Biblatex's textcite inserts a breaking space between author names and citation number

Question

I have the following document :

\documentclass{article}
\usepackage[backend=biber,style=numeric,maxnames=2,maxbibnames=6,firstinits]{biblatex}
\bibliography{sample}

\begin{document}
Here we want to generate a long sentence so the citation will split \textcite{fictive}.
\printbibliography
\end{document}

with corresponding bib file :

@article{fictive,
    author = {John Doe and John Smith and John Carpenter and John McCain},
    year = 2012,
    title = {Super awesome paper},
    journal = {Super awesome journal}}

The rendering of this document is such :

Here we want to generate a long sentence so the citation will split Doe et al.
[1].

With the line break exactly at the same place. This doesn't feel right. I would prefer the following, i.e. having a non-breaking space instead of a breaking space between authors and citation number :

Here we want to generate a long sentence so the citation will split Doe 
et al. [1].

Writing it textually in a tex file :

Doe et al.~[1]

Anyone else agree that this is the right way to do it? How do I go about changing this?

Answer 1

The biblatex command \addnbspace is a non-breakable variant of \addspace. You can swap these commands in the textcite bibliography macro defined in numeric.cbx. This can easily be done by adding the following to your preamble.

\usepackage{xpatch}
\xpatchbibmacro{textcite}{\addspace}{\addnbspace}{}{}

The patch will also work for the numeric-comp and numeric-verb styles.

In your MWE this induces a linebreak in "et al." To avoid this, you can increase the penalty in breaking at \addabbrvspace - the space used in abbreviated localization strings. In biblatex.def this penalty is assigned the value:

\defcounter{abbrvpenalty}{\hyphenpenalty}

which defaults to 50. You can increase the penalty at the risk of some overfull boxes with, say:

\defcounter{abbrvpenalty}{9000}

or:

\xpretobibmacro{textcite}{\defcounter{abbrvpenalty}{9000}}{}{}

Values at or above 10000 will make \addabbrvspace non-breakable.