fix(omp): avoid unsupported calculateCost import

Fix OMP installation by removing the unsupported calculateCost runtime import from pi-ai.

tests/helpers.ts

@@ -79,6 +79,7 @@ export function makeModel(overrides: Partial<ModelLike> = {}): ModelLike {
     api: "commandcode-custom",
     provider: "commandcode",
     maxTokens: 384_000,
+    cost: { input: 0.14, output: 0.28, cacheRead: 0.028, cacheWrite: 0 },
     ...overrides,
   }
 }

tests/test-cost.ts

@@ -0,0 +1,99 @@
+/**
+ * Regression test for the local cost calculation.
+ *
+ * The provider ships its own cost function because Oh My Pi's legacy pi-ai
+ * shim does not export `calculateCost` (see issue #24). This test locks the
+ * local implementation to pi-ai's upstream `calculateCost` so the two cannot
+ * drift while pi remains the reference host.
+ */
+
+import assert from "node:assert/strict"
+import { describe, it } from "node:test"
+
+import { calculateCost, type Model } from "@earendil-works/pi-ai"
+
+import { calculateCommandCodeCost } from "../src/cost.ts"
+import type { Usage } from "../src/types.ts"
+
+type CostTable = Model<"openai-completions">["cost"]
+
+const COST_FIXTURES: Record<string, CostTable> = {
+  "zero-cost-model": { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+  "claude-sonnet-4-6": { input: 3, output: 15, cacheRead: 0.3, cacheWrite: 3.75 },
+  "deepseek/deepseek-v4-pro": {
+    input: 0.435,
+    output: 0.87,
+    cacheRead: 0.003625,
+    cacheWrite: 0,
+  },
+  "Qwen/Qwen3.7-Max": { input: 1.25, output: 3.75, cacheRead: 0.25, cacheWrite: 1.56 },
+  "gpt-5.5": { input: 5, output: 30, cacheRead: 0.5, cacheWrite: 0 },
+}
+
+const USAGE_CASES = [
+  { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+  { input: 1, output: 1, cacheRead: 1, cacheWrite: 1 },
+  { input: 812, output: 187, cacheRead: 52_000, cacheWrite: 3_100 },
+  { input: 1_000_000, output: 65_536, cacheRead: 998_877, cacheWrite: 123_456 },
+  { input: 7, output: 999_999_999, cacheRead: 0.5, cacheWrite: 42 },
+]
+
+function piAiModel(id: string, cost: CostTable): Model<"openai-completions"> {
+  return {
+    id,
+    name: id,
+    api: "openai-completions",
+    provider: "commandcode",
+    baseUrl: "https://api.commandcode.ai",
+    reasoning: false,
+    input: ["text"],
+    cost,
+    contextWindow: 1_000_000,
+    maxTokens: 65_536,
+  }
+}
+
+function freshUsage(tokens: (typeof USAGE_CASES)[number]): Usage {
+  return {
+    ...tokens,
+    totalTokens: tokens.input + tokens.output + tokens.cacheRead + tokens.cacheWrite,
+    cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+  }
+}
+
+describe("calculateCommandCodeCost()", () => {
+  it("matches pi-ai calculateCost exactly for all cost fields", () => {
+    for (const [id, cost] of Object.entries(COST_FIXTURES)) {
+      const model = piAiModel(id, cost)
+
+      for (const tokens of USAGE_CASES) {
+        const ours = freshUsage(tokens)
+        const upstream = freshUsage(tokens)
+
+        calculateCommandCodeCost(model, ours)
+        calculateCost(model, upstream)
+
+        for (const key of ["input", "output", "cacheRead", "cacheWrite", "total"] as const) {
+          assert.equal(
+            ours.cost[key],
+            upstream.cost[key],
+            `${id} cost.${key} for tokens=${JSON.stringify(tokens)}`,
+          )
+        }
+      }
+    }
+  })
+
+  it("writes the total as the sum of all cost components", () => {
+    const model = piAiModel("claude-sonnet-4-6", COST_FIXTURES["claude-sonnet-4-6"])
+    const usage = freshUsage({ input: 1_000, output: 500, cacheRead: 10_000, cacheWrite: 2_000 })
+
+    calculateCommandCodeCost(model, usage)
+
+    assert.equal(
+      usage.cost.total,
+      usage.cost.input + usage.cost.output + usage.cost.cacheRead + usage.cost.cacheWrite,
+    )
+    assert.ok(usage.cost.total > 0)
+  })
+})