prompt-snippets

1import type { EngineInterface, Register } from 'claude-code'
2
3import { expand, parseCommand } from './snippets'
4import type { Snippets } from './snippets'
5
6const KEY = 'snippets'
7
8async function load($: EngineInterface): Promise<Snippets> {
9  const value = await $.store.get(KEY)
10
11  return typeof value === 'object' && value !== null ? (value as Snippets) : {}
12}
13
14export const register: Register = on => {
15  on('session.start', async ($, e, next) => {
16    await $.command.register({
17      name: 'snip',
18      description: 'Prompt snippets: add <name> <text> | rm <name> | list | show <name>; use ;;name in a prompt',
19    })
20
21    return next(e)
22  })
23
24  on('command.run', { command: 'snip' }, async ($, e) => {
25    const cmd = parseCommand(e.args)
26    if (cmd.action === 'error') return { text: cmd.message }
27    const snippets = await load($)
28    if (cmd.action === 'list') {
29      const names = Object.keys(snippets).sort()
30
31      return { text: names.length === 0 ? 'No snippets yet.' : `Snippets: ${names.map(n => `;;${n}`).join(' ')}` }
32    }
33    if (cmd.action === 'show') {
34      const body = Object.hasOwn(snippets, cmd.name) ? snippets[cmd.name] : undefined
35
36      return { text: body === undefined ? `No snippet "${cmd.name}".` : `;;${cmd.name} = ${body}` }
37    }
38    if (cmd.action === 'rm') {
39      if (!Object.hasOwn(snippets, cmd.name)) return { text: `No snippet "${cmd.name}".` }
40      const { [cmd.name]: _removed, ...rest } = snippets
41      await $.store.set(KEY, rest)
42
43      return { text: `Removed ;;${cmd.name}.` }
44    }
45    await $.store.set(KEY, { ...snippets, [cmd.name]: cmd.text })
46
47    return { text: `Saved ;;${cmd.name}.` }
48  })
49
50  on('prompt.submit', async ($, e, next) => {
51    if (!e.text.includes(';;') || e.text.trimStart().startsWith('/snip')) return next(e)
52    const { text, unknown } = expand(e.text, await load($))
53    if (unknown.length > 0) $.ui.toast(`Unknown snippet${unknown.length === 1 ? '' : 's'}: ${unknown.map(n => `;;${n}`).join(', ')}`)
54
55    return next({ ...e, text })
56  })
57}
58

1export type Snippets = Record<string, string>
2
3const NAME = /^[a-z0-9_-]+$/
4const TOKEN = /;;([a-z0-9_-]+)(?![A-Za-z0-9_-])/g
5
6export const isValidName = (name: string) => NAME.test(name)
7
8export type Command =
9  | { action: 'add'; name: string; text: string }
10  | { action: 'rm'; name: string }
11  | { action: 'show'; name: string }
12  | { action: 'list' }
13  | { action: 'error'; message: string }
14
15export function parseCommand(args: string): Command {
16  const m = /^\s*(\S+)(?:\s+(\S+))?(?:\s+([\s\S]*))?$/.exec(args)
17  const action = m?.[1] ?? 'list'
18  const name = m?.[2] ?? ''
19  const text = (m?.[3] ?? '').trim()
20  if (action === 'list') return { action: 'list' }
21  if (action !== 'add' && action !== 'rm' && action !== 'show') {
22    return { action: 'error', message: 'Usage: /snip add <name> <text> | rm <name> | list | show <name>' }
23  }
24  if (!isValidName(name)) return { action: 'error', message: `Invalid name "${name}": use a-z, 0-9, _ and -.` }
25  if (action === 'add') {
26    return text === '' ? { action: 'error', message: 'Usage: /snip add <name> <text>' } : { action, name, text }
27  }
28
29  return { action, name } as Command
30}
31
32export function expand(text: string, snippets: Snippets): { text: string; unknown: string[] } {
33  const unknown: string[] = []
34  const out = text.replace(TOKEN, (token, name: string, offset: number) => {
35    const before = offset === 0 ? '' : text.charAt(offset - 1)
36    if (/[A-Za-z0-9_;-]/.test(before)) return token
37    const body = Object.hasOwn(snippets, name) ? snippets[name] : undefined
38    if (body === undefined) {
39      if (!unknown.includes(name)) unknown.push(name)
40      return token
41    }
42
43    return body
44  })
45
46  return { text: out, unknown }
47}
48