fix(handlers/channels_test): use RowError() to trigger rows.Err() in List test

The previous approach of adding a second row with matching columns does
not trigger rows.Err() in sqlmock v1.5.2. rows.Err() is only set
when RowError(n, err) or SetError(err) is called explicitly.

Use RowError(0, errors.New("connection lost")) instead — this causes
Scan() to fail on row 0 and sets rows.Err() so the handler's new
rows.Err() check is exercised by the test.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/handlers/channels_test.go

@@ -7,6 +7,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -1013,6 +1014,54 @@ func TestChannelHandler_Webhook_Discord_InvalidSig_Returns401(t *testing.T) {
 	}
 }
 
+// TestChannelHandler_List_RowsErr_LogsError verifies that when the row iterator
+// returns an error after the last row (mid-stream DB error), rows.Err() is
+// detected and logged, but the partial results are still returned as 200 OK.
+// This is the fix for the missing rows.Err() check in List().
+func TestChannelHandler_List_RowsErr_LogsError(t *testing.T) {
+	mock := setupTestDB(t)
+	handler := NewChannelHandler(newTestChannelManager())
+
+	// Return one valid row, then mark row 0 as having a scan error.
+	// RowError(n, err) causes Scan() to fail on row n, and sets rows.Err()
+	// to the error. sqlmock docs: "you can register errors on specific row
+	// indexes so that they will be returned on scan."
+	rows := sqlmock.NewRows([]string{
+		"id", "workspace_id", "channel_type", "channel_config", "enabled",
+		"allowed_users", "last_message_at", "message_count", "created_at", "updated_at",
+	}).AddRow(
+		"ch-row-err", "ws-1", "telegram",
+		[]byte(`{"bot_token":"123:AAA","chat_id":"-100"}`),
+		true, []byte(`[]`), nil, 5, nil, nil,
+	)
+	rows = rows.RowError(0, errors.New("connection lost"))
+
+	mock.ExpectQuery("SELECT .* FROM workspace_channels WHERE workspace_id").
+		WithArgs("ws-1").
+		WillReturnRows(rows)
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Request, _ = http.NewRequest("GET", "/workspaces/ws-1/channels", nil)
+	c.Params = gin.Params{{Key: "id", Value: "ws-1"}}
+
+	handler.List(c)
+
+	// Partial results still returned — the bug was silent 200 with partial data.
+	if w.Code != 200 {
+		t.Errorf("expected 200 (partial results on rows.Err), got %d: %s", w.Code, w.Body.String())
+	}
+	// The rows.Err() is logged, not surfaced to the client (non-fatal).
+	var result []map[string]interface{}
+	json.Unmarshal(w.Body.Bytes(), &result)
+	if len(result) == 0 {
+		t.Error("expected at least partial results despite rows.Err")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("sqlmock expectations not met: %v", err)
+	}
+}
+
 // TestChannelHandler_Webhook_Discord_ValidSig_PingAccepted verifies that a
 // correctly signed Discord PING (type=1) passes the signature gate and the
 // handler returns 200 (PING returns nil msg → "ignored" status).