Add SharingId for the X-Gandi-Sharing-Id header

README.md

@@ -11,6 +11,12 @@ This package only supports **API Key authentication**. Refer to the [Gandi's Pub
 
 Start by [retrieving your API key](https://account.gandi.net/) from the _Security_ section in Gandi account admin panel to be able to make authenticated requests to the API.
 
+### Cross-organization access
+
+If the PAT user's default organization is not the one that owns the domain you want to manage, list endpoints (`/v5/domain/domains`, `/v5/livedns/domains`) will still find the domain because Gandi filters by all visible orgs, but per-record-set endpoints will return `404`. Setting `Provider.SharingId` to the UUID of the org that owns the domain causes the provider to send `X-Gandi-Sharing-Id: <uuid>` on every request, and the per-record-set endpoints then succeed.
+
+Note: the documented form of this hint is the [`sharing_id` query string parameter](https://api.gandi.net/docs/reference/#Sharing-ID), but in practice that form doesn't reach per-record-set endpoints. The `X-Gandi-Sharing-Id` header is empirically required there but isn't currently part of the public reference.
+
 ## Technical limitations
 
 The [LiveDNS documentation](https://api.gandi.net/docs/livedns/) states that records with the same name and type are merged so that their `rrset_values` are grouped together.

client.go

@@ -161,6 +161,9 @@ func (p *Provider) getDomain(ctx context.Context, zone string) (gandiDomain, err
 func (p *Provider) doRequest(req *http.Request, result interface{}) (gandiStatus, error) {
 	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", p.BearerToken))
 	req.Header.Set("Accept", "application/json")
+	if p.SharingId != "" {
+		req.Header.Set("X-Gandi-Sharing-Id", p.SharingId)
+	}
 
 	resp, err := http.DefaultClient.Do(req)
 

provider.go

@@ -12,6 +12,7 @@ import (
 // Provider implements the libdns interfaces for Gandi.
 type Provider struct {
 	BearerToken string `json:"bearer_token,omitempty"`
+	SharingId   string `json:"sharing_id,omitempty"`
 
 	domains map[string]gandiDomain
 	mutex   sync.Mutex