diff --git a/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx b/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
index a6ba797f33dd..148610cded06 100644
--- a/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
@@ -1094,7 +1094,7 @@ export function Prompt(props: PromptProps) {
               textColor={keybind.leader ? theme.textMuted : theme.text}
               focusedTextColor={keybind.leader ? theme.textMuted : theme.text}
               minHeight={1}
-              maxHeight={6}
+              maxHeight={sync.data.config.experimental?.max_prompt_input_lines ?? 6}
               onContentChange={() => {
                 const value = input.plainText
                 setStore("prompt", "input", value)
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 3a933f81e967..8742881e9c24 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -260,6 +260,9 @@ export const Info = Schema.Struct({
       mcp_timeout: Schema.optional(PositiveInt).annotate({
         description: "Timeout in milliseconds for model context protocol (MCP) requests",
       }),
+      max_prompt_input_lines: Schema.optional(Schema.Number.check(Schema.isInt()).check(Schema.isBetween(1, 99))).annotate({
+        description: "Maximum number of lines for the prompt input text box (1-99, default: 6)",
+      }),
     }),
   ),
 })
diff --git a/packages/opencode/test/tool/task.test.ts b/packages/opencode/test/tool/task.test.ts
index a8d62bb68c6f..9e4b990641a2 100644
--- a/packages/opencode/test/tool/task.test.ts
+++ b/packages/opencode/test/tool/task.test.ts
@@ -378,6 +378,7 @@ describe("tool.task", () => {
             },
           },
           experimental: {
+            max_prompt_input_lines: 6,
             primary_tools: ["bash", "read"],
           },
         },
diff --git a/packages/sdk/js/src/v2/gen/types.gen.ts b/packages/sdk/js/src/v2/gen/types.gen.ts
index 86c5a762b114..084c03d9303b 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -1236,6 +1236,10 @@ export type Config = {
     primary_tools?: Array<string>
     continue_loop_on_deny?: boolean
     mcp_timeout?: number
+    /**
+     * Maximum number of lines for the prompt input text box (1-99, default: 6)
+     */
+    max_prompt_input_lines?: number
   }
 }