Align validator identity and span domain checks

internal/framework/proposals/apply_test.go

@@ -109,6 +109,26 @@ func TestApplyProposalsStaleProposalSkippedAfterEarlierChange(t *testing.T) {
 	}
 }
 
+func TestApplyProposalsRechecksBlankResultAfterEarlierDeletion(t *testing.T) {
+	transcript := &schema.Transcript{Segments: []schema.Segment{{ID: 1, Text: "a b"}}}
+	proposed := []EnrichedCorrectionProposal{
+		{CorrectionProposal: CorrectionProposal{TargetSegmentID: 1, OriginalText: "a", CorrectedText: "", Confidence: 1}, ProposalMetadata: ProposalMetadata{ProposalIndex: 0}},
+		{CorrectionProposal: CorrectionProposal{TargetSegmentID: 1, OriginalText: "b", CorrectedText: "", Confidence: 1}, ProposalMetadata: ProposalMetadata{ProposalIndex: 1}},
+	}
+	for _, candidate := range proposed {
+		if preview := PreviewProposalForSegment(&transcript.Segments[0], candidate.CorrectionProposal, ReplacementPolicyRequireUnique); !preview.Applicable {
+			t.Fatalf("proposal must be initially applicable: %+v", preview)
+		}
+	}
+	result := ApplyProposals(transcript, proposed, ReplacementPolicyRequireUnique)
+	if got := result.Transcript.Segments[0].Text; got != " b" {
+		t.Fatalf("expected literal surviving text, got %q", got)
+	}
+	if len(result.Applied) != 1 || len(result.Skipped) != 1 || result.Skipped[0].SkipReason != SkipReasonEmptyResultingText {
+		t.Fatalf("expected second deletion skipped after reevaluation: %+v", result)
+	}
+}
+
 func TestApplyProposalsMissingSegmentSkip(t *testing.T) {
 	transcript := &schema.Transcript{Segments: []schema.Segment{{ID: 1, Text: "hello"}}}
 	proposals := []EnrichedCorrectionProposal{

internal/framework/proposals/preview_test.go

@@ -139,6 +139,30 @@ func TestPreviewProposalForSegmentAllowsEmptyCorrectedTextWhenSegmentRemainsNonE
 	}
 }
 
+func TestPreviewProposalForSegmentWhitespaceSpan(t *testing.T) {
+	proposal := CorrectionProposal{TargetSegmentID: 8, OriginalText: "  ", CorrectedText: " ", Confidence: 0.9}
+	unique := PreviewProposalForSegment(&schema.Segment{ID: 8, Text: "hello  world"}, proposal, ReplacementPolicyRequireUnique)
+	if !unique.Applicable || unique.CorrectedSegmentText != "hello world" || unique.ReplacementCount != 1 {
+		t.Fatalf("unexpected spacing preview: %+v", unique)
+	}
+	segment := &schema.Segment{ID: 8, Text: "a  b  c"}
+	ambiguous := PreviewProposalForSegment(segment, proposal, ReplacementPolicyRequireUnique)
+	if ambiguous.Applicable || ambiguous.SkipReason != SkipReasonAmbiguousOriginal {
+		t.Fatalf("expected ambiguity under require_unique: %+v", ambiguous)
+	}
+	all := PreviewProposalForSegment(segment, proposal, ReplacementPolicyReplaceAll)
+	if !all.Applicable || all.CorrectedSegmentText != "a b c" || all.ReplacementCount != 2 {
+		t.Fatalf("expected replace_all to correct both spans: %+v", all)
+	}
+}
+
+func TestPreviewProposalForSegmentRejectsEmptyOriginalText(t *testing.T) {
+	preview := PreviewProposalForSegment(&schema.Segment{ID: 8, Text: "hello"}, CorrectionProposal{TargetSegmentID: 8, OriginalText: "", CorrectedText: "x", Confidence: 0.9}, ReplacementPolicyRequireUnique)
+	if preview.Applicable || preview.SkipReason != SkipReasonInvalidProposal {
+		t.Fatalf("expected invalid empty original: %+v", preview)
+	}
+}
+
 func TestPreviewProposalForSegmentRejectsEmptyResultingSegment(t *testing.T) {
 	segment := &schema.Segment{ID: 8, Text: "uh"}
 	proposal := CorrectionProposal{

internal/framework/proposals/proposal.go

@@ -2,7 +2,6 @@ package proposals
 
 import (
 	"fmt"
-	"strings"
 )
 
 // CorrectionProposal is the base proposal emitted by correction modules.
@@ -35,7 +34,7 @@ func (p CorrectionProposal) Validate() error {
 	if p.TargetSegmentID <= 0 {
 		return fmt.Errorf("proposal id must be positive")
 	}
-	if strings.TrimSpace(p.OriginalText) == "" {
+	if p.OriginalText == "" {
 		return fmt.Errorf("proposal original_text must not be empty")
 	}
 	if p.Confidence < 0.0 || p.Confidence > 1.0 {

internal/framework/proposals/proposal_test.go

@@ -48,6 +48,13 @@ func TestCorrectionProposalValidate_AllowsEmptyCorrectedText(t *testing.T) {
 	}
 }
 
+func TestCorrectionProposalValidate_AllowsWhitespaceOriginalText(t *testing.T) {
+	proposal := CorrectionProposal{TargetSegmentID: 42, OriginalText: "  ", CorrectedText: " ", Confidence: 0.95}
+	if err := proposal.Validate(); err != nil {
+		t.Fatalf("expected whitespace span to be valid, got %v", err)
+	}
+}
+
 func TestCorrectionProposalValidate_InvalidConfidence(t *testing.T) {
 	proposal := CorrectionProposal{
 		TargetSegmentID: 42,