init claude-code

utils/tokenBudget.ts

@@ -0,0 +1,73 @@
+// Shorthand (+500k) anchored to start/end to avoid false positives in natural language.
+// Verbose (use/spend 2M tokens) matches anywhere.
+const SHORTHAND_START_RE = /^\s*\+(\d+(?:\.\d+)?)\s*(k|m|b)\b/i
+// Lookbehind (?<=\s) is avoided — it defeats YARR JIT in JSC, and the
+// interpreter scans O(n) even with the $ anchor. Capture the whitespace
+// instead; callers offset match.index by 1 where position matters.
+const SHORTHAND_END_RE = /\s\+(\d+(?:\.\d+)?)\s*(k|m|b)\s*[.!?]?\s*$/i
+const VERBOSE_RE = /\b(?:use|spend)\s+(\d+(?:\.\d+)?)\s*(k|m|b)\s*tokens?\b/i
+const VERBOSE_RE_G = new RegExp(VERBOSE_RE.source, 'gi')
+
+const MULTIPLIERS: Record<string, number> = {
+  k: 1_000,
+  m: 1_000_000,
+  b: 1_000_000_000,
+}
+
+function parseBudgetMatch(value: string, suffix: string): number {
+  return parseFloat(value) * MULTIPLIERS[suffix.toLowerCase()]!
+}
+
+export function parseTokenBudget(text: string): number | null {
+  const startMatch = text.match(SHORTHAND_START_RE)
+  if (startMatch) return parseBudgetMatch(startMatch[1]!, startMatch[2]!)
+  const endMatch = text.match(SHORTHAND_END_RE)
+  if (endMatch) return parseBudgetMatch(endMatch[1]!, endMatch[2]!)
+  const verboseMatch = text.match(VERBOSE_RE)
+  if (verboseMatch) return parseBudgetMatch(verboseMatch[1]!, verboseMatch[2]!)
+  return null
+}
+
+export function findTokenBudgetPositions(
+  text: string,
+): Array<{ start: number; end: number }> {
+  const positions: Array<{ start: number; end: number }> = []
+  const startMatch = text.match(SHORTHAND_START_RE)
+  if (startMatch) {
+    const offset =
+      startMatch.index! +
+      startMatch[0].length -
+      startMatch[0].trimStart().length
+    positions.push({
+      start: offset,
+      end: startMatch.index! + startMatch[0].length,
+    })
+  }
+  const endMatch = text.match(SHORTHAND_END_RE)
+  if (endMatch) {
+    // Avoid double-counting when input is just "+500k"
+    const endStart = endMatch.index! + 1 // +1: regex includes leading \s
+    const alreadyCovered = positions.some(
+      p => endStart >= p.start && endStart < p.end,
+    )
+    if (!alreadyCovered) {
+      positions.push({
+        start: endStart,
+        end: endMatch.index! + endMatch[0].length,
+      })
+    }
+  }
+  for (const match of text.matchAll(VERBOSE_RE_G)) {
+    positions.push({ start: match.index, end: match.index + match[0].length })
+  }
+  return positions
+}
+
+export function getBudgetContinuationMessage(
+  pct: number,
+  turnTokens: number,
+  budget: number,
+): string {
+  const fmt = (n: number): string => new Intl.NumberFormat('en-US').format(n)
+  return `Stopped at ${pct}% of token target (${fmt(turnTokens)} / ${fmt(budget)}). Keep working \u2014 do not summarize.`
+}