Update hosted-agents samples to gpt-5.4-mini (#607)

Replace gpt-4.1-mini with gpt-5.4-mini across the python and csharp hosted-agents samples, and bump the langgraph-chat azure.yaml model version to 2026-03-17 (SKU remains GlobalStandard).

Author: therealjohn

samples/csharp/hosted-agents/agent-framework/a2a/01-delegation/caller/agent.manifest.yaml

@@ -36,7 +36,7 @@ parameters:
         (printed by executor/scripts/setup-a2a after enabling incoming A2A).
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME
   - kind: connection
     name: math-expert-a2a

samples/csharp/hosted-agents/agent-framework/a2a/01-delegation/executor/agent.manifest.yaml

@@ -28,5 +28,5 @@ template:
       value: "{{AZURE_AI_MODEL_DEPLOYMENT_NAME}}"
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME

samples/csharp/hosted-agents/agent-framework/agent-skills/agent.manifest.yaml

@@ -45,5 +45,5 @@ parameters:
 
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME

samples/csharp/hosted-agents/agent-framework/azure-search-rag/Program.cs

@@ -15,7 +15,7 @@
 
 var projectEndpoint = new Uri(Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT")
     ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT environment variable is not set."));
-var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-4.1-mini";
+var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-5.4-mini";
 var searchEndpoint = new Uri(Environment.GetEnvironmentVariable("AZURE_SEARCH_ENDPOINT")
     ?? throw new InvalidOperationException("AZURE_SEARCH_ENDPOINT environment variable is not set."));
 var indexName = Environment.GetEnvironmentVariable("AZURE_SEARCH_INDEX_NAME") ?? "contoso-outdoors";

samples/csharp/hosted-agents/agent-framework/azure-search-rag/agent.manifest.yaml

@@ -36,7 +36,7 @@ parameters:
   properties: []
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME
   - kind: tool
     id: azure_ai_search

samples/csharp/hosted-agents/agent-framework/file-tools/.env.example

@@ -1,4 +1,4 @@
 FOUNDRY_PROJECT_ENDPOINT=https://<account>.services.ai.azure.com/api/projects/<project>
-AZURE_AI_MODEL_DEPLOYMENT_NAME=gpt-4.1-mini
+AZURE_AI_MODEL_DEPLOYMENT_NAME=gpt-5.4-mini
 ASPNETCORE_URLS=http://+:8088
 ASPNETCORE_ENVIRONMENT=Development

samples/csharp/hosted-agents/agent-framework/file-tools/Program.cs

@@ -14,7 +14,7 @@
 var projectEndpoint = new Uri(Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT")
     ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT environment variable is not set."));
 
-var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-4.1-mini";
+var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-5.4-mini";
 
 // Bundled root: files copied into the published output via csproj <Content Include="resources\**">.
 // In the container this resolves to /app/resources/.

samples/csharp/hosted-agents/agent-framework/file-tools/agent.manifest.yaml

@@ -34,5 +34,5 @@ parameters:
 
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME

samples/csharp/hosted-agents/agent-framework/foundry-memory-rag/Program.cs

@@ -23,7 +23,7 @@
 
 var projectEndpoint = new Uri(Environment.GetEnvironmentVariable("FOUNDRY_PROJECT_ENDPOINT")
     ?? throw new InvalidOperationException("FOUNDRY_PROJECT_ENDPOINT environment variable is not set."));
-var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-4.1-mini";
+var deployment = Environment.GetEnvironmentVariable("AZURE_AI_MODEL_DEPLOYMENT_NAME") ?? "gpt-5.4-mini";
 var embeddingDeployment = Environment.GetEnvironmentVariable("AZURE_AI_EMBEDDING_DEPLOYMENT_NAME") ?? "text-embedding-3-small";
 var memoryStoreName = Environment.GetEnvironmentVariable("AZURE_AI_MEMORY_STORE_ID") ?? "foundry-memory-rag-store";
 

samples/csharp/hosted-agents/agent-framework/foundry-memory-rag/agent.manifest.yaml

@@ -34,7 +34,7 @@ parameters:
   properties: []
 resources:
   - kind: model
-    id: gpt-4.1-mini
+    id: gpt-5.4-mini
     name: AZURE_AI_MODEL_DEPLOYMENT_NAME
   - kind: model
     id: text-embedding-3-small