ctx-slim

1import { atom, read, update } from 'claude-code'
2import type { EngineInterface, Register } from 'claude-code'
3
4type Api = EngineInterface
5type Keep = (server: string) => boolean
6
7const NOTICE_MS = 30_000
8
9// 每个会话只提示一次：记在会话级 state 里，/reload-plugins 后也不会再提示
10const notified = atom({ plugin: 'ctx-slim', key: 'notified' } as const, false)
11
12// 状态条带里的提示，显示 NOTICE_MS 后清掉
13let notice: { servers: string[]; saved: number } | null = null
14
15// 说明文本是一段总述，后面每个服务器一节 `## <名字>`
16export function filterInstructions(text: string, keep: Keep): string | null {
17  const [head = '', ...blocks] = text.split(/\n(?=## )/)
18  if (blocks.length === 0) return text
19  const kept = blocks.filter(b => keep((b.split('\n')[0] ?? '').slice(3).trim()))
20  if (kept.length === blocks.length) return text
21  return kept.length === 0 ? null : [head, ...kept].join('\n')
22}
23
24export function droppedServers(text: string, keep: Keep): string[] {
25  return text
26    .split(/\n(?=## )/)
27    .slice(1)
28    .map(b => (b.split('\n')[0] ?? '').slice(3).trim())
29    .filter(name => !keep(name))
30}
31
32export type Condition = { kind: 'path' | 'file' | 'text'; value: string }
33export type Rule = { server: string; conditions: Condition[] }
34
35// 规则串：「服务器: 条件 | 条件; 服务器: 条件」。条件：path~子串、file=文件名、text=文字。
36// 写错的段直接跳过；一条有效条件都没有的规则也跳过（不会因此把说明删掉）。
37export function parseRules(spec: string): Rule[] {
38  return spec
39    .split(/[;\n]/)
40    .map(segment => segment.trim())
41    .flatMap(segment => {
42      const colon = segment.indexOf(':')
43      if (colon <= 0) return []
44      const server = segment.slice(0, colon).trim().toLowerCase()
45      const conditions = segment
46        .slice(colon + 1)
47        .split('|')
48        .flatMap((raw): Condition[] => {
49          const m = /^\s*(path)\s*~\s*(.+?)\s*$|^\s*(file|text)\s*=\s*(.+?)\s*$/.exec(raw)
50          if (!m) return []
51          if (m[1] && m[2]) return [{ kind: 'path', value: m[2].toLowerCase() }]
52          if (m[3] && m[4]) return [{ kind: m[3] as 'file' | 'text', value: m[4] }]
53          return []
54        })
55      return server && conditions.length > 0 ? [{ server, conditions }] : []
56    })
57}
58
59async function keeper($: Api, rules: Rule[]): Promise<Keep> {
60  const cwd = await $.session.cwd()
61  const home = (await $.env.get('HOME')) ?? ''
62  const lower = cwd.toLowerCase()
63  const conditions = rules.flatMap(r => r.conditions)
64
65  // file=：从当前目录往上找，在 HOME 之下时找到 HOME 为止
66  const files = new Map<string, boolean>()
67  const names = [...new Set(conditions.filter(c => c.kind === 'file').map(c => c.value))]
68  if (names.length > 0) {
69    const stop = home !== '' && cwd.startsWith(home) ? home : ''
70    const dirs: string[] = []
71    for (let d = cwd; d.length > stop.length && d !== '/'; d = d.slice(0, d.lastIndexOf('/')) || '/') dirs.push(d)
72    for (const name of names) {
73      files.set(name, (await Promise.all(dirs.map(d => $.fs.exists(`${d}/${name}`)))).some(Boolean))
74    }
75  }
76  // text=：CLAUDE.md / AGENTS.md（含上级目录与 @include）
77  const needsText = conditions.some(c => c.kind === 'text')
78  const instructions = needsText ? await $.fs.ancestors({ names: ['CLAUDE.md', 'AGENTS.md'] }).catch(() => []) : []
79
80  const holds = (c: Condition) =>
81    c.kind === 'path' ? lower.includes(c.value) : c.kind === 'file' ? files.get(c.value) === true : instructions.some(i => i.content.includes(c.value))
82
83  return server => {
84    const rule = rules.find(r => r.server === server.toLowerCase())
85    return rule === undefined || rule.conditions.some(holds)
86  }
87}
88
89export const register: Register = (on, options) => {
90  // 没配规则就什么都不做：不改说明，也不显示提示
91  const rules = parseRules(typeof options.rules === 'string' ? options.rules : '')
92  if (rules.length === 0) return
93
94  on('prompt.attachment', { type: 'mcp_instructions_delta' }, async ($, e, next) => {
95    const result = await next(e)
96    if (!result.text) return result
97    const keep = await keeper($, rules)
98    const dropped = droppedServers(result.text, keep)
99    if (dropped.length === 0) return result
100    const text = filterInstructions(result.text, keep)
101    if (await read($, notified)) return { ...result, text }
102    await update($, notified, () => true)
103    notice = { servers: dropped, saved: result.text.length - (text?.length ?? 0) }
104    $.ui.invalidate('ui.render')
105    $.clock.after(NOTICE_MS, () => {
106      notice = null
107      $.ui.invalidate('ui.render')
108    })
109    return { ...result, text }
110  })
111
112  on('ui.render', { component: 'AbovePrompt' }, async ($, e, next) => {
113    const below = await next(e)
114    if (!notice || e.props.hasSurvey) return below
115    const { Box, Text } = $.ui.resolve(e)
116    return (
117      <Box flexDirection="column">
118        <Box flexDirection="row" gap={1}>
119          <Text color="success" bold>
120            ▍精简
121          </Text>
122          <Text>本目录省略了 {notice.servers.join('、')} 的 MCP 说明</Text>
123          <Text dimColor>−{notice.saved} 字符</Text>
124        </Box>
125        {below}
126      </Box>
127    )
128  })
129}
130

1export type CtxSlimNotified = boolean
2
3declare module 'claude-code' {
4  interface PluginState {
5    'ctx-slim': {
6      /** whether this session has already shown the trimming notice */
7      notified: CtxSlimNotified
8    }
9  }
10}
11