Fix quarto preview subdir/file.qmd crashing with doubled path

[cderv]

quarto preview subdir/page.qmd in a website project crashes with readfile subdir\subdir\page.qmd — a doubled path. quarto render works fine.

Root Cause

Preview makes two render calls: renderFormats (receives the original relative path) then renderProject (normalizes to absolute). The first call creates a cached ExecutionTarget with source: "subdir/page.qmd". The second gets a cache hit with the stale relative source.

projectPath() was designed for output filenames — it resolves relative paths via join(dirname(target.source), path).

quarto-cli/src/command/render/render.ts

Lines 389 to 405 in 0f97e05

	const projectPath = (path: string) => {
	if (context.project) {
	if (isAbsolute(path)) {
	return relative(
	normalizePath(context.project.dir),
	normalizePath(path),
	);
	} else {
	return relative(
	normalizePath(context.project.dir),
	normalizePath(join(dirname(context.target.source), path)),
	);
	}
	} else {
	return path;
	}
	};

But then, context.target.source itself is passed through this function.

quarto-cli/src/command/render/render.ts

Line 414 in 0f97e05

input: projectPath(context.target.source),

When target.source was relative, dirname + join doubled the subdirectory:

join(dirname("subdir/page.qmd"), "subdir/page.qmd") → "subdir/subdir/page.qmd"

projectPath(finalOutput!) is used correctly though — output filenames like page.html do need the dirname + join resolution.

quarto-cli/src/command/render/render.ts

Line 424 in 0f97e05

: projectPath(finalOutput!),

Fix

Split projectPath into two functions with distinct responsibilities:

• projectRelativeInput(sourcePath) — for the source file path. Uses normalizePath directly, which handles both relative and absolute paths, because our normalizePath function does make path absolute if not.
• projectOutputPath(path) — for output filenames (like page.html). Preserves the existing dirname + join logic since output names are relative to the source directory.

Bisect

Last good: v1.9.17. First bad: v1.9.18 (77633b3).

Related

Follow up on preview fixes that introduced this

• Fix preview crash on re-render (BadResource error) #13967 (for issue BadResource error during preview re-render #13955)

which was a regression of broader quarto preview behavior change

• Manage projectcontext objects correctly on preview #13804

Also, in a way related to this observation we've done since new single project context is out

• Single file rendering vs Project rendering: inconsistency in input path which is relative vs absolute  #12401

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[cderv]

@cscheid tests are passing, and I think this is a change that make sense and solve the problem.

I can now run preview correct.

So if good to you, please merge and build a new prerelease.