% --- Streaming SSE parsing and event dispatch ---
\begin{figure}[htbp]
\centering
\begin{tikzpicture}[vqfont]

% Pipeline backbone
\node[vqpurple, minimum height=1.5cm, text width=2.0cm] (prov) at (0,0)
  {\textbf{Provider}\\\vqsmall \texttt{/v1/messages}\\ streaming HTTP};
\node[vqblue, minimum height=1.5cm, text width=2.35cm] (buf) at (3.5,0)
  {\textbf{Byte buffer}\\\vqsmall append chunk;\\split on \texttt{\textbackslash n};\\\textit{keep partial line}};
\node[vqblue, minimum height=1.5cm, text width=2.2cm] (disp) at (7.05,0)
  {\textbf{Dispatch}\\\vqsmall parse \texttt{data:} line\\$\to$ JSON;\\switch on \texttt{type}};

% Right-hand output channels
\node[vqgreen,  text width=3.0cm] (txt)  at (11.0, 2.55)
  {\textbf{Answer channel}\\\vqsmall \texttt{text\_delta} $\to$ accumulate $+$ stream};
\node[vqgreen,  text width=3.0cm] (think) at (11.0, 1.05)
  {\textbf{Reasoning channel}\\\vqsmall \texttt{thinking\_delta} $\to$ separate panel};
\node[vqorange, text width=3.0cm] (tool) at (11.0,-0.65)
  {\textbf{Tool assembler}\\\vqsmall \texttt{start} $\cdot$ \texttt{input\_json\_delta}$^\ast$ $\cdot$ \texttt{stop} $\to$ args};
\node[vqred,    text width=3.0cm] (tok)  at (11.0,-2.35)
  {\textbf{Token ledger}\\\vqsmall \texttt{message\_start/}\allowbreak\texttt{delta/}\allowbreak\texttt{stop} $\to$ usage};

% Backbone arrows
\draw[vqflow] (prov) -- node[vqtag, above]{raw bytes} (buf);
\draw[vqflow] (buf)  -- node[vqtag, above]{\texttt{data:} lines} (disp);

% Fan-out
\draw[vqarr] (disp.east) to[out=20,in=180]  (txt.west);
\draw[vqarr] (disp.east) to[out=8,in=180]   (think.west);
\draw[vqarr] (disp.east) to[out=-8,in=180]  (tool.west);
\draw[vqarr] (disp.east) to[out=-22,in=180] (tok.west);

% Downstream consequences
\draw[vqdash] (tool.south) to[out=-90,in=-90] node[vqtag, below, pos=0.5]{executable $\to$ loop} (disp.south);

\end{tikzpicture}
\caption{\textbf{Streaming transport and event dispatch.} The server reads the provider's
Server-Sent Event stream as raw bytes, buffers them, and splits on newlines while \emph{retaining
the trailing partial line} (frames do not align with packet boundaries). Each \texttt{data:} line
is parsed to JSON and dispatched on its \texttt{type} onto four channels: answer text is
accumulated and forwarded; private reasoning is forwarded to a separate panel; a tool call is
assembled from a \texttt{content\_block\_start}, a sequence of \texttt{input\_json\_delta}
fragments ($\ast$), and a closing \texttt{content\_block\_stop}, becoming executable only once the
block closes; and usage events feed the token ledger. Heavy arrows are the byte backbone; thin
arrows are per-event dispatch.}
\label{fig:streaming}
\end{figure}