refactor: dedup identical opus-tier rates in modelPricing EXACT_RATES (#4163)

.changelog/next/changed-issue-4163.md

@@ -0,0 +1 @@
+- Deduped the identical Claude Opus rate rows in the usage-cost table: the tier now shares one rate pair and the opus family rule derives its pointer, so an opus model bump no longer needs a second hand-edit (#4163)

server/lib/modelPricing.js

@@ -31,16 +31,32 @@
 
 export const PRICING_AS_OF = '2026-07-12';
 
+/**
+ * Every shipped Claude Opus generation bills at the same published rate, so the
+ * tier owns one [input, output] pair rather than a hand-copied literal per row.
+ * `OPUS_MODEL_IDS` is ordered NEWEST FIRST: its head is the id the `/opus/i`
+ * family rule reports for opus ids the table doesn't list, so an opus bump is a
+ * single prepend here — the family rule no longer has to be re-pointed by hand
+ * (it was, at every bump through migration 206, for zero behavioral effect).
+ */
+const OPUS_TIER_RATES = [5.0, 25.0];
+const OPUS_MODEL_IDS = [
+  'claude-opus-5',
+  'claude-opus-4-8',
+  'claude-opus-4-7',
+  'claude-opus-4-6',
+  'claude-opus-4-5',
+];
+
 /** USD per 1M tokens: [input, output]. Exact model-id matches. */
 const EXACT_RATES = {
   // Anthropic
   'claude-fable-5': [10.0, 50.0],
   'claude-mythos-5': [10.0, 50.0],
-  'claude-opus-5': [5.0, 25.0],
-  'claude-opus-4-8': [5.0, 25.0],
-  'claude-opus-4-7': [5.0, 25.0],
-  'claude-opus-4-6': [5.0, 25.0],
-  'claude-opus-4-5': [5.0, 25.0],
+  // Cloned per row so each key owns its pair exactly as the hand-written rows
+  // above and below do — sharing one array across five keys would make any
+  // future edit to one opus row silently rewrite the whole tier.
+  ...Object.fromEntries(OPUS_MODEL_IDS.map((id) => [id, [...OPUS_TIER_RATES]])),
   'claude-sonnet-5': [2.0, 10.0], // intro pricing through 2026-08-31 ($3/$15 after)
   'claude-sonnet-4-6': [3.0, 15.0],
   'claude-sonnet-4-5': [3.0, 15.0],
@@ -94,7 +110,10 @@ const EXACT_KEYS_BY_LENGTH = Object.keys(EXACT_RATES).sort((a, b) => b.length -
  */
 const FAMILY_RULES = [
   { test: /fable|mythos/i, rateModel: 'claude-fable-5' },
-  { test: /opus/i, rateModel: 'claude-opus-5' },
+  // Reports the newest listed opus id (see OPUS_MODEL_IDS) — the whole tier
+  // shares one rate pair, so the pointer only supplies the label, and deriving
+  // it means an opus bump never has to edit this line.
+  { test: /opus/i, rateModel: OPUS_MODEL_IDS[0] },
   { test: /sonnet[-.]?5/i, rateModel: 'claude-sonnet-5' },
   { test: /sonnet/i, rateModel: 'claude-sonnet-4-5' },
   { test: /haiku/i, rateModel: 'claude-haiku-4-5' },

server/lib/modelPricing.test.js

@@ -10,11 +10,68 @@ describe('resolveModelRates', () => {
   });
 
   it('resolves CLI shorthand model names via family rules', () => {
-    expect(resolveModelRates('claude-code', 'opus')).toMatchObject({ rateModel: 'claude-opus-5', matched: 'family' });
+    // Asserted by RATES, not by pointer id: the whole opus tier shares one rate
+    // pair, so which listed opus id gets reported is a bump-to-bump detail the
+    // suite should not have to be edited for. The pointer's validity is pinned
+    // by the dedicated test below.
+    expect(resolveModelRates('claude-code', 'opus')).toMatchObject({ inputPer1M: 5, outputPer1M: 25, matched: 'family' });
     expect(resolveModelRates('claude-code', 'sonnet')).toMatchObject({ rateModel: 'claude-sonnet-4-5', matched: 'family' });
     expect(resolveModelRates('claude-code', 'haiku')).toMatchObject({ rateModel: 'claude-haiku-4-5', matched: 'family' });
   });
 
+  // #4163: the opus tier is one shared rate pair, and the `/opus/i` family rule
+  // derives its pointer from the model list instead of naming an id by hand.
+  // These three pin the properties that made the hand-maintained pointer safe,
+  // so a future opus bump is a one-line prepend with no other edit anywhere.
+  describe('opus tier', () => {
+    const LISTED_OPUS_IDS = [
+      'claude-opus-5', 'claude-opus-4-8', 'claude-opus-4-7', 'claude-opus-4-6', 'claude-opus-4-5',
+    ];
+
+    it('bills every listed opus generation at the same tier rates', () => {
+      for (const id of LISTED_OPUS_IDS) {
+        expect(resolveModelRates('claude-code', id)).toMatchObject({
+          rateModel: id, inputPer1M: 5, outputPer1M: 25, matched: 'exact',
+        });
+      }
+    });
+
+    // The point of the dedup: an opus id the table has never heard of still
+    // prices at $5/$25 without anyone re-pointing a family rule at it.
+    it('prices an unlisted opus id at tier rates without a pointer bump', () => {
+      for (const id of [
+        'opus', 'claude-opus-9', 'claude-opus-6-2', 'global.anthropic.claude-opus-7-20270101-v1:0',
+      ]) {
+        expect(resolveModelRates('claude-code', id)).toMatchObject({
+          inputPer1M: 5, outputPer1M: 25, matched: 'family',
+        });
+      }
+    });
+
+    // The family rule reports a LABEL, and downstream code leans on it: the UI
+    // prints "Priced as <rateModel>", and usageReconciler compares two ids'
+    // rateModel to decide whether they are the same family. So the pointer must
+    // stay a non-null, exactly-resolvable key whose rates agree with the tier —
+    // a null or synthetic label would silently break both.
+    it('reports a family label that is itself an exact table id at the same rates', () => {
+      const viaFamily = resolveModelRates('claude-code', 'opus');
+      // Shape-matched rather than hardcoded to the current head id, so the next
+      // opus bump doesn't have to edit this suite — that per-bump edit is what
+      // the refactor removed. The exact-resolution check below is what actually
+      // pins the pointer to a real table key.
+      expect(viaFamily.rateModel).toMatch(/^claude-opus-\d/);
+      expect(resolveModelRates('claude-code', viaFamily.rateModel)).toMatchObject({
+        rateModel: viaFamily.rateModel,
+        inputPer1M: viaFamily.inputPer1M,
+        outputPer1M: viaFamily.outputPer1M,
+        matched: 'exact',
+      });
+      // …and every opus id agrees on that label, which is what lets the
+      // reconciler treat `opus` and `claude-opus-N` as one model.
+      expect(resolveModelRates('claude-code', 'claude-opus-9').rateModel).toBe(viaFamily.rateModel);
+    });
+  });
+
   it('resolves fable/mythos to the Claude 5 flagship rates', () => {
     expect(resolveModelRates('claude-code', 'claude-fable-5')).toMatchObject({ inputPer1M: 10, outputPer1M: 50 });
     expect(resolveModelRates('claude-code', 'fable')).toMatchObject({ rateModel: 'claude-fable-5', matched: 'family' });