TeXposit checks .tex files as you work, without compiling. These static checks catch the mistakes that otherwise surface later as a failed build or as [?] in the PDF.

What is checked

Braces and environments: unclosed or unexpected { and }, an \end that does not match its \begin, an unclosed \begin, mismatched $ and $$ delimiters, and duplicate labels.
Citations: a \cite key that is not in any .bib file.
Labels: a \ref with no matching \label.
Packages: a command that needs a package you have not loaded (for example \textcolor without xcolor), and a \usepackage for a package that is not in the TeX Live installation.
Style: a figure or table without a label, a label placed before its caption, TODO comments, straight double quotes instead of the LaTeX pair, lowercase section headings, \hline where booktabs would be cleaner, numbers in math mode that could use siunitx, and duplicated lines.
Accessibility: PDF/UA and PDF/A source rules. These run only when the project uses a PDF standard.

Reading the results

Issues are marked in the editor, and hovering shows the message and its severity (error, warning or info). Missing citations, undefined references and unknown packages appear as a red highlight on the name instead of an underline.

The hover tooltip can offer:

a suggested replacement, for example a similar existing citation key,
a quick fix such as adding the missing \usepackage,
a Fix with AI link, which opens the assistant with the problem already described.

In a .bib file, each entry shows how many times it is cited, or that it is not cited.

Checks by the assistant

The assistant checks its own edits. After it edits a .tex, .md or .bib file, the system runs the static checks and gives it any problems on its next turn. It also has tools you can ask for by name:

verify_latex checks braces, environments, duplicate labels and unescaped &, _ and #. Those characters are a common cause of fatal errors that leave citations as [?] even when the .bib file is fine. With fix enabled it escapes them in place. It never auto-fixes structural problems, only reports them.
dry_compile compiles a scratch copy of the project with the real LaTeX toolchain and returns the errors and warnings. Your PDF preview and build output are untouched.
verify_bib checks .bib syntax, duplicate keys, unused entries and cited-but-missing entries.

The static checks never run LaTeX. A project can pass them and still fail to compile, so use dry_compile, or compile normally, when you need to know.

A good order of work

Fix the errors the editor marks.
Compile.
If the PDF still shows [?], that is an unresolved citation or reference. It can also be a side effect of a fatal error elsewhere in the document, so read the compile log before editing the bibliography. See Common Errors.