ShopAndEat

A self-hosted meal-planning and grocery-shopping app built with ASP.NET Core Blazor Server. Plan meals from recipes, derive a consolidated shopping list of missing ingredients, and let an LLM-powered Shopping Agent drive an actual online grocery cart (currently Coop.ch) through a companion browser extension.

Features

• Meal planning: schedule recipes onto a calendar; articles and units are managed centrally and reused across recipes
• Shopping list generation: derives the consolidated list of missing ingredients for a given time range, considering what's already in stock
• Shopping Agent: a chat-based assistant (Mistral LLM via Microsoft.Extensions.AI) that takes the shopping list, searches products on the configured online shop, asks for clarification on ambiguous items, and fills the real shopping cart - with resilient retry/fallback-model handling for rate limits and transient failures
• Browser extension bridge: a Manifest V3 extension executes the Shopping Agent's tool calls (product search, add-to-cart, navigation) directly on the shop's website via a JS-interop bridge (postMessage relay through Blazor Server), so no shop API integration is required
• Preferences: the agent remembers confirmed product choices and reminders per article, scoped per shop
• OpenTelemetry tracing & metrics: both the classic web app and the Shopping Agent emit traces/metrics to an OTLP endpoint (e.g. the .NET Aspire Dashboard)

Architecture

Project	Responsibility
DataLayer	EF Core entities, DbContext, migrations
DTO	API/UI data-transfer records, mapped from/to entities
BizDbAccess	Repository layer around DataLayer
BizLogic	Legacy business logic (meals, recipes, ingredient lists)
ServiceLayer	Modern service layer (typed IDs, CancellationToken throughout, TimeProvider)
ShoppingAgent	The LLM-driven chat assistant: conversation/tool-call orchestration, resilient IChatClient decorator, Razor UI
ShopAndEat	ASP.NET Core host: API controllers, classic Blazor pages (meals/recipes/articles), DI wiring
BrowserExtension	Manifest V3 extension that bridges the Shopping Agent's tool calls to the real shop website

The ShoppingAgent feature slice follows modern .NET patterns throughout (strongly-typed IDs, DTOs-as-records, TimeProvider, primary constructors, [LoggerMessage]); the legacy meal/recipe/article pages use an older, more traditional layering that is being incrementally modernized.

Local Development

Prerequisites

• .NET SDK (see global.json for the exact version)
• A Mistral AI API key for the Shopping Agent

Run

dotnet user-secrets set "LlmClient:ApiKey" "<your-mistral-api-key>" --project ShopAndEat
dotnet run --project ShopAndEat

The app listens on the port configured in ShopAndEat/Properties/launchSettings.json. On first start it creates a SQLite database at the path configured under ConnectionStrings:SQLite.

Test

dotnet build ShopAndEat.slnx --no-restore
dotnet test ShopAndEat.slnx --no-build

The suite is NUnit + FluentAssertions + NSubstitute + bUnit (for Razor components), verified with Stryker mutation testing. A few Category=System tests spin up the app via WebApplicationFactory/Testcontainers and are slower - filter them out for quick local iteration:

dotnet test ShopAndEat.slnx --no-build --filter "Category!=System"

Live, opt-in integration tests against a real Mistral endpoint live under Tests/LlmIntegration/ - see below.

Browser Extension

The extension uses one Manifest V3 codebase for Chrome 121+ (service worker) and Firefox 140+ (background scripts). Firefox 128 introduced the MAIN execution world used to read the shop's CSRF token; the minimum is 140 to support Firefox's built-in data transmission consent at installation.

Chrome / Chromium-based browsers: load BrowserExtension/ as an unpacked extension (chrome://extensions → Developer mode → Load unpacked).

Firefox (temporary, for development): go to about:debugging#/runtime/this-firefox → Load Temporary Add-on… → select BrowserExtension/manifest.json. This installation is removed when Firefox restarts and is sufficient for local development against a ShopAndEat instance running on localhost.

Firefox (permanent): regular (non-Developer-Edition/Nightly/ESR) Firefox only loads a permanently installed extension if it is signed by Mozilla. The extension can be self-distributed (no public AMO listing required) — see Self-distribution and Signing and distribution overview. Package and sign with web-ext sign, then install the resulting .xpi file.

The extension exchanges tool requests and results with the ShopAndEat page through a window.postMessage content-script bridge; the app handles server communication. Set Allowed host URLs in the extension's options to your instance's shopping page, for example https://your-host/shopAndEat/shopping*. Grant website access to that host and Coop, sign in to Coop in the same browser profile, then reload the shopping page.

Existing saved URL patterns, including explicit ports, remain valid. Firefox cannot register content-script patterns containing ports (Firefox bug 1362809), so registration uses a deduplicated pattern without the port. Before announcing a connection and before executing each tool request, the background script checks the sender's URL against the original saved patterns, including ports. A pattern without an explicit port allows all ports of that host. Changes apply to subsequent requests; reload the page to activate the bridge after adding a new URL.

The Firefox manifest declares required transmission of search terms, website activity (cart operations), and website content (product details and cart contents) to the configured shop and ShopAndEat instance. ShopAndEat's Shopping Agent processes these results with its configured LLM provider. Firefox asks for consent during installation; the extension does not read passwords or payment details. See Firefox built-in data consent.

Extension verification

Run the dependency-free authorization and registration regression tests with node --test Tests/BrowserExtension/bridge.test.cjs.

Before using a signed release, verify the real flow in Firefox against your own ShopAndEat instance and Coop account: search, inspect product details, add an item, inspect the cart, and remove that item. Local simulated-shop tests do not establish compatibility with Coop's live login, page timing or bot protection. Mozilla signing, signed-XPI installation, browser restarts and background suspension also require release verification.

Configuration

Key sections in appsettings.json (see the file for the full set of defaults):

• ConnectionStrings:SQLite - path to the SQLite database file
• LlmClient - Mistral endpoint, default/fallback model, timeout and retry settings
• Agent - tool-calling loop limits, retry and model-fallback toggles
• Extension - timeout for the browser-extension tool-call bridge
• Shops - configured online shops (key, display name, base/cart URLs)

Docker

docker compose up

docker-compose.yml wires up the app together with an Aspire Dashboard for viewing traces/metrics, and reads the Mistral API key from a Docker secret at ./secrets/LlmClient__ApiKey.

Live LLM Integration Tests

The Tests/LlmIntegration/ test suite validates the ShoppingAgent end-to-end with a real Mistral API client. These tests are opt-in only and excluded from normal CI/local test runs.

Prerequisites

• A valid Mistral API key: https://console.mistral.ai/
• The key must be set via the LlmClient__ApiKey environment variable

Running Live Tests Locally

$env:LlmClient__ApiKey = 'your-mistral-api-key'
dotnet test --filter "Category=LlmIntegration"

Or run a single scenario:

dotnet test --filter "Category=LlmIntegration&Name~ResearchPhase_SearchProducts"

Test Coverage

The suite covers all user-facing ShoppingAgent flows: research (product search, details, preferences), clarification, confirmation, cart operations, shop switching, multi-step end-to-end scenarios, and resilience (empty results, consecutive requests, state preservation across turns).

• Tests use a real Mistral client to exercise actual LLM reasoning
• A scripted shop tool executor provides deterministic, repeatable behavior (no real shop API calls)
• Behavioral assertions only: tests verify tool execution and state transitions, not exact LLM wording
• Tests are marked [Explicit] and tagged [Category("LlmIntegration")], so they never run unless explicitly requested
• Running the full suite (~19 tests) typically costs less than $0.01 USD in Mistral API usage

License

Do No Harm License