Fix the five resilience review findings

internal/framework/proposal_generation/generate_test.go

@@ -51,6 +51,7 @@ func (f *fakeStructuredClient) CompleteStructured(ctx context.Context, req contr
 }
 
 type captureDiagnosticsWriter struct {
+	err                 error
 	lastStage           string
 	lastRequestMetadata any
 	lastRequestPayload  any
@@ -62,7 +63,7 @@ func (w *captureDiagnosticsWriter) WriteInteraction(stage string, requestMetadat
 	w.lastRequestPayload = requestPayload
 	_ = responsePayload
 	_ = errorPayload
-	return InteractionArtifacts{}, nil
+	return InteractionArtifacts{}, w.err
 }
 
 func defaultRequest(t *testing.T) Request {
@@ -383,3 +384,16 @@ func TestGenerateCandidatesClientError(t *testing.T) {
 		t.Fatalf("expected error diagnostics artifact under %s", req.DiagnosticsDir)
 	}
 }
+
+func TestProposalDiagnosticFailureDoesNotChangeOperation(t *testing.T) {
+	cause := errors.New("diagnostic storage unavailable")
+	req := defaultRequest(t)
+	req.LLMClient = &fakeStructuredClient{responses: []StructuredCorrectionSet{{}}}
+	req.DiagnosticsWriter = &captureDiagnosticsWriter{err: cause}
+	var reported error
+	req.ReportDiagnosticError = func(err error) { reported = err }
+	result, err := GenerateCandidates(context.Background(), req)
+	if err != nil || !errors.Is(reported, cause) || len(result.Operations) != 1 || !result.Operations[0].Succeeded || len(result.Operations[0].RecoveryReasons) != 0 || result.Artifacts.ResponsePayloadPath != "" {
+		t.Fatalf("debug failure changed outcome: %+v %v reported=%v", result, err, reported)
+	}
+}