more tools

packages/opencode/src/tool/util/file-times.ts

@@ -21,4 +21,18 @@ export namespace FileTimes {
   export function get(sessionID: string, file: string) {
     return state().read[sessionID]?.[file]
   }
+
+  export async function assert(sessionID: string, filepath: string) {
+    const time = get(sessionID, filepath)
+    if (!time)
+      throw new Error(
+        `You must read the file ${filepath} before overwriting it. Use the Read tool first`,
+      )
+    const stats = await Bun.file(filepath).stat()
+    if (stats.mtime.getTime() > time.getTime()) {
+      throw new Error(
+        `File ${filepath} has been modified since it was last read.\nLast modification: ${stats.mtime.toISOString()}\nLast read: ${time.toISOString()}\n\nPlease read the file again before modifying it.`,
+      )
+    }
+  }
 }