Add fourmolu + hlint with scripts and git hooks (Atlas-style)

- Create scripts/build, scripts/test, scripts/run, scripts/install-hooks
- Create git-hooks/pre-commit (auto-format staged .hs files)
- Create git-hooks/pre-push (check formatting + hlint before push)
- Handle git worktrees correctly in hook installation
- Run fourmolu on all source files to fix existing formatting

scripts/build

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
+echo "Formatting with fourmolu..."
+./hs fourmolu --mode inplace app/ src/ test/
+
+echo "Linting with hlint..."
+./hs hlint app/ src/ test/
+
+echo "Building..."
+./hs stack build --copy-bins --local-bin-path /work/build

scripts/git-hooks/pre-commit

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# Pre-commit hook: format staged Haskell files with fourmolu.
+# Installed by: scripts/install-hooks
+set -euo pipefail
+
+PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+
+# Get staged .hs files (handles filenames with spaces)
+staged=$(git -C "$PROJECT_DIR" diff --cached --name-only --diff-filter=ACM -- '*.hs')
+if [ -z "$staged" ]; then
+    exit 0
+fi
+
+# Collect the files into an array
+mapfile -t files <<< "$staged"
+
+echo "--- Formatting staged Haskell files with fourmolu..."
+if ! "$PROJECT_DIR/hs" fourmolu --mode inplace "${files[@]}"; then
+    echo "ERROR: fourmolu formatting failed" >&2
+    exit 1
+fi
+
+# Re-stage any files that were modified by formatting
+changed=0
+for f in "${files[@]}"; do
+    if ! git -C "$PROJECT_DIR" diff --quiet "$f"; then
+        git -C "$PROJECT_DIR" add "$f"
+        changed=$((changed + 1))
+    fi
+done
+
+if [ "$changed" -gt 0 ]; then
+    echo "--- Formatted $changed file(s) — re-staged automatically"
+fi

scripts/git-hooks/pre-push

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Pre-push hook: check formatting and hlint before pushing.
+# Installed by: scripts/install-hooks
+set -euo pipefail
+
+PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+
+echo "--- Checking formatting with fourmolu..."
+if ! "$PROJECT_DIR/hs" fourmolu --mode check app/ src/ test/; then
+    echo ""
+    echo "ERROR: Formatting check failed. Run './scripts/build' to auto-format."
+    echo "       (fourmolu --mode inplace app/ src/ test/)"
+    exit 1
+fi
+echo "OK"
+
+echo "--- Linting with hlint..."
+if ! "$PROJECT_DIR/hs" hlint app/ src/ test/; then
+    echo ""
+    echo "ERROR: Hlint found warnings. Fix them before pushing."
+    exit 1
+fi
+echo "OK"

scripts/install-hooks

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Install git hooks for the roux-server project.
+# Run once:  ./scripts/install-hooks
+set -euo pipefail
+
+HOOK_SRC="$(cd "$(dirname "${BASH_SOURCE[0]}")/git-hooks" && pwd)"
+# Determine git hooks directory — supports both regular repos and worktrees
+GIT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)/.git"
+if [ -f "$GIT_DIR" ]; then
+    # Worktree: .git is a file pointing to the real gitdir
+    GIT_DIR="$(cut -d' ' -f2 "$GIT_DIR")"
+fi
+HOOK_DST="${GIT_DIR}/hooks"
+
+mkdir -p "$HOOK_DST"
+echo "Installing git hooks from $HOOK_SRC -> $HOOK_DST"
+
+for hook in "$HOOK_SRC"/*; do
+    name=$(basename "$hook")
+    ln -sf "$hook" "$HOOK_DST/$name"
+    echo "  $name installed"
+done
+
+echo "Done."

scripts/run

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+./hs stack exec roux-server -- "$@"

scripts/test

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
+echo "Checking formatting with fourmolu..."
+./hs fourmolu --mode check app/ src/ test/
+
+echo "Linting with hlint..."
+./hs hlint app/ src/ test/
+
+echo "Running tests..."
+./hs stack test