diff --git a/spec/graph_replication_retry_spec.cr b/spec/graph_replication_retry_spec.cr
new file mode 100644
index 00000000..98f73888
--- /dev/null
+++ b/spec/graph_replication_retry_spec.cr
@@ -0,0 +1,152 @@
+require "./helper"
+
+module PlaceOS::Api
+  describe GraphReplicationRetry do
+    replication_lag_error = -> do
+      Office365::Exception.new(
+        HTTP::Status::NOT_FOUND,
+        {error: {code: "Request_ResourceNotFound", message: "Resource 'x' does not exist or one of its queried reference-property objects are not present."}}.to_json,
+        "Not Found"
+      )
+    end
+
+    app_not_backed_error = -> do
+      Office365::Exception.new(
+        HTTP::Status::BAD_REQUEST,
+        {error: {code: "Request_BadRequest", message: "The appId 'x' of the service principal does not reference a valid application object.", details: [{code: "NoBackingApplicationObject", message: "The appId 'x' of the service principal does not reference a valid application object.", target: "appId"}]}}.to_json,
+        "Bad Request"
+      )
+    end
+
+    directory_busy_error = -> do
+      Office365::Exception.new(
+        HTTP::Status::NOT_FOUND,
+        {error: {code: "Directory_ObjectNotFound", message: "Unable to read the company information from the directory."}}.to_json,
+        "Not Found"
+      )
+    end
+
+    stale_scope_error = -> do
+      Office365::Exception.new(
+        HTTP::Status::BAD_REQUEST,
+        {error: {code: "Request_BadRequest", message: "Property api.preAuthorizedApplications.delegatedPermissionIds has a Permission Id that cannot be found in the AppPermissions sets.", details: [{code: "InvalidValue", message: "Property api.preAuthorizedApplications.delegatedPermissionIds has a Permission Id that cannot be found in the AppPermissions sets.", target: "api.preAuthorizedApplications.delegatedPermissionIds"}]}}.to_json,
+        "Bad Request"
+      )
+    end
+
+    duplicate_create_error = -> do
+      Office365::Exception.new(
+        HTTP::Status::CONFLICT,
+        {error: {code: "Request_MultipleObjectsWithSameKeyValue", message: "The service principal cannot be created, updated, or restored because the service principal name x is already in use.", details: [{code: "ObjectConflict", message: "already in use", target: "servicePrincipalNames"}]}}.to_json,
+        "Conflict"
+      )
+    end
+
+    it "returns the block value when the call succeeds" do
+      GraphReplicationRetry.run { 42 }.should eq 42
+    end
+
+    it "retries a get-or-create that double-created off a stale read" do
+      attempts = 0
+      value = GraphReplicationRetry.run(backoff: {0, 0, 0}) do
+        attempts += 1
+        raise duplicate_create_error.call if attempts < 2
+        :converged
+      end
+      value.should eq :converged
+      attempts.should eq 2
+    end
+
+    it "retries pre-authorization racing the scope it references" do
+      attempts = 0
+      value = GraphReplicationRetry.run(backoff: {0, 0, 0}) do
+        attempts += 1
+        raise stale_scope_error.call if attempts < 2
+        :materialised
+      end
+      value.should eq :materialised
+      attempts.should eq 2
+    end
+
+    it "does not retry InvalidValue errors on other properties" do
+      attempts = 0
+      expect_raises(Office365::Exception) do
+        GraphReplicationRetry.run(backoff: {0, 0}) do
+          attempts += 1
+          raise Office365::Exception.new(
+            HTTP::Status::BAD_REQUEST,
+            {error: {code: "Request_BadRequest", message: "bad", details: [{code: "InvalidValue", message: "bad", target: "identifierUris"}]}}.to_json,
+            "Bad Request"
+          )
+        end
+      end
+      attempts.should eq 1
+    end
+
+    it "retries transient directory reads while the tenant replicates" do
+      attempts = 0
+      value = GraphReplicationRetry.run(backoff: {0, 0, 0}) do
+        attempts += 1
+        raise directory_busy_error.call if attempts < 2
+        :materialised
+      end
+      value.should eq :materialised
+      attempts.should eq 2
+    end
+
+    it "retries service principal creation racing the application object" do
+      attempts = 0
+      value = GraphReplicationRetry.run(backoff: {0, 0, 0}) do
+        attempts += 1
+        raise app_not_backed_error.call if attempts < 3
+        :materialised
+      end
+      value.should eq :materialised
+      attempts.should eq 3
+    end
+
+    it "retries replication lag until the object materialises" do
+      attempts = 0
+      value = GraphReplicationRetry.run(backoff: {0, 0, 0}) do
+        attempts += 1
+        raise replication_lag_error.call if attempts < 3
+        :materialised
+      end
+      value.should eq :materialised
+      attempts.should eq 3
+    end
+
+    it "gives up once the backoff schedule is exhausted" do
+      attempts = 0
+      expect_raises(Office365::Exception, /Request_ResourceNotFound/) do
+        GraphReplicationRetry.run(backoff: {0, 0}) do
+          attempts += 1
+          raise replication_lag_error.call
+        end
+      end
+      attempts.should eq 3
+    end
+
+    it "does not retry other graph errors" do
+      attempts = 0
+      expect_raises(Office365::Exception) do
+        GraphReplicationRetry.run(backoff: {0, 0}) do
+          attempts += 1
+          raise Office365::Exception.new(HTTP::Status::FORBIDDEN, {error: {code: "Authorization_RequestDenied", message: "denied"}}.to_json, "Forbidden")
+        end
+      end
+      attempts.should eq 1
+    end
+
+    it "does not retry 404s that are not replication lag" do
+      attempts = 0
+      expect_raises(Office365::Exception) do
+        GraphReplicationRetry.run(backoff: {0, 0}) do
+          attempts += 1
+          raise Office365::Exception.new(HTTP::Status::NOT_FOUND, "gone", "Not Found")
+        end
+      end
+      attempts.should eq 1
+    end
+  end
+end
diff --git a/src/placeos-rest-api/controllers/tenant_consent.cr b/src/placeos-rest-api/controllers/tenant_consent.cr
index a2287f60..d91562cc 100644
--- a/src/placeos-rest-api/controllers/tenant_consent.cr
+++ b/src/placeos-rest-api/controllers/tenant_consent.cr
@@ -61,8 +61,6 @@ module PlaceOS::Api
           create_outlook_config(auth_app[:client_id])
           strat.update!(client_id: auth_app[:client_id], client_secret: auth_app[:client_secret])
           update_auth(authority, strat.id.as(String))
-        ensure
-          update_app_redirect_uri(false)
         end
       else
         Log.warn { {message: "Admin declined consent", error: error.to_s, description: error_description.to_s} }
@@ -81,11 +79,13 @@ module PlaceOS::Api
       app = Office365::Application.single_tenant_app("PlaceOS Bookings Visualiser")
         .add_required_resource(ra)
 
-      created_app = client.create_application(app)
+      created_app = GraphReplicationRetry.run { client.create_application(app) }
       Log.debug { {message: "App registerd with Application permissions", tenant: tenant_id, client_id: created_app.app_id.as(String)} }
 
       ra.each do |resource|
-        client.application_add_app_role_assignment(created_app.app_id.as(String), resource["id"])
+        GraphReplicationRetry.run do
+          client.application_add_app_role_assignment(created_app.app_id.as(String), resource["id"])
+        end
       end
 
       created_app.app_id.as(String)
@@ -107,11 +107,13 @@ module PlaceOS::Api
         .add_web_redirect_uri("https://#{domain}/auth/oauth2/callback?id=#{strat_id}")
         .add_required_resource(ra)
 
-      created_app = client.create_application(app)
+      created_app = GraphReplicationRetry.run { client.create_application(app) }
       Log.debug { {message: "App registerd with Delegated permissions", tenant: tenant_id, client_id: created_app.app_id.as(String)} }
 
-      client.application_add_oauth2_permission_grant(created_app.app_id.as(String), "Calendars.ReadWrite Calendars.ReadWrite.Shared Group.Read.All User.Read.All offline_access openid profile")
-      secret = client.application_add_pwd(created_app.app_id.as(String), "PlaceOS User Auth Secret")
+      GraphReplicationRetry.run do
+        client.application_add_oauth2_permission_grant(created_app.app_id.as(String), "Calendars.ReadWrite Calendars.ReadWrite.Shared Group.Read.All User.Read.All offline_access openid profile")
+      end
+      secret = GraphReplicationRetry.run { client.application_add_pwd(created_app.app_id.as(String), "PlaceOS User Auth Secret") }
       {client_id: created_app.app_id.as(String), client_secret: secret.secret_text.as(String)}
     end
 
@@ -121,7 +123,7 @@ module PlaceOS::Api
 
     private def update_app_redirect_uri(add : Bool = true) : Nil
       client = get_client
-      app = client.get_application(PLACE_APP_CLIENT_ID, "id,web")
+      app = GraphReplicationRetry.run { client.get_application(PLACE_APP_CLIENT_ID, "id,web") }
       app_redirect_uris = app.web.try &.redirect_uris || [] of String
 
       return nil if add && app_redirect_uris.includes?(redirect_url)
@@ -135,7 +137,7 @@ module PlaceOS::Api
       app.web.not_nil!.redirect_uris = app_redirect_uris
       web = {"web" => app.web}
       begin
-        client.update_application(PLACE_APP_CLIENT_ID, web.to_json)
+        GraphReplicationRetry.run { client.update_application(PLACE_APP_CLIENT_ID, web.to_json) }
       rescue ex : Office365::Exception
         return nil if already_exists_error?(ex.http_body)
         raise ex
@@ -144,7 +146,7 @@ module PlaceOS::Api
 
     private def add_outlook_plugin_auth(app_id : String) : Nil
       client = get_client
-      app = client.get_application(app_id)
+      app = GraphReplicationRetry.run { client.get_application(app_id) }
       app_redirect_uris = app.web.try &.redirect_uris || [] of String
       app_redirect_uris.push("#{domain_url}/outlook/#/book/spaces")
 
@@ -171,7 +173,7 @@ module PlaceOS::Api
           ],
         },
       }
-      client.update_application(app_id, updated.to_json)
+      GraphReplicationRetry.run { client.update_application(app_id, updated.to_json) }
 
       updated = {
         "api": {
@@ -185,7 +187,7 @@ module PlaceOS::Api
           ],
         },
       }
-      client.update_application(app_id, updated.to_json)
+      GraphReplicationRetry.run { client.update_application(app_id, updated.to_json) }
     end
 
     private def create_outlook_repo : Nil
diff --git a/src/placeos-rest-api/utilities/graph-replication-retry.cr b/src/placeos-rest-api/utilities/graph-replication-retry.cr
new file mode 100644
index 00000000..a81ba234
--- /dev/null
+++ b/src/placeos-rest-api/utilities/graph-replication-retry.cr
@@ -0,0 +1,75 @@
+require "json"
+require "office365"
+
+module PlaceOS::Api
+  # Microsoft Graph is eventually consistent: a directory object that was just
+  # created (an application registration or service principal) is not always
+  # visible to an immediately following request that references it. Graph
+  # signals this as a 404 with the error code `Request_ResourceNotFound`.
+  #
+  # Retry exactly that case with a backoff; every other error propagates
+  # untouched.
+  module GraphReplicationRetry
+    Log = ::Log.for(self)
+
+    # seconds between attempts, ~35s in total. Replication typically settles
+    # within a few seconds but has been observed (sandbox tenant, 2026-08-04)
+    # taking 25s+.
+    BACKOFF = {1, 2, 4, 8, 8, 12}
+
+    def self.run(backoff = BACKOFF, & : -> T) : T forall T
+      attempt = 0
+      loop do
+        begin
+          return yield
+        rescue error : ::Office365::Exception
+          delay = backoff[attempt]?
+          raise error unless delay && replication_lag?(error)
+          attempt += 1
+          Log.warn { "graph resource not replicated yet (attempt #{attempt}), retrying in #{delay}s" }
+          sleep delay.seconds
+        end
+      end
+    end
+
+    def self.replication_lag?(error : ::Office365::Exception) : Bool
+      body = JSON.parse(error.http_body)
+      case error.http_status
+      when .not_found?
+        # Request_ResourceNotFound: a just-created object is not yet visible
+        # to a request referencing it.
+        # Directory_ObjectNotFound ("Unable to read the company information
+        # from the directory"): transient directory read failure while the
+        # tenant is busy replicating - documented by Microsoft as retryable.
+        body.dig?("error", "code").try(&.as_s?).in?("Request_ResourceNotFound", "Directory_ObjectNotFound")
+      when .bad_request?
+        # NoBackingApplicationObject: a service principal cannot be created
+        # because the application object registered moments earlier has not
+        # replicated yet.
+        # InvalidValue on preAuthorizedApplications.delegatedPermissionIds:
+        # the PATCH that added the permission scope moments earlier has not
+        # replicated, so the follow-up PATCH fails validation against a stale
+        # copy of the application. Deliberately narrow - a generic InvalidValue
+        # retry would mask real validation errors.
+        details = body.dig?("error", "details").try(&.as_a?) || [] of JSON::Any
+        details.any? do |detail|
+          code = detail["code"]?.try(&.as_s?)
+          target = detail["target"]?.try(&.as_s?)
+          code == "NoBackingApplicationObject" ||
+            (code == "InvalidValue" && target == "api.preAuthorizedApplications.delegatedPermissionIds")
+        end
+      when .conflict?
+        # Request_MultipleObjectsWithSameKeyValue on a service principal
+        # create: the preceding existence check read a stale replica that did
+        # not yet list the service principal created moments earlier, so the
+        # get-or-create tried to create it twice. Retrying converges - the
+        # next read eventually sees the object and the create is skipped.
+        body.dig?("error", "code").try(&.as_s?) == "Request_MultipleObjectsWithSameKeyValue"
+      else
+        false
+      end
+    rescue JSON::ParseException
+      false
+    end
+  end
+end