init

constants/system.ts

@@ -0,0 +1,95 @@
+// Critical system constants extracted to break circular dependencies
+
+import { feature } from 'bun:bundle'
+import { getFeatureValue_CACHED_MAY_BE_STALE } from '../services/analytics/growthbook.js'
+import { logForDebugging } from '../utils/debug.js'
+import { isEnvDefinedFalsy } from '../utils/envUtils.js'
+import { getAPIProvider } from '../utils/model/providers.js'
+import { getWorkload } from '../utils/workloadContext.js'
+
+const DEFAULT_PREFIX = `You are Claude Code, Anthropic's official CLI for Claude.`
+const AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX = `You are Claude Code, Anthropic's official CLI for Claude, running within the Claude Agent SDK.`
+const AGENT_SDK_PREFIX = `You are a Claude agent, built on Anthropic's Claude Agent SDK.`
+
+const CLI_SYSPROMPT_PREFIX_VALUES = [
+  DEFAULT_PREFIX,
+  AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX,
+  AGENT_SDK_PREFIX,
+] as const
+
+export type CLISyspromptPrefix = (typeof CLI_SYSPROMPT_PREFIX_VALUES)[number]
+
+/**
+ * All possible CLI sysprompt prefix values, used by splitSysPromptPrefix
+ * to identify prefix blocks by content rather than position.
+ */
+export const CLI_SYSPROMPT_PREFIXES: ReadonlySet<string> = new Set(
+  CLI_SYSPROMPT_PREFIX_VALUES,
+)
+
+export function getCLISyspromptPrefix(options?: {
+  isNonInteractive: boolean
+  hasAppendSystemPrompt: boolean
+}): CLISyspromptPrefix {
+  const apiProvider = getAPIProvider()
+  if (apiProvider === 'vertex') {
+    return DEFAULT_PREFIX
+  }
+
+  if (options?.isNonInteractive) {
+    if (options.hasAppendSystemPrompt) {
+      return AGENT_SDK_CLAUDE_CODE_PRESET_PREFIX
+    }
+    return AGENT_SDK_PREFIX
+  }
+  return DEFAULT_PREFIX
+}
+
+/**
+ * Check if attribution header is enabled.
+ * Enabled by default, can be disabled via env var or GrowthBook killswitch.
+ */
+function isAttributionHeaderEnabled(): boolean {
+  if (isEnvDefinedFalsy(process.env.CLAUDE_CODE_ATTRIBUTION_HEADER)) {
+    return false
+  }
+  return getFeatureValue_CACHED_MAY_BE_STALE('tengu_attribution_header', true)
+}
+
+/**
+ * Get attribution header for API requests.
+ * Returns a header string with cc_version (including fingerprint) and cc_entrypoint.
+ * Enabled by default, can be disabled via env var or GrowthBook killswitch.
+ *
+ * When NATIVE_CLIENT_ATTESTATION is enabled, includes a `cch=00000` placeholder.
+ * Before the request is sent, Bun's native HTTP stack finds this placeholder
+ * in the request body and overwrites the zeros with a computed hash. The
+ * server verifies this token to confirm the request came from a real Claude
+ * Code client. See bun-anthropic/src/http/Attestation.zig for implementation.
+ *
+ * We use a placeholder (instead of injecting from Zig) because same-length
+ * replacement avoids Content-Length changes and buffer reallocation.
+ */
+export function getAttributionHeader(fingerprint: string): string {
+  if (!isAttributionHeaderEnabled()) {
+    return ''
+  }
+
+  const version = `${MACRO.VERSION}.${fingerprint}`
+  const entrypoint = process.env.CLAUDE_CODE_ENTRYPOINT ?? 'unknown'
+
+  // cch=00000 placeholder is overwritten by Bun's HTTP stack with attestation token
+  const cch = feature('NATIVE_CLIENT_ATTESTATION') ? ' cch=00000;' : ''
+  // cc_workload: turn-scoped hint so the API can route e.g. cron-initiated
+  // requests to a lower QoS pool. Absent = interactive default. Safe re:
+  // fingerprint (computed from msg chars + version only, line 78 above) and
+  // cch attestation (placeholder overwritten in serialized body bytes after
+  // this string is built). Server _parse_cc_header tolerates unknown extra
+  // fields so old API deploys silently ignore this.
+  const workload = getWorkload()
+  const workloadPair = workload ? ` cc_workload=${workload};` : ''
+  const header = `x-anthropic-billing-header: cc_version=${version}; cc_entrypoint=${entrypoint};${cch}${workloadPair}`
+
+  logForDebugging(`attribution header ${header}`)
+  return header
+}