Summary

Adds a --account persistent flag to the root command so any authenticated subcommand can be scoped to a specific GitHub account without requiring gh auth switch first.

Motivation

Users with multiple GitHub accounts (personal + work, multiple orgs) frequently need to run a single command as a different identity from the currently active one. Today that requires an explicit gh auth switch which changes global state. --account allows per-invocation identity selection with no side effects on other sessions.

What Changed

pkg/cmd/root/root.go

• Added --account as a PersistentFlag on the root command so all subcommands inherit it.
• In PersistentPreRunE, after the existing auth check, calls the new applyAccountFlag helper.
• Added applyAccountFlag(cfg gh.Config, account string) error — a pure function that:
  1. No-ops when account is empty (default behaviour unchanged).
  2. Looks up DefaultHost() from the auth config.
  3. Calls UsersForHost(hostname) to get the list of authenticated users.
  4. Returns a descriptive error if the requested account is not in that list, with guidance:
     account "alice" is not authenticated on github.com. To add it run: gh auth login --hostname github.com
  5. On success, calls TokenForUser(hostname, account) then SetActiveToken(token, source) so all downstream HTTP calls in that invocation use the correct credential.

pkg/cmd/root/root_test.go (new)

• 4 table-driven tests covering:
  • empty account (no-op)
  • account present and authenticated (token installed)
  • account not in the authenticated list (descriptive error)
  • multiple accounts, correct one selected

Flag Name Choice

--user was the natural first choice but conflicts with local flags already on several subcommands (codespace list, auth token, run list, secret list). Cobra panics at AddCommand when a persistent root flag shares a name with a local child flag. --account has zero conflicts across pkg/cmd/.

Testing

go test ./pkg/cmd/root/... -run Test_applyAccountFlag   # 4/4 pass
go test ./...                                           # zero failures