Summary

• Fix hang when sbt client spawns server subprocess on Linux
• When the server is forked with --detach-stdio, stdout/stderr now redirect to DISCARD instead of inheriting from parent
• On Linux, inherited pipes have ~64KB buffers that block writes when full, causing the server to hang during initialization (e.g., when printing lint warnings for projects with 45+ subprojects)

Root Cause

When NetworkClient.waitForServer spawns the server process:

1. stdout/stderr were inherited from the parent process
2. The client communicates with the server via socket, never consuming stdout/stderr
3. On Linux, once the pipe buffer fills (~64KB), FileOutputStream.writeBytes blocks indefinitely
4. This caused the server to hang before creating active.json

Workarounds that worked (confirming the diagnosis):

• --debug flag (affects logging behavior)
• -Dsbt.log.noformat=true (reduces output volume)

Fix

Add .redirectOutput(Redirect.DISCARD).redirectError(Redirect.DISCARD) to the ProcessBuilder, which redirects to /dev/null on Unix.

Test plan

• Code compiles successfully
• Verified client doesn't read from process stdout/stderr (communicates via socket)
• Manual test on Linux with 45+ subproject build (cannot reproduce on macOS due to different pipe buffering)

Fixes #8442

Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=148254234