Fix duplicated Quarto markdown list text

NEWS.md

@@ -20,6 +20,8 @@
 
 ## Minor improvements and bug fixes
 
+* Fixed duplicate text in Quarto output when `fmt_markdown()` cells contain a list without preceding text (#2140).
+
 * Fixed LaTeX and RTF output for unformatted `Date` columns, which now show calendar dates instead of day counts since the Unix epoch (#2177). (@LeonidasZhak, #2180)
 
 * Rows in LaTeX output tables no longer overlap when cell text contains line breaks (#2178). (#2179)

R/quarto.R

@@ -60,12 +60,31 @@ process_md_quarto <- function(text, md_engine_fn) {
     )
 
   # Tweak start and end of non_na_text
-  non_na_text <- paste0("<span data-qmd-base64=\"", non_na_text, "\">")
+  # Use block containers when Markdown contains block-level HTML; Quarto
+  # otherwise parses lists as inline content and duplicates their text.
+  block_tags <-
+    paste0(
+      "address|article|aside|blockquote|div|dl|fieldset|figure|footer|",
+      "h[1-6]|header|hr|main|nav|ol|p|pre|section|table|ul"
+    )
+
+  block_content <-
+    grepl(
+      paste0("<(", block_tags, ")([[:space:]>])"),
+      non_na_text_processed
+    )
+
+  container_tag <- ifelse(block_content, "div", "span")
+
+  non_na_text <-
+    paste0(
+      "<", container_tag, " data-qmd-base64=\"", non_na_text, "\">"
+    )
 
   non_na_text <-
     paste0(
-      non_na_text, "<span class='gt_from_md'>",
-      non_na_text_processed, "</span></span>"
+      non_na_text, "<", container_tag, " class='gt_from_md'>",
+      non_na_text_processed, "</", container_tag, "></", container_tag, ">"
     )
 
   text[nzchar(text, keepNA = FALSE)] <- non_na_text

tests/testthat/test-fmt_markdown.R

@@ -94,6 +94,26 @@ There's a quick reference [here](https://commonmark.org/help/).
   )
 })
 
+test_that("fmt_markdown() uses block containers when rendered by Quarto", {
+  withr::local_envvar(QUARTO_BIN_PATH = "quarto")
+
+  tab <-
+    tibble::tibble(
+      text = c("- bullet point 1\n- bullet point 2", "*inline text*")
+    ) |>
+    gt() |>
+    fmt_markdown()
+
+  output <- (tab |> render_formats_test(context = "html"))[["text"]]
+
+  expect_match(output[[1]], "^<div data-qmd-base64=")
+  expect_match(output[[1]], "<div class='gt_from_md'>")
+  expect_match(output[[1]], "<li>bullet point 1</li>")
+  expect_match(output[[1]], "<li>bullet point 2</li>")
+  expect_match(output[[2]], "^<span data-qmd-base64=")
+  expect_match(output[[2]], "<span class='gt_from_md'>")
+})
+
 test_that("LaTeX formulas render correctly in HTML", {
 
   gt_tbl <-