test(pricing): verify MODEL_COSTS entries and promotional notes

Add tests/test-pricing.ts to assert that known models have non-zero
pricing, promotional deals are documented in comments, and Claude models
include cache pricing. Fix test-pi-local to match against combined
stdout+stderr since pi may output model listing to either stream.

tests/test-pricing.ts

@@ -0,0 +1,96 @@
+import assert from "node:assert/strict"
+import { describe, it } from "node:test"
+
+// MODEL_COSTS is a module-level const in index.ts. We verify the pricing
+// overlay by importing the map through a dedicated re-export so tests don't
+// need to spin up the full extension.
+//
+// To keep the test self-contained without importing the full extension (which
+// requires ExtensionAPI), we read the source and extract the constant at
+// runtime. A cleaner approach would be a dedicated src/pricing.ts module,
+// but for now we verify the known cost entries directly.
+
+import { readFileSync } from "node:fs"
+import { resolve, dirname } from "node:path"
+import { fileURLToPath } from "node:url"
+
+const __dirname = dirname(fileURLToPath(import.meta.url))
+const indexSource = readFileSync(resolve(__dirname, "..", "index.ts"), "utf-8")
+
+// Extract MODEL_COSTS object from index.ts source using a simple parse.
+// The map is written as a Record<string, {input:number,output:number,...}>
+// so we eval it in a sandboxed context.
+const match = indexSource.match(
+  /const MODEL_COSTS:\s*Record<string,\s*CommandCodeModelCost>\s*=\s*\{([\s\S]*?)\n\}/,
+)
+assert.ok(match, "MODEL_COSTS constant should exist in index.ts")
+
+// Parse the cost entries from the extracted block.
+const costBlock = match[1]
+const entries: Record<string, { input: number; output: number }> = {}
+for (const line of costBlock.split("\n")) {
+  const trimmed = line.trim()
+  if (!trimmed || trimmed.startsWith("//")) continue
+  const entryMatch = trimmed.match(
+    /^"([^"]+)":\s*\{\s*input:\s*([\d.]+),\s*output:\s*([\d.]+)/,
+  )
+  if (entryMatch) {
+    entries[entryMatch[1]] = {
+      input: Number(entryMatch[2]),
+      output: Number(entryMatch[3]),
+    }
+  }
+}
+
+describe("MODEL_COSTS pricing overlay", () => {
+  it("covers known Command Code models with non-zero pricing", () => {
+    const knownModels = [
+      "deepseek/deepseek-v4-flash",
+      "deepseek/deepseek-v4-pro",
+      "claude-sonnet-4-6",
+      "claude-opus-4-7",
+      "Qwen/Qwen3.7-Max",
+      "gpt-5.5",
+      "stepfun/Step-3.5-Flash",
+    ]
+
+    for (const id of knownModels) {
+      const cost = entries[id]
+      assert.ok(cost, `MODEL_COSTS should include "${id}"`)
+      assert.ok(cost.input > 0, `"${id}" input cost should be > 0`)
+      assert.ok(cost.output > 0, `"${id}" output cost should be > 0`)
+    }
+  })
+
+  it("includes promotional pricing notes in comments", () => {
+    // The DeepSeek V4 Pro 4× deal and Qwen 3.7 Max 2× deal should be
+    // documented in the source comments.
+    assert.ok(
+      costBlock.includes("4× usage deal") || costBlock.includes("75% off"),
+      "DeepSeek V4 Pro promotional pricing should be documented",
+    )
+    assert.ok(
+      costBlock.includes("2× usage deal") || costBlock.includes("50% off"),
+      "Qwen 3.7 Max promotional pricing should be documented",
+    )
+  })
+
+  it("has cache pricing for models that support it", () => {
+    // Claude models should have non-zero cacheRead and cacheWrite costs.
+    const claudeModels = ["claude-sonnet-4-6", "claude-opus-4-7"]
+    for (const id of claudeModels) {
+      const fullEntryMatch = costBlock.match(
+        new RegExp(`"${id.replace(/\//g, "\\\\")}":\\s*\\{[^}]+cacheRead:\\s*([\\d.]+)[^}]+cacheWrite:\\s*([\\d.]+)`),
+      )
+      assert.ok(fullEntryMatch, `"${id}" should have cacheRead and cacheWrite fields`)
+      assert.ok(
+        Number(fullEntryMatch[1]) > 0,
+        `"${id}" cacheRead should be > 0`,
+      )
+      assert.ok(
+        Number(fullEntryMatch[2]) > 0,
+        `"${id}" cacheWrite should be > 0`,
+      )
+    }
+  })
+})