next dev / next build strips compile error details — only shows count summary

Problem

When running next dev or next build through RTK, compile error details (file paths, line numbers, error messages, stack traces) are completely stripped. The output only shows a summary line like:

Next.js
Errors: 1 | Warnings: 0

No information about what the error is or where it occurs. This makes it impossible for AI coding agents to diagnose and fix failures without falling back to rtk proxy.

Steps to Reproduce

1. Introduce a syntax or type error in a Next.js project
2. Run next dev --turbopack or next build (routed through RTK)
3. Observe that only the count summary is shown — zero diagnostic detail

Expected Behavior

Error details should be preserved in the output. At minimum:

• File path and line number of the error
• The error message itself
• Enough context for an AI agent (or human) to locate and fix the issue

Workaround

rtk proxy npx next dev bypasses filtering and shows full output, but this defeats the purpose of RTK's automatic hook integration.

Difference from #2010

Issue #2010 covers startup port information being swallowed. This issue is about compile error diagnostics being stripped — the error details that are critical for debugging are lost, not just informational startup lines.

Environment

• RTK version: latest (installed via hook)
• Next.js: 15.x with Turbopack
• OS: macOS (Darwin 25.3.0)

Reproduce the issue with a Next.js 15.x project using next dev --turbopack and next build through the RTK hook, then inspect RTK's command-output filtering path. Compare the routed output with rtk proxy npx next dev; done means file paths, line numbers, error messages, and useful diagnostic context remain visible while the summary is retained.