Ctrl+G (edit in $EDITOR) breaks ask_user question mode (regression of #4230) #5004

Describe the bug

Regression of #4230 (closed as completed 2026-07-30).

When Copilot asks a question during planning (plan mode) and I select the last option to enter free text, pressing Ctrl+G — the "edit prompt in $EDITOR" shortcut that works for a normal prompt — exits question mode instead of opening my editor. It is not clear whether an answer was accepted or the question was abandoned; the session state afterward is ambiguous.

Under the hood the keypress is registered as a cancel of the elicitation. In a session where this reproduced, the tool call telemetry shows the freeform ask_user question completing with elicitation_action: "cancel" and result "User cancelled the request." — i.e. Ctrl+G silently cancels the question rather than round-tripping the answer through $EDITOR.

Previously fixed under #4230, but the behavior is back (or a closely related regression).

Affected version

GitHub Copilot CLI 1.0.89

Steps to reproduce the behavior

1. Start in plan mode (or any flow where Copilot calls a question/elicitation).
2. Trigger a question that offers a freeform "type your own answer" option (e.g. a text field).
3. Select that option and start typing an answer.
4. Press Ctrl+G (the normal "edit prompt in $EDITOR" shortcut).

Result: Question prompt is torn down. No editor opens with the freeform answer, and there is no clear accepted/abandoned signal. Internally the elicitation completes with elicitation_action: "cancel" (result: "User cancelled the request.").

Expected behavior

Ctrl+G should open the current freeform answer in $EDITOR and, on save, return the edited text to the question's freeform field while staying in question mode — the same round-trip behavior it has for a normal prompt.

Alternatively, if Ctrl+G is not supported in that context, it should be disabled there with a clear message instead of silently cancelling the question.

Additional context

• Regression of Ctrl+G (edit in $EDITOR) breaks ask_user question mode #4230 "Ctrl+G (edit in $EDITOR) breaks ask_user question mode" (closed as completed).
• OS: Linux (WSL).
• Reproduced in plan mode with model gpt-5.6-sol; the question was a freeform multi-field ask_user elicitation.
• Session telemetry for the cancelled elicitation: elicitation_action: "cancel", elicitation_field_types: ["string"], result "User cancelled the request."