complexity-lens

1import { atom, read, update } from 'claude-code'
2import type { EngineInterface, Register } from 'claude-code'
3
4import type { Row, Shown } from '../types'
5
6const rows = atom({ plugin: 'complexity-lens', key: 'rows' } as const, [])
7const problem = atom({ plugin: 'complexity-lens', key: 'problem' } as const, null)
8
9const WATCHED = ['Read', 'Edit', 'Write'] as const
10const SHOWN = 4
11const CODE = /\.(rs|ts|tsx|js|jsx|py|go)$/
12
13async function measure($: EngineInterface, path: string): Promise<Shown | undefined> {
14  try {
15    const ran = await $.process.run(
16      ['python3', `${$.plugin.root}/scripts/complexity_rank.py`, '--json', path],
17      { timeoutMs: 20000, cwd: path.slice(0, path.lastIndexOf('/')) || '/' },
18    )
19    if (ran.exitCode !== 0) {
20      await update($, problem, () => `rank exit ${ran.exitCode}`)
21      return undefined
22    }
23    const [measured] = JSON.parse(ran.stdout) as Row[]
24    if (!measured) return undefined
25    const before = (await read($, rows)).find(r => r.file === measured.file)
26    const row: Shown = { ...measured, baseline: before ? before.baseline : measured.over_threshold_fns }
27    await update($, rows, list => [row, ...list.filter(r => r.file !== row.file)].slice(0, 12))
28    if (grew(row)) {
29      $.ui.toast(`${row.file}: functions over limit ${row.baseline} → ${row.over_threshold_fns}`)
30    }
31    await update($, problem, () => null)
32    return row
33  } catch (err) {
34    await update($, problem, () => `rank failed: ${String(err).slice(0, 60)}`)
35    return undefined
36  }
37}
38
39function grew(r: Shown): boolean {
40  return r.over_threshold_fns !== null && r.baseline !== null && r.over_threshold_fns > r.baseline
41}
42
43type Level = 'grew' | 'over' | 'calm'
44
45function level(r: Shown): Level {
46  if (grew(r)) return 'grew'
47  return (r.over_threshold_fns ?? 0) > 0 ? 'over' : 'calm'
48}
49
50const LEVEL_RANK: Record<Level, number> = { grew: 0, over: 1, calm: 2 }
51const LEVEL_COLOR: Record<Level, string | undefined> = { grew: 'red', over: 'yellow', calm: undefined }
52
53function agentNote(row: Shown): string | undefined {
54  const over = row.over_threshold_fns ?? 0
55  if (over === 0 && row.score === 0 && !grew(row)) return undefined
56  const change = grew(row) ? ` (was ${row.baseline} at the start of this request)` : ''
57  const limit =
58    row.per_function_source === 'lizard'
59      ? 'cyclomatic 10, lizard'
60      : row.per_function_source === 'biome'
61        ? 'cognitive 20, Biome'
62        : 'not counted'
63  return (
64    `complexity-lens: ${row.file} has ${row.over_threshold_fns ?? 'unknown'} function(s) over the per-function limit (${limit})${change}; ` +
65    `file complexity ${row.complexity}, ${row.density} per 100 lines, recent churn ${row.churn ?? 'n/a'}, hotspot score ${row.score}` +
66    `${row.flags.length ? ` [${row.flags.join(', ')}]` : ''}. Keep new functions under the limit, or name the reason.`
67  )
68}
69
70function overText(r: Shown): string | undefined {
71  if (r.over_threshold_fns === null) return undefined
72  return grew(r) ? `${r.over_threshold_fns} over limit (+${r.over_threshold_fns - (r.baseline ?? 0)})` : `${r.over_threshold_fns} over limit`
73}
74
75function details(r: Shown): string {
76  const notes = r.flags.map(f => (f === 'scc-only' ? 'rough' : f === 'young' ? 'new file' : f))
77  const parts = [
78    `complexity ${r.complexity}`,
79    `${Math.round(r.density)} per 100 lines`,
80    `changed ${r.churn ?? '?'}×`,
81    `score ${r.score}`,
82  ]
83  return `${parts.join(' · ')}${notes.length ? `  (${notes.join(', ')})` : ''}`
84}
85
86export const register: Register = on => {
87  let scc = true
88
89  on('session.start', async ($, e, next) => {
90    try {
91      await $.process.run(['scc', '--version'], { timeoutMs: 5000 })
92    } catch (err) {
93      scc = false
94      await update($, problem, () => `scc unavailable: ${String(err).slice(0, 60)}`)
95    }
96    return next(e)
97  })
98
99  on('prompt.submit', async ($, e, next) => {
100    await update($, rows, () => [])
101    await update($, problem, () => null)
102    return next(e)
103  })
104
105  on('tool.call', { tool: WATCHED }, async ($, e, next) => {
106    const result = await next(e)
107    const path = e.file_path
108    if (!scc || !path || result.deny !== undefined || result.isError || !CODE.test(path)) return result
109    if (e.tool === 'Read') {
110      void measure($, path)
111      return result
112    }
113    const measured = await measure($, path)
114    const note = measured ? agentNote(measured) : undefined
115    return note ? { ...result, context: [...(result.context ?? []), note] } : result
116  })
117
118  on('ui.render', { component: 'AbovePrompt' }, async ($, e, next) => {
119    const list = await read($, rows)
120    const issue = await read($, problem)
121    if (list.length === 0 && issue === null) return next(e)
122
123    const below = await next(e)
124    const { Box, Text } = $.ui.resolve(e)
125    const top = [...list]
126      .sort((a, b) => LEVEL_RANK[level(a)] - LEVEL_RANK[level(b)] || b.score - a.score || b.complexity - a.complexity)
127      .slice(0, SHOWN)
128
129    return (
130      <Box flexDirection="column">
131        {below}
132        {issue !== null ? <Text color="yellow">complexity-lens: {issue}</Text> : null}
133        {top.map(r => {
134          const lvl = level(r)
135          const over = overText(r)
136          return (
137            <Box key={r.file} flexDirection="row" columnGap={1}>
138              <Text color={LEVEL_COLOR[lvl]} bold={lvl === 'grew'} dimColor={lvl === 'calm'}>
139                {r.file.split('/').slice(-2).join('/')}
140              </Text>
141              {over === undefined ? null : (
142                <Text color={LEVEL_COLOR[lvl]} bold={lvl === 'grew'} dimColor={lvl === 'calm'}>
143                  {over}
144                </Text>
145              )}
146              <Text dimColor wrap="truncate-end">
147                {details(r)}
148              </Text>
149            </Box>
150          )
151        })}
152      </Box>
153    )
154  })
155}
156

1export type Row = {
2  file: string
3  code: number
4  complexity: number
5  density: number
6  churn: number | null
7  over_threshold_fns: number | null
8  per_function_source: 'biome' | 'lizard' | null
9  score: number
10  flags: string[]
11}
12
13export type Shown = Row & { baseline: number | null }
14
15declare module 'claude-code' {
16  interface PluginState {
17    'complexity-lens': { rows: Shown[]; problem: string | null }
18  }
19}
20