fix: preserve query result text

[emrberk]

Summary

• remove HTML entity decoding from the modern and legacy result grids
• preserve result values exactly in rendered cells, clipboard output, and Markdown export
• preserve leading whitespace so plain-text EXPLAIN plans keep their hierarchy
• update result-grid and Markdown tests for literal HTML-entity-looking values

Problem

QuestDB's HTTP EXPLAIN response historically contained HTML entities as a Web Console presentation workaround. The console compensated by applying unescapeHtml to every result value, not only to structural query-plan indentation.

That made ordinary query results lossy: legitimate values such as  , <, >, &, ", and ' could be changed even though they were user data. Trying to detect EXPLAIN queries client-side would still be fragile and would not resolve collisions between plan structure and SQL literals embedded in a plan.

Closes #587.

Solution

The paired QuestDB server change returns EXPLAIN plans as plain text. With that contract, the Web Console can treat every response value as data:

• remove all unescapeHtml calls and the unused helper
• preserve whitespace in both grid implementations with white-space: pre
• leave query-plan Markdown rows untouched
• keep entity-looking strings literal in display, copy, and export paths

No client-side EXPLAIN detection or SQL tokenization is needed.

Validation

• focused ResultGrid unit tests: 40 passed
• TypeScript typecheck passed
• relevant ESLint checks passed
• production build passed
• manually validated ordinary entity-like values, real leading spaces, raw angle brackets, EXPLAIN indentation, comparison operators, SQL literals inside EXPLAIN, and Markdown copy against the paired development server

Related

• QuestDB server fix: fix(http): return EXPLAIN plans as plain text questdb#7406
• Original issue: Web Console decodes HTML entities in results, corrupting displayed and copied values #587

[emrberk]

Review — PR #588 "fix: preserve query result text" (Level 3)

Quality gate: typecheck ✅ · lint ✅ · build ✅ · unit tests ✅ (1510 passed, incl. the new toSingleLineDisplay and updated markdown/copy tests).

Issues

#	Issue	Category	Severity	Location	Description	Repro	Suggested fix
1	EXPLAIN plans show literal &nbsp;/&lt; on un-upgraded servers	Query execution & data integrity	Moderate	in-diff (display path now emits server text verbatim; depends on paired server contract)	The fix's correctness relies entirely on the paired server change (questdb#7406) returning EXPLAIN plans as plain text. Against a server that hasn't shipped it, EXPLAIN indentation (&nbsp;) and operators (&lt;,&gt;) now render as literal entity text in the grid, and copy/Markdown export the same broken text. Confirmed demo.questdb.io — the /exec proxy target in the modified vite.config.mts — still entity-encodes: dataset:[["&nbsp;&nbsp;filter: 100&lt;amount"], ...]. There is no buildVersion guard gating the behavior. In the normal bundled binary the console ships with its own server so both halves land together; the risk is decoupled deployments (this dev branch → demo, QuestDB Cloud console served independently of the engine, or a standalone console pointed at an older instance).	• Run EXPLAIN SELECT * FROM trades WHERE amount > 100 in the Result grid or a notebook cell against any server without questdb#7406 (e.g. this branch's own dev server → demo.questdb.io) • Plan renders as &nbsp;&nbsp;filter: 100&lt;amount instead of indented filter: 100<amount	Confirm questdb#7406 is released everywhere this console build can reach before merging, and coordinate the release. (Client-side re-scoping the unescape to the QUERY PLAN column is not a clean fix — it would re-corrupt entity-looking SQL literals embedded in a plan, which is exactly why the server-side fix was chosen.)
2	Embedded tabs now render as wide tab-stops	Styling & theming	Minor	in-diff (styles.ts CellText, _grid.scss .qg-r: nowrap→pre)	toSingleLineDisplay collapses only [\r\n], not \t. Under the old white-space: nowrap a tab collapsed to normal inter-word spacing; under white-space: pre a VARCHAR/STRING value containing a literal tab now advances to the next tab stop, showing a visibly wide gap in both grids. Cosmetic only — no data loss (copy preserves the raw tab), fixed row height clips overflow. Arguably intended, since the PR's goal is to preserve whitespace.	• Query SELECT 'a' || chr(9) || 'b' • Cell shows a wide tab gap instead of a single space	If undesired, collapse tabs too: text.replace(/[\r\n\t]+/g, " ") in toSingleLineDisplay, plus a test case. Otherwise document as intended.
3	Legacy copy fallback drops newlines	Async/structure	Minor	in-diff (src/js/console/grid.js:1716)	In copyActiveCellToClipboard, valueToCopy is seeded from focusedCell.textContent, which #588 made a newline-collapsed string (toSingleLineDisplay). The primary branch correctly re-derives the raw value via getDisplayedCellValue, but if data[pageIndex][rowInPage] is absent the code falls back to the collapsed textContent — contradicting the adjacent comment ("must not leak into the clipboard"). Before #588 the fallback still carried raw newlines. Practically unreachable: a focused/visible cell's data page is loaded, so the fallback shouldn't fire under real interaction.	• Focus a cell whose data page has been evicted, then Cmd+C (not reproducible through normal scrolling/focus)	Seed the fallback from the raw datum, or accept the current behavior given it's unreachable — low priority.

False-positives

• React correctness / async / hooks — No hooks, deps arrays, refs, timers, subscriptions, or memo comparisons changed. GridCell (React.memo) already computed displayValue inline in render before the PR; swapping unescapeHtml for toSingleLineDisplay at the same site changes nothing about render behavior. Clean.
• U+2028/U+2029 (and NEL) render as line breaks under white-space: pre — Empirically false in Chromium: cell height is identical to a plain single line (17px) for these chars; only \n/\r break (and those are stripped by toSingleLineDisplay). Not a regression.
• XSS reintroduced by removing unescapeHtml — Both grids write the value as a text node (cell.textContent / JSX {displayValue}), never innerHTML. The deleted helper was a display transform (added in fix: render HTML entities in grid cells after XSS fix #525), never a security control. The only escapeHtml use left is quick-vis.ts SlimSelect labels, untouched and still correct.
• Copy/Markdown output re-rendered as HTML → entity or markup corruption — Every buildResultPageMarkdown/formatCellValueForCopy consumer (main Result panel, notebook actions bar, legacy grid, Cmd+C) pipes straight to copyToClipboard. No path feeds grid copy into react-markdown/the AI assistant. Clipboard is the terminal sink. All callsites SAFE.
• Width-sampling regression — sampleColumnWidths uses formatCellValue length; newline→space is length-neutral, and display no longer shortens &→&, so sampled width now matches display better than before. Neutral/improvement, not a bug.
• toSingleLineDisplay needs a non-string guard — getDisplayedCellValue provably returns a string for all non-null cell data (null is handled earlier), and every TS caller passes a string. Adding String(text) would be defensive dead-weight; dropped per the repo's minimalism.

Summary

Verdict: Approve, pending one confirmation. The change is correct, well-scoped, and well-tested. Removing unescapeHtml is a genuine fix — verified that server data arrives raw (a literal 'a&b' returns a&b, which the old console corrupted to a&b), and both grids render/copy via text nodes so there's no XSS surface. Display-vs-copy semantics (collapse newlines for display, preserve them for copy/export) are consistent across the React grid, the legacy grid, and the Markdown paths.

The one thing to resolve: Finding #1 — the console now depends on the paired server change (questdb#7406) for EXPLAIN rendering, and the demo/dev server this branch proxies to hasn't shipped it, so EXPLAIN plans visibly regress there. This is a documented, intentional tradeoff, but merge should be coordinated with the server release (and reviewers should be aware the local dev experience against demo will show entity-encoded plans until then).

Regressions/tradeoffs: old-server EXPLAIN rendering (Finding #1); tabs now render wider (Finding #2, likely intended).

Verification tally: 3 findings verified (1 Moderate, 2 Minor); 6 draft findings dropped as false positives (verified against source + empirical browser/curl tests). In-diff vs out-of-diff: 3 in-diff, 0 out-of-diff — Agent 12 walked all six consumer callsites (ResultGridAdapter, ResultActionsBar, ResultGridPanel/InlineResultTable, useGridKeyboardNav, legacy grid.js, quick-vis) and found every one SAFE; the changed symbols are pure display/copy utilities whose output only reaches the DOM as text or the clipboard, so a zero out-of-diff count is correct here, not an underrun.