feat(coredata): add widest-scope connector loader

LoadOneByOrganizationIDAndProvider returns the effective OAuth2
connector for an (organization, provider) pair. When legacy rows
leave multiple candidates behind (pre-auto-reconnect installs), it
picks the row with the widest stored scope set and tiebreaks by
most recent updated_at.

This is correct for Google Workspace where the SCIM bridge's
4-scope row must win over the access review's 2-scope row so the
caller always sees a token that can run SCIM operations. The
selector reads the decrypted scope set through Connection.Scopes,
so it is robust against token-refresh updated_at churn that would
mislead a pure SQL ORDER BY.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/coredata/connector.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"fmt"
 	"maps"
+	"sort"
 	"time"
 
 	"github.com/jackc/pgx/v5"
@@ -116,6 +117,58 @@ func (c *Connectors) LoadAllByOrganizationIDProtocolAndProvider(
 	return nil
 }
 
+// LoadOneByOrganizationIDAndProvider loads the effective OAuth2
+// connector for an (organization, provider) pair, picking the row with
+// the widest stored scope set. Ties are broken by most recent
+// updated_at. Returns ErrResourceNotFound if no OAuth2 row exists.
+func (c *Connector) LoadOneByOrganizationIDAndProvider(
+	ctx context.Context,
+	conn pg.Querier,
+	scope Scoper,
+	encryptionKey cipher.EncryptionKey,
+	organizationID gid.GID,
+	provider ConnectorProvider,
+) error {
+	var connectors Connectors
+	if err := connectors.LoadAllByOrganizationIDProtocolAndProvider(
+		ctx,
+		conn,
+		scope,
+		organizationID,
+		ConnectorProtocolOAuth2,
+		provider,
+		encryptionKey,
+	); err != nil {
+		return fmt.Errorf("cannot load connectors: %w", err)
+	}
+
+	if len(connectors) == 0 {
+		return ErrResourceNotFound
+	}
+
+	// Widest-scope-wins, tiebreak by most recent updated_at.
+	sort.SliceStable(connectors, func(i, j int) bool {
+		ci, cj := connectorScopeCount(connectors[i]), connectorScopeCount(connectors[j])
+		if ci != cj {
+			return ci > cj
+		}
+		return connectors[i].UpdatedAt.After(connectors[j].UpdatedAt)
+	})
+
+	*c = *connectors[0]
+	return nil
+}
+
+// connectorScopeCount returns the number of scopes granted on a
+// decrypted connector's connection. Returns 0 if the connection is nil.
+// Used by the widest-scope selector.
+func connectorScopeCount(c *Connector) int {
+	if c == nil || c.Connection == nil {
+		return 0
+	}
+	return len(c.Connection.Scopes())
+}
+
 func (c *Connectors) LoadByOrganizationIDWithoutDecryptedConnection(
 	ctx context.Context,
 	conn pg.Querier,

pkg/coredata/connector_test.go

@@ -0,0 +1,94 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package coredata
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.probo.inc/probo/pkg/connector"
+)
+
+func TestConnectorScopeCount(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name string
+		in   *Connector
+		want int
+	}{
+		{
+			name: "nil connector",
+			in:   nil,
+			want: 0,
+		},
+		{
+			name: "nil connection",
+			in:   &Connector{},
+			want: 0,
+		},
+		{
+			name: "oauth2 empty scope",
+			in: &Connector{
+				Connection: &connector.OAuth2Connection{Scope: ""},
+			},
+			want: 0,
+		},
+		{
+			name: "oauth2 single scope",
+			in: &Connector{
+				Connection: &connector.OAuth2Connection{Scope: "read:user"},
+			},
+			want: 1,
+		},
+		{
+			name: "oauth2 multiple scopes",
+			in: &Connector{
+				Connection: &connector.OAuth2Connection{Scope: "read:user write:user admin:org"},
+			},
+			want: 3,
+		},
+		{
+			name: "oauth2 github comma scopes",
+			in: &Connector{
+				Connection: &connector.OAuth2Connection{Scope: "repo,gist,user"},
+			},
+			want: 3,
+		},
+		{
+			name: "slack multi scope",
+			in: &Connector{
+				Connection: &connector.SlackConnection{
+					OAuth2Connection: connector.OAuth2Connection{Scope: "chat:write channels:join incoming-webhook"},
+				},
+			},
+			want: 3,
+		},
+		{
+			name: "unknown connection type",
+			in: &Connector{
+				Connection: &connector.APIKeyConnection{},
+			},
+			want: 0,
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, c.want, connectorScopeCount(c.in))
+		})
+	}
+}