# CLAUDE.md — Project Conventions

## File Operations

- When asked to edit a file, use Glob/Grep to locate it rather than asking the user for the path.
- Prefer targeted reads (offset + limit) over reading entire large files.
- Before creating a new file, check whether a suitable one already exists.
- Do not re-read a file after editing it to verify — edits would have errored if they failed.

## Editing Conventions

- When editing R/Quarto files, check for stale object/column name references after renames (e.g., `title` -> new name) across the entire file, not just the edit site.
- Make the minimal change needed — do not refactor or clean up surrounding code unless asked.
- Do not add comments, docstrings, or type annotations to code you did not change.
- Avoid backwards-compatibility shims for removed code; delete unused code outright.

## R Conventions

- This project uses data.table, not data.frame/dplyr. Always use data.table syntax (e.g., `DT[, .(col)]`, `:=`) and verify column access patterns work on data.table objects before finalizing edits.
- Use `set*` functions (`setnames`, `setorder`, `setkey`) for in-place mutations to avoid copies.
- Prefer `fread`/`fwrite` over `read.csv`/`write.csv`.
- Do not load tidyverse or dplyr unless explicitly requested.

## Performance / Memory

- Large datasets hit R memory limits — prefer chunking, avoid unnecessary copies, and add defensive guards for list vs data.table structures before `rbindlist`.
- Never use `rbind` in a loop; accumulate results in a list and call `rbindlist` once.
- Avoid `apply`-family functions on large data.tables; use vectorized data.table operations instead.
- Check `object.size()` / `lobstr::obj_size()` when debugging memory issues rather than guessing.

## Token Efficiency

- Do not summarize what you just did at the end of a response — the diff is visible.
- Do not repeat back the user's request before answering.
- Skip pleasantries and filler phrases ("Great question!", "Certainly!", etc.).
- When reading code to answer a question, read only the relevant section, not the whole file.
- Use `files_with_matches` output mode for Grep unless line content is needed.