link

rpic extension. link makes an object a hyperlink: its SVG shape group is wrapped in <a href="…">, so clicking the shape — label included — navigates to the URL. No JavaScript, no host wiring: it’s native SVG, and it works wherever the SVG is a real document (inline-embedded, <img src>, or opened directly).

Two forms write to the same hook — and since this page is a host document, these are live links (click them!):

.PS
box "rpic.dev" fit link "https://rpic.dev"     # inline, at creation

A: circle "GitHub" rad 0.42 at last box + (1.6, 0)
arrow from last box.e to A.w
link A "https://github.com/milkway/rpic-lang"  # statement: by label
.PE

The statement form uses pic’s native references — labels and ordinals — so it also reaches shapes drawn inside macros (circuit elements!), and lets link lines cluster at the end of a picture.

Rules

• SVG-only. PNG and PDF render the identical picture, just without the link (the raster pipeline flattens the anchor to a plain group).
• Validated, not raw. The URL must be non-empty, free of whitespace and control characters (percent-encode them), and must not use a script-executing scheme (javascript:, vbscript:, data:) — a host that renders untrusted pictures inline must not gain an XSS surface. Relative URLs, #fragments and mailto: all pass.
• Reapplying replaces — the last link wins. (Unlike class, URLs don’t compose.)
• The anchor wraps outside the <g id="sN"> group: the stable ids and the animate/GSAP contract are untouched, and class + link compose on the same shape.
• The anchor carries class="rpic-link", so the common a:not([class]) prose pattern in host pages (underline, link colour) never restyles the picture’s labels — and .rpic-link is your styling hook when you do want a hover affordance.
• The compile bundle’s objects entries carry a "link" key when set, so editors and players can surface it.
• link is contextual: link = 2 is still an assignment and box wid link still reads the variable. Unused, the output is byte-for-byte classic.
• Blocks are not supported yet — link the inner objects instead. A point label has no drawn shape, so linking it is an error.

Cross-linking a diagram

Fragments (#…) and relative URLs pass validation, so a picture can link into its own page — a table of contents that is also the system diagram:

.PS
B1: box "Rules" fit link "#rules"
arrow
B2: box "Cross-linking" fit link "#cross-linking-a-diagram"
.PE

Design notes: docs/extensions.md.