[arnav] add backend pytest CI workflow and local test runner script

.github/workflows/test.yml

@@ -0,0 +1,44 @@
+name: Backend tests
+
+# Runs the backend pytest suite (mirrors `bash scripts/test.sh`) on every PR
+# and every push to main. Tests are fully self-contained — they stub the
+# Anthropic API and the Claude Code CLI — so no secrets or services are
+# required.
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+concurrency:
+  group: tests-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  pytest:
+    name: pytest
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+          cache-dependency-path: |
+            backend/requirements.txt
+            backend/requirements-dev.txt
+
+      - name: Install backend deps
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install \
+            -r backend/requirements.txt \
+            -r backend/requirements-dev.txt
+
+      - name: Run pytest
+        run: python -m pytest backend/tests/ -v

scripts/test.sh

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+#!/bin/bash
+# Run the backend pytest suite. Creates backend/.venv if missing, installs
+# requirements.txt + requirements-dev.txt the first time (or whenever
+# pytest isn't importable), then invokes pytest.
+#
+# Usage:
+#   bash scripts/test.sh                    # run everything (~30s; 500 stress iters)
+#   bash scripts/test.sh --quick            # cap DISCONNECT_STRESS_N at 20 for fast iteration
+#   bash scripts/test.sh -k disconnect      # forward any pytest args
+#   bash scripts/test.sh backend/tests/test_analytics.py -v
+#
+# Env:
+#   DISCONNECT_STRESS_N   Override the stress-iteration count for
+#                         test_disconnect_resilience.py (default 500;
+#                         --quick sets it to 20).
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+BACKEND_DIR="$PROJECT_ROOT/backend"
+VENV_DIR="$BACKEND_DIR/.venv"
+PYTHON_BIN="$VENV_DIR/bin/python"
+
+# --- Parse our one wrapper flag, then forward the rest to pytest ----------
+QUICK=0
+PYTEST_ARGS=()
+for arg in "$@"; do
+    case "$arg" in
+        --quick) QUICK=1 ;;
+        *) PYTEST_ARGS+=("$arg") ;;
+    esac
+done
+
+# --- Ensure venv exists ---------------------------------------------------
+if [[ ! -x "$PYTHON_BIN" ]]; then
+    echo "==> Creating venv at $VENV_DIR"
+    python3 -m venv "$VENV_DIR"
+fi
+
+# --- Ensure pytest is installed (idempotent: only re-installs if missing) -
+if ! "$PYTHON_BIN" -c "import pytest, pytest_asyncio" >/dev/null 2>&1; then
+    echo "==> Installing backend deps + dev deps into $VENV_DIR"
+    "$PYTHON_BIN" -m pip install --upgrade pip >/dev/null
+    "$PYTHON_BIN" -m pip install \
+        -r "$BACKEND_DIR/requirements.txt" \
+        -r "$BACKEND_DIR/requirements-dev.txt"
+fi
+
+# --- Default target = backend/tests/ if caller didn't pass any path -------
+if [[ ${#PYTEST_ARGS[@]} -eq 0 ]]; then
+    PYTEST_ARGS=(backend/tests/ -v)
+fi
+
+# --- --quick: dial the disconnect stress loop way down --------------------
+if [[ "$QUICK" -eq 1 ]]; then
+    export DISCONNECT_STRESS_N="${DISCONNECT_STRESS_N:-20}"
+    echo "==> --quick: DISCONNECT_STRESS_N=$DISCONNECT_STRESS_N"
+fi
+
+# Run from project root so `from backend.apps...` imports resolve.
+cd "$PROJECT_ROOT"
+echo "==> Running: pytest ${PYTEST_ARGS[*]}"
+exec "$PYTHON_BIN" -m pytest "${PYTEST_ARGS[@]}"