diff --git a/sidecars/reddit-post/README.md b/sidecars/reddit-post/README.md
index 04a2663..f2a6190 100644
--- a/sidecars/reddit-post/README.md
+++ b/sidecars/reddit-post/README.md
@@ -19,3 +19,19 @@ failure:
 
     {"success": true, "url": "https://www.reddit.com/r/test/comments/.../"}
     {"success": false, "error": "Login did not complete — possible CAPTCHA or 2FA prompt"}
+
+## Notes
+
+- On a failed run, Playwright retains a screenshot and trace under
+  `test-results/` for debugging (`npx playwright show-trace test-results/.../trace.zip`).
+  These are gitignored and not committed, but they persist on disk and may
+  contain the username you passed in (the password field is masked in the
+  browser, so its value isn't captured). Clear `test-results/` if you want
+  to remove them.
+- The post-composer selectors (text-post tab, title/body fields, submit
+  button) are marked `UNVERIFIED` in `tests/reddit-post.spec.js` — they've
+  only been confirmed as far as this sidecar's original development
+  environment could reach live Reddit before being network-blocked. If a
+  real run on your own network fails after a successful login, start by
+  checking those selectors with:
+  `npx playwright codegen https://www.reddit.com/r/test/submit`
diff --git a/sidecars/reddit-post/run.sh b/sidecars/reddit-post/run.sh
index aebc038..974970f 100755
--- a/sidecars/reddit-post/run.sh
+++ b/sidecars/reddit-post/run.sh
@@ -20,7 +20,8 @@ for arg in "$@"; do
     --body=*) BODY="${arg#*=}" ;;
     --headed) HEADLESS_FLAG="false" ;;
     *)
-      echo "{\"success\": false, \"error\": \"Unknown argument: $arg\"}"
+      UNKNOWN_FLAG="${arg%%=*}"
+      echo "{\"success\": false, \"error\": \"Unknown argument: $UNKNOWN_FLAG\"}"
       exit 1
       ;;
   esac