off by one errors are fun!

components/form.js

@@ -155,23 +155,23 @@ export function MarkdownInput ({ label, topLevel, groupClassName, onChange, setH
                       setHasImgLink(mdHas(e.target.value, ['link', 'image']))
                     }
                     // check for at-mention editing
-                    const { value } = e.target
+                    const { value, selectionStart } = e.target
                     let priorSpace = -1
-                    for (let i = e.target.selectionStart; i >= 0; i--) {
+                    for (let i = selectionStart - 1; i >= 0; i--) {
                       if ([' ', '\n'].includes(value[i])) {
                         priorSpace = i
                         break
                       }
                     }
                     let nextSpace = value.length
-                    for (let i = e.target.selectionStart; i <= value.length; i++) {
+                    for (let i = selectionStart; i <= value.length; i++) {
                       if ([' ', '\n'].includes(value[i])) {
                         nextSpace = i
                         break
                       }
                     }
                     const currentSequence = value.substring(priorSpace + 1, nextSpace)
-                    console.log({ currentSequence })
+                    // console.log({ value, selectionStart, priorSpace, nextSpace, currentSequence })
 
                     // currently typing an at-mention, let's query for matching users
                     setAtMentionQuery(currentSequence)