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..6faac56
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,25 @@
+# SolarSphere Offline-First MVP Agents
+
+This repository contains a production-oriented Python MVP for SolarSphere, an offline-first geospatial visualization scaffold. The code focuses on data contracts, a pluggable data-source adapter surface, deterministic delta reconciliation, and a lightweight render summary suitable for testing and extension.
+
+Architecture overview
+- Core data primitives: Asset, TelemetryPoint, WeatherLayer, Event.
+- Data sources: pluggable adapters (CSV, REST, MQTT, etc.). CSVAdapter is implemented for MVP.
+- Delta reconciliation: deterministic, replay-friendly merge of local and remote deltas.
+- Lightweight renderer: builds a serializable snapshot suitable for downstream visualization without a browser runtime.
+- Packaging: Python package under idea78_solarsphere_offline_first with a small, exportable API.
+
+Tech stack decisions
+- Language: Python 3.9+ for rapid prototyping, strong typing, and easy packaging.
+- No external GUI dependencies yet; a JSON-friendly render path is provided to support future WebGL/Canvas rendering layers.
+- Tests: pytest-based unit tests ensure data models, adapters, and delta logic behave deterministically.
+
+Testing and commands
+- Run tests locally: ./test.sh
+- Build package: python3 -m build
+- Inspect package: pytest tests -q
+
+Contributing rules
+- Add small, well-scoped changes; prefer minimal surface area.
+- Update AGENTS.md if you add new architecture or data contracts.
+- Ensure tests cover new behavior.
diff --git a/README.md b/README.md
index 23f73ff..2bd893b 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,30 @@
-# idea78-solarsphere-offline-first
+# SolarSphere Offline-First MVP
 
-Source logic for Idea #78
\ No newline at end of file
+Overview
+- A Python-based MVP for offline-first geospatial visualization and telemetry replay. Focuses on simple, well-defined data contracts and deterministic delta reconciliation that can run entirely offline with optional data-sync when connectivity returns.
+
+What’s included
+- Core data primitives: Asset, TelemetryPoint, WeatherLayer, Event
+- CSV-based telemetry adapter for MVP data ingestion
+- Delta reconciliation utilities for deterministic merges
+- Lightweight render summary producing JSON suitable for downstream tooling
+- Minimal CLI and a test suite to validate core behavior
+
+Getting started
+- Install dependencies and run tests: `bash test.sh`
+- Package: `python3 -m build` (also in test script)
+
+Project structure (high level)
+- src/idea78_solarsphere_offline_first/: Python package with core models, adapters, delta logic, and rendering helpers
+- tests/: Unit tests for models, delta logic, and adapters
+- AGENTS.md: Architecture and contribution guidance
+- test.sh: Test runner that executes tests and packaging checks
+
+Usage example (quick)
+- Load a CSV telemetry file via CSVAdapter, reconcile with a local delta, and render a snapshot:
+  - adapter = CSVAdapter("telemetry.csv")
+  - telem = adapter.load_telemetry()
+  - snapshot = render.render_snapshot([asset], telem, weather, events)
+  - print(snapshot)
+
+This repository adheres to the contribution guidelines described in AGENTS.md and is designed to be extended in sprint fashion.
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..965af01
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,16 @@
+[build-system]
+requires = ["setuptools>=42", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "idea78_solarsphere_offline_first"
+version = "0.1.0"
+description = "Offline-first geospatial visualization scaffolding for SolarSphere MVP"
+readme = "README.md"
+requires-python = ">=3.9"
+dependencies = []
+
+[tool.setuptools]
+package-dir = {"" = "src"}
+
+# Removed legacy setuptools.find block to ensure compatibility with current build backends
diff --git a/src/idea78_solarsphere_offline_first/__init__.py b/src/idea78_solarsphere_offline_first/__init__.py
new file mode 100644
index 0000000..7d06195
--- /dev/null
+++ b/src/idea78_solarsphere_offline_first/__init__.py
@@ -0,0 +1,5 @@
+"""Idea78 SolarSphere Offline-First package initializer"""
+
+__version__ = "0.1.0"
+
+from .core import Asset, TelemetryPoint, WeatherLayer, Event  # re-export core types
diff --git a/src/idea78_solarsphere_offline_first/core.py b/src/idea78_solarsphere_offline_first/core.py
new file mode 100644
index 0000000..1ade642
--- /dev/null
+++ b/src/idea78_solarsphere_offline_first/core.py
@@ -0,0 +1,55 @@
+"""Core data primitives for SolarSphere offline-first MVP."""
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import List, Dict
+import json
+
+
+@dataclass
+class Asset:
+    site_id: str
+    location: Dict[str, float]  # e.g., {"lat": 12.34, "lon": 56.78}
+    layers: List[str] = field(default_factory=list)
+    version: int = 1
+
+    def to_json(self) -> str:
+        return json.dumps(self, default=lambda o: o.__dict__, sort_keys=True)
+
+
+@dataclass
+class TelemetryPoint:
+    site_id: str
+    ts: int  # epoch milliseconds
+    lat: float
+    lon: float
+    metric: str
+    value: float
+    quality: str = "good"
+
+    def to_json(self) -> str:
+        return json.dumps(self, default=lambda o: o.__dict__, sort_keys=True)
+
+
+@dataclass
+class WeatherLayer:
+    region: str
+    ts: int
+    param: str
+    value: float
+    source: str
+
+    def to_json(self) -> str:
+        return json.dumps(self, default=lambda o: o.__dict__, sort_keys=True)
+
+
+@dataclass
+class Event:
+    ts: int
+    site_id: str
+    type: str
+    description: str
+    severity: str
+
+    def to_json(self) -> str:
+        return json.dumps(self, default=lambda o: o.__dict__, sort_keys=True)
diff --git a/src/idea78_solarsphere_offline_first/csv_adapter.py b/src/idea78_solarsphere_offline_first/csv_adapter.py
new file mode 100644
index 0000000..cbd0b5b
--- /dev/null
+++ b/src/idea78_solarsphere_offline_first/csv_adapter.py
@@ -0,0 +1,40 @@
+"""CSV-based adapter for ingesting telemetry data (MVP)."""
+from __future__ import annotations
+
+import csv
+from typing import List
+
+from .core import TelemetryPoint
+
+
+class CSVAdapter:
+    """Simple CSV data adapter for TelemetryPoint ingest.
+
+    Expected CSV header:
+      site_id,ts,lat,lon,metric,value,quality
+    """
+
+    def __init__(self, path: str):
+        self.path = path
+
+    def load_assets(self) -> List:
+        # MVP: not implemented for tests; return empty list
+        return []
+
+    def load_telemetry(self) -> List[TelemetryPoint]:
+        pts: List[TelemetryPoint] = []
+        with open(self.path, newline="") as f:
+            reader = csv.DictReader(f)
+            for row in reader:
+                pts.append(
+                    TelemetryPoint(
+                        site_id=row["site_id"],
+                        ts=int(row["ts"]),
+                        lat=float(row["lat"]),
+                        lon=float(row["lon"]),
+                        metric=row["metric"],
+                        value=float(row["value"]),
+                        quality=row.get("quality", "good"),
+                    )
+                )
+        return pts
diff --git a/src/idea78_solarsphere_offline_first/delta.py b/src/idea78_solarsphere_offline_first/delta.py
new file mode 100644
index 0000000..0c7867c
--- /dev/null
+++ b/src/idea78_solarsphere_offline_first/delta.py
@@ -0,0 +1,35 @@
+"""Deterministic, replay-friendly delta reconciliation helpers."""
+from __future__ import annotations
+
+from typing import List, Dict, Tuple
+from .core import TelemetryPoint
+
+
+def _key(pt: TelemetryPoint) -> Tuple[str, int, str]:
+    # Unique key for a telemetry point by site, timestamp, and metric
+    return (pt.site_id, pt.ts, pt.metric)
+
+
+def reconcile_deltas(local: List[TelemetryPoint], remote: List[TelemetryPoint]) -> List[TelemetryPoint]:
+    """Deterministically merge local and remote telemetry points.
+
+    Remote data takes precedence when keys collide. The function returns a new
+    list containing the merged view. Order is not guaranteed but deterministic
+    with respect to the input keys.
+    """
+    merged: Dict[Tuple[str, int, str], TelemetryPoint] = {}
+
+    for p in local:
+        merged[_key(p)] = p
+    for p in remote:
+        merged[_key(p)] = p
+
+    return list(merged.values())
+
+
+class TelemetryDelta:
+    def __init__(self, delta: List[TelemetryPoint], ts: int, anchor: str, signature: str):
+        self.delta = delta
+        self.ts = ts
+        self.anchor = anchor
+        self.signature = signature
diff --git a/src/idea78_solarsphere_offline_first/render.py b/src/idea78_solarsphere_offline_first/render.py
new file mode 100644
index 0000000..0193ac3
--- /dev/null
+++ b/src/idea78_solarsphere_offline_first/render.py
@@ -0,0 +1,18 @@
+"""Lightweight render summary for offline-first MVP.
+
+This is intentionally data-centric (JSON-friendly) to support downstream
+visualization layers without a browser runtime in this MVP.
+"""
+from __future__ import annotations
+
+from typing import List
+from .core import Asset, TelemetryPoint, WeatherLayer, Event
+
+
+def render_snapshot(assets: List[Asset], telemetry: List[TelemetryPoint], weather: List[WeatherLayer], events: List[Event]) -> dict:
+    return {
+        "assets": [a.__dict__ for a in assets],
+        "telemetry_count": len(telemetry),
+        "weather_count": len(weather),
+        "events": len(events),
+    }
diff --git a/test.sh b/test.sh
new file mode 100755
index 0000000..7f29ad2
--- /dev/null
+++ b/test.sh
@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Basic test suite and packaging verification for SolarSphere MVP
+echo "Running tests..."
+pytest -q
+
+echo "Building package..."
+python3 -m build
+
+echo "All tests passed and package built."
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..c7ac40f
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,7 @@
+import os
+import sys
+
+# Ensure the local src package is importable by pytest
+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)
diff --git a/tests/test_csv_adapter.py b/tests/test_csv_adapter.py
new file mode 100644
index 0000000..f80c1b0
--- /dev/null
+++ b/tests/test_csv_adapter.py
@@ -0,0 +1,20 @@
+import tempfile
+import os
+from idea78_solarsphere_offline_first.csv_adapter import CSVAdapter
+from idea78_solarsphere_offline_first.core import TelemetryPoint
+
+
+def test_csv_adapter_loads_telemetry_points():
+    with tempfile.NamedTemporaryFile(mode="w+", delete=False, suffix=".csv") as tf:
+        tf.write("site_id,ts,lat,lon,metric,value,quality\n")
+        tf.write("siteA,1000,1.0,2.0,temperature,25.0,good\n")
+        tf.flush()
+        path = tf.name
+
+    adapter = CSVAdapter(path)
+    pts = adapter.load_telemetry()
+    assert isinstance(pts, list) and len(pts) == 1
+    p = pts[0]
+    assert isinstance(p, TelemetryPoint)
+    assert p.site_id == "siteA" and p.metric == "temperature" and p.value == 25.0
+    os.unlink(path)
diff --git a/tests/test_delta.py b/tests/test_delta.py
new file mode 100644
index 0000000..312a169
--- /dev/null
+++ b/tests/test_delta.py
@@ -0,0 +1,10 @@
+from idea78_solarsphere_offline_first.core import TelemetryPoint
+from idea78_solarsphere_offline_first.delta import reconcile_deltas
+
+
+def test_reconcile_deltas_basic_override():
+    local = [TelemetryPoint(site_id="S1", ts=1000, lat=0.0, lon=0.0, metric="temp", value=20.0)]
+    remote = [TelemetryPoint(site_id="S1", ts=1000, lat=0.0, lon=0.0, metric="temp", value=22.5)]
+    merged = reconcile_deltas(local, remote)
+    assert len(merged) == 1
+    assert merged[0].value == 22.5
diff --git a/tests/test_models.py b/tests/test_models.py
new file mode 100644
index 0000000..5be3ac6
--- /dev/null
+++ b/tests/test_models.py
@@ -0,0 +1,18 @@
+from idea78_solarsphere_offline_first.core import Asset, TelemetryPoint, WeatherLayer, Event
+
+
+def test_asset_dataclass():
+    a = Asset(site_id="site-01", location={"lat": 12.34, "lon": 56.78}, layers=["terrain", "overlay"], version=1)
+    assert a.site_id == "site-01"
+    assert isinstance(a.layers, list) and a.layers[0] == "terrain"
+
+
+def test_telemetry_point_dataclass():
+    t = TelemetryPoint(site_id="site-01", ts=1234567890, lat=12.3, lon=45.6, metric="temp", value=22.5)
+    assert t.metric == "temp" and t.value == 22.5
+
+
+def test_weather_event_dataclass():
+    w = WeatherLayer(region="region-1", ts=1000, param="wind", value=5.4, source="sim")
+    e = Event(ts=1000, site_id="site-01", type="maintenance", description="routine check", severity="low")
+    assert w.param == "wind" and e.severity == "low"