fix(web): Fixed issue where Sourcebot would not index the new default branch when changed

[brendan-kellam]

This PR fixes the issue where when the default branch changes, new commits would not be re-indexed. The issue was that the HEAD symbolic ref was not getting updated to the new default branch. This PR adds that.

Additionally, this PR makes the default branch appear in most places instead of HEAD, where applicable.

Fixes #40

Summary by CodeRabbit

• New Features

  • Added an option to show or hide branch names in file headers.

• Bug Fixes

  • Indexing now starts from a repository's actual default branch (not always HEAD), and respects remote default-branch changes.
  • Fetch operations update local HEAD to match the remote default branch when available and avoid exposing credentials in logs.
  • Branch-filtering in search now responds to explicit revision filters in queries; branch display logic simplified.

• Documentation

  • Changelog updated to reflect default-branch and UI display fixes.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

Detects remote default branch during fetch, optionally updates local HEAD to that branch, exposes helpers to read remote/local default branch, uses local default branch for initial revision selection during indexing, and makes branch-display visibility in the UI query-driven.

Changes

Cohort / File(s)	Summary
Git helpers & fetch behavior packages/backend/src/git.ts	Added getRemoteDefaultBranch and getLocalDefaultBranch. fetchRepository queries remote default via git ls-remote --symref, may update local HEAD to that remote branch, and always unsets http.extraHeader in a finally block. Credential-leaking errors suppressed.
Repository indexing default selection packages/backend/src/repoIndexManager.ts	After fetch/clone and config upsert, call getLocalDefaultBranch(path) and set initial revisions to that branch when available; fallback to HEAD if undefined.
PathHeader branch visibility prop packages/web/src/app/[domain]/components/pathHeader.tsx	Added optional isBranchDisplayNameVisible?: boolean prop; branch display rendering now gated by isBranchDisplayNameVisible && branchDisplayName.
Query-driven branch filtering flag packages/web/src/app/[domain]/search/components/searchResultsPage.tsx	isBranchFilteringEnabled now derives from whether searchQuery contains rev: rather than inspecting file branch lists.
FileMatch branch display wiring packages/web/src/app/[domain]/search/components/searchResultsPanel/fileMatchContainer.tsx	branchDisplayName computation simplified to depend only on branches.length; passes isBranchDisplayNameVisible (wired to isBranchFilteringEnabled) into PathHeader.
Changelog CHANGELOG.md	Added entries describing indexing fix for changed default branch and UI change to display default branch name instead of HEAD.

Sequence Diagram(s)

mermaid
sequenceDiagram
autonumber
participant RepoIndexManager
participant GitModule
participant RemoteGit
RepoIndexManager->>GitModule: fetchRepository(path, cloneUrl, authHeader?)
GitModule->>RemoteGit: git ls-remote --symref HEAD (query default)
alt remote default branch found
RemoteGit-->>GitModule: remote default ref (refs/heads/main)
GitModule->>GitModule: symbolic-ref HEAD -> refs/heads/main
GitModule-->>RepoIndexManager: return detected default branch
else not found
RemoteGit-->>GitModule: no symref / error
GitModule-->>RepoIndexManager: undefined
end
RepoIndexManager->>GitModule: getLocalDefaultBranch(path)
GitModule-->>RepoIndexManager: local default branch (or undefined)
RepoIndexManager->>RepoIndexManager: set initial revision = localDefault ?? HEAD

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Possibly related PRs

• chore(web): Add isBranchFilteringEnabled flag to search_finished event #781: Modifies the same isBranchFilteringEnabled computation and propagation in searchResultsPage.tsx.
• feature: File explorer #336: Related changes to PathHeader component and its props that introduced or previously modified branch display behavior.

Suggested reviewers

• msukkari

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main objective: fixing the issue where Sourcebot doesn't index the new default branch when changed, matching the PR's primary goal.
Linked Issues check	✅ Passed	The PR addresses issue #40 by implementing remote default branch detection (getRemoteDefaultBranch), local default branch resolution (getLocalDefaultBranch), and updating the indexing logic to use the current default branch instead of hard-coded HEAD.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing issue #40: backend changes detect and handle default branch updates, and UI changes display the correct default branch name instead of HEAD.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

---

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[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

packages/backend/src/git.ts (1)

147-150: Guard cleanup to avoid masking fetch errors.

In the finally block (line 150), git config --unset fails with exit code 5 when the key is missing or the value pattern doesn't match, which would replace the original error caught in the except block. Wrap the cleanup in its own try-catch to prevent error masking.

Suggested fix

     } finally {
         if (authHeader) {
-            await git.raw(["config", "--unset", "http.extraHeader", authHeader]);
+            try {
+                await git.raw(["config", "--unset", "http.extraHeader", authHeader]);
+            } catch (error: unknown) {
+                logger.debug(
+                    `Failed to unset http.extraHeader for ${path}: ${
+                        error instanceof Error ? error.message : error
+                    }`
+                );
+            }
         }
     }