fix(provider): apply config model cost overrides at runtime

packages/opencode/src/provider/provider.ts

@@ -1083,6 +1083,7 @@ export namespace Provider {
       const configProvider = config.provider?.[providerID]
 
       for (const [modelID, model] of Object.entries(provider.models)) {
+        const configModel = configProvider?.models?.[modelID]
         model.api.id = model.api.id ?? model.id ?? modelID
         if (
           modelID === "gpt-5-chat-latest" ||
@@ -1099,8 +1100,31 @@ export namespace Provider {
 
         model.variants = mapValues(ProviderTransform.variants(model), (v) => v)
 
+        if (configModel?.cost) {
+          model.cost = {
+            ...model.cost,
+            input: configModel.cost.input ?? model.cost.input,
+            output: configModel.cost.output ?? model.cost.output,
+            cache: {
+              read: configModel.cost.cache_read ?? model.cost.cache.read,
+              write: configModel.cost.cache_write ?? model.cost.cache.write,
+            },
+            experimentalOver200K: configModel.cost.context_over_200k
+              ? {
+                  input: configModel.cost.context_over_200k.input,
+                  output: configModel.cost.context_over_200k.output,
+                  cache: {
+                    read: configModel.cost.context_over_200k.cache_read ?? model.cost.experimentalOver200K?.cache.read ?? 0,
+                    write:
+                      configModel.cost.context_over_200k.cache_write ?? model.cost.experimentalOver200K?.cache.write ?? 0,
+                  },
+                }
+              : model.cost.experimentalOver200K,
+          }
+        }
+
         // Filter out disabled variants from config
-        const configVariants = configProvider?.models?.[modelID]?.variants
+        const configVariants = configModel?.variants
         if (configVariants && model.variants) {
           const merged = mergeDeep(model.variants, configVariants)
           model.variants = mapValues(

packages/opencode/test/provider/provider.test.ts

@@ -1213,6 +1213,65 @@ test("model cost overrides existing cost values", async () => {
   })
 })
 
+test("OPENCODE_CONFIG_CONTENT overrides cost for configured model", async () => {
+  const overrideCost = {
+    input: 9.876543,
+    output: 21.234567,
+    cache_read: 3.210987,
+    cache_write: 4.109876,
+  }
+
+  const original = process.env["OPENCODE_CONFIG_CONTENT"]
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+        }),
+      )
+    },
+  })
+
+  try {
+    process.env["OPENCODE_CONFIG_CONTENT"] = JSON.stringify({
+      $schema: "https://opencode.ai/config.json",
+      provider: {
+        "fictional-provider": {
+          npm: "@ai-sdk/openai-compatible",
+          env: [],
+          models: {
+            "fictional-model": {
+              cost: overrideCost,
+            },
+          },
+          options: {
+            apiKey: "test-api-key",
+          },
+        },
+      },
+    })
+
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        const providers = await Provider.list()
+        const model = providers["fictional-provider"].models["fictional-model"]
+        expect(model.cost.input).toBe(overrideCost.input)
+        expect(model.cost.output).toBe(overrideCost.output)
+        expect(model.cost.cache.read).toBe(overrideCost.cache_read)
+        expect(model.cost.cache.write).toBe(overrideCost.cache_write)
+      },
+    })
+  } finally {
+    if (original !== undefined) {
+      process.env["OPENCODE_CONFIG_CONTENT"] = original
+    } else {
+      delete process.env["OPENCODE_CONFIG_CONTENT"]
+    }
+  }
+})
+
 test("completely new provider not in database can be configured", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {