Extract safecsv writer for spreadsheet-safe exports

Wrap encoding/csv with formula-safe cell sanitization and
use it from log export streaming.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/iam/log_export_csv.go

@@ -22,7 +22,6 @@ package iam
 
 import (
 	"context"
-	"encoding/csv"
 	"fmt"
 	"strconv"
 	"strings"
@@ -33,6 +32,7 @@ import (
 	"go.probo.inc/probo/pkg/gid"
 	"go.probo.inc/probo/pkg/mail"
 	"go.probo.inc/probo/pkg/page"
+	"go.probo.inc/probo/pkg/safecsv"
 )
 
 type (
@@ -93,7 +93,7 @@ func (s *LogExportService) streamAuditLogCSV(
 	organizationID gid.GID,
 	organizationName string,
 	filter *coredata.AuditLogEntryFilter,
-	w *csv.Writer,
+	w *safecsv.Writer,
 ) error {
 	if err := w.Write(auditLogExportCSVHeader); err != nil {
 		return fmt.Errorf("cannot write audit log CSV header: %w", err)
@@ -148,7 +148,7 @@ func (s *LogExportService) streamSCIMEventCSV(
 	organizationID gid.GID,
 	organizationName string,
 	filter *coredata.SCIMEventFilter,
-	w *csv.Writer,
+	w *safecsv.Writer,
 ) error {
 	if err := w.Write(scimEventExportCSVHeader); err != nil {
 		return fmt.Errorf("cannot write SCIM event CSV header: %w", err)
@@ -207,7 +207,7 @@ func auditLogEntryCSVRow(
 	entry *coredata.AuditLogEntry,
 	actor auditLogActorExportInfo,
 ) []string {
-	return csvExportRow(
+	return []string{
 		organizationName,
 		entry.ID.String(),
 		entry.CreatedAt.Format(time.RFC3339),
@@ -218,7 +218,7 @@ func auditLogEntryCSVRow(
 		entry.Action,
 		entry.ResourceType,
 		entry.ResourceID.String(),
-	)
+	}
 }
 
 func scimEventCSVRow(
@@ -233,7 +233,7 @@ func scimEventCSVRow(
 		email = scimEmailFromUserName(event.UserName)
 	}
 
-	return csvExportRow(
+	return []string{
 		organizationName,
 		event.ID.String(),
 		event.CreatedAt.Format(time.RFC3339),
@@ -245,7 +245,7 @@ func scimEventCSVRow(
 		strconv.Itoa(event.StatusCode),
 		stringPtrValue(event.ErrorMessage),
 		event.IPAddress.String(),
-	)
+	}
 }
 
 func loadAuditLogActorExportInfo(
@@ -381,28 +381,6 @@ func uniqueNonEmptyStrings(values []string) []string {
 	return out
 }
 
-func csvExportRow(fields ...string) []string {
-	row := make([]string, len(fields))
-	for i, field := range fields {
-		row[i] = csvSafeCell(field)
-	}
-
-	return row
-}
-
-func csvSafeCell(value string) string {
-	if value == "" {
-		return value
-	}
-
-	switch value[0] {
-	case '=', '+', '-', '@', '\t', '\r':
-		return "'" + value
-	default:
-		return value
-	}
-}
-
 func scimEmailFromUserName(userName string) string {
 	userName = strings.TrimSpace(userName)
 	if userName == "" {

pkg/iam/log_export_csv_test.go

@@ -33,16 +33,6 @@ func TestUniqueNonEmptyStrings(t *testing.T) {
 	assert.Equal(t, []string{"a", "b"}, got)
 }
 
-func TestCsvSafeCell(t *testing.T) {
-	t.Parallel()
-
-	assert.Equal(t, "plain", csvSafeCell("plain"))
-	assert.Equal(t, "'=1+1", csvSafeCell("=1+1"))
-	assert.Equal(t, "'+cmd", csvSafeCell("+cmd"))
-	assert.Equal(t, "'-2", csvSafeCell("-2"))
-	assert.Equal(t, "'@sum", csvSafeCell("@sum"))
-}
-
 func TestScimEmailFromUserName(t *testing.T) {
 	t.Parallel()
 

pkg/iam/log_export_service.go

@@ -22,7 +22,6 @@ package iam
 
 import (
 	"context"
-	"encoding/csv"
 	"fmt"
 	"io"
 	"strings"
@@ -35,6 +34,7 @@ import (
 	"go.probo.inc/probo/pkg/filemanager"
 	"go.probo.inc/probo/pkg/gid"
 	"go.probo.inc/probo/pkg/mail"
+	"go.probo.inc/probo/pkg/safecsv"
 )
 
 type LogExportService struct {
@@ -228,7 +228,7 @@ func (s *LogExportService) streamCSV(
 				return fmt.Errorf("cannot load organization for log export: %w", err)
 			}
 
-			w := csv.NewWriter(pw)
+			w := safecsv.NewWriter(pw)
 
 			switch exportJob.Type {
 			case coredata.ExportJobTypeAuditLog:

pkg/safecsv/cell.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package safecsv
+
+// SanitizeRecord returns a copy of record with spreadsheet-safe cell values.
+func SanitizeRecord(record []string) []string {
+	if len(record) == 0 {
+		return record
+	}
+
+	out := make([]string, len(record))
+	for i, field := range record {
+		out[i] = SanitizeCell(field)
+	}
+
+	return out
+}
+
+// SanitizeCell prefixes values that spreadsheet tools may interpret as formulas.
+func SanitizeCell(value string) string {
+	if value == "" {
+		return value
+	}
+
+	switch value[0] {
+	case '=', '+', '-', '@', '\t', '\r':
+		return "'" + value
+	default:
+		return value
+	}
+}

pkg/safecsv/cell_test.go

@@ -0,0 +1,52 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package safecsv
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSanitizeCell(t *testing.T) {
+	t.Parallel()
+
+	assert.Equal(t, "plain", SanitizeCell("plain"))
+	assert.Equal(t, "'=1+1", SanitizeCell("=1+1"))
+	assert.Equal(t, "'+cmd", SanitizeCell("+cmd"))
+	assert.Equal(t, "'-2", SanitizeCell("-2"))
+	assert.Equal(t, "'@sum", SanitizeCell("@sum"))
+}
+
+func TestWriterWrite(t *testing.T) {
+	t.Parallel()
+
+	var buf bytes.Buffer
+
+	w := NewWriter(&buf)
+	require.NoError(t, w.WriteRow("ok", "=evil"))
+	w.Flush()
+	require.NoError(t, w.Error())
+
+	assert.Equal(t, "ok,'=evil\n", buf.String())
+}

pkg/safecsv/writer.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package safecsv
+
+import (
+	"encoding/csv"
+	"io"
+)
+
+type Writer struct {
+	inner *csv.Writer
+}
+
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{inner: csv.NewWriter(w)}
+}
+
+func (w *Writer) Write(record []string) error {
+	return w.inner.Write(SanitizeRecord(record))
+}
+
+func (w *Writer) WriteRow(fields ...string) error {
+	return w.Write(fields)
+}
+
+func (w *Writer) Flush() {
+	w.inner.Flush()
+}
+
+func (w *Writer) Error() error {
+	return w.inner.Error()
+}