Support for using font not system installed

[attakei]

For #20

Summary by CodeRabbit

• New Features

  • Added a --font-paths option to specify directories containing custom fonts when generating PDFs.
  • Custom font paths can also be provided through the TYPST_FONT_PATHS environment variable.
  • Font paths from command-line settings and the environment are combined when both are provided.

• Documentation

  • Documented the new option, accepted format, default value, and usage for PDF font support.

• Tests

  • Added coverage for default, command-line, environment-based, and combined font path configurations.

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📝 Walkthrough

Walkthrough

Adds a --font-paths PDF writer option and documents it. Writer.translate() combines configured paths with paths from TYPST_FONT_PATHS, split using the platform path separator, then passes them to typst.compile. Tests cover default, configured, environment-only, and combined font path resolution.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related issues

• Issue 21 — This change implements custom font support through TYPST_FONT_PATHS and Typst compilation font paths.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title matches the main change of allowing custom font paths for fonts not installed on the system.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 2

🧹 Nitpick comments (1)

src/rst2typst/pdf.py (1)

50-51: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Ignore empty environment variable values.

If TYPST_FONT_PATHS is defined but empty (e.g., TYPST_FONT_PATHS=""), split(os.pathsep) will return [""], passing an empty string as a font path to Typst. Using os.environ.get(...) prevents this.

♻️ Proposed refactor

-        if "TYPST_FONT_PATHS" in os.environ:
-            font_paths += os.environ["TYPST_FONT_PATHS"].split(os.pathsep)
+        if env_paths := os.environ.get("TYPST_FONT_PATHS"):
+            font_paths += env_paths.split(os.pathsep)

(Note: If you need to support Python 3.7 or earlier where the walrus operator is not available, you can assign it first and then check if it's truthy).

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/rst2typst/pdf.py` around lines 50 - 51, Update the TYPST_FONT_PATHS
handling to retrieve the environment value and only split and append its entries
when the value is non-empty, ensuring an empty variable does not add an empty
font path.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/cli.rst`:
- Around line 77-85: Refine the prose in the --font-paths documentation for
grammatical correctness and readability, including the description of custom
font directories and the explanation of when to provide a folder path. Preserve
the option name, type, default value, and intended behavior.

In `@src/rst2typst/pdf.py`:
- Around line 29-37: Update the --font-paths argument definition to parse
multiple paths as a list instead of storing one raw string, using the existing
downstream font_paths handling with an append action or equivalent
comma-separated-list validation. Preserve the default empty-list behavior.

---

Nitpick comments:
In `@src/rst2typst/pdf.py`:
- Around line 50-51: Update the TYPST_FONT_PATHS handling to retrieve the
environment value and only split and append its entries when the value is
non-empty, ensuring an empty variable does not add an empty font path.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

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Configuration used: Organization UI

Review profile: CHILL

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Run ID: a8f98dc1-c301-4e7d-9641-132315b2e050

📥 Commits

Reviewing files that changed from the base of the PR and between 029023e and b4e7201.

📒 Files selected for processing (3)

• docs/cli.rst
• src/rst2typst/pdf.py
• tests/test_pdf.py