Land the branches and tags pane as its own branch

[Defmon3]

Seen on: component/git-history

What it fixes

The History tab shows only the current branch. This piece adds the branches and tags pane: local, remote, and tag trees, search, paging, picking a branch or tag to show its history, an all-branches view, and starred favorites remembered per repository, in a third pane on wide layouts and a sheet on narrow ones.

Why we need it

It is PR 7 of the series in the Git History series issue (#8). It is the largest interaction surface of the feature, and reviewing it on its own keeps the earlier PRs small.

How to fix it

Cut a fresh branch on top of the details pane piece carrying the refs pane, the refs hook, the ref tree helper, the favorites state, and their tests. The default-branch marker fixed in the server piece becomes visible here. The PR description states the end state from the series issue. Nothing deferred.

[Defmon3]

Technical appendix: Land the branches and tags pane as its own branch

Investigated on branch component/git-history at commit 821fc7f, base upstream/main at a6797b3.

Findings

• apps/web/src/components/git-history/GitHistoryRefsPane.tsx (459 lines, new): component GitRefsPane with section, folder, ref, and error rows through LegendList, the filter input, and the Retry refs button. GitHistoryRefsPane.test.ts (new).
• apps/web/src/components/git-history/useGitHistoryRefs.ts (238 lines, new): useGitHistoryRefs, selection scoped by environment and repository path, expanded sections, and the rule that remote refs and tags are requested only when their section is expanded, a filter is active, or the selected revision lives in that namespace. useGitHistoryRefs.test.tsx (new).
• apps/web/src/lib/gitRefTree.ts (88 lines, new): buildGitRefTree, filterGitRefTree. Test alongside.
• In apps/web/src/components/GitHistoryPanel.tsx: the Branches header button and the Sheet that hosts the pane on narrow layouts.
• Favorites: gitHistoryFavoriteStorageKey builds a local-storage key from the environment id and repository path, toggleGitHistoryFavorite adds or removes a branch name, the hook keeps the list through useLocalStorage with a string-array schema and derives the favoriteRefs rows from the local refs, and the pane renders a Favorites section with a star toggle per local branch. A repository opened through two environments has two lists.
• Size: about 850 source lines plus tests.
• The pane reads ref.isDefault for its marker; the server sets it only for the remote namespace today (see the default-branch issue, fixed in the ref page piece).

Findings: test state

• apps/web/src/components/git-history/useGitHistoryRefs.test.tsx passes on this branch (run 2026-09-04).

The problem

Observed: the branches pane is inseparable from the panel today.

Once done: a branch on top of the details pane piece lets a user browse and search local branches, remote branches, and tags, star local branches and see them first, and show any ref, or all branches, in the list.