1  // Critical system constants extracted to break circular dependencies
 2  
 3  import { feature } from 'bun:bundle'
 4  import { getFeatureValue_CACHED_MAY_BE_STALE } from '../services/analytics/growthbook.js'
 5  import { logForDebugging } from '../utils/debug.js'
 6  import { isEnvDefinedFalsy } from '../utils/envUtils.js'
 7  import { getAPIProvider } from '../utils/model/providers.js'
 8  import { getWorkload } from '../utils/workloadContext.js'
 9  
10  const DEFAULT_PREFIX = `You are Claude Code, Anthropic's official CLI for Claude.`
11  const AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX = `You are Claude Code, Anthropic's official CLI for Claude, running within the Claude Agent SDK.`
12  const AGENT_SDK_PREFIX = `You are a Claude agent, built on Anthropic's Claude Agent SDK.`
13  
14  const CLI_SYSPROMPT_PREFIX_VALUES = [
15    DEFAULT_PREFIX,
16    AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX,
17    AGENT_SDK_PREFIX,
18  ] as const
19  
20  export type CLISyspromptPrefix = (typeof CLI_SYSPROMPT_PREFIX_VALUES)[number]
21  
22  /**
23   * All possible CLI sysprompt prefix values, used by splitSysPromptPrefix
24   * to identify prefix blocks by content rather than position.
25   */
26  export const CLI_SYSPROMPT_PREFIXES: ReadonlySet<string> = new Set(
27    CLI_SYSPROMPT_PREFIX_VALUES,
28  )
29  
30  export function getCLISyspromptPrefix(options?: {
31    isNonInteractive: boolean
32    hasAppendSystemPrompt: boolean
33  }): CLISyspromptPrefix {
34    const apiProvider = getAPIProvider()
35    if (apiProvider === 'vertex') {
36      return DEFAULT_PREFIX
37    }
38  
39    if (options?.isNonInteractive) {
40      if (options.hasAppendSystemPrompt) {
41        return AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX
42      }
43      return AGENT_SDK_PREFIX
44    }
45    return DEFAULT_PREFIX
46  }
47  
48  /**
49   * Check if attribution header is enabled.
50   * Enabled by default, can be disabled via env var or GrowthBook killswitch.
51   */
52  function isAttributionHeaderEnabled(): boolean {
53    if (isEnvDefinedFalsy(process.env.CLAUDE_CODE_ATTRIBUTION_HEADER)) {
54      return false
55    }
56    return getFeatureValue_CACHED_MAY_BE_STALE('tengu_attribution_header', true)
57  }
58  
59  /**
60   * Get attribution header for API requests.
61   * Returns a header string with cc_version (including fingerprint) and cc_entrypoint.
62   * Enabled by default, can be disabled via env var or GrowthBook killswitch.
63   *
64   * When NATIVE_CLIENT_ATTESTATION is enabled, includes a `cch=00000` placeholder.
65   * Before the request is sent, Bun's native HTTP stack finds this placeholder
66   * in the request body and overwrites the zeros with a computed hash. The
67   * server verifies this token to confirm the request came from a real Claude
68   * Code client. See bun-anthropic/src/http/Attestation.zig for implementation.
69   *
70   * We use a placeholder (instead of injecting from Zig) because same-length
71   * replacement avoids Content-Length changes and buffer reallocation.
72   */
73  export function getAttributionHeader(fingerprint: string): string {
74    if (!isAttributionHeaderEnabled()) {
75      return ''
76    }
77  
78    const version = `${MACRO.VERSION}.${fingerprint}`
79    const entrypoint = process.env.CLAUDE_CODE_ENTRYPOINT ?? 'unknown'
80  
81    // cch=00000 placeholder is overwritten by Bun's HTTP stack with attestation token
82    const cch = feature('NATIVE_CLIENT_ATTESTATION') ? ' cch=00000;' : ''
83    // cc_workload: turn-scoped hint so the API can route e.g. cron-initiated
84    // requests to a lower QoS pool. Absent = interactive default. Safe re:
85    // fingerprint (computed from msg chars + version only, line 78 above) and
86    // cch attestation (placeholder overwritten in serialized body bytes after
87    // this string is built). Server _parse_cc_header tolerates unknown extra
88    // fields so old API deploys silently ignore this.
89    const workload = getWorkload()
90    const workloadPair = workload ? ` cc_workload=${workload};` : ''
91    const header = `x-anthropic-billing-header: cc_version=${version}; cc_entrypoint=${entrypoint};${cch}${workloadPair}`
92  
93    logForDebugging(`attribution header ${header}`)
94    return header
95  }