cleanup, docs

site/doc/pages/file_fsync.txt

@@ -1,9 +1,20 @@
-file_fsync
+:sig
+bool file_fsync(u64 h)
 
-Filesystem nicety added to the wasm host membrane. Path arguments are policy-gated; operations return an empty value or false on denial/error. file_fsync() takes an open file handle and flushes it with fsync().
+:params
+h : handle from file_open() opened for writing
+return value : true if the flush succeeded
+
+:content
+Flushes a handle's buffered writes to disk, so the data survives a crash or power loss. Call it before `file_close()` when durability matters (e.g. after writing a checkpoint).
+
+:example
+u64 h = file_open("/tmp/doc-fsync.txt", "w");
+file_write(h, "durable");
+print(file_fsync(h) ? "flushed to disk" : "fsync failed", "\n");
+file_close(h);
 
 :see
 >sys
-
-:example
-print("file_fsync example\n");
+file_write
+file_close