diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..bd5590b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,21 @@
+node_modules/
+.npmrc
+.env
+.env.*
+__tests__/
+coverage/
+.nyc_output/
+dist/
+build/
+.cache/
+*.log
+.DS_Store
+tmp/
+.tmp/
+__pycache__/
+*.pyc
+.venv/
+venv/
+*.egg-info/
+.pytest_cache/
+READY_TO_PUBLISH
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..9d49c1a
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,26 @@
+ARCHITECTURE
+- Mobile AR Digital Twin MVP skeleton for cross-vendor assets (PV, inverter, wind, storage)
+- Core: Python-based digital twin engine with TelemetrySample, AssetModel, TwinEngine
+- API: FastAPI scaffold for telemetry ingestion and health endpoints
+- Offline caching layer (intentional MVP kept in-memory for simplicity; ready to swap to SQLite)
+- Data contracts and adapters: TelemetrySample, AnomalySignal, Alert, GovernanceLog (minimal stubs)
+
+TECH STACK
+- Language: Python 3.9+
+- Core: ar_grid_tutor_mobile_ar_digital_twin_for.core
+- API: api.app (FastAPI)
+- Tests: tests/ with pytest
+- Packaging: pyproject.toml with setuptools
+
+TESTING & RUNNING
+- Run unit tests: ./test.sh (requires pytest and build tooling)
+- Build package: python3 -m build
+- Run API locally (dev): uvicorn api.app:app --reload --port 8000
+
+CONTRIBUTING RULES
+- Use the provided test.sh to verify local changes before publishing
+- Do not modify READY_TO_PUBLISH unless you completed a publishable milestone
+- AGENTS.md is the canonical onboarding doc for agents; do not delete
+
+NOTE
+- This is an MVP skeleton designed for extension; future work will flesh out offline storage, adapters, and governance modules.
diff --git a/README.md b/README.md
index 81f9312..1335710 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,31 @@
-# ar-grid-tutor-mobile-ar-digital-twin-for
+# AR Grid Tutor: Mobile AR Digital Twin (MVP Skeleton)
 
-A mobile-first augmented reality platform that uses vendor-neutral digital twins of solar panels, inverters, wind turbines, and storage assets to guide technicians on-site. It overlays real-time health indicators, maintenance steps, and safety guidan
\ No newline at end of file
+This repository provides a production-minded MVP scaffold for a mobile-first AR platform that leverages vendor-neutral digital twins for DER assets (solar, inverter, wind, storage). The core components include:
+- A lightweight digital twin engine that reconciles telemetry with archived models
+- An API scaffold (FastAPI) for telemetry ingestion and health checks
+- A packaging-ready Python project with packaging metadata and tests
+- Offline-friendly architecture notes and forward-looking integration points
+
+Highlights
+- Core data contracts: TelemetrySample, AssetModel, and delta reconciliation results
+- Minimal but extensible API to ingest telemetry and query health
+- Tests validating core reconciliation behavior
+
+Project layout
+- pyproject.toml: packaging metadata and build-system configuration
+- src/ar_grid_tutor_mobile_ar_digital_twin_for/: core library (TelemetrySample, AssetModel, TwinEngine)
+- api/app.py: FastAPI endpoints for telemetry ingestion and health check
+- tests/: pytest-based unit tests
+- test.sh: test runner that also builds the package
+- AGENTS.md: contributor and architecture guide
+- README.md: this document
+- READY_TO_PUBLISH: (empty file created upon milestone completion)
+
+How to run locally
+- Install dependencies (virtualenv recommended):
+  pip install -r requirements.txt  # if you add, otherwise install via build tooling
+- Run tests: ./test.sh
+- Run API (for development): uvicorn api.app:app --reload
+
+Notes
+- This MVP intentionally uses in-memory state for simplicity; the architecture supports plugging in a SQLite/PostgreSQL cache and a fuller offline sync layer in future iterations.
diff --git a/api/app.py b/api/app.py
new file mode 100644
index 0000000..52ce509
--- /dev/null
+++ b/api/app.py
@@ -0,0 +1,28 @@
+from fastapi import FastAPI
+from pydantic import BaseModel
+from typing import Dict, Any
+
+from ar_grid_tutor_mobile_ar_digital_twin_for.core import TelemetrySample, TwinEngine
+
+app = FastAPI(title="AR Grid Tutor DT Twin API")
+
+_engine = TwinEngine()
+
+
+class TelemetryPayload(BaseModel):
+    asset_id: str
+    timestamp: float
+    metrics: Dict[str, float]
+
+
+@app.post("/telemetry")
+def ingest_telemetry(payload: TelemetryPayload):
+    sample = TelemetrySample(asset_id=payload.asset_id, timestamp=payload.timestamp, metrics=payload.metrics)
+    result = _engine.reconcile(sample)
+    return {"status": "ok", "result": result}
+
+
+@app.get("/health")
+def health():
+    # Minimal health indicator for orchestration
+    return {"status": "healthy", "assets_tracked": list(_engine.models.keys())}
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..70d3a60
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,18 @@
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "ar-grid-tutor-mobile-ar-digital-twin-for"
+version = "0.1.0"
+description = "Mobile AR Digital Twin MVP skeleton for on-site renewable asset maintenance"
+requires-python = ">=3.9"
+readme = "README.md"
+dependencies = [
+  "fastapi>=0.97.0",
+  "uvicorn>=0.23.0",
+  "pydantic>=1.10.0",
+]
+
+[tool.setuptools.packages.find]
+where = ["src"]
diff --git a/src/ar_grid_tutor_mobile_ar_digital_twin_for/__init__.py b/src/ar_grid_tutor_mobile_ar_digital_twin_for/__init__.py
new file mode 100644
index 0000000..aaa421f
--- /dev/null
+++ b/src/ar_grid_tutor_mobile_ar_digital_twin_for/__init__.py
@@ -0,0 +1,5 @@
+"""ar-grid-tutor-mobile-ar-digital-twin-for package init"""
+
+from .core import TelemetrySample, AssetModel, TwinEngine  # re-export for convenience
+
+__all__ = ["TelemetrySample", "AssetModel", "TwinEngine"]
diff --git a/src/ar_grid_tutor_mobile_ar_digital_twin_for/core.py b/src/ar_grid_tutor_mobile_ar_digital_twin_for/core.py
new file mode 100644
index 0000000..2ac2b4c
--- /dev/null
+++ b/src/ar_grid_tutor_mobile_ar_digital_twin_for/core.py
@@ -0,0 +1,62 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Dict, Any, Optional
+
+
+@dataclass
+class TelemetrySample:
+    asset_id: str
+    timestamp: float
+    metrics: Dict[str, float]  # e.g., {"voltage": 480.0, "temp": 65.0}
+
+
+@dataclass
+class AssetModel:
+    asset_id: str
+    version: int = 1
+    schema: Dict[str, Any] = field(default_factory=dict)  # canonical baseline or last known state
+
+
+class TwinEngine:
+    """A tiny, production-ready skeleton of a digital twin engine.
+
+    Responsibilities (minimal MVP):
+    - Maintain per-asset models (archive of baseline and version)
+    - Reconcile incoming telemetry against the archived model to compute deltas
+    - Update the model with the latest telemetry as baseline for next reconciliation
+    """
+
+    def __init__(self, initial_models: Optional[Dict[str, AssetModel]] = None):
+        self.models: Dict[str, AssetModel] = initial_models or {}
+
+    def register_model(self, asset_id: str, baseline: Optional[Dict[str, Any]] = None) -> AssetModel:
+        model = AssetModel(asset_id=asset_id, version=1, schema={"baseline": baseline or {}})
+        self.models[asset_id] = model
+        return model
+
+    def reconcile(self, sample: TelemetrySample) -> Dict[str, Any]:
+        """Compute a simple delta against the current baseline and update state.
+
+        Returns a dict with delta and new baseline.
+        """
+        asset_id = sample.asset_id
+        model = self.models.get(asset_id) or self.register_model(asset_id)
+        baseline = model.schema.get("baseline", {})
+
+        delta: Dict[str, float] = {}
+        for k, v in sample.metrics.items():
+            b = baseline.get(k, 0.0)
+            delta[k] = float(v) - float(b)
+
+        # Update baseline to current telemetry for next reconciliation
+        model.schema["baseline"] = dict(sample.metrics)
+        model.version += 1
+        self.models[asset_id] = model
+
+        return {
+            "asset_id": asset_id,
+            "version": model.version,
+            "delta": delta,
+            "new_baseline": model.schema["baseline"],
+        }
diff --git a/test.sh b/test.sh
new file mode 100644
index 0000000..b0b0535
--- /dev/null
+++ b/test.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "Running tests..."
+pytest -q
+echo "Building package..."
+python3 -m build
+echo "All tests passed and build completed."
diff --git a/tests/test_engine.py b/tests/test_engine.py
new file mode 100644
index 0000000..3c8d057
--- /dev/null
+++ b/tests/test_engine.py
@@ -0,0 +1,30 @@
+import math
+import sys
+import os
+
+# Ensure the local src package is importable when tests run from repo root
+src_path = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "src"))
+if src_path not in sys.path:
+    sys.path.insert(0, src_path)
+
+from ar_grid_tutor_mobile_ar_digital_twin_for.core import TelemetrySample, TwinEngine
+
+
+def test_reconcile_updates_baseline_and_delta():
+    engine = TwinEngine()
+    asset_id = "solar-1"
+    # initial telemetry comes in; baseline starts empty
+    sample1 = TelemetrySample(asset_id=asset_id, timestamp=1.0, metrics={"voltage": 480.0, "temp": 25.0})
+    out1 = engine.reconcile(sample1)
+    assert out1["asset_id"] == asset_id
+    assert out1["version"] == 2  # since initial register creates version 1 and reconcile increments to 2
+    assert isinstance(out1["delta"], dict)
+    assert out1["delta"]["voltage"] == 480.0 - 0.0
+
+    # second sample with changed values
+    sample2 = TelemetrySample(asset_id=asset_id, timestamp=2.0, metrics={"voltage": 485.0, "temp": 27.0})
+    out2 = engine.reconcile(sample2)
+    assert out2["asset_id"] == asset_id
+    assert out2["version"] == 3
+    assert math.isclose(out2["delta"]["voltage"], 5.0, rel_tol=1e-6)
+    assert out2["new_baseline"]["voltage"] == 485.0