Arguments: $ARGUMENTS. If the first word is html use HTML mode, unless otherwise instructed use terminal mode. The rest is the topic. With no topic, explain what the conversation is currently about.

Both modes

Show the real mechanism: the actual components, data flow and state changes, with real names, shapes and numbers. A labelled box saying "processing" explains nothing.
Picture first, prose second. Prose is short captions keyed to the picture.
Captions follow Simplified Technical English: max 20 words per step, 25 per description, active voice, one idea per sentence, plain words with one meaning. Keep code and identifiers verbatim.
For code in the current project, read it first and cite path:line.

Terminal mode

Draw an ASCII diagram, at most 80 columns wide. Stack vertically rather than in one long row.
Follow it with numbered captions that use the diagram's labels.