Rewrite Gel currentUser global provider logic to use SessionHost

The former impl was nice because it was decoupled from Gel driver logic.
But it was a lot of logic to figure out this "current user" from the `ExecutionContext`,
and that would've felt really bad to couple to the DB layer.

Mainly the former impl doesn't work going forward, because it assumed the session would not change within the GQL operation.
This is one of the main features we're making room for.
So now that the session can change, we don't know when to read what the current user should be.
We need to take the current ALS value right when the query is being executed.

Now that we're slicing the layers differently, giving the session/"current user" its own holder (ALS), we don't have to "dig deep" into the `ExecutionContext` to pull out this value.
Coupling this `SessionHost` to the `Gel` service is less painful than it would've been previously and allows us to read the current ALS value right when needed.

Perhaps there is another way to decouple this later. Maybe with some query events/hooks?

Author: CarsonF

src/components/authentication/authentication.module.ts

@@ -8,7 +8,6 @@ import { AuthenticationGelRepository } from './authentication.gel.repository';
 import { AuthenticationRepository } from './authentication.repository';
 import { AuthenticationService } from './authentication.service';
 import { CryptoService } from './crypto.service';
-import { GelCurrentUserProvider } from './current-user.provider';
 import {
   LoginExtraInfoResolver,
   RegisterExtraInfoResolver,
@@ -41,8 +40,6 @@ import { SessionResolver } from './session.resolver';
     CryptoService,
     SessionInterceptor,
     { provide: APP_INTERCEPTOR, useExisting: SessionInterceptor },
-    GelCurrentUserProvider,
-    { provide: APP_INTERCEPTOR, useExisting: GelCurrentUserProvider },
     { provide: SessionHost, useClass: SessionHostImpl },
     SessionPipe,
   ],

src/components/authentication/current-user.provider.ts

@@ -1,10 +1,12 @@
 /* eslint-disable @typescript-eslint/unified-signatures */
 import { Injectable, Optional } from '@nestjs/common';
+import { isUUID } from 'class-validator';
 import { type $, type Executor } from 'gel';
 import { type QueryArgs } from 'gel/dist/ifaces';
 import { TraceLayer } from '~/common';
 import { retry, type RetryOptions } from '~/common/retry';
 import { TracingService } from '~/core/tracing';
+import { SessionHost } from '../../components/authentication/session.host';
 import { TypedEdgeQL } from './edgeql';
 import { cleanError } from './errors';
 import { InlineQueryRuntimeMap } from './generated-client/inline-queries';
@@ -21,6 +23,7 @@ export class Gel {
     private readonly transactionContext: TransactionContext,
     private readonly optionsContext: OptionsContext,
     private readonly tracing: TracingService,
+    private readonly sessionHost: SessionHost,
     @Optional() private readonly childOptions: ApplyOptions[] = [],
     @Optional() private childExecutor?: Executor,
   ) {}
@@ -31,6 +34,7 @@ export class Gel {
       this.transactionContext,
       this.optionsContext,
       this.tracing,
+      this.sessionHost,
       [...this.childOptions],
       this.childExecutor,
     );
@@ -111,6 +115,11 @@ export class Gel {
     const queryNames = getCurrentQueryNames();
     const traceName = queryNames?.xray ?? 'Query';
 
+    let currentActorId = this.sessionHost.current$.value?.userId;
+    // TODO temporarily check if UUID before applying global.
+    // Once migration is complete this can be removed.
+    currentActorId = isUUID(currentActorId) ? currentActorId : undefined;
+
     return await this.tracing.capture(traceName, async (segment) => {
       // Show this segment separately in the service map
       segment.namespace = 'remote';
@@ -122,8 +131,18 @@ export class Gel {
       };
 
       return await this.usingOptions(
-        (opts) =>
-          opts.tag || !queryNames ? opts : opts.withQueryTag(queryNames.gel),
+        (opts) => {
+          if (queryNames && !opts.tag) {
+            opts = opts.withQueryTag(queryNames.gel);
+          }
+          // TODO sync caching strategy with the solution that resolves
+          // https://github.com/geldata/gel-js/issues/1280
+          if (currentActorId && !opts.globals.get('currentActorId')) {
+            opts = opts.withGlobals({ currentActorId });
+          }
+
+          return opts;
+        },
         () => this.doRun(query, args),
       );
     });