Compilation turns LaTeX source into the PDF you submit or share. It depends on the selected document root, engine, packages, bibliography and any generated data assets. A source save and a successful build are separate events.
Choose the root and engine
Open the dropdown beside Recompile. Choose the complete document containing \documentclass and \begin{document}. An included section usually cannot compile independently. If your paper and supplement have separate roots, choose the one you want or use Compile all documents.
Use the engine required by your template. pdfLaTeX is common for conventional templates. XeLaTeX and LuaLaTeX support workflows involving modern fonts and Unicode, but packages and templates can have engine-specific requirements. A command such as \setmainfont typically comes from fontspec and belongs with XeLaTeX or LuaLaTeX, not pdfLaTeX.
The packaged desktop app provides its prepared TeX runtime. A source checkout/browser installation needs the local toolchain described in the repository README. A missing tool is an environment problem, not necessarily a mistake in your manuscript.
Build and inspect
Choose Recompile or press ⌘Enter. The build pipeline first refreshes active remote dependencies, takes a consistent local data snapshot, generates required Figure Studio assets, and then invokes LaTeX. Required refresh or generation failures stop the build instead of silently replacing current data with old output.
The PDF toolbar says when the PDF no longer matches the source. The refresh button at its left turns the accent colour, and an Out of date dot appears beside Auto; point at the dot to see which files changed since the build. Click the refresh button (or Recompile) to update it. With Auto on, the PDF rebuilds by itself once you pause typing.
On success, inspect the PDF and the build status. Warnings can remain after a successful build; unresolved references, overflow and font substitutions may still need attention. Bibliography and cross-reference work can require repeated TeX passes handled by the build tooling.
On failure, the previous PDF may remain visible. Treat it as the last successful output, not evidence that the current source compiled.
The build log opens by itself only when a build you started (Recompile, ⌘Enter, or the Visual editor's compile) fails, and only where it fits beside the source. Automatic builds after typing, the PDF's refresh button, and builds started by an agent or another window never open it; the Build log button in the footer turns red and shows the error count instead. In PDF-only view a failed build shows a short message rather than rearranging your panes. If you close the log, it stays closed for that same failure; a different failure, or one that comes back after a clean build, opens it again. Reopening the workspace always starts with the log closed.
Move between the source and the PDF
With a compiled source project and SyncTeX information, double-click a word in the PDF to jump to source.
To go the other way, put the cursor where you are working and choose Show in PDF: press ⌘⇧J, click the → arrow on the divider between the source and the PDF, use Show in PDF in the editor's tab bar or the Visual toolbar, or search for it with ⌘K. If the PDF is not on screen, it opens beside the text first. The matching spot on the page is highlighted for a moment. The ← arrow on the divider does the reverse for the part of the PDF you are looking at. When the PDF is already visible, double-clicking a word in the source also follows along; in a LaTeX-only view a double-click just selects the word.
The mapping comes from the last build, in any file the build included, not just the main one. If the PDF has no SyncTeX data (it was made elsewhere, or build files were cleaned), VersoFold asks you to recompile. A file that is not part of the last build, such as a new section not yet \input, says so. Lines edited since the last build map approximately until you recompile. An arbitrary imported PDF has no editable LaTeX source to jump to.
Clicking a citation in the PDF opens its card in References. In the LaTeX editor a click only places the cursor, and in the Visual editor clicking a citation edits its command. Select text to comment, attach context for the agent, check evidence or link a result when that action is available. Check the quote before saving when the PDF uses unusual columns, ligatures or reading order.
Read the build log
Open Build log in the Recompile menu or press ⌘J. Start with the first error, because later errors may be consequences. Open the source location when the compiler provides one and inspect the surrounding lines.
Undefined control sequence: a misspelled command or missing package is common.
Missing file: check relative paths and filename case.
Missing math delimiter or brace: inspect the preceding equation or command, not only the reported line.
Undefined citations/references: confirm keys, labels and bibliography configuration, then rebuild.
Overfull box: the document compiled, but content may extend beyond its intended width.
Use troubleshooting for a more detailed diagnostic sequence.
Packages, cleanup and freshness
When a package is missing, inspect the package-management prompt and available runtime. Install the required package through the supported environment controls, then retry. Do not add random packages without identifying the missing command or file.
Clean build files removes generated build intermediates so the next build can start fresh. It is useful for stale auxiliary state after a structural change; it is not a substitute for correcting invalid source.
Build with cached data and Build with last assets are explicit fallback choices for dependency or asset failures. They produce visibly stale evidence and require a complete previous copy. Resolve freshness before claiming a final submission is reproducible.
Related: page budgets, remote data, Figure Studio.