huskies: merge 1251 story script/check gates duplication and cognitive complexity

script/check

@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
-# Pre-commit quality gate: fmt-check, clippy, cargo check, and doc-coverage.
-# Run this before committing to catch fmt drift, clippy warnings, compile
-# errors, and missing doc comments without waiting for the full test suite.
+# Pre-commit quality gate: fmt-check, clippy, duplication, cargo check, and
+# doc-coverage. Run this before committing to catch fmt drift, clippy
+# warnings, duplicate code, compile errors, and missing doc comments without
+# waiting for the full test suite.
 set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
@@ -11,7 +12,20 @@ echo "=== Checking Rust formatting ==="
 cargo fmt --manifest-path "$PROJECT_ROOT/Cargo.toml" --all --check
 
 echo "=== Running cargo clippy ==="
-cargo clippy --manifest-path "$PROJECT_ROOT/Cargo.toml" --workspace --all-targets -- -D warnings
+# clippy::cognitive_complexity is allow-by-default; -W activates it so that
+# -D warnings turns violations into a hard failure. The threshold it's
+# measured against lives in clippy.toml (committed, not passed ad hoc).
+cargo clippy --manifest-path "$PROJECT_ROOT/Cargo.toml" --workspace --all-targets -- -W clippy::cognitive_complexity -D warnings
+
+echo "=== Checking code duplication (jscpd) ==="
+if ! command -v jscpd &>/dev/null; then
+  echo "FAIL: jscpd is not installed. Install it with 'npm install -g jscpd' before running script/check." >&2
+  exit 1
+fi
+# Duplication threshold lives in .jscpd.json (committed, not passed ad hoc).
+# jscpd exits non-zero automatically when duplication exceeds that threshold.
+jscpd --config "$PROJECT_ROOT/.jscpd.json" \
+  "$PROJECT_ROOT/server/src" "$PROJECT_ROOT/frontend/src" "$PROJECT_ROOT/crates"
 
 echo "=== Checking doc coverage on changed files ==="
 cargo run --manifest-path "$PROJECT_ROOT/Cargo.toml" -p source-map-gen --bin source-map-check --quiet -- --worktree "$PROJECT_ROOT" --base master