Add a worktree environment helper

AGENTS.md

@@ -42,6 +42,9 @@ AWS_ATHENA_WORKGROUP=<workgroup>
 AWS_ATHENA_SPARK_WORKGROUP=<spark-workgroup>
 ```
 
+In a git worktree, run `just worktree-env` once to link the main checkout's
+gitignored `.env` into the worktree.
+
 ```bash
 export $(cat .env | xargs) && uv run pytest tests/pyathena/test_file.py -v
 ```

justfile

@@ -5,6 +5,10 @@ TOX_VERSION := "4.34.1"
 default:
     @just --list
 
+# Link the main checkout's gitignored .env into a worktree
+worktree-env:
+    scripts/worktree-env.sh
+
 # Auto-fix formatting and imports
 format:
     # TODO: https://github.com/astral-sh/uv/issues/5903

scripts/worktree-env.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+worktree_root=$(git rev-parse --show-toplevel)
+common_dir=$(git rev-parse --path-format=absolute --git-common-dir)
+main_root=$(cd "$(dirname "$common_dir")" && pwd -P)
+
+cd "$worktree_root"
+
+if [ "$(pwd -P)" = "$main_root" ]; then
+    echo "This is the main checkout; nothing to link."
+    exit 0
+fi
+
+if [ -e .env ] && [ ! -L .env ]; then
+    echo ".env is already a regular file in this worktree; nothing to link."
+    exit 0
+fi
+
+if [ ! -f "$main_root/.env" ]; then
+    echo "error: $main_root/.env does not exist" >&2
+    exit 1
+fi
+
+ln -sfn "$main_root/.env" .env
+echo "Linked .env -> $main_root/.env"