feat(app): reveal search row-selection checkboxes on hover - #3164

…3117)

Resolves HDX-5365.

> **Stacked on #3171.** Base is `cursor/fix-virtualized-row-height-d7eb`; it will retarget to `main` once that merges. See "Virtualized row heights" below.

## Why

The only way to expand a search result row inline is the 16px chevron, which is a poor hit target when you are scanning logs during an incident. Comparable tools expand on row click.

Rather than change what a row click does for everyone, this adds a preference. **The default is unchanged** — a row click still opens the side panel. Users who want the bigger hit target can opt in.

## What changed

**Preferences → Search results → Row click**, defaulting to `Open side panel`. Set it to `Expand inline` and:

- a row click toggles inline expansion instead of opening the side panel;
- the side panel moves to a hover button on the row (`Open in side panel`, beside the existing copy buttons), and the expanded row's maximize button still opens it;
- row clicks keep driving the side panel while it is open, so browsing row to row inside the panel is unchanged. Closing the panel returns clicks to inline expansion.

Stored as an optional `rowClickAction`. Stored preferences that predate the field are returned as-is rather than merged with the defaults, so readers fall back to `DEFAULT_ROW_CLICK_ACTION`.

Two table variants need care regardless of the preference:

- Tables that hide the expand column (surrounding context, patterns) have nowhere to put inline details, so they always open the side panel.
- The ClickHouse dashboard's slowest-queries list renders inline details but passes no `onRowDetailsClick`, so it always expands inline and offers neither the hover button nor the expanded row's maximize button — both would only write URL params nothing reads.

Routing a row click needs to know whether a side panel is available and whether one is already open, and two signals did not actually mean that:

- `highlightedLineId` was passed to the table even when the panel was not mounted. `rowWhere`/`rowSource` survive a source switch while closing the panel clears both, so a stale `rowWhere` left the table highlighting a row with no panel on screen. The panel is now hoisted into one `sidePanel` element that both its own mount and `highlightedLineId` derive from.
- `ExpandedLogRow` gated its maximize button on `{openSidebar && …}`, the return value of a `useCallback` and so always truthy. It now takes `canOpenSidePanel`.

`DBRowTableIconButton` also gained an `aria-label` from its title, which the row hover buttons had been missing.

## Virtualized row heights

Reported against this branch: expand and collapse a few rows, scroll, and the table goes blank under the header.

That bug is on `main` today — it reproduces identically through the chevron, with this PR's `packages/app/src` reverted. A row and its inline expansion are two `tr`s sharing one virtual index, and both were measured, so the expanded one took over that index's `ResizeObserver` registration and left its height cached there after collapsing. Every expand/collapse shrank the render window.

Fixed separately in **#3171** so it lands for chevron users regardless of this PR, and merged in here so this branch does not ship the bigger hit target on top of it. That merge is the only reason `DBRowTable.tsx` now renders a `tbody` per row.

## Tests

- Seven unit tests in `DBRowTable.test.tsx`: the side panel on row click by default (and no redundant hover button in that mode), then under `expand` — inline expand/collapse on body click, the hover button, `showExpandButton={false}`, and the open-panel case; plus the no-side-panel table expanding inline regardless of the preference. These are the first tests in that file to render virtualized body rows, hence the geometry mocks.
- The inline-expand test also asserts the expanded row exposes `Open in side panel` and that clicking it writes the `rowWhere` param, so `canOpenSidePanel` is pinned in both directions — hardcoding it to `false` fails the test rather than staying green.
- `UserPreferencesModal.test.tsx` drives the select: the default for users with no stored preference, a stored value round-tripping into the control, and picking an option writing `rowClickAction`. A wrong storage key or option value now fails instead of passing green.
- E2E: the specs that reach the side panel go back to a plain row click, since that is the default again. A new `Row click set to expand inline` describe seeds the preference before navigating and asserts a row body click expands inline without opening the panel, collapses on a second click, and that the hover button opens the panel.
- `virtualized-row-heights.spec.ts` comes in from #3171 and covers the virtualizer regression.

## Rebase onto `main`

Rebased past #3140 and #3164, which added row multi-select and hover-revealed selection checkboxes to the same row component. No textual conflicts, and the two features compose: the checkbox lives in its own cell and stops propagation, so it does not compete with the row-body click.

CI lint was failing only because this branch predated the `--max-warnings` bump on `main`. The rebase picks that up; the one warning this PR did add (an unsafe cast in the new `Select` handler) is gone, so the app count is back under the ceiling rather than exactly on it.

Verification: `make ci-lint` and `make ci-unit` green (244 suites, 3948 tests after the merge). All 94 `search/` E2E tests re-run — 85 passed, 1 flaky-then-passed, and 2 `search-filters.spec.ts` failures that reproduce identically with this PR's `packages/app/src` reverted to `origin/main`, so they are environmental and not from this change. `correlated-metric-source`, `span-links` and `traces-workflow` also pass.

## Walkthrough

The reported repro, end to end on this branch: two row clicks opening the side panel on the default setting, switching the preference to `Expand inline`, expanding and collapsing six rows, then scrolling — the table stays full.

<a href="https://cursor.com/agents/bc-b2c91bdd-e466-447c-942d-dce15159d7eb/artifacts?path=%2Fopt%2Fcursor%2Fartifacts%2Fvirtualized_scroll_repro_fixed.mp4"><img src="https://cursor.com/artifacts/c/art-27481ff4-27fa-4bca-bbe1-3c2abee4f889" alt="virtualized_scroll_repro_fixed.mp4" /></a>

Default — a row click opens the side panel, unchanged:

![Log search with the row side panel open showing Overview, Column Values, Surrounding Context and Infrastructure tabs](https://cursor.com/artifacts/c/art-5932460f-fe67-497d-a59e-71d72be3bb16)

The opt-in:

![Preferences modal showing the Search results section with Row click set to Expand inline](https://cursor.com/artifacts/c/art-3426a775-142f-4fd0-a69f-796378278862)

With it on, a row click expands in place, with no side panel:

![A result row expanded inline showing its Column Values tab, with the rest of the table still visible below](https://cursor.com/artifacts/c/art-59069505-4579-4dab-828c-4a6c316d83f9)

Hovering a row shows both features side by side — the selection checkbox on the left, and this PR's `Open in side panel` button among the row action icons on the right:

![A hovered result row showing the multi-select checkbox at the left and the row action icons including Open in side panel at the right](https://cursor.com/artifacts/c/art-5977cdc5-af08-4768-bd8d-20de43e7655a)



Linear Issue: [HDX-5365](https://linear.app/clickhouse/issue/HDX-5365/expand-log-inline-on-row-click)

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Co-authored-by: Cursor Agent <199161495+cursoragent@users.noreply.github.com>