Last EHR

Read the chart broadly. Write only what a human approved. Last EHR is the agent layer for a headless FHIR EHR. It does three things, and the write protocol is only one of them.

It reads the chart broadly. 25 of US Core 9.0.0's 27 readable resource types, across 23 patient-scoped sections, following references so authors, encounters, and provenance stop being dead pointers. Counted in the open, with the ceiling published rather than implied, in FHIR coverage.

It is built so the agent cannot fake an absence. "She has never had a flu shot" is the answer a chart agent must never invent, so a read reports when its window was capped, when a reference lookup was refused, and when a code filter matched nothing in a section that does hold records. Filters that a section cannot apply are refused with the legal values instead of silently dropped. These are safety-boundary tests, not best-effort behavior.

Every write is a proposal. Show the exact resource, require an explicit human decision, commit exactly what was reviewed, and record what created it. That half is a small protocol, Approval-Gated Agent Writes on FHIR (v0.1 draft): Proposal → Decision → Commit → Audit. Two implementations run here, a web approval card and MCP elicitation-gated write tools, plus a conformance suite that checks implementations with its own FHIR reads. Independent implementations and criticism are invited.

Five FHIR backends sit behind one interface. This repository is the reference implementation: bring your own FHIR backend and model key for a real agent (Medplum for the authenticated path, or any verified adapter for synthetic evaluation), or start with the zero-key local synthetic walkthrough.

Last EHR is a layer, not an EHR. It runs on top of a headless FHIR backend (Medplum for authenticated use; HAPI FHIR, Firely Server, Aidbox, or Oystehr for synthetic evaluation) and talks to it over the FHIR API. It is not the system of record, stores no PHI of its own, and never bundles or forks the backend.

Status: early / alpha. APIs, structure, and scope will change. Use synthetic data only. · License: Apache-2.0

Try the live demo: no sign-up, synthetic data, and every write goes through the approval gate.

Start here

30-second synthetic-data walkthrough

1. Open the live demo.
2. Ask: Find patients named Smith.
3. Ask: Record a heart rate of 72 bpm for Maria Garcia.
4. Inspect the proposed write, then approve it. The data is synthetic and the approval card shows exactly what will be saved.

For MCP, @lastehr/mcp is deliberately a separate surface that is read-only by default (search_patients, show_patient_info, read_chart_section, and read_document — the same bounded chart reads the web agent gets), with one opt-in: elicitation-gated write proposals a human approves per action. Configure a least-privilege Medplum token before connecting it to a real project; full setup is in the MCP guide and the Official MCP Registry listing.

Want to inspect the read surface before configuring Medplum? From a checkout, npm run mcp:demo starts the included local HAPI stack, resets the four synthetic fixture charts, and prints a Claude Code/Cursor configuration. That checkout-only MCP Local Lab needs no FHIR/Medplum credentials or model-provider API key of its own and is restricted to fixture patients. Your MCP client still uses its normal account and may send those synthetic results to its model provider. It is not the published package, generic HAPI support, or a path for PHI.

For a deterministic safety-mechanics check, npm run eval creates a separate synthetic target, proves the proposal/approval and denial paths, verifies chart association, cleans up, and writes a scrubbed report. It is not a clinical, authorization, or compliance certification; see the evaluation guide.

What it does

• A chat agent (Vercel AI SDK) with FHIR tools. It reads the chart (search patients, view a patient chart, read one filtered chart section) and writes to it (add a note, record an observation, create a follow-up task), streamed and rendered as structured cards.
• Writes are confirmation-gated: the agent proposes a write, you approve it, and only then is it saved. Nothing touches the chart without your click. Approved writes carry the standard AIAST security label, with optional Provenance recording author-agent and human-verifier roles (role labels, not user identity).
• The gate is a specified protocol, not just app behavior: Approval-Gated Agent Writes on FHIR (v0.1 draft) names the rules — only an explicit approval commits, every ambiguous outcome fails closed, policy can only narrow the gate — and the conformance suite tests an implementing MCP stdio server's gate mechanics with independent FHIR reads. CI runs it against this repository's own server on every pull request and merge.
• Authentication, multi-tenancy, and access control are delegated to your Medplum project (Project = tenant, ProjectMembership = user, AccessPolicy = RBAC). Last EHR doesn't reimplement any of that, and writes are bounded by your AccessPolicy.

Support status

Last EHR is Medplum-supported for authenticated deployments and includes a local, no-auth HAPI FHIR mode for synthetic-data evaluation. Firely Server (FHIR_BACKEND=firely), Aidbox (FHIR_BACKEND=aidbox), and Oystehr (FHIR_BACKEND=oystehr) are verified synthetic-evaluation adapters: each passed both contract harnesses and the FHIR Agent Safety Eval against a disposable synthetic target. Other FHIR R4 backends need an adapter before they are supported. See the full support matrix for the web, SMART, MCP, auth, and evaluation boundaries before choosing a path.

Self-hosted demos can offer a backend picker (swap the EHR under the live agent, per session) and an "under the hood" panel streaming the agent's FHIR operations — both off by default; see the support matrix for the eligibility rules and npm run check:backends for preflight.

What it isn't

• Not a charting EHR, not a system of record, and not a Medplum replacement. It's a thin agent layer: a small, growing set of tools over your FHIR backend.
• Not a guarantee. The approval gate is a human-in-the-loop boundary, not a safety proof: it stops unilateral writes, but it relies on you reading what you approve. Models can propose wrong or fabricated clinical facts, and approval fatigue is real. Last EHR provides the gate; you provide the review.

How it works

Next.js 15 (App Router) + React 19. The agent lives in app/api/chat/route.ts (streamText + FHIR tools); the FHIR calls go through a small backend interface (lib/fhir/backend.ts) with five built-in adapters: Medplum (hosted or self-hosted, token-authenticated), plus local HAPI FHIR, Firely Server, Aidbox, and Oystehr for synthetic evaluation (docs/support.md). The interface is four methods plus contract notes, so an adapter for another headless EHR is a small, well-scoped contribution. See docs/adapters.md and the roadmap.