Remove orphaned Lua filter entry points (quarto-pre.lua, crossref-standalone.lua)

[cderv]

@cscheid does it seems ok to remove to you ? I believe so

🤖 analysis ⬇️

Description

Removes two standalone pandoc --lua-filter entry points that are dead code — nothing in the codebase invokes them, and one can no longer even load. Removing them prevents a future maintainer from resurrecting a broken entry point.

src/resources/filters/quarto-pre/quarto-pre.lua

• The pre/post filter passes were consolidated into the custom-AST main.lua pipeline in PR Feature: custom AST nodes #3694 "Feature: custom AST nodes" (commit 56888bb9, 2022-12-19). That commit removed the filters.ts invocations of both quarto-pre/quarto-pre.lua and quarto-post/quarto-post.lua, and deleted quarto-post/quarto-post.lua from disk — but left quarto-pre.lua behind. (quarto-post.lua had first been removed as unused in 2020, commit b58522fc, then briefly reintroduced.)
• Zero references outside itself since then.
• Additionally non-loadable: line 51 does import("code.lua"), but src/resources/filters/quarto-pre/code.lua has never existed at that path. Later mechanical Lua refactors edited the file without noticing the dangling import — because nothing ever executes it.

src/resources/filters/crossref/crossref-standalone.lua

• Created in commit 80548e60 "recreate quarto-init and crossref for IDE support" (2023-01-02) but never wired up: the string crossref-standalone appears in no other file in the entire history. IDE crossref support uses crossref/crossref.lua (src/command/editor-support/crossref.ts), not this file.

Verification

• Confirmed zero references to either basename across all files at HEAD (.ts, .lua, build configs, workspace files).
• Built the dev bundle and confirmed removal breaks nothing: quarto render to html/typst and quarto editor-support crossref all succeed unchanged.

Checklist

I have (if applicable):

• referenced the GitHub issue this PR closes
• updated the appropriate changelog in the PR — n/a (internal dead-code removal, not user-facing)
• ensured the present test suite passes — smoke-verified render + editor-support paths against a built bundle
• added new tests — n/a (pure deletion of unreferenced code)
• created a separate documentation PR

AI-assisted PR

• AI tool used: Claude Code
• Codebase grounding: local clone; full git history analysis; built dev bundle for runtime verification
• Human review: I have reviewed, tested, and verified the AI-generated content before submitting.

[posit-snyk-bot]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues

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[cscheid]

I think they're not ok to remove. Have Claude check quarto-dev/quarto for standalone filter usage from the visual editor and extensions.

[cderv]

I think they're not ok to remove. Have Claude check quarto-dev/quarto for standalone filter usage from the visual editor and extensions.

Oh cross project usage !! Tricky - I'll definitely add a note somewhere in the file that this could happen and it would avoid future claude to tell me it could deleted them 😅 I was glad to verify this - I'll check and report.

[cscheid]

Yeah, I've made that mistake before too :)

We have cross-project dependencies on quarto-dev/quarto and rstudio/rstudio (though I think not applicable in this particular case). It would be great to coordinate and write those down.

[cderv]

So I had 🤖 checked the cross-project usage, and it turns out the two files are safe to remove.

The standalone-filter concern is real, but it points at crossref.lua, not the files this PR removes. The visual editor and RStudio both run our crossref filter standalone (a bare pandoc --defaults/--lua-filter pass, outside quarto render) to build the xref autocomplete index. They load:

• filters/quarto-init/quarto-init.lua
• filters/crossref/crossref.lua
• filters/qmd-reader.lua

Consumers:

• Visual editor (quarto-dev/quarto): packages/editor-server/src/core/xref.ts (indexSourceFile)
• RStudio (rstudio/rstudio): src/cpp/session/modules/quarto/SessionQuartoXRefs.cpp

Neither references crossref-standalone.lua or quarto-pre.lua (nor does any renamed/vendored copy — checked a GitHub-wide code search too).

The decisive check: what actually ships. package/src/common/prepare-dist.ts doesn't ship src/resources/filters/ verbatim — it wipes share/filters and rebuilds it via inlineFilters() from a fixed list (main, pagebreak, quarto-init, crossref, customwriter, qmd-reader, llms, leveloneanalysis) + modules/, inlining each -- [import]. So:

• The three consumer-referenced filters are all in that list → present in every installed Quarto. ✅
• crossref-standalone.lua and quarto-pre.lua are not in the list and nothing else copies them → never shipped in any release. No external consumer could have loaded them from the share path.
• The installed crossref/crossref.lua is itself the fully-inlined standalone bundle — the build auto-generates the standalone crossref filter, which is why the hand-written crossref-standalone.lua was a redundant orphan.

Writing it down: added on this branch —

• .claude/rules/filters/cross-project-consumers.md — path-scoped, surfaces automatically on any edit under src/resources/filters/** or the packaging inline list, with a removal checklist.
• dev-docs/cross-project-dependencies.md — the broader list of quarto-dev/quarto + rstudio/rstudio touch-points on quarto-cli.

So future 🤖 gets warned before assuming a filter is dead.

[cscheid]

This is great!