prune merged branches

[skarim]

Prune merged branches during sync

Add a --prune flag to gh stack sync that deletes local branches (and their remote-tracking refs) for merged PRs. In interactive terminals, users are prompted if they would like to prune merged branches. Non-interactive sessions (agents) require the explicit flag.

Changes

• Prune flag (cmd/sync.go): New --prune flag deletes local branches for merged PRs. Deletes both the local branch (git branch -D) and the remote-tracking ref (git branch -dr) so git checkout can't resurrect the branch. If the user is on a pruned branch, checkout moves to the nearest active branch or trunk.
• Interactive prompt (cmd/sync.go): When --prune is not set and the terminal is interactive, prompts "Prune N merged branches?" with default yes. Skipped entirely in non-interactive sessions.
• ConfirmFn hook (internal/config/config.go): New test hook following the existing SelectFn pattern — allows tests to inject mock confirm responses.
• DeleteTrackingRef (internal/git): New git operation to delete local remote-tracking refs (git branch -dr origin/<branch>).
• TUI merged-branch guards (internal/tui/stackview, internal/tui/modifyview): Merged branches can no longer be selected via keyboard navigation, mouse click, or Enter/checkout in either the view or modify TUI. Cursor skips over merged nodes.
• Stack API fix (cmd/submit.go): Include merged PRs in the PUT payload to the stacks API — omitting them caused "Stack contents have changed" rejections on partially-merged stacks.

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[Copilot]

Pull request overview

Adds an optional “prune merged branches” flow to gh stack sync, including a new --prune flag and an interactive confirmation prompt (interactive only). Also updates TUI behavior to prevent interacting with merged branches and fixes stack API syncing to include merged PRs so partially-merged stacks don’t get rejected.

Changes:

• Add gh stack sync --prune to delete local merged branches and their remote-tracking refs, with interactive confirmation when the flag isn’t provided.
• Add ConfirmFn test hook and a new git op (DeleteTrackingRef) to support pruning behavior and testing.
• Harden TUI navigation/selection against merged nodes and include merged PRs in stack API update payloads.

Show a summary per file

File	Description
skills/gh-stack/SKILL.md	Documents gh stack sync --prune usage in the skill guide.
README.md	Adds --prune flag docs and mentions interactive pruning behavior.
docs/src/content/docs/reference/cli.md	Updates CLI reference docs for the new prune step/flag.
docs/src/content/docs/guides/workflows.md	Notes pruning as an additional sync step (with --prune).
docs/src/content/docs/guides/stacked-prs.md	Mentions optional pruning as part of sync behavior.
cmd/sync.go	Implements --prune, interactive confirm prompt, branch switching, and pruning operations.
cmd/sync_test.go	Adds extensive coverage for prune flows (flagged, interactive confirm, switching behavior, failures).
internal/config/config.go	Adds ConfirmFn hook for tests to override confirm prompting.
internal/git/gitops.go	Extends git ops interface + default implementation with DeleteTrackingRef.
internal/git/git.go	Exposes DeleteTrackingRef via package-level wrapper.
internal/git/mock_ops.go	Extends git mock with DeleteTrackingRefFn + method implementation.
internal/tui/stackview/model.go	Prevents cursor/checkout/mouse selection of merged branches; cursor skips merged nodes.
internal/tui/stackview/model_test.go	Adds tests verifying cursor initialization/navigation skips merged nodes and enter guard.
internal/tui/modifyview/model.go	Makes modify TUI cursor movement skip merged branches; blocks mouse selection of merged nodes.
internal/tui/modifyview/model_test.go	Adds cursor navigation test for merged-node skipping in modify view.
cmd/submit.go	Includes merged PRs in stack API PUT payload to avoid “Stack contents have changed” rejections.
cmd/submit_test.go	Updates test expectation to require merged PRs included in payload.

Copilot's findings

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Comments suppressed due to low confidence (2)

internal/tui/stackview/model.go:242

• The merged-branch guard returns early before handling result.OpenURL (and toggles), which prevents users from clicking PR/commit/file links on merged branches. If the intent is only to prevent selecting/checkout, consider still honoring OpenURL (and possibly expand/collapse) while skipping cursor movement/selection for merged nodes.

	// Don't allow selecting merged branches.
	if m.nodes[result.NodeIndex].Ref.IsMerged() {
		return m, nil
	}

	m.cursor = result.NodeIndex

	if result.OpenURL != "" {
		shared.OpenBrowserInBackground(result.OpenURL)
	}

internal/tui/modifyview/model.go:882

• The merged-branch guard returns early before processing result.OpenURL (and toggles), which prevents clicking PR/commit/file links on merged branches. If merged branches should only be non-selectable, consider still honoring OpenURL (and optionally toggles) while skipping cursor selection.

	// Don't allow selecting merged branches.
	if m.nodes[result.NodeIndex].Ref.IsMerged() {
		return m, nil
	}

	m.cursor = result.NodeIndex

	if result.OpenURL != "" {
		shared.OpenBrowserInBackground(result.OpenURL)
	}

• Files reviewed: 17/17 changed files
• Comments generated: 3

[ktravers]

The skip/include merged branches changes seem like they could be their own separate PR, but I might be misunderstanding the connection between those and pruned branches 🤷‍♀️

Otherwise looks good, appreciate the solid test coverage and documentation as always ✨ 🚀