Ascii Diagram

ASCII Diagrams

Method — do not hand-draw

Hand-drawn ASCII art is misaligned by one or two columns almost every time, and neither you nor a reviewer spots it by reading. Alignment is arithmetic, so make arithmetic do it:

1. Write a small Python script that builds the diagram from data — a fixed inner width W, and helpers that pad every line to it.
2. End the script with an assertion that every box line is exactly W + 2 characters. Print WIDTH CHECK: all aligned, or the list of offending (index, length) pairs.
3. Run it. If the check fails, fix the script and run again.
4. Paste only the verified output into the page.

Never repair a diagram by editing the rendered text — an edit that looks right in one place shifts another line you are not looking at, and the next reader inherits a diagram no check has passed.

W = 64 is a good default: wide enough for two annotated columns. Raise it only when the page renders in a wide container, and keep the total under 76 columns so the diagram survives narrow panes and diffs.

Character rules

• Box drawing: ┌ ┐ └ ┘ ─ │ ├ ┤ ┬ ┴ ┼. Arrows: ▼ ▲ ◀ ▶, or -> and <-.
• Every character must be single-width. Ambiguous-width characters shift columns in some terminals, which is invisible where you author and broken where it is read: ✅ 1. 2. 3. ❌ ①②③, emoji, CJK
• Hold one style throughout: ✅ ─ everywhere ❌ ─ in one box and - in the next, ▼ beside v

Content rules

• The diagram teaches the same structure the prose names, in the same words: if the text says "four phases", the diagram labels four phases with those names.
• Label edges, not just nodes — what flows along the arrow, and which way. An arrow pointing against the flow is worse than no arrow.
• Annotate with consequences, not mechanism: ✅ nothing has run yet ❌ (lazy description) · ✅ wait right here ❌ (park thread)
• Put the one fact readers most often get wrong on the spine of the diagram, where it cannot be skipped.
• Every element earns its place. Cut anything that repeats the prose without adding shape.

Output

Put the diagram in the page inside a plain fence with no language tag, so no tooling tries to compile it:

```
┌──────────────┐
│   Ledger     │
└──────┬───────┘
       │ record(name, by)
       ▼

Keep the script out of the page — it is scaffolding for producing the picture, not content for the reader. Report its WIDTH CHECK line in your result so the next reader knows the diagram was verified rather than eyeballed.

Worked shape

W = 64  # inner width; every box line ends up W + 2 with the borders


def box(label, note=""):
    body = f" {label}".ljust(W) if not note else f" {label}".ljust(W - len(note) - 1) + note + " "
    return [f"┌{'─' * W}┐", f"│{body}│", f"└{'─' * W}┘"]


lines = box("Ledger", "counts only grow") + ["    │ record(name, by)", "    ▼"] + box("Window")

bad = [(i, len(l)) for i, l in enumerate(lines) if l.startswith(("┌", "│", "└")) and len(l) != W + 2]
print("WIDTH CHECK: all aligned" if not bad else f"WIDTH CHECK FAILED: {bad}")
print("\n".join(lines))

Two things to tune per diagram: W, and whether the 76-column cap applies to the target.