% --- Recursive tool-calling loop flowchart ---
\begin{figure}[htbp]
\centering
\begin{tikzpicture}[vqfont, node distance=0.72cm]

\node[vqteal, text width=3.2cm] (start)
  {\textbf{User query}\\\vqsmall (+ optional image)};
\node[vqblue, below=of start, text width=4.4cm] (stream)
  {\textbf{Stream model call}\\\vqsmall system prompt $+$ context $+$ tools};
\node[vqdecision, below=0.95cm of stream, text width=1.9cm] (dec)
  {\vqsmall tools\\requested?};
\node[vqgreen, right=2.0cm of dec, text width=3.0cm] (final)
  {\textbf{Final report}\\\vqsmall accumulated text $\to$ export};

\node[vqblue, below=1.0cm of dec, text width=4.6cm] (asst)
  {\textbf{Append} assistant \texttt{tool\_use} blocks};
\node[vqblue, below=of asst, text width=6.0cm] (batch)
  {\textbf{For each batch ($\leq 5$ tools)}\\\vqsmall execute in batch $\cdot$ stream typed result $\cdot$ \textsc{wait} 500\,ms};
\node[vqblue, below=of batch, text width=4.6cm] (res)
  {\textbf{Append} user \texttt{tool\_result} blocks};

% Edges
\draw[vqarr] (start) -- (stream);
\draw[vqarr] (stream) -- (dec);
\draw[vqarr] (dec) -- node[above, vqsmall]{no} (final);
\draw[vqarr] (dec) -- node[right, vqsmall]{yes} (asst);
\draw[vqarr] (asst) -- (batch);
\draw[vqarr] (batch) -- (res);

% Recursion arrow (left side, back up to stream)
\draw[vqflow] (res.west) -- ++(-2.55,0)
  node[vqtag, midway, above]{recurse}
  |- (stream.west);

\end{tikzpicture}
\caption{\textbf{The recursive tool-calling loop.} A single routine streams one model call. If no
tools are requested, the accumulated text is the report and the recursion unwinds. Otherwise the
server appends the model's \texttt{tool\_use} blocks (as an assistant turn), executes the requested
tools in throttled batches of at most five, appends the matching \texttt{tool\_result} blocks (as
a user turn), and \emph{re-enters} the same routine with the augmented context (heavy teal arrow).
The strict pairing of \texttt{tool\_use} and \texttt{tool\_result} blocks across the recursion is
the loop's central invariant.}
\label{fig:loop}
\end{figure}