Local AI Developer Reference

Advanced developer reference for programming against Local AI in FrameworX 10.1.5: AI.Execute deep semantics, hook attachment via reflection, custom MCP tool exposure, audit and redaction patterns, error envelope decision matrix, and worked code for non-trivial integrations.

Technical Reference → Programming and APIs Reference → Local AI Developer Reference

Version 10.1.5+

Audience and scope

This page is for solution developers and integrators who need to go beyond the configuration UI and reference docs — attaching audit hooks, exposing custom tools to the LLM, building diagnostic instrumentation around chat turns, or wrapping AI.Execute in higher-level abstractions specific to their solution.

The two surfaces, side by side

AI.Execute deep semantics

Signatures — canonical and legacy

// Canonical surface (use this in new code).
// Requires T.Toolkit.LocalAI in NamespaceDeclarations.
string       reply = AI.Execute(string query);          // sync wrapper
Task<string> reply = AI.ExecuteAsync(string query);     // native async

// Or fully qualified, no NamespaceDeclarations entry needed:
string       reply = T.Toolkit.LocalAI.AI.Execute(query);
Task<string> reply = T.Toolkit.LocalAI.AI.ExecuteAsync(query);

// Legacy aliases — [Obsolete] (CS0618), hidden from IntelliSense, forward
// to the canonical methods above. Kept for backward compatibility only.
string       reply = TK.AIExecute(string query);
Task<string> reply = TK.AIExecuteAsync(string query);

Sync vs async — pick the right wrapper

The synchronous wrapper unwraps the async call via the platform helper T.Library.tRPC.AsyncHelpers.RunSync. Do NOT use raw .Result or .GetAwaiter().GetResult() on AI.ExecuteAsync:

• .Result deadlocks under a UI SynchronizationContext (Display CodeBehind, certain Designer-side scripts).
• .GetAwaiter().GetResult() swallows the unwrap and surfaces an AggregateException instead of the inner exception, hiding the real cause.

The platform helper handles SynchronizationContext correctly and unwraps AggregateException to the inner exception. The same helper is the right pattern anywhere in FrameworX where sync-over-async is needed.

The ambient ObjectServer

AI.Execute resolves its ObjectServer from TK.ObjServer — the ambient ObjectServer in the calling code path. In a Server-domain script context this is the server-side ObjectServer; in a Display CodeBehind context it is the client-side instance.

The platform does not block client-side callers with a runtime gate; it relies on platform safety nets (secret resolver short-circuit, defensive defaults, master kill-switch) to surface a normal HTTP-error envelope rather than silently transmit unauthenticated traffic. See Local AI Architecture Reference § "Why no runtime view-client gate" for the full rationale.

Query format — plain vs structured

The query parameter accepts two shapes:

Structured fields:

Reply envelope — parsing pattern

The reply is always parseable JSON. Idiomatic dispatch:

string replyJson = AI.Execute(query);
JObject reply    = JObject.Parse(replyJson);

string status = reply.Value<string>("status");        // never null
long   ms     = reply.Value<long>("latencyMs");       // always parseable
string text   = reply.Value<string>("text") ?? "";

switch (status)
{
    case "ok":
        ConsumeAnswer(text);
        break;
    case "disabled":
        // Master kill-switch is off. warnings[] names the gate.
        LogDisabled((JArray)reply["warnings"]);
        break;
    case "truncated":
        // Wall-clock budget exceeded. text may carry a partial answer.
        ConsumePartial(text, (JArray)reply["warnings"]);
        break;
    default: // "error"
        LogError((JArray)reply["warnings"], ms);
        break;
}

Failure modes — exhaustive

AI.Execute never throws — every failure path lands here. The legacy TK.AIExecute alias inherits this contract through the forwarder.

Hook attachment via reflection (cached path)

The cached ChatRequest path raises two hooks per turn:

Hook semantics

• Multicast. Multiple handlers may attach; the chain runs sequentially.
• Async. Each handler is Func<string, Task<string>>; awaited in order.
• Mutation. Returning modified JSON is honoured; subsequent handlers see the modified version. Returning null is treated as "no mutation".
• Error isolation. A throwing handler is caught; warnings[] records "<HookName> handler '<MethodName>' threw: <message>"; the chain proceeds with the un-mutated input.
• No status flip. Hook failures do NOT change the envelope's status from ok to error — the LLM call still proceeds. status="error" is reserved for chain-aborting failures (HTTP error, malformed query, etc.).
• Cached path only. Atomic AI.Execute calls do NOT raise these hooks — chat-attached behaviour does not apply.

Attaching a handler

In 10.1.5, attachment uses reflection from a Server-domain script. The first-class binding surface (@Solution.AI.OnBeforeChat += handler) is post-10.1.5 work.

using System;
using System.Reflection;
using System.Threading.Tasks;
using Newtonsoft.Json.Linq;

public class LocalAIHookSetup
{
    // Call this once at solution startup — typically from a ServerStartup task
    // or a Server.Class method invoked during initialization.
    public static void AttachAll()
    {
        AttachOnBeforeChat(RedactPII);
        AttachOnAfterChatReply(LogReplyToAudit);
    }

    // ---- handler implementations ----

    static async Task<string> RedactPII(string queryJson)
    {
        try
        {
            var query = JObject.Parse(queryJson);
            string user = query.Value<string>("user") ?? "";

            // Strip 9-digit sequences that look like SSNs.
            user = System.Text.RegularExpressions.Regex.Replace(
                user, @"\b\d{3}-?\d{2}-?\d{4}\b", "[REDACTED]");

            query["user"] = user;
            return query.ToString();
        }
        catch
        {
            // Returning the input unchanged on failure is safe; the chain
            // will continue with the un-mutated input either way.
            return queryJson;
        }
    }

    static async Task<string> LogReplyToAudit(string replyJson)
    {
        try
        {
            var reply = JObject.Parse(replyJson);
            string status = reply.Value<string>("status") ?? "";
            long   ms     = reply.Value<long>("latencyMs");
            string text   = reply.Value<string>("text") ?? "";

            // Append to a Dataset, write to a tag, or emit to a custom log.
            // (See your Datasets module configuration for the right table.)
            // TK.WriteToDataset("AIChatAudit", new { status, ms, text, when = DateTime.UtcNow });
            return replyJson;
        }
        catch
        {
            return replyJson;
        }
    }

    // ---- reflection plumbing ----

    static void AttachOnBeforeChat(Func<string, Task<string>> handler)
        => AttachHook("OnBeforeChat", handler);

    static void AttachOnAfterChatReply(Func<string, Task<string>> handler)
        => AttachHook("OnAfterChatReply", handler);

    static void AttachHook(string eventName, Func<string, Task<string>> handler)
    {
        var aiType = T.Library.TAssembly.GetType(null, "T.Toolkit.LocalAI.LocalAIService");
        if (aiType == null)
            throw new InvalidOperationException("Local AI service type not found.");

        var getMethod = aiType.GetMethod(
            "Get",
            BindingFlags.NonPublic | BindingFlags.Static,
            null,
            new[] { typeof(ObjectServer) },
            null);

        var instance = getMethod.Invoke(null, new object[] { TK.ObjServer });

        var eventInfo = aiType.GetEvent(
            eventName,
            BindingFlags.NonPublic | BindingFlags.Instance);

        eventInfo.AddEventHandler(instance, handler);
    }
}

Detaching a handler

Symmetric: keep the Func<string, Task<string>> reference around and call eventInfo.RemoveEventHandler(instance, handler) when the handler should stop firing. Handlers attached via lambda without a captured reference cannot be detached individually.

Lifetime considerations

• Handlers persist for the lifetime of the TServer process — there is no automatic detach on solution reload.
• If AttachAll is called more than once (multiple ServerStartup invocations on certain reload paths), each attachment adds another handler to the chain. To avoid double-firing, gate with a static bool _attached or detach previously-attached handlers first.
• Throwing from a handler is safe (caught, recorded in warnings, chain continues), but a slow handler is not — the platform awaits each handler sequentially and counts the elapsed time against the 60 s wall-clock budget. Keep handlers fast or move slow work onto a fire-and-forget task.

Custom MCP tools — exposing solution methods to the LLM

The cached ChatRequest path can dispatch solution-authored tools when SolutionSettings.ModelOptions bit 0x20 (EnableCustomTools) is set in addition to the master bit 0x02.

Authoring a custom tool

A custom tool is a Script.Class method tagged with the platform's MCP-tool attribute. The class registers itself at solution startup; the cached path's tool-catalog assembler discovers tagged methods and exposes them to the LLM as OpenAI-compatible tools[] entries.

// In a Script.Class, e.g. "PlantTools":
public class PlantTools
{
    // Each method exposed to the LLM is a public method on a Script.Class
    // instance. The platform's tool-catalog discovery enumerates these
    // methods and builds OpenAI-compatible function descriptors from
    // their parameter signatures and XML doc comments.

    /// <summary>
    /// Returns the current production rate for a given line, in units/hour.
    /// </summary>
    /// <param name="lineId">Production line identifier (e.g. "Line1").</param>
    public double GetProductionRate(string lineId)
    {
        // Read from the live solution. Toolkit access works because the
        // method runs in TServer under a server-side ObjectServer.
        return (double)TK.GetTagValue($"Tag.{lineId}.ProductionRate");
    }

    /// <summary>
    /// Returns the count of active alarms in the named area.
    /// </summary>
    /// <param name="area">Plant area name (e.g. "BoilerHouse").</param>
    public int GetActiveAlarmCount(string area)
    {
        // Replace with the right tag / dataset query for your solution.
        return TK.QueryActiveAlarms(area).Count;
    }
}

How the LLM sees the tools

At chat-turn assembly, the platform inspects the registered Script.Class methods and produces function descriptors of the form:

{
  "type": "function",
  "function": {
    "name": "PlantTools_GetProductionRate",
    "description": "Returns the current production rate for a given line, in units/hour.",
    "parameters": {
      "type": "object",
      "properties": {
        "lineId": { "type": "string", "description": "Production line identifier (e.g. Line1)." }
      },
      "required": [ "lineId" ]
    }
  }
}

Argument descriptions are pulled from the XML <param> tags; method descriptions from <summary>. Write these as if they were API docs — the LLM reads them to decide when to call.

Dispatch trace

Every tool dispatch appears in the reply envelope's toolTrace[] array (see Local AI Reply Envelope Schema):

{
  "name":      "PlantTools_GetProductionRate",
  "args":      { "lineId": "Line1" },
  "result":    245.7,
  "status":    "ok",
  "timestamp": "2026-04-26T14:32:15.123Z",
  "elapsedMs": 4
}

Custom tool guidelines

• Pure functions are easiest. A method that reads tags and returns a value is straightforward to expose. Methods with side effects (writing tags, sending emails) demand more thought — the LLM will call the method when it judges the call useful, which may not match operator expectations.
• Parameter types should be JSON-friendly. Strings, numbers, booleans, arrays, and POCOs that serialize cleanly. Avoid passing platform-internal types.
• Return types should be small and structured. A few hundred bytes of structured JSON is ideal. Returning a 10 MB payload bloats the LLM context for the rest of the turn and may push the wall-clock budget.
• Document well. The LLM picks tools based on the descriptions. Vague descriptions produce vague tool selection.
• Mind the per-turn cap. The cached path enforces MaxToolDispatchesPerTurn = 5. If a chat turn realistically needs more than 5 dispatches, consider consolidating multiple reads into a single coarser-grained tool that returns a structured payload.

Audit logging — capturing every chat turn

Pattern: attach a single OnAfterChatReply hook that writes the turn outcome to a dataset row, a tag, or both. Recommended schema:

For the matching OnBeforeChat half (capturing the query that produced the reply), correlate by inserting an opaque turnId into the query's metadata field and reading it back in the after-hook.

Redaction — stripping content from queries before they leave the platform

Pattern: attach a single OnBeforeChat hook that walks the structured query, applies redaction rules to the user field (and context if needed), and returns the modified JSON.

Considerations:

• Apply to structured fields only. If the caller passed plain text, parse-and-rewrap to structured form, redact, and re-stringify.
• Failure-safe defaults. If parsing fails, return the input unchanged — the platform's chain semantics ensure the un-mutated input flows through.
• Stack with audit. The audit hook (above) sees the redacted query, not the original. If you need both, write the original to audit before the redaction hook runs (handler order is registration order).

Performance characteristics

Why the per-turn cap is 5

The cached path enforces MaxToolDispatchesPerTurn = 5 in 10.1.5. The cap is intentionally conservative for CPU-only deployments — common on industrial PCs and edge gateways without GPUs — where each LLM POST can take 5–15 seconds. A turn that hits the cap consumes up to 6 LLM POSTs (5 dispatches plus the terminal answer), which on the slow end of CPU latency lands inside the 60-second wall-clock budget. On GPU-class hardware (~0.5–2.5 s per POST) the cap is not the binding constraint — the wall-clock budget is. Realistic SCADA queries (single-tag read, alarm count, multi-tag diagnosis) rarely exceed 3–4 dispatches; 5 covers the typical operator interaction comfortably while preventing runaway loops.

For the cold-load cost, set OLLAMA_KEEP_ALIVE=24h in the environment of the Ollama host so the model stays resident.

Threading and ordering

• Cached path runs on the TCPServer dispatch thread for the inbound ServiceClient call. Hook handlers and tool dispatches execute synchronously on the same thread (each await chained sequentially).
• Atomic path runs on the calling script's thread. The sync wrapper unwraps async via AsyncHelpers.RunSync; the underlying async chain runs on whichever thread pool slot the platform helper assigns.
• Multiple concurrent chat turns from different Display panels are isolated by transcript cache key (ClientInfo.Guid). The Local AI service singleton is per-ObjectServer, so multiple turns share the singleton but operate on distinct cache entries and distinct outbound HTTP contexts.
• Hook handler ordering is registration order. If two handlers depend on each other (e.g., audit must see the original before redaction), register them in the order they should fire.

Worked example: chat-turn audit dataset

Wire OnAfterChatReply to append a row to a dataset called AIChatAudit on every cached turn. Datasets module configuration is out of scope for this page; the hook implementation:

static async Task<string> AppendChatAudit(string replyJson)
{
    try
    {
        var reply = JObject.Parse(replyJson);
        var row = new JObject
        {
            ["WhenUtc"]        = DateTime.UtcNow.ToString("o"),
            ["Status"]         = reply.Value<string>("status"),
            ["LatencyMs"]      = reply.Value<long>("latencyMs"),
            ["AnswerExcerpt"]  = Truncate(reply.Value<string>("text") ?? "", 256),
            ["Warnings"]       = string.Join("; ",
                                   ((JArray)reply["warnings"])
                                       .Values<string>()),
            ["ToolCount"]      = ((JArray)reply["toolTrace"]).Count,
            ["UserName"]       = TK.UserName ?? "",
            ["ClientGuid"]     = TK.ClientGuid ?? ""
        };

        // Replace with your dataset insert call.
        // TK.DatasetInsert("AIChatAudit", row);
    }
    catch
    {
        // Audit failures must not break chat — swallow and continue.
    }
    return replyJson;
}

static string Truncate(string s, int max)
    => s.Length <= max ? s : s.Substring(0, max - 1) + "…";

Worked example: rate-limit per operator

Reject queries exceeding N per minute per operator by returning a query JSON with a sentinel user message that produces a fast deterministic reply (or by returning unmutated and side-channel-rejecting via a separate mechanism).

using System.Collections.Concurrent;

static readonly ConcurrentDictionary<string, (DateTime windowStart, int count)> _rl
    = new ConcurrentDictionary<string, (DateTime, int)>();

const int MaxPerMinute = 30;

static async Task<string> RateLimit(string queryJson)
{
    string user = TK.UserName ?? "anon";
    var now = DateTime.UtcNow;

    var (windowStart, count) = _rl.GetOrAdd(user, _ => (now, 0));
    if ((now - windowStart).TotalSeconds >= 60)
    {
        windowStart = now;
        count = 0;
    }
    count++;
    _rl[user] = (windowStart, count);

    if (count > MaxPerMinute)
    {
        // Rewrite the query to a no-op that the LLM will answer briefly.
        // The reply envelope still comes back as status="ok" — log the
        // limit-hit elsewhere if you need a hard reject signal.
        var capped = new JObject
        {
            ["system"] = "Reply with the exact text: 'Rate limit reached. Please wait a moment.'",
            ["user"]   = "ack"
        };
        return capped.ToString();
    }
    return queryJson;
}

For a hard-reject pattern (returning status="error" directly without an LLM round-trip), the post-10.1.5 first-class binding surface will expose a "short-circuit" signal. In 10.1.5, the LLM round-trip happens regardless — the rewrite above keeps the round-trip cheap and predictable.

Anti-patterns

• Don't poll the reply envelope. AI.Execute is sync; it returns when the reply is ready. There is no "result tag" for an async result that needs polling.
• Don't ignore status. Treating text as authoritative without checking status means a disabled or error envelope (with empty text) silently produces an empty UI field. Always dispatch on status.
• Don't catch and re-throw inside hooks. Hook errors are caught by the platform and recorded in warnings[]. Re-throwing achieves nothing the platform doesn't already do, and sometimes loses the original exception.
• Don't depend on hook ordering across solution loads. If hooks A and B both register at startup, they run in registration order — but if a future change reorders the registration, behaviour changes silently. Make hooks order-independent where possible.
• Don't block on slow I/O inside a hook. The platform awaits each handler sequentially against the 60 s budget. Long-running work belongs in a fire-and-forget task spawned from the hook, not in the hook itself.
• Don't pass huge context blobs. A 50 KB context object inflates the LLM prompt for every turn. Trim to the minimum the LLM needs to answer.
• Don't expose tools that decompose work the LLM would otherwise batch. Five fine-grained "GetTagX", "GetTagY", "GetTagZ" tools force the LLM to make 3 dispatches when one "GetPlantSnapshot" tool returning all three values would do it in one. Coarse-grained tools fit the per-turn cap better.
• Don't author new code against TK.AIExecute. The legacy alias compiles with a CS0618 warning and is hidden from IntelliSense. Use AI.Execute from the T.Toolkit.LocalAI namespace.

Cross-references

• Local AI — capability page with quick-start and worked examples.
• Local AI Architecture Reference — internal architecture, code organization, gate semantics.
• Local AI Configuration — endpoint, master enable, bitmask.
• ChatRequest Action Reference — operator-chat surface.
• AI.Execute API Reference — atomic script API surface (canonical AI.Execute + legacy alias migration).
• Local AI Reply Envelope Schema — uniform reply schema.
• SecuritySecrets Authentication for Local AI — credential management.
• AI Runtime Developer Reference — peer reference for the AI Runtime Connector (external AI clients connecting to TServer).

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