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# .NET Assist — Debug and SQL evidence

Generated SQL providers send structured execution metadata to the trusted
`IDiagnosticSqlLogSink`. Install `SafeSqlEvidenceSink` to retain a bounded,
privacy-projected evidence while still emitting the default operator-readable log.

```csharp
using System.Collections.Generic;
using System.IO;
using System.Linq;
using TeaQL.Core;
using TeaQL.DataService;
using TeaQL.Runtime;

namespace Generated;

public sealed record SafeSqlEvidence(
    string Operation,
    string ParameterizedSql,
    int ParameterCount,
    long ElapsedMicros,
    int? ResultCount,
    long? AffectedRows,
    string ResultSummary,
    IReadOnlyList<TraceNode> TraceChain,
    IReadOnlyList<TraceNode> TracePath);

public static class DebugEvidence
{
    public static IReadOnlyList<SafeSqlEvidence> Safe(SafeSqlEvidenceSink sink) => sink.Snapshot();
}

public sealed class SafeSqlEvidenceSink : IDiagnosticSqlLogSink
{
    private const int Capacity = 256;
    private readonly object gate = new();
    private readonly List<SafeSqlEvidence> entries = new();
    private readonly TextDiagnosticSqlLogSink text;

    public SafeSqlEvidenceSink(TextWriter? writer = null) => text = new(writer);

    public void Write(ExecutionMetadata metadata)
    {
        text.Write(metadata);
        var elapsed = metadata.EndedAt - metadata.StartedAt;
        var summary = metadata.ResultCount is not null
            ? $"{metadata.ResultCount} rows returned"
            : metadata.AffectedRows is not null ? $"{metadata.AffectedRows} rows affected" : "";
        var safe = new SafeSqlEvidence(
            metadata.Operation.ToString().ToLowerInvariant(),
            metadata.ParameterizedQuery ?? "",
            metadata.ParameterCount,
            (long)(elapsed.TotalMilliseconds * 1_000),
            metadata.ResultCount,
            metadata.AffectedRows is null ? null : checked((long)metadata.AffectedRows.Value),
            summary,
            Copy(metadata.RequestTraceChain),
            Copy(metadata.TraceChain));
        lock (gate)
        {
            if (entries.Count == Capacity) entries.RemoveAt(0);
            entries.Add(safe);
        }
    }

    public IReadOnlyList<SafeSqlEvidence> Snapshot()
    {
        lock (gate) return entries.Select(entry => entry with {
            TraceChain = Copy(entry.TraceChain), TracePath = Copy(entry.TracePath)
        }).ToArray();
    }

    private static IReadOnlyList<TraceNode> Copy(IEnumerable<TraceNode> nodes) =>
        System.Array.AsReadOnly(nodes.Select(node => node with { }).ToArray());

    public void Clear()
    {
        lock (gate) entries.Clear();
    }
}
```

Every query still requires non-empty `Comment(...)` and `Purpose(...)`;
every mutation requires `AuditAs(...)`. Preserve not-found, checker,
optimistic-conflict, and provider failures rather than returning an empty
successful result.

Query and mutation logs and `TextDiagnosticSqlLogSink` are enabled by default.
Use `context.EnableQuerySqlLog()`, `context.DisableQuerySqlLog()`,
`context.EnableMutationSqlLog()`, and `context.DisableMutationSqlLog()`
independently. Call `sink.Clear()` when a diagnostic window starts. Each metadata entry retains a
typed multi-level trace, parameterized SQL, copy-paste `DebugQuery`, elapsed
time, result count, and affected rows. Comment, purpose, and audit reason are
provider-populated metadata and are rendered separately from the SQL text.
`TraceChain` retains purpose, business comments, and native Q operation names
that locate the corresponding source calls. `TracePath` retains physical
provider and SQL execution steps; it is not the request ancestry. Preserve both
without fabricating a SQL statement for every business node. Nested requests
retain their own explicit comments or the runtime's model-aware default.
Passing `null` to `WithDiagnosticSqlLogSink` removes operator output. Rendered
SQL must never be exported as ordinary telemetry or returned in an HTTP
response.

---

## TeaQL seven-language assist contract

Apply the verified Rust semantic ceiling while using only the exact DOTNET generated and
runtime APIs. Discover APIs through the generated application AGENTS.md and progressive
model-aware Assist. Do not inspect generated domain-library source.

- Do not create plurals by appending `s` or `es`; use the centralized generated plural.
- Human and non-human entities use different generated predicate vocabularies. Preserve
  forms such as “who are active” and “whose email is”; never infer them from English.
- Configure filters, projection, paging, and other query options before `purpose(...)`.
  Comment may appear anywhere in the chain. Purpose enters the executable stage; execution
  requires both values, but comment does not have to immediately precede purpose.
- Every execute/list/stream and every save accepts exactly one context argument:
  `UserContext`. Name that argument `context`, never `runtime`; data services and global
  policy are injected when the context is built. Reserve `runtime` for process-level
  runtime ownership, provider/pool setup, and module assembly.
- Tenant, merchant, identity, permissions, request policy, purpose policy, hard limit,
  and continuous-page cursor policy come only from trusted context, never dynamic JSON or TFP.
- If the required operation is absent after current entity/action and required field
  Assist, stop that path and report MISSING_ASSIST. Do not guess an API or search the
  generated library as a fallback.
- Create each application-owned source file once. After its first compile attempt,
  repair only the smallest block identified by the exact compiler or test diagnostic.
  Preserve unrelated code; do not rewrite the complete file as an error-recovery loop.
- Before a repair that would replace more than 25% of an existing application file,
  stop and report LARGE_REWRITE_REQUEST with the file, exact diagnostic, reason, and
  estimated scope. Initial creation and model-driven regeneration are not repairs.

Capability: `debug`.

- Capture purpose, comment, trace/correlation id, runtime-projected expanded masked
  SQL and its masking mode, duration, row count, provider and the native response.
- Preserve the immutable row audit event and the customizable App Audit Sink as
  separate paths. Redact credentials, tokens, connection strings, and customer data.
- Document only switches and hooks present in the selected runtime source.


## Standard OpenTelemetry module

Use the optional standard module supplied by the selected TeaQL runtime. Match
its version to the runtime dependency selected by the model and workspace;
keep local source or internal Registry overrides during development. Do not
upgrade to an unrelated public release just to enable telemetry. A runtime
without this module reports `module_unavailable`; package installation alone
does not enable export.

On a supported backend, configure these trusted process variables before startup, never
through a query, JSON or TFP payload:

```bash
export TEAQL_TELEMETRY_ENABLED=true
export TEAQL_TELEMETRY_SERVICE_NAME=payment-service
export TEAQL_TELEMETRY_OTLP_ENDPOINT=http://localhost:4318
```

Without enablement, startup reports `disabled` and all three activation variables;
no SDK export resources are created. Enabled startup reports safe effective
settings, full recording and masking. Invalid settings produce a fixed safe
diagnostic, not a claim of successful export. Never print credentials or raw
configuration values.

The module automatically records supported Q, graph mutation and physical SQL
operations as traces, logs and metrics. SQL is expanded with masked parameters;
plaintext debugging never authorizes plaintext telemetry export. Full recording
does not promise lossless delivery when bounded queues or exporters fail.
Do not add per-method spans or replace the customer's global SDK providers.

Keep schema reconciliation explicit. Run the generated ensure-schema and seed
flow through the same configured runtime to observe startup settings and audited,
idempotent seeding. Telemetry setup must not run ensure-schema implicitly.
Flush and shut down the owned pipeline at application shutdown, not per query.
Exporter failures do not change business results; durable business audit remains
an independent path.


### .NET assembly

Add the optional NuGet package `TeaQL.Telemetry.OpenTelemetry` to the application,
using the exact same version as `TeaQL.Runtime`. Context startup discovers it
automatically. Set the three variables before launching the process; no SDK
initialization or per-method instrumentation is required. Keep the optional
package out of the generated domain library's mandatory dependencies.