oppi.li
source dump of claude code
1/**
2 * Read tool output limits. Two caps apply to text reads:
3 *
4 * | limit | default | checks | cost | on overflow |
5 * |---------------|---------|---------------------------|---------------|-----------------|
6 * | maxSizeBytes | 256 KB | TOTAL FILE SIZE (not out) | 1 stat | throws pre-read |
7 * | maxTokens | 25000 | actual output tokens | API roundtrip | throws post-read|
8 *
9 * Known mismatch: maxSizeBytes gates on total file size, not the slice.
10 * Tested truncating instead of throwing for explicit-limit reads that
11 * exceed the byte cap (#21841, Mar 2026). Reverted: tool error rate
12 * dropped but mean tokens rose — the throw path yields a ~100-byte error
13 * tool-result while truncation yields ~25K tokens of content at the cap.
14 */
15import memoize from 'lodash-es/memoize.js'
16import { getFeatureValue_CACHED_MAY_BE_STALE } from 'src/services/analytics/growthbook.js'
17import { MAX_OUTPUT_SIZE } from 'src/utils/file.js'
18export const DEFAULT_MAX_OUTPUT_TOKENS = 25000
19
20/**
21 * Env var override for max output tokens. Returns undefined when unset/invalid
22 * so the caller can fall through to the next precedence tier.
23 */
24function getEnvMaxTokens(): number | undefined {
25 const override = process.env.CLAUDE_CODE_FILE_READ_MAX_OUTPUT_TOKENS
26 if (override) {
27 const parsed = parseInt(override, 10)
28 if (!isNaN(parsed) && parsed > 0) {
29 return parsed
30 }
31 }
32 return undefined
33}
34
35export type FileReadingLimits = {
36 maxTokens: number
37 maxSizeBytes: number
38 includeMaxSizeInPrompt?: boolean
39 targetedRangeNudge?: boolean
40}
41
42/**
43 * Default limits for Read tool when the ToolUseContext doesn't supply an
44 * override. Memoized so the GrowthBook value is fixed at first call — avoids
45 * the cap changing mid-session as the flag refreshes in the background.
46 *
47 * Precedence for maxTokens: env var > GrowthBook > DEFAULT_MAX_OUTPUT_TOKENS.
48 * (Env var is a user-set override, should beat experiment infrastructure.)
49 *
50 * Defensive: each field is individually validated; invalid values fall
51 * through to the hardcoded defaults (no route to cap=0).
52 */
53export const getDefaultFileReadingLimits = memoize((): FileReadingLimits => {
54 const override =
55 getFeatureValue_CACHED_MAY_BE_STALE<Partial<FileReadingLimits> | null>(
56 'tengu_amber_wren',
57 {},
58 )
59
60 const maxSizeBytes =
61 typeof override?.maxSizeBytes === 'number' &&
62 Number.isFinite(override.maxSizeBytes) &&
63 override.maxSizeBytes > 0
64 ? override.maxSizeBytes
65 : MAX_OUTPUT_SIZE
66
67 const envMaxTokens = getEnvMaxTokens()
68 const maxTokens =
69 envMaxTokens ??
70 (typeof override?.maxTokens === 'number' &&
71 Number.isFinite(override.maxTokens) &&
72 override.maxTokens > 0
73 ? override.maxTokens
74 : DEFAULT_MAX_OUTPUT_TOKENS)
75
76 const includeMaxSizeInPrompt =
77 typeof override?.includeMaxSizeInPrompt === 'boolean'
78 ? override.includeMaxSizeInPrompt
79 : undefined
80
81 const targetedRangeNudge =
82 typeof override?.targetedRangeNudge === 'boolean'
83 ? override.targetedRangeNudge
84 : undefined
85
86 return {
87 maxSizeBytes,
88 maxTokens,
89 includeMaxSizeInPrompt,
90 targetedRangeNudge,
91 }
92})