[skarim]

Adds gh stack add --fork to start an independent stack from the current branch, including a branch in another stack. Each stack remains linear, with no tree-wide operations or changes to storage and recovery formats.

Functionality and user impact

• Create separate workstreams. add --fork starts a new local stack. Mid-stack add offers to fork interactively; ordinary top-of-stack add still extends the stack.
• Resolve shared bases correctly. When a branch is both a member and another stack's base, commands select its member stack. Head branches still cannot belong to multiple stacks.
• Repair child history. sync and rebase handle rewritten parents and single-PR retargets using validated boundaries and the existing consent/recovery behavior.
• Guard unsafe operations. submit checks non-default bases before pushing; modify blocks renaming, dropping, or folding locally known child-stack bases. Closed single PRs with missing bases fail with guidance.

Key areas to review

• cmd/add.go and internal/stack/stack.go: shared creation/adoption flow, bypassing the empty-layer commit shortcut for forks, and member-first resolution.
• cmd/utils.go: single-PR base discovery and publishing guards. Check closed-PR evidence before metadata refresh, and the distinction between local-only and deleted remote bases.
• bottomRebaseCutoff, cmd/rebase.go, and cmd/sync.go: for parent rewrites, gate bottom-branch --onto on a valid recorded base while retaining ordinary rebase and recovery paths.
• cmd/modify.go: reject destructive fork-point changes before ApplyPlan, without rewriting dependent stacks.

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_{Stack created with GitHub Stacks CLI • Give Feedback 💬}

[Copilot]

🔵 Needs a closer look

Shared history-rewrite and publishing changes require human review, and base-handling defects remain unresolved.

4 open issues

• Distinguish intentional local base changes from server retargets · New
• Query closed PR history even when tracking ref is pruned · New
• Validate the selected remote before skipping base checks · New
• Exclude closed PRs from the local-only base exemption · New

What changed in this PR

Adds basic branching-stack support: independent linear stacks can depend on branches in other stacks without introducing tree-wide operations or changing storage and recovery formats.

Changes:

• Adds add --fork and interactive mid-stack forking, including existing-branch adoption.
• Prefers member-stack selection and guards destructive edits to locally known child-stack bases.
• Adds publishing checks, child-history repair, tests, and workflow documentation.

File	Description
skills/​gh-stack/​SKILL.md	Documents fork commands, safeguards, and limitations.
skills/​gh-stack/​references/​stack-design.md	Explains dependent-stack design and workflow.
internal/​stack/​stack.go	Adds member-first stack lookup.
internal/​stack/​stack_test.go	Tests lookup precedence and ambiguity.
internal/​github/​github.go	Includes base names in PR details.
docs/​src/​content/​docs/​reference/​cli.md	Documents fork behavior and publishing requirements.
docs/​src/​content/​docs/​guides/​workflows.md	Adds a dependent-stack workflow guide.
docs/​src/​content/​docs/​faq.md	Clarifies support for shared stack bases.
cmd/​worktree_utils.go	Uses member-first lookup for navigation.
cmd/​view.go	Updates stack selection and retarget warnings.
cmd/​view_test.go	Tests shared bases and single-PR retarget display.
cmd/​utils.go	Adds base discovery, validation, and rebase boundaries.
cmd/​utils_test.go	Tests selection, discovery, and publication evidence.
cmd/​trunk_target_test.go	Updates local-only trunk test setup.
cmd/​sync.go	Integrates base evidence and rewritten-parent repair.
cmd/​sync_test.go	Tests linked-parent repair and single-PR retargets.
cmd/​submit.go	Adds member-first selection and base preflight.
cmd/​submit_test.go	Tests publishing guards and shared-base selection.
cmd/​rebase.go	Integrates base discovery and bottom-branch cutoffs.
cmd/​rebase_test.go	Tests rewrite boundaries, retargets, and recovery.
cmd/​push.go	Integrates member-first selection and base validation.
cmd/​push_test.go	Tests shared-base selection and retarget protection.
cmd/​navigate_test.go	Tests navigation through shared-base branches.
cmd/​modify.go	Guards destructive edits to child-stack bases.
cmd/​modify_test.go	Tests dependent-base action restrictions.
cmd/​merge.go	Prefers the member stack during merge selection.
cmd/​merge_test.go	Tests member-first remote-stack selection.
cmd/​init.go	Points existing stack members toward add --fork.
cmd/​checkout.go	Uses member-first lookup for branch targets.
cmd/​checkout_test.go	Tests numeric member-branch resolution.
cmd/​add.go	Implements explicit and prompted stack forks.
cmd/​add_test.go	Tests fork creation, adoption, commits, and refusals.

_{Review effort: Max}

[skarim]

Closing out this PR because it has gotten too large. Will break up and reopen as a stack.