diff --git a/frontend/src/components/pilot/script/ParameterizationPreview.tsx b/frontend/src/components/pilot/script/ParameterizationPreview.tsx
index 65b7d0a2..12ede89e 100644
--- a/frontend/src/components/pilot/script/ParameterizationPreview.tsx
+++ b/frontend/src/components/pilot/script/ParameterizationPreview.tsx
@@ -80,10 +80,27 @@ function tokenize(body: string, highlightValues: Record<string, string> | undefi
     while (cursor < seg.text.length) {
       let matched: { key: string; value: string } | null = null
       for (const [key, value] of valueEntries) {
-        if (seg.text.startsWith(value, cursor)) {
-          matched = { key, value }
-          break
-        }
+        if (!seg.text.startsWith(value, cursor)) continue
+        // Word-boundary guard: a single-char value like "D" (drive letter)
+        // would otherwise light up every capital D in identifiers like
+        // `Get-ADUser`. We only require a boundary on a side of the value
+        // that itself starts/ends with a word char, so values that begin or
+        // end in punctuation (e.g. "D:\\Folder") still match cleanly.
+        const valueStartsWithWordChar = /^\w/.test(value)
+        const valueEndsWithWordChar = /\w$/.test(value)
+        const before = cursor > 0 ? seg.text[cursor - 1] : undefined
+        const after = cursor + value.length < seg.text.length
+          ? seg.text[cursor + value.length]
+          : undefined
+        const startBounded = !valueStartsWithWordChar
+          || before === undefined
+          || !/\w/.test(before)
+        const endBounded = !valueEndsWithWordChar
+          || after === undefined
+          || !/\w/.test(after)
+        if (!startBounded || !endBounded) continue
+        matched = { key, value }
+        break
       }
       if (matched) {
         flushPending()