Add Diagnostic

Add a New Diagnostic Code

• Find the catalog. Grep for defineDiagnostics to locate the codes object the new entry belongs in. With several catalogs, pick by area.
• Pick the code. PREFIX_XNNNN: PREFIX is the project name uppercased (NUXT, I18N); X is the area letter (B build, R runtime, C config, D deprecation); NNNN is the next free number. Read existing codes to choose. Never rename or reuse a published code.
• Add the entry:

LIB_R0001: {
  why: (p: { hook: string }) => `${p.hook}() must run at the top of setup().`, // string or typed fn; becomes Error.message (required)
  fix: 'Move the call into setup() or a composable it calls.', // optional, but add whenever the fix is known
  docs: 'https://example.com/custom', // optional: overrides docsBase, or `false` to opt out
},

• why is the only required field. Params from why and fix are intersected and required at the call site.
• Runtime fields (cause, sources) are passed at the call site, never in the definition.

• Call it: diagnostics.LIB_R0001({ hook }) to report, throw diagnostics.LIB_R0001({ hook, cause: err }) to raise. Both run the reporters.

Full API and reporter/formatter/plugin details: the nostics skill.