diff --git a/src/agent.rs b/src/agent.rs
index a4a3db3..1592bd1 100644
--- a/src/agent.rs
+++ b/src/agent.rs
@@ -1625,7 +1625,7 @@ printf 'a,b\n1,2\n' > report.csv && printf 'hello box' > '/tmp/anybot-up/上傳
         }
         assert!(results[0].contains("served"), "{}", results[0]);
         assert!(results[1].contains("檔案測試"), "{}", results[1]);
-        assert!(results[2].contains("已把 /tmp/anybot-up/上傳測試.txt 放進上傳欄位"), "{}", results[2]);
+        assert!(results[2].contains("已把 /tmp/anybot-up/上傳測試.txt 放進上傳欄位，欄位裡現在是：上傳測試.txt（9 位元組）") && results[2].contains("已選：上傳測試.txt 9"), "{}", results[2]);
         assert!(results[3].contains("已選：上傳測試.txt 9"), "{}", results[3]);
         assert!(results[4].contains("這台電腦上沒有「/tmp/anybot-up/沒有這個.txt」"), "{}", results[4]);
         assert!(results[5].contains("下載好了：/home/bot/Downloads/report.csv"), "{}", results[5]);
diff --git a/src/browser.rs b/src/browser.rs
index c11221f..f6fcd98 100644
--- a/src/browser.rs
+++ b/src/browser.rs
@@ -727,10 +727,20 @@ pub fn run(name: &str, args: &Value) -> Result<(String, Option<String>), String>
                 let js = format!("(() => {{ let el = {}; if (el && el.tagName !== 'INPUT') el = el.querySelector('input[type=file]') || el.closest('label')?.querySelector('input[type=file]'); return el || document.querySelector('input[type=file]'); }})()", find_js(&rf, &text));
                 let r = tab.call("Runtime.evaluate", json!({"expression": js, "returnByValue": false}))?;
                 let obj = r["result"]["objectId"].as_str().ok_or("這一頁找不到上傳檔案的欄位")?.to_string();
+                let before = snapshot(&mut tab);
                 tab.call("DOM.setFileInputFiles", json!({"files": [full], "objectId": obj}))?;
                 tab.eval(&format!("(() => {{ const el = {js}; if (el) el.dispatchEvent(new Event('change', {{bubbles: true}})); return 1; }})()"))?;
                 settle(1000);
-                Ok((format!("已把 {full} 放進上傳欄位。"), None))
+                // What the field holds now (a page that shows nothing about it left the bot
+                // checking with five more steps), and what the page did with it.
+                let held = tab.eval(&format!("(() => {{ const el = {js}; return el && el.files ? Array.from(el.files).map(f => f.name + '（' + f.size + ' 位元組）').join('、') : ''; }})()")).ok().and_then(|v| v.as_str().map(String::from)).unwrap_or_default();
+                if held.is_empty() {
+                    return Err(format!("放了 {full}，但上傳欄位還是空的（這一頁可能要先按「上傳」之類的按鈕，或欄位不是這一個）。"));
+                }
+                let after = snapshot(&mut tab);
+                let seen = changes(&before, &after);
+                let seen = if seen.contains("沒有變化") { String::new() } else { format!("\n{seen}") };
+                Ok((format!("已把 {full} 放進上傳欄位，欄位裡現在是：{held}。{seen}"), None))
             }
             "browser_download" => {
                 // The file lands on the browser's own disk: Bot 的電腦's when it runs there.