refactor(webapp,database): drop isTest backfill, hide legacy tag in UI

The Session.isTest backfill (and the array_remove of the "playground" tag)
is removed from the migration, which now only adds the column. Existing
sessions keep isTest=false; only sessions created from the Test playground
going forward set it.

The legacy "playground" tag is hidden from the Tags display in both the
sessions list and detail presenters (via LEGACY_PLAYGROUND_TAG) so it does
not surface on pre-isTest rows, without mutating historical data.

Author: samejr

.server-changes/sessions-test-column.md

@@ -3,4 +3,4 @@ area: webapp
 type: feature
 ---
 
-Agent sessions started from the Test playground are now flagged with a real `Session.isTest` boolean instead of a `"playground"` tag, surfaced as a dedicated "Test" column (check icon) in the Sessions table on both the Sessions and Agent pages, plus a matching property on the session detail page. Existing sessions are backfilled and the now-redundant tag is removed.
+Agent sessions started from the Test playground are now flagged with a real `Session.isTest` boolean instead of a `"playground"` tag, surfaced as a dedicated "Test" column (check icon) in the Sessions table on both the Sessions and Agent pages, plus a matching property on the session detail page. The legacy `"playground"` tag is hidden from the Tags display on pre-existing sessions.

apps/webapp/app/presenters/v3/SessionListPresenter.server.ts

@@ -7,6 +7,7 @@ import { findDisplayableEnvironment } from "~/models/runtimeEnvironment.server";
 import {
   type SessionStatus,
   SessionsRepository,
+  LEGACY_PLAYGROUND_TAG,
 } from "~/services/sessionsRepository/sessionsRepository.server";
 import { ServiceValidationError } from "~/v3/services/baseService.server";
 import { findCurrentWorkerFromEnvironment } from "~/v3/models/workerDeployment.server";
@@ -226,7 +227,12 @@ export class SessionListPresenter {
           type: session.type,
           taskIdentifier: session.taskIdentifier,
           isTest: session.isTest,
-          tags: session.tags ? [...session.tags].sort((a, b) => a.localeCompare(b)) : [],
+          // Hide the legacy "playground" tag (pre-isTest sessions) from display.
+          tags: session.tags
+            ? [...session.tags]
+                .filter((t) => t !== LEGACY_PLAYGROUND_TAG)
+                .sort((a, b) => a.localeCompare(b))
+            : [],
           status,
           closedAt: session.closedAt ? session.closedAt.toISOString() : undefined,
           closedReason: session.closedReason ?? undefined,

apps/webapp/app/presenters/v3/SessionPresenter.server.ts

@@ -4,6 +4,7 @@ import { env } from "~/env.server";
 import { findDisplayableEnvironment } from "~/models/runtimeEnvironment.server";
 import { chatSnapshotStorageKey } from "~/services/realtime/chatSnapshot.server";
 import { resolveSessionByIdOrExternalId } from "~/services/realtime/sessions.server";
+import { LEGACY_PLAYGROUND_TAG } from "~/services/sessionsRepository/sessionsRepository.server";
 import { logger } from "~/services/logger.server";
 import { generatePresignedUrl } from "~/v3/objectStore.server";
 import { runStore } from "~/v3/runStore.server";
@@ -178,7 +179,12 @@ export class SessionPresenter {
       type: session.type,
       taskIdentifier: session.taskIdentifier,
       isTest: session.isTest,
-      tags: session.tags ? [...session.tags].sort((a, b) => a.localeCompare(b)) : [],
+      // Hide the legacy "playground" tag (pre-isTest sessions) from display.
+      tags: session.tags
+        ? [...session.tags]
+            .filter((t) => t !== LEGACY_PLAYGROUND_TAG)
+            .sort((a, b) => a.localeCompare(b))
+        : [],
       metadata: session.metadata,
       triggerConfig: session.triggerConfig,
       streamBasinName: session.streamBasinName,

apps/webapp/app/services/sessionsRepository/sessionsRepository.server.ts

@@ -24,6 +24,13 @@ export type SessionsRepositoryOptions = {
 export const SessionStatus = z.enum(["ACTIVE", "CLOSED", "EXPIRED"]);
 export type SessionStatus = z.infer<typeof SessionStatus>;
 
+/**
+ * Legacy marker tag for sessions created from the Test/playground before the
+ * `Session.isTest` boolean existed. New sessions set `isTest` instead; this tag
+ * is hidden from the Tags display so it doesn't surface on pre-isTest rows.
+ */
+export const LEGACY_PLAYGROUND_TAG = "playground";
+
 const SessionListInputOptionsSchema = z.object({
   organizationId: z.string(),
   projectId: z.string(),

internal-packages/database/prisma/migrations/20260621000000_add_is_test_to_session/migration.sql

@@ -1,12 +1,2 @@
 -- AlterTable
 ALTER TABLE "Session" ADD COLUMN     "isTest" BOOLEAN NOT NULL DEFAULT false;
-
--- Backfill: legacy Test sessions were marked with a "playground" tag. Flag them
--- as test and strip the now-redundant tag (the Test column replaces it), so the
--- list and detail views render consistently without read-time tag filtering.
--- Bounded one-shot over the playground subset; matches existing in-migration
--- backfill precedent. (Prisma wraps each migration in a single transaction, so
--- batching with intermediate commits isn't possible here.)
-UPDATE "Session"
-SET "isTest" = true, "tags" = array_remove("tags", 'playground')
-WHERE 'playground' = ANY("tags");