Configured Confidential Client Flow using Microsoft.Identity.Web and .AddMicrosoftIdentityWebApp.
Configured .AddInMemoryTokenCaches() for prototype token persistence.
Implemented ITokenAcquisition within the SyncEngine for obtaining tokens on behalf of users asynchronously to support background/webhook execution flows using a custom constructed ClaimsPrincipal mapped to the user's HomeAccountId.

SQLite + EF Core integration (Microsoft.EntityFrameworkCore.Sqlite).
Models:
- UserConfig: Stores UserId, HomeAccountId, Email, SubscriptionId, Expiration, and LastDeltaLink.
- WebhookLog: Stores raw json payloads, endpoint types, and timestamps.
Dashboard (SyncController): Shows both active users and real-time webhook logs in a responsive, clean Bootstrap table format.

NotificationsController implemented with /api/notifications/listen and /api/notifications/lifecycle.
Transparency First: Every incoming request stream is captured and immediately persisted to WebhookLogs before parsing.
Handshake Validation: Instant response logic for validationToken parameters returning text/plain.
Security Check: The payloads are deserialized to confirm the clientState against the configuration string. If valid, the engine triggers an asynchronous background sync job for the subscriptionId.

Encapsulated logic inside SyncEngine.cs using GraphServiceClient.
Uses Delta Query with stateful links saved back to the database.
Implements custom SHA-256 deduplication on events grouping by Subject + Start + End.
Exports a CSV file via the OneDrive Graph API Drives["me"].Items["root:/SyncResults.csv:"].Content.PutAsync(stream).

Added SubscriptionRenewalService inheriting from BackgroundService.
Triggers every 12 hours. Scans the database for Expiration < 24h.
Re-authenticates the user contexts and patches their graph subscriptions to a new 4230 minutes limit.

Overhauled the default Home/Index.cshtml landing page.
Created an Onboard action triggered by a "Connect Microsoft Calendar" button that forces authorization.
Completes the initial flow by storing user information, running a baseline delta query, setting up the webhook subscription, and then safely redirecting the user to the transparency dashboard.