fix: Unblock cloud branch picker during slow remote load

[charlesvien]

Problem

Cloud branch picker was disabled while the slow GitHub remote was loading, blocking users from typing a known branch name and forcing them to wait on a request that often takes seconds.

Closes #1984

Changes

1. Stop disabling the picker while cloud branches are still loading
2. Add "Use 'input' as branch name" action as the auto-highlighted first item so it is keyboard-reachable during the slow fetch
3. Debounce branch search at 300ms instead of useDeferredValue to coalesce keystrokes into one request
4. Skip debounce on empty search so closing the picker clears stale results immediately
5. Refactor Combobox item rendering to handle the new sentinel action

How did you test this?

Manually

Publish to changelog?

no

[charlesvien]

• fix: Preserve cloud reasoning level after initial prompt #2272
• fix: Unblock cloud branch picker during slow remote load #2269 👈 (View in Graphite)
• fix: Make file references in agent messages clickable in command center #2271
• fix: Render at-mentioned chips as @labels in task titles #2270
• fix: Buffer feature-flag subscribers registered before init #2267 : 1 other dependent PR (#2268 )
• feat: Add nightly cleanup of stale draft releases #2239
• main

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[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
apps/code/src/renderer/features/git-interaction/components/BranchSelector.test.tsx:61-103
Tests 2 and 3 test the same `showUseInputBranchAction` visibility condition with different `cloudSearchQuery` values (one that matches an existing branch, one that doesn't). Per the team's preference for parameterised tests, these could be merged into a single `it.each` case.

```suggestion
  it.each([
    { cloudSearchQuery: "brand-new-branch", expectVisible: true },
    { cloudSearchQuery: "main", expectVisible: false },
  ])(
    "shows the typed-name action only when input does not match an existing branch ($cloudSearchQuery)",
    async ({ cloudSearchQuery, expectVisible }) => {
      const user = userEvent.setup();
      renderInTheme(
        <BranchSelector
          repoPath="owner/repo"
          currentBranch={null}
          workspaceMode="cloud"
          cloudBranches={["main", "feature-a"]}
          cloudBranchesLoading={false}
          cloudSearchQuery={cloudSearchQuery}
          onBranchSelect={vi.fn()}
          onCloudSearchChange={vi.fn()}
        />,
      );

      await user.click(screen.getByRole("combobox", { name: "Branch" }));

      if (expectVisible) {
        expect(
          await screen.findByText(`Use "${cloudSearchQuery}" as branch name`),
        ).toBeInTheDocument();
      } else {
        expect(
          screen.queryByText(new RegExp(`Use "${cloudSearchQuery}" as branch name`)),
        ).not.toBeInTheDocument();
      }
    },
  );
```

_{Reviews (1): Last reviewed commit: "address branch picker review feedback" | Re-trigger Greptile}

[graphite-app]

Merge activity

• May 21, 6:37 PM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.
• May 21, 7:05 PM UTC: Graphite couldn't merge this PR because it failed for an unknown reason (GitHub is reporting that this PR is not mergeable, despite passing required status checks defined by your branch protection rules. Please check your rulesets for additional blocking criteria. Graphite Merge Queue does not currently support rulesets. Please contact Graphite support for further assistance.).