github copilot (v1.0.24) now support modifiedArgs

:robot: This was written by an AI agent on behalf of @paolomainardi.

Summary

Since Copilot CLI v1.0.24 (April 10, 2026), preToolUse hooks support modifiedArgs for transparent command rewriting — the same capability Claude Code has had via updatedInput. The official docs now list modifiedArgs as a supported output field.

However, rtk hook copilot (tested on RTK 0.39.0) is a complete no-op: it returns empty stdout + exit 0 for every command, regardless of whether a rewrite exists.

Reproduction

# Claude hook — works (transparent rewrite)
echo '{"tool_name":"bash","tool_input":{"command":"git status"}}' | rtk hook claude
# → {"hookSpecificOutput":{"hookEventName":"PreToolUse",...,"updatedInput":{"command":"rtk git status"}}}

# Copilot hook — no-op (empty output, exit 0)
echo '{"toolName":"terminal","toolInput":{"command":"git status"}}' | rtk hook copilot
# → (nothing)

# But the rewrite engine knows what to do:
rtk hook check --agent copilot git status
# → rtk git status

Expected behavior

rtk hook copilot should output modifiedArgs in the Copilot CLI format:

{"modifiedArgs":{"command":"rtk git status"}}

This would make the Copilot hook functionally equivalent to the Claude Code hook, enabling transparent rewrite instead of the current no-op behavior.

Context

• The older deny-with-suggestion approach (from #593) was designed before Copilot CLI supported modifiedArgs. Now that it does, the hook should use it.
• exclude_commands should also be respected in the copilot hook path, same as for Claude Code.
• Related: #1774 (rtk init -g --copilot global setup), #1425 (run_in_terminal not recognized)
• The current no-op means Copilot RTK integration relies entirely on instructions ("always prefix with rtk"), which teaches the AI to bypass safety patterns in tools like OpenCode that match on command prefixes.

Environment

• RTK: 0.39.0
• Copilot CLI: tested against v1.0.44 docs (installed version 0.0.405)
• OS: Linux (Arch)