y-change

1import { atom, read, update } from 'claude-code'
2import type { Register } from 'claude-code'
3
4import type { Change } from '../types'
5
6const PANE = 'y-change'
7const TITLE = '변경 이유'
8// changes kept, and diff rows drawn per change
9const MAX_CHANGES = 30
10const MAX_ROWS = 80
11
12const changes = atom({ plugin: 'y-change', key: 'changes' } as const, [])
13
14type Hunk = { oldStart: number; newStart: number; lines: string[] }
15
16// the tool's patch as unified hunks, cut to MAX_ROWS; a cut hunk gets its counts again so it still parses
17const toDiff = (hunks: readonly Hunk[]) => {
18  let room = MAX_ROWS
19  const out: string[] = []
20
21  for (const hunk of hunks) {
22    if (room <= 0) break
23    const lines = hunk.lines.slice(0, room)
24    room -= lines.length
25    const count = (mark: string) => lines.filter(l => l[0] === ' ' || l[0] === mark).length
26    out.push(`@@ -${hunk.oldStart},${count('-')} +${hunk.newStart},${count('+')} @@`, ...lines)
27  }
28
29  const total = hunks.reduce((n, hunk) => n + hunk.lines.length, 0)
30
31  return { diff: out.join('\n'), more: total - (MAX_ROWS - room) }
32}
33
34// asked over the session's own transcript, so the model answers from why it made the change
35const ask = (pending: readonly Change[]) => `[y-change] For each code change below, which you made earlier in this conversation, explain it to a reader who has never used this programming language. Write in the language the user has been writing in.
36
37For each change cover:
381. What changed: in plain words, line by line where that helps.
392. Why: the reason for this change in this conversation (the request, the bug, the constraint that led to it). If the conversation does not show the reason, say so instead of guessing.
403. Language notes: each piece of syntax, keyword or library call in the diff a newcomer to the language would not know, in a sentence each.
41
42Start each change's explanation with a line holding exactly \`### <number>\`, then markdown. Write nothing before the first such line.
43
44${pending.map((c, i) => `### ${i + 1}: ${c.file}\n\`\`\`diff\n${c.diff}\n\`\`\``).join('\n\n')}`
45
46// '### 1\n…\n### 2\n…' -> the texts by their number
47const parse = (text: string) => {
48  const parts = text.split(/^### (\d+).*$/m)
49  const whys = new Map<number, string>()
50  for (let i = 1; i < parts.length; i += 2) whys.set(Number(parts[i]), (parts[i + 1] ?? '').trim())
51
52  return whys
53}
54
55export const register: Register = on => {
56  on('session.start', async ($, e, next) => {
57    await $.command.register({ name: 'y-change', description: '코드 변경 이유 pane 열기/닫기' })
58
59    return next(e)
60  })
61
62  // a toggle; a pane waiting undrawn (opened unasked in a narrow terminal) is opened, not closed
63  on('command.run', { command: 'y-change' }, async $ => {
64    const isShown = (await $.ui.panes()).some(pane => pane.id === PANE && pane.isPlaced)
65    if (isShown) {
66      await $.ui.close({ id: PANE })
67
68      return { text: '변경 이유 pane을 닫았습니다.' }
69    }
70    await $.ui.open({ id: PANE, title: TITLE })
71
72    return { text: '변경 이유 pane을 열었습니다.' }
73  })
74
75  on('tool.call', { tool: ['Edit', 'Write'] }, async ($, e, next) => {
76    const ran = await next(e)
77    if (ran.deny !== undefined || ran.isError === true || ran.result.staged) return ran
78
79    const { diff, more } = toDiff(ran.result.structuredPatch)
80    if (diff === '') return ran
81
82    const change: Change = { id: e.tool_use_id, file: ran.result.gitDiff?.filename ?? ran.result.filePath, diff, more }
83    await update($, changes, list => [...list, change].slice(-MAX_CHANGES))
84
85    return ran
86  })
87
88  // one question per turn for everything it changed; what stays unexplained is asked again next turn
89  on('turn.complete', async ($, e, next) => {
90    const done = await next(e)
91    if (e.agentId !== undefined) return done
92
93    const pending = (await read($, changes)).filter(c => c.why === undefined)
94    if (pending.length === 0) return done
95
96    const asked = await $.model.fork({ prompt: ask(pending) })
97    if (!asked.isAnswered) {
98      $.ui.toast(`y-change: 변경 이유를 만들지 못했습니다 (${asked.reason})`)
99
100      return done
101    }
102
103    const whys = parse(asked.text)
104    const byId = new Map(pending.map((c, i) => [c.id, whys.get(i + 1)]))
105    await update($, changes, list => list.map(c => (byId.get(c.id) ? { ...c, why: byId.get(c.id) } : c)))
106
107    return done
108  })
109
110  on('ui.render', { component: 'Pane', requestId: PANE }, async ($, e) => {
111    const { Box, Text, Code, Markdown } = $.ui.resolve(e)
112    const list = await read($, changes)
113
114    return (
115      <Box flexDirection="column">
116        {list.length === 0 && <Text dimColor>아직 변경이 없습니다. Claude가 파일을 수정하면 diff와 변경 이유가 여기에 표시됩니다.</Text>}
117        {/* newest first, so the latest change shows without scrolling */}
118        {[...list].reverse().map(c => (
119          <Box flexDirection="column" marginBottom={1}>
120            <Text bold>{c.file}</Text>
121            <Code source={c.diff} path={c.file} format="diff" />
122            {c.more > 0 && <Text dimColor>… {c.more}줄 더</Text>}
123            {c.why === undefined
124              ? <Text dimColor>이번 턴이 끝나면 변경 이유를 설명합니다.</Text>
125              : <Markdown text={c.why} />}
126          </Box>
127        ))}
128      </Box>
129    )
130  })
131}
132

1// one Edit or Write Claude made: `diff` is unified hunks cut to a few rows, `more` the rows cut,
2// `why` the explanation, absent until the turn that made the change ends
3export type Change = { id: string; file: string; diff: string; more: number; why?: string }
4
5declare module 'claude-code' {
6  interface PluginState {
7    'y-change': { changes: Change[] }
8  }
9}
10