Windows uv venv local quarto install has problems with backslashes --- patch included!

[reckoner]

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

diff --git a/share/filters/main.lua b/share/filters/main.lua
--- a/share/filters/main.lua
+++ b/share/filters/main.lua
@@ -3040,7 +3040,11 @@ function isInlineEl(el)
 end
 
 function compileTemplate(template, meta)
-  local f = io.open(pandoc.utils.stringify(template), "r")
+  template = pandoc.utils.stringify(template)
+  -- Pandoc treats the separator before `.venv` as an escape while parsing
+  -- the title-block attribute on Windows. Restore the resulting missing one.
+  template = template:gsub("([^/\\])%.venv", "%1/.venv")
+  local f = io.open(template, "r")
   if f then
     local contents = f:read("*all")
     f:close()

Steps to reproduce

You create a local uv venv .venv, then install quarto-cli using uv pip install quarto-cli and it won't work unless you use that patch.

Actual behavior

complains about lua code. The error is not informative.

Expected behavior

actually compile a document

Your environment

• windows 10, powershell 7

Quarto check output

Quarto 1.9.38
[>] Checking environment information...
      Quarto cache location: C:\Users\reckoner\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
      Pandoc version 3.8.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.4.5: OK
      Typst version 0.14.2: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.9.38
      Path: D:\data_science\.venv\Lib\site-packages\quarto_cli\bin
      CodePage: 1252
[>] Checking tools....................OK
      TinyTeX: v2026.04
      Chromium: (not installed)
      Chrome Headless Shell: (not installed)
      VeraPDF: (not installed)
[>] Checking LaTeX....................OK
      Using: TinyTex
      Path: C:\Users\reckoner\AppData\Roaming\TinyTeX\bin\windows\
      Version: 2026
[>] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe
      Source: Windows Registry
[>] Checking basic markdown render....OK
[>] Checking R installation...........(None)
      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/
[>] Checking Python 3 installation....(None)
      Unable to locate an installed version of Python 3.
      Install Python 3 from https://www.python.org/downloads/
[>] Checking Julia installation...

[mcanouil]

@reckoner Thanks for the report, but it's incomplete.
Nothing from what you shared generates an error, you implied an error when rendering something, without actually showing so nor the exact context and error itself.

Also see Troubleshooting guide to enable debug and extended stack trace.
Finally, you've stated/checked "installed the latest version of Quarto CLI", but the latest is not 1.9.38 as reported by yourself. The latest is 1.10.18.