Hearth

The problem

There's water under the sink and your hands are wet. Where's the shut-off? Which washer fits? Do you need a plumber? US households spend $2,041 a year on maintenance plus $1,143 on emergency repairs (Angi 2025, our source; we did not verify it independently). Nobody owns those first 15 minutes.

What Hearth does

Hearth remembers your house: every appliance, filter size, shut-off and past repair, captured by voice or a label photo. When something breaks:

Fixes it with you. One clarifying question, then step cards on the Echo Show that circle your valve in your photo.
Orders the exact-fit part. Matched to your asset. Alexa reads the commitment aloud and orders only after a clear yes.
Hands off to a pro. If it's beyond DIY, Hearth writes a complete job brief for Alexa's Home Services partners.
Stops on danger. Gas, electrical, structural and sewage problems end in a hard stop with a fixed message, no steps and an offer to call a pro. No language model decides when to stop.
Plans the weekend. "Your furnace filter is 94 days old." Reorder in two turns, remembered across sessions.

Tech implementation

Self-hosted MCP server, protocol 2025-11-25, Streamable HTTP, 12 tools, 8 MCP Apps widgets (Card, Carousel, List).
33/33 conformance checks. Worst tool p95 53 ms against the 500 ms budget. 916 unit tests. All 5 journeys pass end to end in a browser.
OAuth 2.1 + PKCE (S256), RFC 9728/8414 metadata, and a 401 with no WWW-Authenticate header, as the Alexa+ checklist requires.
Deterministic tools. No LLM runs inside a tool; the orchestrator does the reasoning (Bedrock, a local Qwen3 4B, or a rules engine).
Claude Desktop calls the same server through mcp-remote.
AWS CDK stack (Fargate, ALB, CloudFront, DynamoDB, Secrets Manager, Bedrock Guardrail) that synthesizes. Not deployed.

What's real vs simulated

Entrants can't get Alexa+ devices, so the demo runs on our open-source simulated Alexa+ host, a genuine MCP client, labelled on every screen. Payments are simulated or Stripe test mode.

Why it matters

Hearth sends Home Services partners qualified, fully briefed jobs and drives repeat parts orders through Alexa+ checkout. It complements those partners and doesn't replace them.

For the ecosystem

A standalone Apache-2.0 host simulator package (packages/host-sim-core) for builders who can't get the gated inspector.
A 32-entry friction log with a concrete fix for each issue.

Code: https://github.com/Bhavya-Dhoot/hearth (Apache-2.0)