fix: solve #3862 — Copilot CLI rejects prompt as positional arg

[github-actions]

Root cause

The Copilot prompt-launch command was being built as:

copilot -i --allow-tool=write "$(cat <<'SUPERSET_PROMPT_…'
<prompt>
SUPERSET_PROMPT_…
)"

The GitHub Copilot CLI treats -i as interactive mode, which accepts no positional arguments. Passing the heredoc-quoted prompt as a positional therefore fails with:

error: too many arguments. Expected 0 arguments but got 1.

This blocks launching Copilot from the new workspace modal whenever a prompt is supplied.

The fix

Replace -i with the --prompt flag in Copilot's promptCommand, placing the flag last so the existing prompt-builder (${command} "$(cat <<EOF…)") emits the heredoc as the value of --prompt:

copilot --allow-tool=write --prompt "$(cat <<'SUPERSET_PROMPT_…' … )"

The same change is applied to LEGACY_BUILTIN_TERMINAL_AGENT_OVERRIDES.copilot.promptCommand in agent-permissions-migration.ts so pre-#3546 users running the YOLO migration are not migrated into the broken shape.

The non-prompt command (copilot --allow-tool=write) is unchanged — Copilot starts in interactive mode by default when no flags are supplied.

Tests

• Added passes copilot prompts via --prompt flag, not as positional in packages/shared/src/agent-command.test.ts — fails on the buggy copilot -i … shape and passes on the fix.
• All 614 tests in packages/shared/ pass.

Closes #3862

---

Summary by cubic

Fixes #3862 by passing Copilot prompts via the --prompt flag instead of a positional arg, so launching from the new workspace modal works again. Interactive mode -i no longer rejects prompts.

• Bug Fixes
  • Updated copilot promptCommand to copilot --allow-tool=write --prompt "$(cat <<'…')"; removed -i.
  • Applied the same change in LEGACY_BUILTIN_TERMINAL_AGENT_OVERRIDES.copilot.promptCommand to avoid migrating users into the broken command shape.

^{Written for commit 4db6d9d. Summary will update on new commits. Review in cubic}