cys

1import type { Register } from 'claude-code'
2
3const TOOL = 'mcp__cys__register'
4
5const DESCRIPTION =
6  'Register temporary files or directories you created for this task, by exact absolute path, right after creating them. ' +
7  'Use the native path form of this machine (C:\\... on Windows, /... elsewhere). ' +
8  'Also register the paths your subagents report. Never register deliverables or files that existed before the task. ' +
9  'CYS never deletes anything: at the end of the turn it lists the registered paths still on disk once, so you can delete what is no longer needed.'
10
11const SUBAGENT_CONTEXT =
12  'CYS: if you have the mcp__cys__register tool, register each temporary file or directory you create with it. ' +
13  'Otherwise list their absolute paths in your final report, so the main agent registers them.'
14
15// The store refuses keys over 256 characters, so keys carry a hash of the
16// path and the value carries the path itself.
17const hash = (text: string) => {
18  let h1 = 0xdeadbeef
19  let h2 = 0x41c6ce57
20  for (let i = 0; i < text.length; i++) {
21    const c = text.charCodeAt(i)
22    h1 = Math.imul(h1 ^ c, 2654435761)
23    h2 = Math.imul(h2 ^ c, 1597334677)
24  }
25  h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507) ^ Math.imul(h2 ^ (h2 >>> 13), 3266489909)
26  h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507) ^ Math.imul(h1 ^ (h1 >>> 13), 3266489909)
27  return (4294967296 * (2097151 & h2) + (h1 >>> 0)).toString(16)
28}
29
30const cleanupText =(paths: string[]) =>
31  'CYS has registered temporary paths to review:\n' +
32  paths.join('\n') +
33  '\nReview ownership and whether each is still needed. Delete only task-created disposable paths; ' +
34  'preserve user, pre-existing, tracked, and needed files. Report any path you keep and why. ' +
35  'Do this cleanup pass once, then finish.'
36
37// $.fs.exists rejects network locations; registration refuses these spellings
38// so the agent gets a clear reason up front. Stop does not depend on it.
39const rejection = (path: string, isWindows: boolean) => {
40  if (/[\r\n]/.test(path)) return 'contains a line break'
41  if (/^[\\/][\\/]/.test(path)) return 'network or device path'
42  if (/^[A-Za-z]:(?![\\/])/.test(path)) return 'drive-relative path'
43  if (isWindows ? /^[A-Za-z]:[\\/]/.test(path) : path.startsWith('/')) return undefined
44  return isWindows ? 'not an absolute Windows path such as C:\\...' : 'not an absolute path'
45}
46
47export const register: Register = on => {
48  on('session.start', async ($, e, next) => {
49    await $.tool.register({
50      name: 'register',
51      description: DESCRIPTION,
52      inputSchema: {
53        type: 'object',
54        properties: { paths: { type: 'array', items: { type: 'string' }, minItems: 1 } },
55        required: ['paths'],
56      },
57    })
58    return next(e)
59  })
60
61  on('classic.SubagentStart', async ($, e, next) => {
62    const result = await next(e)
63    return { ...result, additionalContext: [...(result.additionalContext ?? []), SUBAGENT_CONTEXT] }
64  })
65
66  on('tool.call', { tool: TOOL }, async ($, e) => {
67    const session = await $.session.id()
68    const isWindows = /^([A-Za-z]:|\\\\)/.test(await $.session.cwd())
69    const paths: unknown = (e as { paths?: unknown }).paths
70    const lines: string[] = []
71    for (const path of Array.isArray(paths) ? paths : []) {
72      const reason = typeof path === 'string' ? rejection(path, isWindows) : 'not a string'
73      if (reason) {
74        lines.push(`not registered (${reason}): ${String(path)}`)
75        continue
76      }
77      try {
78        await $.store.set(`${session}\n${hash(path)}`, path)
79        lines.push(`registered: ${path}`)
80      } catch {
81        lines.push(`not registered (store refused it): ${path}`)
82      }
83    }
84    return { result: lines.length > 0 ? lines.join('\n') : 'No paths given.' }
85  })
86
87  on('classic.Stop', async ($, e, next) => {
88    const result = await next(e)
89    if (e.stop_hook_active || (e.background_tasks?.length ?? 0) > 0 || result.preventContinuation) return result
90    const prefix = `${e.session_id}\n`
91    const present: string[] = []
92    for (const key of await $.store.keys()) {
93      if (!key.startsWith(prefix)) continue
94      const path = await $.store.get(key)
95      await $.store.delete(key)
96      if (typeof path !== 'string') continue
97      const isPresent = await $.fs.stat(path).then(
98        () => true,
99        () => $.fs.exists(path).catch(() => true),
100      )
101      if (isPresent) present.push(path)
102    }
103    if (present.length === 0) return result
104    return { ...result, additionalContext: [...(result.additionalContext ?? []), cleanupText(present)] }
105  })
106}
107