feat: OpenTelemetry trace export (closes #362)

Add opt-in OpenTelemetry trace export for waza eval runs. Span hierarchy
is eval → task → turn → tool_call/model_call, with attributes following
the OpenTelemetry GenAI semantic conventions (gen_ai.system,
gen_ai.request.model, gen_ai.usage.input_tokens, gen_ai.tool.name, …).

Off by default — when --otel-exporter is not set the OTel SDK is not
initialized and there is no runtime overhead. Three exporters are
supported:

  --otel-exporter otlp   --otel-endpoint host:port [--otel-headers …]
  --otel-exporter stdout
  --otel-exporter file   --otel-file path

Default redaction strips prompt/tool-arg/tool-result/completion content;
only sha256 and byte length are emitted. Pass --otel-include-payloads to
record full content for private debugging.

The implementation is a thin wrapper around the existing event emission
in internal/orchestration/runner.go; nothing about the runner's control
flow changed. internal/telemetry encapsulates Provider/Config/spans and
exposes no-op tracers when disabled, so callers can always wrap work in
spans without conditionals.

Tests cover span hierarchy, GenAI attribute names, redaction behavior,
header parsing, and the disabled-provider path without requiring a live
backend. Adds a docs/guides/otel.mdx walkthrough with a local OTel
Collector example and updates the CLI reference + README.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Copilot

README.md

@@ -331,6 +331,11 @@ Run an evaluation benchmark from a spec file.
 | `--skip-graders` | | Skip grading (execution only); grade later with `waza grade` |
 | `--keep-workspace` | | Preserve temp workspaces after execution for debugging |
 | `--auto-file-issue` | | Auto-file or update a GitHub issue for failing runs (requires `gh` and `GITHUB_REPOSITORY`) |
+| `--otel-exporter` | | Export OpenTelemetry traces using `otlp`, `stdout`, or `file`. Off by default. See [OpenTelemetry Tracing](https://microsoft.github.io/waza/guides/otel/). |
+| `--otel-endpoint` | | OTLP endpoint (host:port or URL); only used with `--otel-exporter=otlp` |
+| `--otel-headers` | | Comma-separated `key=value` OTLP headers (e.g. for auth) |
+| `--otel-file` | | File path for span JSON when `--otel-exporter=file` |
+| `--otel-include-payloads` | | Include prompt/tool-arg/tool-result/completion content in spans (default: redacted to `sha256`+length) |
 
 **Result Caching**
 

cmd/waza/cmd_run.go

@@ -37,6 +37,7 @@ import (
 	"github.com/microsoft/waza/internal/reporting"
 	"github.com/microsoft/waza/internal/session"
 	"github.com/microsoft/waza/internal/storage"
+	"github.com/microsoft/waza/internal/telemetry"
 	"github.com/microsoft/waza/internal/trigger"
 	"github.com/microsoft/waza/internal/utils"
 	"github.com/microsoft/waza/internal/workspace"
@@ -76,6 +77,18 @@ var (
 	keepWorkspace   bool
 	autoFileIssue   bool
 
+	otelExporter        string
+	otelEndpoint        string
+	otelHeaders         string
+	otelFile            string
+	otelIncludePayloads bool
+
+	// runTelemetry holds the configured OpenTelemetry provider for the
+	// current `waza run` invocation. It is initialized in runCommandE and
+	// passed to every constructed runner via WithTelemetry. nil when
+	// telemetry is disabled.
+	runTelemetry *telemetry.Provider
+
 	// newCopilotClientFn allows you to override the client used by the copilot engine, for this command.
 	newCopilotClientFn func(clientOptions *copilot.ClientOptions) execution.CopilotClient
 
@@ -157,6 +170,13 @@ You can also specify a skill name to run its eval:
 	cmd.Flags().BoolVar(&keepWorkspace, "keep-workspace", false, "Preserve temp workspace directories after execution for debugging")
 	cmd.Flags().BoolVar(&autoFileIssue, "auto-file-issue", false, "Auto-file or update a GitHub issue for failing runs (requires gh and GITHUB_REPOSITORY)")
 
+	// OpenTelemetry trace export (off by default).
+	cmd.Flags().StringVar(&otelExporter, "otel-exporter", "", "Export OpenTelemetry traces using exporter: otlp|stdout|file (default: disabled)")
+	cmd.Flags().StringVar(&otelEndpoint, "otel-endpoint", "", "OTLP endpoint (host:port or URL); only used with --otel-exporter=otlp")
+	cmd.Flags().StringVar(&otelHeaders, "otel-headers", "", "Comma-separated key=value OTLP headers (e.g. for auth)")
+	cmd.Flags().StringVar(&otelFile, "otel-file", "", "File path for span JSON when --otel-exporter=file")
+	cmd.Flags().BoolVar(&otelIncludePayloads, "otel-include-payloads", false, "Include prompt/tool-arg/tool-result/completion content in spans (default: redacted, only sha256+length emitted)")
+
 	return cmd
 }
 
@@ -207,6 +227,42 @@ func runCommandE(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("--trials must be at least 1")
 	}
 
+	// Initialize OpenTelemetry trace export if requested. The provider
+	// outlives every per-model engine and runner so spans share one root
+	// flush at process exit.
+	otelHeadersMap, err := telemetry.ParseHeaders(otelHeaders)
+	if err != nil {
+		return fmt.Errorf("--otel-headers: %w", err)
+	}
+	telemetryCfg := telemetry.Config{
+		Exporter:        telemetry.ExporterKind(otelExporter),
+		Endpoint:        otelEndpoint,
+		Headers:         otelHeadersMap,
+		FilePath:        otelFile,
+		IncludePayloads: otelIncludePayloads,
+		ServiceName:     "waza",
+		ServiceVersion:  version,
+	}
+	tp, err := telemetry.New(cmd.Context(), telemetryCfg)
+	if err != nil {
+		return fmt.Errorf("init opentelemetry: %w", err)
+	}
+	runTelemetry = tp
+	if tp.Enabled() {
+		// Register globally so libraries that read from the global tracer
+		// provider (e.g. instrumented HTTP clients) can attach to the same
+		// trace. Best-effort — engines without OTel support are unaffected.
+		tp.SetGlobal()
+	}
+	defer func() {
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := tp.Shutdown(shutdownCtx); err != nil {
+			slog.Warn("opentelemetry shutdown failed", "error", err)
+		}
+		runTelemetry = nil
+	}()
+
 	// Apply config defaults for output-dir when not explicitly set
 	if outputDir == "" && !cmd.Flags().Changed("output-dir") && outputPath == "" {
 		wd, _ := os.Getwd() //nolint:errcheck
@@ -715,6 +771,9 @@ func runSingleModel(cmd *cobra.Command, spec *models.EvalSpec, specPath string,
 	if skipGradersFlag {
 		runnerOpts = append(runnerOpts, orchestration.WithSkipGraders())
 	}
+	if runTelemetry != nil && runTelemetry.Enabled() {
+		runnerOpts = append(runnerOpts, orchestration.WithTelemetry(runTelemetry))
+	}
 	runner := newBenchmarkRunner(cfg, engine, runnerOpts...)
 
 	// Setup session logger if enabled

go.mod

@@ -53,6 +53,7 @@ require (
 	github.com/buger/goterm v1.0.4 // indirect
 	github.com/buger/jsonparser v1.1.2 // indirect
 	github.com/catppuccin/go v0.3.0 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/charmbracelet/bubbles v1.0.0 // indirect
 	github.com/charmbracelet/bubbletea v1.3.10 // indirect
@@ -81,6 +82,7 @@ require (
 	github.com/google/jsonschema-go v0.4.2 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/gorilla/css v1.0.1 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/invopop/jsonschema v0.13.0 // indirect
 	github.com/jmespath-community/go-jmespath v1.1.1 // indirect
@@ -116,9 +118,13 @@ require (
 	github.com/yuin/goldmark-emoji v1.0.6 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/otel v1.43.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.43.0 // indirect
+	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.43.0 // indirect
 	go.opentelemetry.io/otel/metric v1.43.0 // indirect
 	go.opentelemetry.io/otel/sdk v1.43.0 // indirect
 	go.opentelemetry.io/otel/trace v1.43.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.10.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/crypto v0.53.0 // indirect
@@ -128,6 +134,7 @@ require (
 	golang.org/x/sys v0.46.0 // indirect
 	golang.org/x/time v0.15.0 // indirect
 	golang.org/x/tools v0.45.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20260401024825-9d38bb4040a9 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260401024825-9d38bb4040a9 // indirect
 	google.golang.org/grpc v1.80.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect

go.sum

@@ -73,6 +73,8 @@ github.com/buger/jsonparser v1.1.2 h1:frqHqw7otoVbk5M8LlE/L7HTnIq2v9RX6EJ48i9AxJ
 github.com/buger/jsonparser v1.1.2/go.mod h1:6RYKKt7H4d4+iWqouImQ9R2FZql3VbhNgx27UK13J/0=
 github.com/catppuccin/go v0.3.0 h1:d+0/YicIq+hSTo5oPuRi5kOpqkVA5tAsU6dNhvRu+aY=
 github.com/catppuccin/go v0.3.0/go.mod h1:8IHJuMGaUUjQM82qBrGNBv7LFq6JI3NnQCF6MOlZjpc=
+github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=
+github.com/cenkalti/backoff/v5 v5.0.3/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/charmbracelet/bubbles v1.0.0 h1:12J8/ak/uCZEMQ6KU7pcfwceyjLlWsDLAxB5fXonfvc=
@@ -162,6 +164,8 @@ github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
 github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 h1:HWRh5R2+9EifMyIHV7ZV+MIZqgz+PMpZ14Jynv3O2Zs=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0/go.mod h1:JfhWUomR1baixubs02l85lZYYOm7LV6om4ceouMv45c=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
 github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/hinshun/vt10x v0.0.0-20220119200601-820417d04eec h1:qv2VnGeEQHchGaZ/u7lxST/RaJw+cv273q79D81Xbog=
@@ -284,6 +288,12 @@ go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ
 go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
 go.opentelemetry.io/otel v1.43.0 h1:mYIM03dnh5zfN7HautFE4ieIig9amkNANT+xcVxAj9I=
 go.opentelemetry.io/otel v1.43.0/go.mod h1:JuG+u74mvjvcm8vj8pI5XiHy1zDeoCS2LB1spIq7Ay0=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0 h1:88Y4s2C8oTui1LGM6bTWkw0ICGcOLCAI5l6zsD1j20k=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0/go.mod h1:Vl1/iaggsuRlrHf/hfPJPvVag77kKyvrLeD10kpMl+A=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.43.0 h1:3iZJKlCZufyRzPzlQhUIWVmfltrXuGyfjREgGP3UUjc=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.43.0/go.mod h1:/G+nUPfhq2e+qiXMGxMwumDrP5jtzU+mWN7/sjT2rak=
+go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.43.0 h1:mS47AX77OtFfKG4vtp+84kuGSFZHTyxtXIN269vChY0=
+go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.43.0/go.mod h1:PJnsC41lAGncJlPUniSwM81gc80GkgWJWr3cu2nKEtU=
 go.opentelemetry.io/otel/metric v1.43.0 h1:d7638QeInOnuwOONPp4JAOGfbCEpYb+K6DVWvdxGzgM=
 go.opentelemetry.io/otel/metric v1.43.0/go.mod h1:RDnPtIxvqlgO8GRW18W6Z/4P462ldprJtfxHxyKd2PY=
 go.opentelemetry.io/otel/sdk v1.43.0 h1:pi5mE86i5rTeLXqoF/hhiBtUNcrAGHLKQdhg4h4V9Dg=
@@ -292,6 +302,8 @@ go.opentelemetry.io/otel/sdk/metric v1.43.0 h1:S88dyqXjJkuBNLeMcVPRFXpRw2fuwdvfC
 go.opentelemetry.io/otel/sdk/metric v1.43.0/go.mod h1:C/RJtwSEJ5hzTiUz5pXF1kILHStzb9zFlIEe85bhj6A=
 go.opentelemetry.io/otel/trace v1.43.0 h1:BkNrHpup+4k4w+ZZ86CZoHHEkohws8AY+WTX09nk+3A=
 go.opentelemetry.io/otel/trace v1.43.0/go.mod h1:/QJhyVBUUswCphDVxq+8mld+AvhXZLhe+8WVFxiFff0=
+go.opentelemetry.io/proto/otlp v1.10.0 h1:IQRWgT5srOCYfiWnpqUYz9CVmbO8bFmKcwYxpuCSL2g=
+go.opentelemetry.io/proto/otlp v1.10.0/go.mod h1:/CV4QoCR/S9yaPj8utp3lvQPoqMtxXdzn7ozvvozVqk=
 go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
 go.uber.org/atomic v1.11.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
 go.uber.org/mock v0.6.0 h1:hyF9dfmbgIX5EfOdasqLsWD6xqpNZlXblLB/Dbnwv3Y=
@@ -353,6 +365,8 @@ golang.org/x/tools v0.45.0/go.mod h1:LuUGqqaXcXMEFEruIVJVm5mgDD8vww/z/SR1gQ4uE/0
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.17.0 h1:VbpOemQlsSMrYmn7T2OUvQ4dqxQXU+ouZFQsZOx50z4=
 gonum.org/v1/gonum v0.17.0/go.mod h1:El3tOrEuMpv2UdMrbNlKEh9vd86bmQ6vqIcDwxEOc1E=
+google.golang.org/genproto/googleapis/api v0.0.0-20260401024825-9d38bb4040a9 h1:VPWxll4HlMw1Vs/qXtN7BvhZqsS9cdAittCNvVENElA=
+google.golang.org/genproto/googleapis/api v0.0.0-20260401024825-9d38bb4040a9/go.mod h1:7QBABkRtR8z+TEnmXTqIqwJLlzrZKVfAUm7tY3yGv0M=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20260401024825-9d38bb4040a9 h1:m8qni9SQFH0tJc1X0vmnpw/0t+AImlSvp30sEupozUg=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20260401024825-9d38bb4040a9/go.mod h1:4Hqkh8ycfw05ld/3BWL7rJOSfebL2Q+DVDeRgYgxUU8=
 google.golang.org/grpc v1.80.0 h1:Xr6m2WmWZLETvUNvIUmeD5OAagMw3FiKmMlTdViWsHM=

internal/orchestration/runner.go

@@ -22,6 +22,7 @@ import (
 	"github.com/microsoft/waza/internal/hooks"
 	"github.com/microsoft/waza/internal/models"
 	"github.com/microsoft/waza/internal/responder"
+	"github.com/microsoft/waza/internal/telemetry"
 	"github.com/microsoft/waza/internal/template"
 	"github.com/microsoft/waza/internal/transcript"
 	"github.com/microsoft/waza/internal/utils"
@@ -72,6 +73,11 @@ type EvalRunner struct {
 	listeners  []ProgressListener
 
 	failureHandler *failures.Handler
+
+	// telemetry is the OpenTelemetry provider used to emit eval/task/turn
+	// spans. Nil means tracing is off; the helpers in internal/telemetry
+	// degrade to no-op tracers in that case.
+	telemetry *telemetry.Provider
 }
 
 // ProgressListener receives progress updates
@@ -145,6 +151,16 @@ func WithSkipGraders() RunnerOption {
 	}
 }
 
+// WithTelemetry attaches an OpenTelemetry provider so the runner emits
+// eval/task/turn/tool_call/model_call spans. Pass nil (or omit) to disable
+// tracing; in that case the runner's internal calls fall through the
+// no-op tracer and the runner behaves exactly as it did before.
+func WithTelemetry(p *telemetry.Provider) RunnerOption {
+	return func(r *EvalRunner) {
+		r.telemetry = p
+	}
+}
+
 // NewEvalRunner creates a new test runner. The caller owns the engine and is responsible for initializing and shutting it down as needed.
 func NewEvalRunner(cfg *config.EvalConfig, engine execution.AgentEngine, opts ...RunnerOption) *EvalRunner {
 	r := &EvalRunner{
@@ -206,11 +222,22 @@ func (r *EvalRunner) RunBenchmark(ctx context.Context) (*models.EvaluationOutcom
 
 	spec := r.cfg.Spec()
 
+	// Open the root telemetry span for the whole eval. The span is a no-op
+	// when telemetry is disabled, so this call is always safe.
+	evalCtx, evalSpan := telemetry.StartEvalSpan(ctx, r.telemetry, telemetry.EvalInfo{
+		Name:   spec.Name,
+		Skill:  spec.SkillName,
+		Engine: spec.Config.EngineType,
+		Model:  spec.Config.ModelID,
+		RunID:  fmt.Sprintf("run-%d", time.Now().Unix()),
+	})
+	defer evalSpan.End()
+
 	if spec.Baseline {
-		return r.runBaselineComparison(ctx)
+		return r.runBaselineComparison(evalCtx)
 	}
 
-	return r.runNormalBenchmark(ctx)
+	return r.runNormalBenchmark(evalCtx)
 }
 
 // runNormalBenchmark executes a normal single-pass evaluation
@@ -904,6 +931,14 @@ func (r *EvalRunner) runConcurrent(ctx context.Context, testCases []*models.Test
 func (r *EvalRunner) runTest(ctx context.Context, tc *models.TestCase, testNum, totalTests int) (models.TestOutcome, bool) {
 	spec := r.cfg.Spec()
 
+	// Open a per-task span. The span ends with the function via defer so
+	// both the cached and uncached paths report timing to the tracer.
+	taskCtx, taskSpan := telemetry.StartTaskSpan(ctx, r.telemetry, telemetry.TaskInfo{
+		TestID:      tc.TestID,
+		DisplayName: tc.DisplayName,
+	})
+	defer taskSpan.End()
+
 	// Check cache if enabled
 	if r.cache != nil {
 		cacheKey, err := cache.CacheKey(spec, tc, r.cfg.FixtureDir())
@@ -913,7 +948,7 @@ func (r *EvalRunner) runTest(ctx context.Context, tc *models.TestCase, testNum,
 				return *cachedOutcome, true
 			}
 			// Run the test and cache the result
-			outcome := r.runTestUncached(ctx, tc, testNum, totalTests)
+			outcome := r.runTestUncached(taskCtx, tc, testNum, totalTests)
 			// Store in cache and log any failures
 			if err := r.cache.Put(cacheKey, &outcome); err != nil {
 				fmt.Fprintf(os.Stderr, "[WARN] Failed to write cache for test %q: %v\n", tc.DisplayName, err)
@@ -923,7 +958,7 @@ func (r *EvalRunner) runTest(ctx context.Context, tc *models.TestCase, testNum,
 	}
 
 	// No cache or cache key generation failed
-	return r.runTestUncached(ctx, tc, testNum, totalTests), false
+	return r.runTestUncached(taskCtx, tc, testNum, totalTests), false
 }
 
 func (r *EvalRunner) writeTaskTranscript(tc *models.TestCase, outcome models.TestOutcome, startTime time.Time) {
@@ -1052,6 +1087,18 @@ func (r *EvalRunner) executeRun(ctx context.Context, tc *models.TestCase, runNum
 		})
 	}
 
+	// Open the per-turn span around the initial Execute call. Follow-ups
+	// (executeFollowUps / executeResponderLoop) are children of the task
+	// span, not this turn — they open their own turn spans below — to keep
+	// the hierarchy flat: task → turn(initial) + turn(follow-up) + ...
+	turnCtx, turnSpan := telemetry.StartTurnSpan(ctx, r.telemetry, telemetry.TurnInfo{
+		Number: runNum,
+		Kind:   "initial",
+		Model:  r.cfg.Spec().Config.ModelID,
+		Prompt: req.Message,
+	})
+	defer turnSpan.End()
+
 	// Emit agent prompt event before execution
 	if r.verbose {
 		r.notifyProgress(ProgressEvent{
@@ -1071,7 +1118,7 @@ func (r *EvalRunner) executeRun(ctx context.Context, tc *models.TestCase, runNum
 			ErrorMsg:   err.Error(),
 		})
 	}
-	execCtx, cancelExec := context.WithTimeout(ctx, timeout)
+	execCtx, cancelExec := context.WithTimeout(turnCtx, timeout)
 	resp, err := r.engine.Execute(execCtx, req)
 	cancelExec()
 	if err != nil {
@@ -1083,6 +1130,11 @@ func (r *EvalRunner) executeRun(ctx context.Context, tc *models.TestCase, runNum
 		})
 	}
 
+	// Emit child tool_call/model_call spans from the engine response. These
+	// are after-the-fact records (waza only learns about them when Execute
+	// returns) so the spans collapse to a single timestamp under the turn.
+	emitChildSpans(turnCtx, r.telemetry, turnSpan, resp, r.cfg.Spec().Config.ModelID)
+
 	// Emit agent response event after execution
 	if r.verbose {
 		r.notifyProgress(ProgressEvent{