Land the branch and tag page read as its own Git History branch

[Defmon3]

Seen on: component/git-history

What it fixes

After the first server PR, a client can page through commits but cannot list the branches and tags to choose from. This piece adds one read that returns a page of local branches, remote branches, or tags, with a search filter, bounded and streamed so a repository with thousands of refs cannot flood the connection.

Why we need it

It is PR 2 of the series in the Git History series issue (#8). It is the read the branches pane depends on, and it carries its own snapshot and cursor logic, which deserves its own review.

How to fix it

Cut a fresh branch on top of the first server piece carrying the ref listing read, its snapshot and cursor handling, its contract, its permission scope, and its tests. The default-branch defect is fixed in this piece rather than carried. The PR description states the end state from the series issue. Deferred: changed files, diffs, and everything under the web app.

[Defmon3]

Technical appendix: Land the branch and tag page read as its own Git History branch

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

Findings: what the piece contains today

• packages/contracts/src/git.ts: VcsHistoryRef (with isDefault required for every namespace), the history refs input with a namespace and a query, and the result with nextCursor. packages/contracts/src/rpc.ts: vcs.listHistoryRefs.
• apps/server/src/vcs/GitVcsDriverCore.ts: listHistoryRefs (about 145 lines), the ref snapshot map with storeRefSnapshot and newRefCursor, invalidateRefSnapshots, and the limits GIT_REF_SNAPSHOT_MAX_REFS (10,000), GIT_REF_SNAPSHOT_MAX_SESSIONS (32), GIT_REF_SNAPSHOT_TTL_MS (2 minutes), GIT_REF_SNAPSHOT_MAX_OUTPUT_BYTES (2 MB).
• apps/server/src/ws.ts and apps/server/src/auth/RpcAuthorization.ts: the handler and read scope.

Size: about 250 source lines plus tests.

Findings: behavior established by reading

• listHistoryRefs runs git for-each-ref with a NUL record separator and a per-record callback, so stdout is never held as one string.
• The query filter is applied per record during enumeration, and one page of at most the requested limit is returned with a cursor; nothing pages further on its own.
• isDefault is computed only for the remote namespace; see the issue "Branches pane never marks the default branch under local branches".
• The same file already has an older ref listing for the branch toolbar (readGitRefsSnapshot, listRefsSnapshotCache, resolveListRefsSnapshot, with LIST_REFS_SNAPSHOT_CACHE_CAPACITY and LIST_REFS_SNAPSHOT_CACHE_TTL). The history listing is a second, independent enumeration with its own snapshot store. Established by reading both; whether one can serve both callers was not investigated.

The problem

Observed: the ref page read exists only inside a branch that also carries the commit reads, the file and diff reads, and the UI.

Once done: a branch on top of the first server piece adds one bounded, filterable ref page read with its tests, and the local default branch is flagged.