add build script for static site generation

Integrates preprocessor, Jinja2 templates, CSS, and JS into a complete
build pipeline that reads markdown lecture notes and produces a static
site in _site/. Includes integration tests and adds _site/ to .gitignore.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: TrevorAustin

.gitignore

@@ -2,4 +2,5 @@
 apikey.js
 *.pyc
 */__pycache__/*
-.worktrees/
+.worktrees/
+_site/

build.py

@@ -0,0 +1,100 @@
+import glob
+import os
+import re
+import shutil
+from pathlib import Path
+
+from jinja2 import Environment, FileSystemLoader
+import markdown
+
+from preprocessor import split_slides, process_slide, rewrite_image_paths
+
+
+def build_site(output_dir: str = "_site"):
+    """Build the entire static site."""
+    root = Path(__file__).parent
+    out = Path(output_dir)
+
+    # Clean output
+    if out.exists():
+        shutil.rmtree(out)
+    out.mkdir(parents=True)
+
+    # Set up Jinja2 — autoescape=False since templates use {{ content }}
+    # with pre-rendered HTML and this is a static site generator, not a web app
+    env = Environment(loader=FileSystemLoader(root / "templates"), autoescape=False)
+
+    # Copy static assets
+    shutil.copytree(root / "static" / "css", out / "css")
+    shutil.copytree(root / "static" / "js", out / "js")
+    shutil.copytree(root / "examples", out / "examples")
+    shutil.copytree(root / "lecture_notes" / "images", out / "lecture_notes" / "images")
+
+    # Find week files (exclude _old files)
+    week_files = sorted(glob.glob(str(root / "lecture_notes" / "week_*.md")))
+    week_files = [f for f in week_files if "_old" not in f]
+
+    weeks = []
+
+    for week_file in week_files:
+        week_num = int(re.search(r"week_(\d+)", week_file).group(1))
+        weeks.append(week_num)
+
+        md_content = Path(week_file).read_text()
+        slide_strings = split_slides(md_content)
+
+        total_slides = len(slide_strings)
+        week_dir = out / "lecture_notes" / f"week_{week_num}"
+
+        for i, slide_md in enumerate(slide_strings, 1):
+            html_content, classes = process_slide(slide_md)
+            html_content = rewrite_image_paths(html_content)
+
+            prev_url = f"/lecture_notes/week_{week_num}/{i - 1}/" if i > 1 else ""
+            next_url = f"/lecture_notes/week_{week_num}/{i + 1}/" if i < total_slides else ""
+            first_url = f"/lecture_notes/week_{week_num}/1/"
+
+            slide_html = env.get_template("slide.html").render(
+                content=html_content,
+                classes=classes,
+                week=week_num,
+                slide_num=i,
+                total_slides=total_slides,
+                prev_url=prev_url,
+                next_url=next_url,
+                first_url=first_url,
+            )
+
+            slide_dir = week_dir / str(i)
+            slide_dir.mkdir(parents=True, exist_ok=True)
+            (slide_dir / "index.html").write_text(slide_html)
+
+    # Lecture notes index
+    lecture_index_html = env.get_template("lecture_index.html").render(weeks=weeks)
+    lectures_dir = out / "lecture_notes"
+    lectures_dir.mkdir(parents=True, exist_ok=True)
+    (lectures_dir / "index.html").write_text(lecture_index_html)
+
+    # Syllabus
+    syllabus_md = (root / "syllabus.md").read_text()
+    md_renderer = markdown.Markdown(
+        extensions=["fenced_code", "codehilite", "tables"],
+        extension_configs={
+            "codehilite": {"css_class": "highlight", "guess_lang": False}
+        },
+    )
+    syllabus_html = md_renderer.convert(syllabus_md)
+    page_html = env.get_template("page.html").render(
+        title="Syllabus", content=syllabus_html
+    )
+    syllabus_dir = out / "syllabus"
+    syllabus_dir.mkdir(parents=True, exist_ok=True)
+    (syllabus_dir / "index.html").write_text(page_html)
+
+    # Homepage
+    homepage_html = env.get_template("index.html").render()
+    (out / "index.html").write_text(homepage_html)
+
+
+if __name__ == "__main__":
+    build_site()

tests/test_build.py

@@ -0,0 +1,39 @@
+import os
+import shutil
+from pathlib import Path
+from build import build_site
+
+
+def test_build_produces_output(tmp_path, monkeypatch):
+    """Smoke test: build produces _site/ with expected structure."""
+    monkeypatch.chdir(Path(__file__).parent.parent)
+    build_site(output_dir=str(tmp_path / "_site"))
+    site = tmp_path / "_site"
+
+    assert (site / "index.html").exists()
+    assert (site / "syllabus" / "index.html").exists()
+    assert (site / "lecture_notes" / "index.html").exists()
+    assert (site / "lecture_notes" / "week_1" / "1" / "index.html").exists()
+    assert (site / "css" / "style.css").exists()
+    assert (site / "js" / "navigation.js").exists()
+    assert (site / "examples").is_dir()
+    assert (site / "lecture_notes" / "images").is_dir()
+
+
+def test_build_slide_has_navigation(tmp_path, monkeypatch):
+    """Slide pages include navigation data attributes."""
+    monkeypatch.chdir(Path(__file__).parent.parent)
+    build_site(output_dir=str(tmp_path / "_site"))
+
+    slide = (tmp_path / "_site" / "lecture_notes" / "week_1" / "2" / "index.html").read_text()
+    assert 'data-prev=' in slide
+    assert 'data-next=' in slide
+    assert 'data-slide-num="2"' in slide
+
+
+def test_build_no_week_8_old(tmp_path, monkeypatch):
+    """week_8_old.md should not produce output."""
+    monkeypatch.chdir(Path(__file__).parent.parent)
+    build_site(output_dir=str(tmp_path / "_site"))
+
+    assert not (tmp_path / "_site" / "lecture_notes" / "week_8_old").exists()