Strengthen validation retries and checkpoint safety

internal/framework/pipeline/runner.go

@@ -61,10 +61,11 @@ type RunInput struct {
 	// single worker so direct framework callers retain deterministic behavior.
 	ExtractWorkers int
 
-	pipeline   ResolvedPipeline
-	llmClient  contracts.StructuredLLMClient
-	stepID     string
-	references map[referenceTargetKey]contracts.ReferenceSet
+	pipeline                  ResolvedPipeline
+	llmClient                 contracts.StructuredLLMClient
+	stepID                    string
+	references                map[referenceTargetKey]contracts.ReferenceSet
+	referenceReuseEligibility map[referenceTargetKey]bool
 }
 
 type RunOutput struct {
@@ -76,6 +77,8 @@ type RunOutput struct {
 	OutputFiles         []contracts.OutputFile        `json:"-"`
 	CheckpointEvents    []CheckpointEvent             `json:"checkpoint_events,omitempty"`
 	ValidationSummaries []artifacts.ValidationSummary `json:"validation_summaries,omitempty"`
+
+	normalizeReuseEligibility map[generatedOutputKey]bool
 }
 
 func (r *Runner) Run(ctx context.Context, input RunInput) (output RunOutput, err error) {
@@ -425,6 +428,7 @@ func (r *Runner) runPreparedSteps(ctx context.Context, input RunInput, checkpoin
 			return fmt.Errorf("prepare generated references for pipeline step %q: %w", step.ID, err)
 		}
 		stepInput.references = stepReferences
+		stepInput.referenceReuseEligibility = buildStepReferenceReuseEligibility(step, output.normalizeReuseEligibility)
 		output.Manifest.References = append(output.Manifest.References, referenceProvenance...)
 		laneOutput, laneErr := r.runLanes(ctx, stepInput, step, checkpoints, loader, doc, sourceInput, sessionID, chunks)
 		if err := mergeLaneOutput(output, laneOutput); err != nil {