v0 state

entry

entry is the persisted record for a single alias.

aliases

aliases maps alias (string) -> \*entry, kept in an avl.Tree for deterministic iteration order in Render.

isAlphanumeric

isAlphanumeric reports whether s is non-empty and made only of \[0-9A-Za-z].

Shorten

Shorten registers \`alias -> url\` owned by the caller. Rules: - alias must be non-empty and alphanumeric; - url must be non-empty; - if the alias is unclaimed, it is created owned by the caller; - if it is already claimed by the caller, the url/note are updated; - if it is claimed by someone else, the call aborts.

Remove

Remove deletes an alias owned by the caller. Aborts if the alias does not exist or the caller is not the owner.

Lookup

Lookup returns the target url for an alias and whether it exists. It is a read-only helper and does NOT increment the click counter.

Render

Render renders Markdown. The root path lists every alias; "/\<alias>" shows a single alias detail and bumps its click counter.

renderIndex

short

short truncates a long address for the index table.

itoa

itoa converts a non-negative int to its decimal string without importing strconv (kept minimal & deterministic).