Positron: Render on Save button applies at project level

Bug description

Checking the "Render on Save" checkbox applies it to all documents in a project. That is, checking the box in one open file, checks it for any other files in the project.

It may be this is the desired behavior (i.e. it is equivalent to checking the setting Quarto > Render: Render on Save), however, it is not the default behavior in RStudio. In RStudio the checkbox with the same name behaves more like setting render-on-save in the document header:

---
editor:
  render-on-save: true
---

If the current behavior is indeed the desired behavior, this needs to be clarified in the docs on quarto.org, which I am happy to do.

Steps to reproduce

Create test-project

quarto create project default test-project test-project

In test-project/

touch other.qmd

Check box for "Render on Save" in other.qmd.

Actual behavior

Box for "Render on Save" is also now checked in test-project.qmd.

Expected behavior

Based on RStudio behavior, Box for "Render on Save" in test-project.qmd should remain unchecked.

Your environment

• Positron Version: 2025.06.0 (Universal) build 145
• Quarto extension 1.122.0

Start by reproducing the behavior in the generated test-project with test-project.qmd and other.qmd, following the listed Positron and Quarto extension versions. Trace how the Render on Save checkbox is stored and determine whether it should remain document-specific like the expected behavior; if project-level behavior is intentional, the docs need clarification instead.