Getting closer. I think.

.github/workflows/nuget_slack_notifications.yml

@@ -2,12 +2,12 @@ name: Check for new core technologies
 
 on:
   schedule:
-   - cron:  '0 10 * * *'
+   - cron:  '0 10 * * 1' # Every Monday at 10:00 AM
   workflow_dispatch:
     inputs:
       daysToSearch:
-        description: "Days of NuGet history to search for package updates"
-        default: "1"
+        description: "Days of NuGet history to search for package updates (0 to search since last run of this workflow on main)"
+        default: "0"
         type: string
       testMode:
         description: "If checked, no notification message will be sent to the team channel, nor will any Github issues be created."
@@ -50,6 +50,7 @@ jobs:
           dotnet publish -o ${{ env.scan-tool-publish-path }}
 
       - name: Find timestamp of most recent run of this workflow and set as an environment variable
+        if: inputs.daysToSearch == '0' || github.event_name == 'schedule'
         env:
           GH_TOKEN: ${{ github.token }}
         run: |

.github/workflows/scripts/nugetSlackNotifications/Program.cs

@@ -23,7 +23,7 @@ public class Program
         private static readonly HttpClient _client = new();
         private static List<NugetVersionData> _newVersions = new();
 
-        private static readonly int _daysToSearch = int.TryParse(Environment.GetEnvironmentVariable("DOTTY_DAYS_TO_SEARCH"), out var days) ? days : 1; // How many days of package release history to scan for changes
+        private static readonly int _daysToSearch = int.TryParse(Environment.GetEnvironmentVariable("DOTTY_DAYS_TO_SEARCH"), out var days) ? int.Max(1, days) : 1; // How many days of package release history to scan for changes
         private static readonly bool _testMode = bool.TryParse(Environment.GetEnvironmentVariable("DOTTY_TEST_MODE"), out var testMode) ? testMode : false;
         private static readonly string _webhook = Environment.GetEnvironmentVariable("DOTTY_WEBHOOK");
         private static readonly string _githubToken = Environment.GetEnvironmentVariable("DOTTY_TOKEN");
@@ -40,7 +40,7 @@ static async Task Main()
             // Otherwise, search from _lastRunTimestamp.
             var searchTime = _lastRunTimestamp == DateTimeOffset.MinValue ? DateTimeOffset.UtcNow.Date.AddDays(-_daysToSearch) : _lastRunTimestamp;
 
-            Log.Information($"Searching for package updates between {searchTime.ToUniversalTime():s}Z and {DateTimeOffset.UtcNow.ToUniversalTime():s}Z.");
+            Log.Information($"Searching for package updates since {searchTime.ToUniversalTime():s}Z.");
 
             // initialize nuget repo
             var ps = new PackageSource("https://api.nuget.org/v3/index.json");