diff --git a/scripts/hooks/cost-tracker.js b/scripts/hooks/cost-tracker.js
index fa3677e4f..e42dc97a1 100755
--- a/scripts/hooks/cost-tracker.js
+++ b/scripts/hooks/cost-tracker.js
@@ -71,11 +71,12 @@ function readHarnessCost(sessionId, maxAgeSeconds) {
 // Approximate per-1M-token billing rates (USD).
 // Cache creation: 1.25x input rate. Cache read: 0.1x input rate.
 // Current-generation list prices: Fable/Mythos 5 $10/$50, Opus 5 and
-// Opus 4.5-4.8 $5/$25, Sonnet 5/4.6 $3/$15, Haiku 4.5 $1/$5. Opus 4.0/4.1
-// and Opus 3 stay on the legacy $15/$75 tier.
+// Opus 4.5-4.8 $5/$25, Sonnet 5 $2/$10, Sonnet 4.6 $3/$15, and Haiku 4.5
+// $1/$5. Opus 4.0/4.1 and Opus 3 stay on the legacy $15/$75 tier.
 const RATE_TABLE = {
   haiku:      { in: 1.00,  out: 5.0,  cacheWrite: 1.25,  cacheRead: 0.10 },
   sonnet:     { in: 3.00,  out: 15.0, cacheWrite: 3.75,  cacheRead: 0.30 },
+  sonnet5:    { in: 2.00,  out: 10.0, cacheWrite: 2.50,  cacheRead: 0.20 },
   opus:       { in: 5.00,  out: 25.0, cacheWrite: 6.25,  cacheRead: 0.50 },
   opusLegacy: { in: 15.00, out: 75.0, cacheWrite: 18.75, cacheRead: 1.50 },
   fable:      { in: 10.00, out: 50.0, cacheWrite: 12.50, cacheRead: 1.00 }
@@ -85,11 +86,16 @@ function getRates(model) {
   const m = String(model || '').toLowerCase();
   if (m.includes('fable') || m.includes('mythos')) return RATE_TABLE.fable;
   if (m.includes('haiku')) return RATE_TABLE.haiku;
+  if (isSonnet5(m)) return RATE_TABLE.sonnet5;
   if (m.includes('opus-4-1') || m.includes('opus-4-0') || m.includes('3-opus')) return RATE_TABLE.opusLegacy;
   if (m.includes('opus'))  return RATE_TABLE.opus;
   return RATE_TABLE.sonnet;
 }
 
+function isSonnet5(model) {
+  return /(?:^|[^a-z0-9])sonnet-5(?:[^a-z0-9]|$)/.test(model);
+}
+
 function toNumber(v) {
   const n = Number(v);
   return Number.isFinite(n) ? n : 0;