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Why LayReX?

You need	LayeredChat gives you
Versioned “personalities” without copy-pasting prompts	OrchestrationProfileManifest + registry keys (OrchestrationRegistryKeys.Compose)
Swap models (OpenAI, Azure, Ollama, MEAI, …)	ILlmChatConnector, OpenAiCompatible, ExtensionsAiChatConnector
RAG / SQL / vectors as first-class context	IDataSourceProvider + PostgreSQL, MongoDB, Qdrant packages
SSE / buses / gateways	RunTurnStreamingAsync → OrchestrationStreamEnvelope
Remote version pods	ExternalForwardUri + HttpOrchestrationForwarder + VersionHost
Composed orchestration layers	LayerStackManifest, LayerContribution, ILayerCompositionService; see docs/LAYER_PACKAGE_FORMAT.md
Optional layer registry + CLI	LayeredChat.ControlPlane, LayReX.ControlPlane.Client, LayReX-CLI

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Packages (NuGet-ready)

Package	Purpose
LayeredChat.Core	Orchestrator, manifests, layer composition, telemetry, streaming, forward DTOs
LayReX.ControlPlane.Client	HTTP client for the optional layer registry (publish from LayReX repo)
LayReX.CLI	Global tool layrex — validate/pack/push bundles (LayReX-CLI)
LayeredChat.Connectors.OpenAiCompatible	OpenAI-style HTTP (sync + SSE)
LayeredChat.Connectors.ExtensionsAi	Microsoft.Extensions.AI.IChatClient
LayeredChat.Data.PostgreSql	SQL slices + postgresql_readonly_select tool
LayeredChat.Data.MongoDb	Mongo find slice + mongodb_find_json tool
LayeredChat.Data.Qdrant	Vector search slice
LayeredChat.Integrations.Mcp	Model Context Protocol tools → IToolCatalog / IToolExecutor (official ModelContextProtocol SDK)

Install from NuGet

Packages are published under the LayeredChat.* IDs on nuget.org. Typical app references:

dotnet add package LayeredChat.Core
dotnet add package LayeredChat.Connectors.OpenAiCompatible

Add connectors, data providers, or MCP as needed (LayeredChat.Connectors.ExtensionsAi, LayeredChat.Data.PostgreSql, LayeredChat.Integrations.Mcp, …).

Publish (maintainers): In the LayReX GitHub repo, add a secret NUGET_API_KEY (API key from nuget.org account API keys, scope Push for LayeredChat.*). Then either push a git tag v0.2.0, or run the Publish NuGet workflow manually and enter the same version string (without v).

Solution: LayeredChat.sln in this folder.

Layout: src/Core/LayeredChat.Core/ is split by feature (Chat/, Llm/, Tools/, Context/, Profiles/, Orchestration/, Forward/, Telemetry/, Agents/ — public namespace remains LayeredChat). Also: src/Connectors/..., src/Data/..., src/Integrations/Mcp, tests/, samples/VersionHost, deploy/version-pod.

Vector mark (SVG, crisp at any size): docs/assets/layeredx-readme-hero.svg

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Easiest API: LayeredChatHost

Instead of new LayeredChatOrchestrator(...) with five dependencies, build a single host object:

var host = LayeredChatHost.CreateBuilder()
    .UseConnector(myConnector)                    // ILlmChatConnector (required)
    .UseDefinitions(orchestrationDefinition)      // or .UseDefinitionRegistry(myRegistry)
    .UseTools(myToolCatalog, myToolExecutor)      // optional; defaults to no tools
    .UseDataSources(myDataSourceRegistry)        // optional; defaults to empty
    .Build();

var result = await host.RunTurnAsync(new LayeredChatTurnRequest { /* ... */ });
// host.Orchestrator — same instance if you need the raw type
// host.CreateAgent(registryKey) — IChatAgent for fixed-profile turns

For dependency injection, register one factory that returns LayeredChatHost (or register LayeredChatOrchestrator resolved from sp.GetRequiredService<LayeredChatHost>().Orchestrator). Decline-all tools: NoOpToolExecutor.Instance with an empty DictionaryToolCatalog.

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Quick start (manual wiring)

1. Define a manifest (JSON) or OrchestrationProfileManifest in code.
2. Register with InMemoryOrchestrationDefinitionRegistry or your own IOrchestrationDefinitionRegistry.
3. Wire connector, IToolCatalog, IToolExecutor, IDataSourceRegistry.
4. Call RunTurnAsync (finished turn) or RunTurnStreamingAsync (envelopes for SSE / SignalR / Kafka).

var registry = new InMemoryOrchestrationDefinitionRegistry();
registry.Register(new OrchestrationDefinition
{
    Manifest = new OrchestrationProfileManifest
    {
        OrchestrationId = "support",
        SemanticVersion = "2.1.0",
        DisplayName = "Support bot",
        AllowedToolNames = new[] { "kb_search" },
        DataSourceIdsInOrder = new[] { "policies_pg" },
        Parameters = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
        {
            ["pgsql.sql"] = "SELECT title, body FROM policies LIMIT 20;"
        }
    }
});

var http = new HttpClient { Timeout = TimeSpan.FromMinutes(5) };
var connector = new OpenAiCompatibleChatConnector(http, new OpenAiCompatibleOptions
{
    BaseUri = new Uri("https://api.openai.com/v1/"),
    Model = "gpt-4o-mini",
    ApiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY")
});

var dataSources = new DataSourceRegistry(new IDataSourceProvider[]
{
    new PostgreSqlParameterDataSource("policies_pg", npgsqlDataSource)
});

var orchestrator = new LayeredChatOrchestrator(
    connector,
    myToolExecutor,
    myToolCatalog,
    registry,
    dataSources);

var result = await orchestrator.RunTurnAsync(new LayeredChatTurnRequest
{
    OrchestrationRegistryKey = OrchestrationRegistryKeys.Compose("support", "2.1.0"),
    SystemInstructionText = "You are a concise support agent.",
    UserMessageContent = "How do I reset my password?",
    PriorMessages = Array.Empty<ChatMessage>(),
    Session = new OrchestrationSessionContext { TenantKey = "acme" }
});

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Agents (named orchestration profiles)

• IChatAgent — fixed OrchestrationRegistryKey with RunTurnAsync / RunTurnStreamingAsync over AgentTurnInput (no key on each call).
• LayeredChatAgent — thin wrapper over LayeredChatOrchestrator.
• LayeredChatAgentRegistry — register many agents (e.g. sales, support) on one orchestrator.

Model Context Protocol (MCP)

1. await McpToolSession.ConnectStdioAsync(...) or ConnectAsync(IClientTransport, ...).
2. Set manifest AllowedToolNames to the MCP tool names (use McpSessionOptions.ToolNamePrefix per server to avoid collisions).
3. Wire orchestrator:

var mcp = await McpToolSession.ConnectStdioAsync(new StdioClientTransportOptions
{
    Name = "tools",
    Command = "npx",
    Arguments = ["-y", "@modelcontextprotocol/server-filesystem", "."]
}, new McpSessionOptions { ToolNamePrefix = "fs_" });

var catalog = McpOrchestrationWiring.CombineHostCatalogThenMcp(hostCatalog, mcp.Catalog);
var executor = McpOrchestrationWiring.RoutePrefixedMcpThenHost("fs_", mcp.Executor, hostExecutor);

4. Use CompositeToolCatalog and RoutedToolExecutor in Core for other merge / routing patterns.

Multi-tenant hosts can implement IMcpToolSessionFactory (LayeredChat.Integrations.Mcp) to create or pool McpToolSession instances per scope key (tenant, user, etc.).

Connectors & LLM versioning

• OpenAI-compatible HTTP — one client for OpenAI, Azure OpenAI, Ollama, vLLM, LiteLLM gateways, etc. Per-request model: LlmRequestOptions.ModelNameOverride. See docs/CONNECTORS.md and OpenAiCompatibleWellKnownEndpoints for common base URLs.
• Microsoft.Extensions.AI — reuse your existing IChatClient registration; tools use declaration-only AIFunctionFactory.CreateDeclaration.
• Manifest hints — LlmAdapterProfileId, PreferredConnectorKind; runtime merge via LayeredChatTurnRequest.ModelAdapterProfile (LlmModelAdapterProfile).

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Data planes

• PostgreSQL — PostgreSqlParameterDataSource (pgsql.sql, pgsql.maxRows); tool PostgreSqlReadonlySelectTool with SELECT / WITH guardrails.
• MongoDB — MongoJsonFindDataSource; tool MongoFindTool.
• Qdrant — QdrantVectorSearchDataSource (vector JSON in manifest or session qdrant.queryVectorJson).
• Composition — CompositeDataSourceRegistry for tenant/global providers.

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Streaming vs finished turns

• Finished: RunTurnAsync → LayeredChatTurnResult (messages, tokens, CorrelationId, OrchestrationId, SemanticVersion).
• Streamed: RunTurnStreamingAsync → OrchestrationStreamEnvelope (AssistantTextDelta, tool lifecycle, TurnResultSummary, TurnCompleted).

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Observability

• IOrchestrationTelemetry on LayeredChatTurnRequest.Hooks — fan out with ChainedOrchestrationTelemetry. See docs/TELEMETRY_AND_BILLING.md for UsageUpdate, ModelRoundCompleted, and turn totals.
• Propagate OrchestrationSessionContext.CorrelationId end-to-end.

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Version pods (containers)

Manifest: externalForwardUri, externalForwardTimeoutSeconds.
Host: IHttpOrchestrationForwarder (HttpOrchestrationForwarder).

• Sample: samples/VersionHost — POST /v1/orchestration/forward
• Image build (run from this directory — the folder that contains LayeredChat.sln):
  docker build -f deploy/version-pod/Dockerfile -t layered-chat-version-host:latest .
• Compose / Kubernetes: deploy/version-pod/

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Build & test

dotnet build LayeredChat.sln
dotnet test tests/LayeredChat.Core.Tests/LayeredChat.Core.Tests.csproj

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Contributing

We love PRs that stay focused and match existing style.

1. Open an issue first for larger changes (connectors, manifest schema, breaking API).
2. Small fixes (docs, tests, typos) can go straight to a PR.
3. Core rule: LayeredChat.Core stays free of Npgsql, MongoDB, Qdrant, and product domains — put adapters in the named packages.
4. Tests: extend LayeredChat.Core.Tests or add a test project next to new packages.
5. Consumers embedding this tree in a larger repo: keep the same dotnet commands with your path prefix (e.g. libs/LayeredChat/).

If you use this library in the wild, a ⭐ on the repo or a short issue with your stack helps us prioritize.

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Security

• Treat SQL / Mongo tools as convenience, not authorization — use read-only DB roles and tenant-scoped connections.
• Never put secrets inside manifests; resolve keys in the host and pass via OrchestrationSessionContext.Properties if needed.

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License

MIT — see LICENSE. Each package also sets PackageLicenseExpression: MIT in MSBuild.

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Repository

Canonical home: github.com/OniuUI/LayReX.

LayReX · LayeredChat is a vendor-neutral LLM orchestration library: the public API lives under the LayeredChat root namespace and carries no host- or domain-specific types. Hero artwork: docs/assets/layeredx-hero.png (replace with your own branding if you fork).