diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 6b4242a225a..681cbed7196 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -937,6 +937,7 @@ export namespace Config {
         .record(
           z.string(),
           ModelsDev.Model.partial().extend({
+            limit: ModelsDev.Model.shape.limit.partial().optional(),
             variants: z
               .record(
                 z.string(),
diff --git a/packages/opencode/src/provider/provider.ts b/packages/opencode/src/provider/provider.ts
index b4836ae047d..473b1d08bb8 100644
--- a/packages/opencode/src/provider/provider.ts
+++ b/packages/opencode/src/provider/provider.ts
@@ -895,6 +895,7 @@ export namespace Provider {
           options: mergeDeep(existingModel?.options ?? {}, model.options ?? {}),
           limit: {
             context: model.limit?.context ?? existingModel?.limit?.context ?? 0,
+            input: model.limit?.input ?? existingModel?.limit?.input,
             output: model.limit?.output ?? existingModel?.limit?.output ?? 0,
           },
           headers: mergeDeep(existingModel?.headers ?? {}, model.headers ?? {}),
diff --git a/packages/opencode/test/provider/provider.test.ts b/packages/opencode/test/provider/provider.test.ts
index 11c943db6f8..a84dd7d10ed 100644
--- a/packages/opencode/test/provider/provider.test.ts
+++ b/packages/opencode/test/provider/provider.test.ts
@@ -750,6 +750,85 @@ test("model inherits properties from existing database model", async () => {
   })
 })
 
+test("existing model supports partial limit.input override", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+          provider: {
+            anthropic: {
+              models: {
+                "claude-sonnet-4-20250514": {
+                  limit: {
+                    input: 123456,
+                  },
+                },
+              },
+            },
+          },
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    init: async () => {
+      Env.set("ANTHROPIC_API_KEY", "test-api-key")
+    },
+    fn: async () => {
+      const providers = await Provider.list()
+      const model = providers["anthropic"].models["claude-sonnet-4-20250514"]
+      expect(model.limit.input).toBe(123456)
+      expect(model.limit.context).toBeGreaterThan(0)
+      expect(model.limit.output).toBeGreaterThan(0)
+    },
+  })
+})
+
+test("custom model preserves configured limit.input", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Bun.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+          provider: {
+            "custom-input-limit": {
+              name: "Custom Input Limit",
+              npm: "@ai-sdk/openai-compatible",
+              env: [],
+              models: {
+                model: {
+                  name: "Model",
+                  tool_call: true,
+                  limit: {
+                    context: 128000,
+                    input: 64000,
+                    output: 4096,
+                  },
+                },
+              },
+              options: { apiKey: "test" },
+            },
+          },
+        }),
+      )
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    fn: async () => {
+      const providers = await Provider.list()
+      const model = providers["custom-input-limit"].models["model"]
+      expect(model.limit.context).toBe(128000)
+      expect(model.limit.input).toBe(64000)
+      expect(model.limit.output).toBe(4096)
+    },
+  })
+})
+
 test("disabled_providers prevents loading even with env var", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {