
• [ ] The variable can be set inline per-command (e.g. CLAUDE_DISPLAY_SCRIPT_OUTPUT=1 ./script.sh) so users can instruct Claude to enable it selectively.
• [ ] Documentation is updated to describe the variable and its behavior.

Alternatives Considered

• A CLI flag (--display-output) — less flexible since it would apply globally per session rather than per script.
• Always showing output — too noisy for routine commands; opt-in is preferable.