fix(integrations): partial unique index so user-link doesn't clobber workspace row

apps/server/src/core/integration/repos/integration-connection.repo.ts

@@ -1,5 +1,6 @@
 import { Injectable } from '@nestjs/common';
 import { InjectKysely } from 'nestjs-kysely';
+import { sql } from 'kysely';
 import { KyselyDB, KyselyTransaction } from '@docmost/db/types/kysely.types';
 import {
   IntegrationConnection,
@@ -124,14 +125,9 @@ export class IntegrationConnectionRepo {
       );
     }
 
-    // Clear any stale non-workspace row for the same (integration, user) to
-    // avoid the uq(integration_id, user_id) constraint blocking the insert.
-    await db
-      .deleteFrom('integrationConnections')
-      .where('integrationId', '=', input.integrationId)
-      .where('userId', '=', input.userId)
-      .where('kind', '!=', 'workspace')
-      .execute();
+    // No need to clear other rows: the migration 20260524T020000 made the
+    // (integration_id, user_id) constraint partial-on-kind='user', so a
+    // workspace insert never conflicts with the installer's user-link row.
 
     return db
       .insertInto('integrationConnections')
@@ -286,6 +282,11 @@ export class IntegrationConnectionRepo {
     trx?: KyselyTransaction,
   ): Promise<IntegrationConnection> {
     const db = dbOrTx(this.db, trx);
+    // Target the partial unique index uq_integration_connections_user_per_integration
+    // (integration_id, user_id) WHERE kind = 'user'. Without the .where() hint,
+    // ON CONFLICT can't match a partial index. The kind discriminator means a
+    // workspace bot row sharing (integration_id, user_id) with this user-link
+    // is no longer a conflict, so we cannot flip its kind.
     return await db
       .insertInto('integrationConnections')
       .values({
@@ -298,12 +299,14 @@ export class IntegrationConnectionRepo {
         accessToken: null,
       })
       .onConflict((oc) =>
-        oc.columns(['integrationId', 'userId']).doUpdateSet({
-          providerUserId: input.providerUserId,
-          metadata: input.metadata as any,
-          kind: 'user',
-          updatedAt: new Date(),
-        }),
+        oc
+          .columns(['integrationId', 'userId'])
+          .where(sql.ref('kind'), '=', 'user')
+          .doUpdateSet({
+            providerUserId: input.providerUserId,
+            metadata: input.metadata as any,
+            updatedAt: new Date(),
+          }),
       )
       .returningAll()
       .executeTakeFirstOrThrow();

apps/server/src/database/migrations/20260524T020000-integration-connections-user-kind-unique.ts

@@ -0,0 +1,56 @@
+import { type Kysely, sql } from 'kysely';
+
+export async function up(db: Kysely<any>): Promise<void> {
+  // The original (integration_id, user_id) unique constraint predates the
+  // `kind` discriminator. For workspace-scoped integrations (Slack), the
+  // installer's user_id appears on BOTH the workspace bot row and their
+  // personal user-link row. The constraint blocks that, and the resulting
+  // upsert-conflict in user-link flow flipped the existing workspace row
+  // to kind='user' (clobbering the bot connection).
+  //
+  // Replace with a partial unique index that only constrains kind='user'
+  // rows. Workspace rows already have their own partial unique index on
+  // (integration_id) WHERE kind = 'workspace'.
+
+  await sql`ALTER TABLE integration_connections DROP CONSTRAINT uq_integration_connections_integration_user`.execute(
+    db,
+  );
+
+  await db.schema
+    .createIndex('uq_integration_connections_user_per_integration')
+    .on('integration_connections')
+    .columns(['integration_id', 'user_id'])
+    .where(sql.ref('kind'), '=', 'user')
+    .unique()
+    .execute();
+
+  // Repair Slack workspace rows that got flipped to kind='user' by the
+  // earlier upsertUserLink bug. User-link rows have NULL access_token by
+  // design; any kind='user' row that still has access_token AND scopes
+  // populated for a Slack integration is the corrupted bot row.
+  await sql`
+    UPDATE integration_connections ic
+    SET kind = 'workspace'
+    FROM integrations i
+    WHERE ic.integration_id = i.id
+      AND i.type = 'slack'
+      AND ic.kind = 'user'
+      AND ic.access_token IS NOT NULL
+      AND ic.scopes IS NOT NULL
+  `.execute(db);
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await db.schema
+    .dropIndex('uq_integration_connections_user_per_integration')
+    .ifExists()
+    .execute();
+
+  // Re-adding the full constraint will fail on any DB that now legitimately
+  // has both a kind='workspace' and kind='user' row for the same
+  // (integration_id, user_id). Operators rolling back should clean those
+  // up first. We don't try to be clever; the constraint name is preserved.
+  await sql`ALTER TABLE integration_connections ADD CONSTRAINT uq_integration_connections_integration_user UNIQUE (integration_id, user_id)`.execute(
+    db,
+  );
+}