No non-interactive way to select a stack when the branch belongs to several (e.g. the trunk)

从 gh stack view 入口开始，跟踪它如何处理多个 stack、交互式选择以及被丢弃的位置参数；将其与现有的 gh stack checkout <n> 选择行为进行比较。完成标准是：gh stack view --stack <number> 可以从共享分支中选择一个 stack，同时不改变已签出的分支，包括已复现的 main 场景。

Summary

When the current branch belongs to more than one stack — most commonly the trunk, which is the base of every stack in the repo — gh stack view fails and offers no non-interactive way out:

$ gh stack view --short
✗ branch "main" belongs to multiple stacks; use an interactive terminal to select one

There is no --stack flag. Combined with gh stack view silently discarding positional arguments (#414), there is currently no way at all to view a specific stack non-interactively.

Why this matters

Two stacks off a shared trunk is the normal state for anyone working on more than one change at a time, not an edge case — and main is in that position permanently, so any script or agent that starts from the default branch hits this immediately.

"Use an interactive terminal" is not available in CI, in a shell script, or to an automated agent. The only workaround is to gh stack checkout <n> first purely to move onto a branch in the desired stack, which mutates the working tree just to perform a read.

Reproduction

# create two stacks that both base off main
git switch main
gh stack view --short      # -> "belongs to multiple stacks; use an interactive terminal"

Public repo with two stacks off a shared main: https://github.com/xn/gh-stack-repro

Expected

A --stack <number> flag on view (and anywhere else this ambiguity can arise), so the stack can be named explicitly without changing the checked-out branch.

Environment

• gh 2.97.0
• gh-stack v0.1.0
• git 2.50.1
• macOS 26.4.1, darwin/arm64