Merge pull request #1 from otapiero/copilot/update-prompt-key-configuration

Auto-apply configured Label from PromptConfiguration during prompt fetching

Author: otapiero

Models/PromptConfiguration.cs

@@ -14,7 +14,9 @@ public sealed class PromptConfiguration
 
     /// <summary>
     /// Optional label to use (e.g., "production", "staging", "latest")
-    /// If neither version nor label is specified, defaults to "production"
+    /// When configured, this label will be automatically used when fetching the prompt,
+    /// unless explicitly overridden by passing a different label to GetPromptAsync/GetChatPromptAsync.
+    /// If neither version nor label is specified, Langfuse will use its default behavior.
     /// </summary>
     public string? Label { get; set; }
 }

README.md

@@ -33,7 +33,7 @@ builder.Services.AddPromptProvider(
 
 - `configureLangfuse`: (optional) Bind Langfuse API credentials and URL
 - `configurePrompts`: (optional) Bind local prompt defaults
-- `configurePromptKeys`: (optional) Map logical prompt names to Langfuse keys/labels
+- `configurePromptKeys`: (optional) Map logical prompt names to Langfuse keys/labels. When a label is configured here, it will be used automatically when fetching prompts unless explicitly overridden.
 
 ### 2. Example `appsettings.json`
 
@@ -62,6 +62,11 @@ builder.Services.AddPromptProvider(
 }
 ```
 
+**Note on Labels**: When you configure a `Label` in `PromptKeys`, it will be automatically used when fetching that prompt. For example:
+- If `ChatTitle` is configured with `"Label": "staging"`, calling `GetPromptAsync("ChatTitle")` will fetch the "staging" label from Langfuse
+- You can still override this by explicitly passing a label: `GetPromptAsync("ChatTitle", label: "production")` will use the "production" label instead
+- If no label is configured and none is provided, Langfuse will use its default behavior (typically "production")
+
 ---
 
 ## Usage Example

Services/PromptService.cs

@@ -163,27 +163,18 @@ public async Task<ChatPromptResponse> CreateChatPromptAsync(CreateChatPromptRequ
 
         var logicalKey = promptKey; // keep original for local fallback
 
-        // If the promptKey matches a configured logical key, use its mapping (string -> actual langfuse key)
-        var promptKeys = _defaultPromptsProvider.GetPromptKeys();
-        string actualKey;
-        if (promptKeys != null && promptKeys.TryGetValue(logicalKey, out var mappedConfig) && mappedConfig is PromptConfiguration config && !string.IsNullOrWhiteSpace(config.Key))
-        {
-            actualKey = config.Key;
-        }
-        else
-        {
-            actualKey = logicalKey;
-        }
+        // Resolve the actual Langfuse key and effective label
+        var (actualKey, effectiveLabel) = ResolvePromptKeyAndLabel(logicalKey, label);
 
         // If Langfuse is configured, try to fetch from it first
         if (_langfuseOptions.Value.IsConfigured())
         {
             try
             {
                 _logger.LogInformation("Fetching prompt '{LogicalKey}' -> '{ActualKey}' (version: {Version}, label: {Label}) from Langfuse",
-                    logicalKey, actualKey, version, label);
+                    logicalKey, actualKey, version, effectiveLabel);
 
-                var langfusePrompt = await _langfuseService.GetPromptAsync(actualKey, version, label, cancellationToken);
+                var langfusePrompt = await _langfuseService.GetPromptAsync(actualKey, version, effectiveLabel, cancellationToken);
 
                 if (langfusePrompt != null)
                 {
@@ -230,27 +221,18 @@ public async Task<ChatPromptResponse> CreateChatPromptAsync(CreateChatPromptRequ
 
         var logicalKey = promptKey;
 
-        // If the promptKey matches a configured logical key, use its mapping
-        var promptKeys = _defaultPromptsProvider.GetPromptKeys();
-        string actualKey;
-        if (promptKeys != null && promptKeys.TryGetValue(logicalKey, out var mappedConfig) && mappedConfig is PromptConfiguration config && !string.IsNullOrWhiteSpace(config.Key))
-        {
-            actualKey = config.Key;
-        }
-        else
-        {
-            actualKey = logicalKey;
-        }
+        // Resolve the actual Langfuse key and effective label
+        var (actualKey, effectiveLabel) = ResolvePromptKeyAndLabel(logicalKey, label);
 
         // If Langfuse is configured, try to fetch from it first
         if (_langfuseOptions.Value.IsConfigured())
         {
             try
             {
                 _logger.LogInformation("Fetching chat prompt '{LogicalKey}' -> '{ActualKey}' (version: {Version}, label: {Label}) from Langfuse",
-                    logicalKey, actualKey, version, label);
+                    logicalKey, actualKey, version, effectiveLabel);
 
-                var langfusePrompt = await _langfuseService.GetChatPromptAsync(actualKey, version, label, cancellationToken);
+                var langfusePrompt = await _langfuseService.GetChatPromptAsync(actualKey, version, effectiveLabel, cancellationToken);
 
                 if (langfusePrompt != null)
                 {
@@ -398,6 +380,29 @@ public async Task<PromptResponse> UpdatePromptLabelsAsync(
         }
     }
 
+    private (string actualKey, string? effectiveLabel) ResolvePromptKeyAndLabel(string logicalKey, string? providedLabel)
+    {
+        var promptKeys = _defaultPromptsProvider.GetPromptKeys();
+        string actualKey;
+        string? effectiveLabel = providedLabel; // Start with the provided label
+        
+        if (promptKeys != null && promptKeys.TryGetValue(logicalKey, out var mappedConfig) && mappedConfig is PromptConfiguration config && !string.IsNullOrWhiteSpace(config.Key))
+        {
+            actualKey = config.Key;
+            // If no label was explicitly provided, use the configured label (if any)
+            if (providedLabel == null && !string.IsNullOrWhiteSpace(config.Label))
+            {
+                effectiveLabel = config.Label;
+            }
+        }
+        else
+        {
+            actualKey = logicalKey;
+        }
+        
+        return (actualKey, effectiveLabel);
+    }
+
     private PromptResponse? GetPromptFromDefaults(string promptKey)
     {
         var defaults = _defaultPromptsProvider.GetDefaults();