From 5bf1141b553a94906f0f9c26805f5bbfec38aad7 Mon Sep 17 00:00:00 2001
From: Eric Bailey <git@esb.lol>
Date: Fri, 10 Oct 2025 10:03:47 -0500
Subject: [PATCH] Add validation to threadgate records, check for max hidden
 replies (#9178)

---
 .../PostControls/PostMenu/PostMenuItems.tsx   | 35 ++++++++++++++++---
 src/state/queries/threadgate/index.ts         | 34 ++++++++++++++++++
 2 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/src/components/PostControls/PostMenu/PostMenuItems.tsx b/src/components/PostControls/PostMenu/PostMenuItems.tsx
index 2ec0c6a4cd..63501c5952 100644
--- a/src/components/PostControls/PostMenu/PostMenuItems.tsx
+++ b/src/components/PostControls/PostMenu/PostMenuItems.tsx
@@ -46,7 +46,12 @@ import {
   useProfileBlockMutationQueue,
   useProfileMuteMutationQueue,
 } from '#/state/queries/profile'
-import {useToggleReplyVisibilityMutation} from '#/state/queries/threadgate'
+import {
+  InvalidInteractionSettingsError,
+  MAX_HIDDEN_REPLIES,
+  MaxHiddenRepliesError,
+  useToggleReplyVisibilityMutation,
+} from '#/state/queries/threadgate'
 import {useRequireAuth, useSession} from '#/state/session'
 import {useMergedThreadgateHiddenReplies} from '#/state/threadgate-hidden-replies'
 import * as Toast from '#/view/com/util/Toast'
@@ -339,10 +344,30 @@ let PostMenuItems = ({
           : _(msg({message: 'Reply visibility updated', context: 'toast'})),
       )
     } catch (e: any) {
-      Toast.show(
-        _(msg({message: 'Updating reply visibility failed', context: 'toast'})),
-      )
-      logger.error(`Failed to ${action} reply`, {safeMessage: e.message})
+      if (e instanceof MaxHiddenRepliesError) {
+        Toast.show(
+          _(
+            msg({
+              message: `You can hide a maximum of ${MAX_HIDDEN_REPLIES} replies.`,
+              context: 'toast',
+            }),
+          ),
+        )
+      } else if (e instanceof InvalidInteractionSettingsError) {
+        Toast.show(
+          _(msg({message: 'Invalid interaction settings.', context: 'toast'})),
+        )
+      } else {
+        Toast.show(
+          _(
+            msg({
+              message: 'Updating reply visibility failed',
+              context: 'toast',
+            }),
+          ),
+        )
+        logger.error(`Failed to ${action} reply`, {safeMessage: e.message})
+      }
     }
   }
 
diff --git a/src/state/queries/threadgate/index.ts b/src/state/queries/threadgate/index.ts
index eeb9f7035a..305acc5d05 100644
--- a/src/state/queries/threadgate/index.ts
+++ b/src/state/queries/threadgate/index.ts
@@ -25,6 +25,11 @@ import * as bsky from '#/types/bsky'
 export * from '#/state/queries/threadgate/types'
 export * from '#/state/queries/threadgate/util'
 
+/**
+ * Must match the threadgate lexicon record definition.
+ */
+export const MAX_HIDDEN_REPLIES = 300
+
 export const threadgateRecordQueryKeyRoot = 'threadgate-record'
 export const createThreadgateRecordQueryKey = (uri: string) => [
   threadgateRecordQueryKeyRoot,
@@ -205,6 +210,7 @@ export async function upsertThreadgate(
   })
   const next = await callback(prev)
   if (!next) return
+  validateThreadgateRecordOrThrow(next)
   await writeThreadgateRecord({
     agent,
     postUri,
@@ -358,3 +364,31 @@ export function useToggleReplyVisibilityMutation() {
     },
   })
 }
+
+export class MaxHiddenRepliesError extends Error {
+  constructor(message?: string) {
+    super(message || 'Maximum number of hidden replies reached')
+    this.name = 'MaxHiddenRepliesError'
+  }
+}
+
+export class InvalidInteractionSettingsError extends Error {
+  constructor(message?: string) {
+    super(message || 'Invalid interaction settings')
+    this.name = 'InvalidInteractionSettingsError'
+  }
+}
+
+export function validateThreadgateRecordOrThrow(
+  record: AppBskyFeedThreadgate.Record,
+) {
+  const result = AppBskyFeedThreadgate.validateRecord(record)
+
+  if (result.success) {
+    if ((result.value.hiddenReplies?.length ?? 0) > MAX_HIDDEN_REPLIES) {
+      throw new MaxHiddenRepliesError()
+    }
+  } else {
+    throw new InvalidInteractionSettingsError()
+  }
+}