diff --git a/cmd/sdrd/pipeline_runtime.go b/cmd/sdrd/pipeline_runtime.go
index 0c60fc0..c578c06 100644
--- a/cmd/sdrd/pipeline_runtime.go
+++ b/cmd/sdrd/pipeline_runtime.go
@@ -74,6 +74,7 @@ type surveillanceLevelSpec struct {
 type surveillancePlan struct {
 	Primary      pipeline.AnalysisLevel
 	Levels       []pipeline.AnalysisLevel
+	LevelSet     pipeline.SurveillanceLevelSet
 	Presentation pipeline.AnalysisLevel
 	Context      pipeline.AnalysisContext
 	Specs        []surveillanceLevelSpec
@@ -414,15 +415,16 @@ func (rt *dspRuntime) buildSurveillanceResult(art *spectrumArtifacts) pipeline.S
 		return pipeline.SurveillanceResult{}
 	}
 	policy := pipeline.PolicyFromConfig(rt.cfg)
-	candidates := pipeline.CandidatesFromSignals(art.detected, "surveillance-detector")
-	scheduled := pipeline.ScheduleCandidates(candidates, policy)
 	plan := art.surveillancePlan
 	if plan.Primary.Name == "" {
 		plan = rt.buildSurveillancePlan(policy)
 	}
+	candidates := pipeline.CandidatesFromSignalsWithLevel(art.detected, "surveillance-detector", plan.Primary)
+	scheduled := pipeline.ScheduleCandidates(candidates, policy)
 	return pipeline.SurveillanceResult{
 		Level:        plan.Primary,
 		Levels:       plan.Levels,
+		LevelSet:     plan.LevelSet,
 		DisplayLevel: plan.Presentation,
 		Context:      plan.Context,
 		Spectra:      art.surveillanceSpectra,
@@ -766,6 +768,7 @@ func (rt *dspRuntime) buildSurveillancePlan(policy pipeline.Policy) surveillance
 	levels := []pipeline.AnalysisLevel{primary}
 	specs := []surveillanceLevelSpec{{Level: primary, Decim: 1, AllowGPU: true}}
 	context := pipeline.AnalysisContext{Surveillance: primary}
+	derivedLevels := make([]pipeline.AnalysisLevel, 0, 2)
 
 	strategy := strings.ToLower(strings.TrimSpace(policy.SurveillanceStrategy))
 	switch strategy {
@@ -779,15 +782,29 @@ func (rt *dspRuntime) buildSurveillancePlan(policy pipeline.Policy) surveillance
 			levels = append(levels, derived)
 			specs = append(specs, surveillanceLevelSpec{Level: derived, Decim: decim, AllowGPU: false})
 			context.Derived = append(context.Derived, derived)
+			derivedLevels = append(derivedLevels, derived)
 		}
 	}
 
 	presentation := analysisLevel("presentation", "presentation", "presentation", baseRate, rt.cfg.Surveillance.DisplayBins, rt.cfg.CenterHz, span, "display", 1, baseRate)
 	context.Presentation = presentation
+	levelSet := pipeline.SurveillanceLevelSet{
+		Primary:      primary,
+		Derived:      append([]pipeline.AnalysisLevel(nil), derivedLevels...),
+		Presentation: presentation,
+	}
+	allLevels := make([]pipeline.AnalysisLevel, 0, 1+len(derivedLevels)+1)
+	allLevels = append(allLevels, primary)
+	allLevels = append(allLevels, derivedLevels...)
+	if presentation.Name != "" {
+		allLevels = append(allLevels, presentation)
+	}
+	levelSet.All = allLevels
 
 	return surveillancePlan{
 		Primary:      primary,
 		Levels:       levels,
+		LevelSet:     levelSet,
 		Presentation: presentation,
 		Context:      context,
 		Specs:        specs,
diff --git a/internal/pipeline/phases.go b/internal/pipeline/phases.go
index 783c9b8..b9ea486 100644
--- a/internal/pipeline/phases.go
+++ b/internal/pipeline/phases.go
@@ -28,9 +28,17 @@ type AnalysisContext struct {
 	Derived      []AnalysisLevel `json:"derived,omitempty"`
 }
 
+type SurveillanceLevelSet struct {
+	Primary      AnalysisLevel   `json:"primary"`
+	Derived      []AnalysisLevel `json:"derived,omitempty"`
+	Presentation AnalysisLevel   `json:"presentation,omitempty"`
+	All          []AnalysisLevel `json:"all,omitempty"`
+}
+
 type SurveillanceResult struct {
 	Level        AnalysisLevel               `json:"level"`
 	Levels       []AnalysisLevel             `json:"levels,omitempty"`
+	LevelSet     SurveillanceLevelSet        `json:"level_set,omitempty"`
 	Candidates   []Candidate                 `json:"candidates"`
 	Scheduled    []ScheduledCandidate        `json:"scheduled,omitempty"`
 	Finished     []detector.Event            `json:"finished"`
diff --git a/internal/pipeline/types.go b/internal/pipeline/types.go
index e248e0c..f5449b0 100644
--- a/internal/pipeline/types.go
+++ b/internal/pipeline/types.go
@@ -8,16 +8,24 @@ import (
 // Candidate is the coarse output of the surveillance detector.
 // It intentionally stays lightweight and cheap to produce.
 type Candidate struct {
-	ID          int64   `json:"id"`
-	CenterHz    float64 `json:"center_hz"`
-	BandwidthHz float64 `json:"bandwidth_hz"`
-	PeakDb      float64 `json:"peak_db"`
-	SNRDb       float64 `json:"snr_db"`
-	FirstBin    int     `json:"first_bin"`
-	LastBin     int     `json:"last_bin"`
-	NoiseDb     float64 `json:"noise_db,omitempty"`
-	Source      string  `json:"source,omitempty"`
-	Hint        string  `json:"hint,omitempty"`
+	ID          int64           `json:"id"`
+	CenterHz    float64         `json:"center_hz"`
+	BandwidthHz float64         `json:"bandwidth_hz"`
+	PeakDb      float64         `json:"peak_db"`
+	SNRDb       float64         `json:"snr_db"`
+	FirstBin    int             `json:"first_bin"`
+	LastBin     int             `json:"last_bin"`
+	NoiseDb     float64         `json:"noise_db,omitempty"`
+	Source      string          `json:"source,omitempty"`
+	Hint        string          `json:"hint,omitempty"`
+	Evidence    []LevelEvidence `json:"evidence,omitempty"`
+}
+
+// LevelEvidence captures which analysis level produced a candidate.
+// This is intentionally lightweight for later multi-level fusion.
+type LevelEvidence struct {
+	Level      AnalysisLevel `json:"level"`
+	Provenance string        `json:"provenance,omitempty"`
 }
 
 // RefinementWindow describes the local analysis span that refinement should use.
@@ -59,3 +67,15 @@ func CandidatesFromSignals(signals []detector.Signal, source string) []Candidate
 	}
 	return out
 }
+
+func CandidatesFromSignalsWithLevel(signals []detector.Signal, source string, level AnalysisLevel) []Candidate {
+	out := CandidatesFromSignals(signals, source)
+	if level.Name == "" && level.FFTSize == 0 && level.SampleRate == 0 {
+		return out
+	}
+	evidence := LevelEvidence{Level: level, Provenance: source}
+	for i := range out {
+		out[i].Evidence = append(out[i].Evidence, evidence)
+	}
+	return out
+}