# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## What This Project Does

A Python package that generates responsive static HTML galleries from scientific plot collections (PDFs and HTMLs). It converts PDFs to PNGs via ImageMagick, organizes plots hierarchically, propagates YAML/JSON metadata through directory trees, and renders everything via a Jinja2 template into a static website served from a web directory.

## Commands

```bash
# Install the package (editable)
pip install -e ".[dev]"

# Run all tests
pytest tests/

# Run a single test file
pytest tests/test_generate_gallery.py -v

# Run a single test by name
pytest tests/test_generate_gallery.py::test_needs_update_missing_target -v

# Generate gallery (CLI entry point after install)
gallery --config config.yaml --verbose

# Generate gallery (legacy script)
python generate_gallery.py --verbose

# Incremental update for one source only
gallery --source /path/to/plots --verbose

# Clean regeneration
gallery --clean --verbose

# Serve output locally
python -m http.server 8000 -d /web/kschmidt/public_html/
```

Code style: black with `line-length = 120`.

## Architecture

### Execution Flow

```
generate() [api.py]
  └── copy_assets()         [builder.py]  — copies assets/ to web output dir
  └── get_template()        [builder.py]  — loads gallery/templates/gallery.html
  └── build_gallery()       [builder.py]  — recursive per-source-directory walk
        └── load_folder_metadata()  [utils/metadata.py]
        └── merge_metadata()        [utils/metadata.py]  — inherits from parent
        └── process_plot_files()    [utils/processing.py]  — PDF→PNG, copy files
        └── save_metadata_cache()   [utils/metadata.py]
        └── render_gallery_page()   [utils/processing.py]  — writes index.html
        └── recurse into subdirs
```

### Key Files

| File | Role |
|------|------|
| `gallery/api.py` | `generate()` — primary public entry point; orchestrates everything |
| `gallery/builder.py` | `build_gallery()` — recursive traversal; `get_template()`, `copy_assets()` |
| `gallery/config.py` | `GalleryConfig`, `GallerySource`, `GalleryDefaults` dataclasses; YAML loading |
| `gallery/cli.py` | CLI (`gallery` command) wrapping `generate()` |
| `gallery/utils/processing.py` | PDF→PNG via ImageMagick subprocess; `needs_update()` timestamp check; `render_gallery_page()` |
| `gallery/utils/metadata.py` | Load/merge/cache YAML+JSON metadata; per-plot metadata resolution |
| `gallery/utils/stats.py` | Directory size/count statistics |
| `gallery/templates/gallery.html` | Single Jinja2 template for all gallery pages |
| `gallery/assets/js/` | Vanilla JS modules loaded as ES modules; `GalleryApp` in `gallery-app.js` orchestrates all managers |
| `gallery/assets/css/` | Modular CSS; `main.css` imports all others via `@import` |
| `config.yaml` | Local deployment config (paths are machine-specific) |

### Config File Format

The YAML config uses a specific structure (not flat — must match `GalleryConfig.from_yaml()`):

```yaml
paths:
  web_folder: "/web/user/public_html"   # required
gallery:
  plot_root: "gallery"
  png_dpi: 400
sources:
  - name: "my_plots"
    path: "/path/to/plots"
metadata:
  cache_enabled: true
  inherit_from_parent: true
```

### Incremental Updates

`needs_update(source, target)` uses a **30-second buffer** on mtime comparisons to handle filesystem timing. This is intentional — avoid tightening it.

When `source_to_update` is passed to `generate()`, only that source's subdirectory is deleted and rebuilt; all other sources stay intact and the root index is re-rendered to include them.

### Metadata Inheritance

`metadata.yaml` (or `.yml`/`.json`) in any source directory is loaded and **merged with parent metadata** (`inherit_from_parent=True` by default). Child directories override parent keys. Per-plot overrides can live in `<plotname>.yaml` files alongside the plot.

### Frontend (Static JS/CSS)

The frontend is vanilla ES modules — no build step. `assets/js/main.js` imports `GalleryApp` from `gallery-app.js`, which instantiates all manager classes (`ThemeManager`, `SearchManager`, `NavigationManager`, etc.). Each manager is self-contained. The template embeds gallery data as JSON in the page; JS reads it at runtime.

### Deployment

The project ships a `Singularity.def` / `web.sif` Apptainer container for HPC environments. CI (`.gitlab-ci.yml`) builds the container and runs pytest inside it. For local development the `.venv` is sufficient.