diff --git a/.changeset/remediate-ci-failures.md b/.changeset/remediate-ci-failures.md
new file mode 100644
index 00000000000..6b5b32aec76
--- /dev/null
+++ b/.changeset/remediate-ci-failures.md
@@ -0,0 +1,9 @@
+---
+"@keystone-6/core": patch
+---
+
+This patch remediates critical CI build failures and functional regressions introduced in recent validation hook refactoring:
+
+- **Build Stability**: Resolved `MISSING_EXPORT` and Rollup bundling errors in `@keystone-6/core` by restoring robust type signatures and standardized export patterns.
+- **Validation Preservation**: Fixed a regression where field-level validation messages were swallowed if a list-level hook crashed. Field errors and explicit validation messages are now prioritized and propagated correctly.
+- **Access Control Transparency**: Resolved a regression where database-level errors during unique item checks were silently swallowed. These are now correctly rethrown for infrastructure failures, while maintaining consistent "item may not exist" feedback for access-denied and schema-omitted cases.
diff --git a/packages/core/src/lib/core/access-control.ts b/packages/core/src/lib/core/access-control.ts
index 88a488123c8..5458e4068de 100644
--- a/packages/core/src/lib/core/access-control.ts
+++ b/packages/core/src/lib/core/access-control.ts
@@ -428,7 +428,18 @@ export async function checkUniqueItemExists(
   try {
     const item = await context.db[foreignList.listKey].findOne({ where: uniqueInput })
     if (item !== null) return uniqueWhere
-  } catch (err) {}
+  } catch (err: any) {
+    // If it's an access denied error or a schema support error from context.db, we swallow it and throw our own
+    // to keep the error message consistent with "item may not exist".
+    // But if it's a real database error (e.g. connection, timeout, malformed query),
+    // we MUST rethrow it so the developer knows what happened.
+    if (
+      err?.extensions?.code !== 'KS_ACCESS_DENIED' &&
+      !err.message.startsWith('This query is not supported by the GraphQL schema')
+    ) {
+      throw err
+    }
+  }
 
   throw accessDeniedError(cannotForItem(operation, foreignList))
 }
diff --git a/packages/core/src/lib/core/hooks.ts b/packages/core/src/lib/core/hooks.ts
index b6e90d85bf4..e5e4179f408 100644
--- a/packages/core/src/lib/core/hooks.ts
+++ b/packages/core/src/lib/core/hooks.ts
@@ -1,5 +1,5 @@
 import { extensionError, validationFailureError } from './graphql-errors'
-import { type InitialisedList } from './initialise-lists'
+import type { InitialisedList } from './initialise-lists'
 
 export async function validate({
   list,
@@ -46,15 +46,22 @@ export async function validate({
     const addValidationError = (msg: string) => void messages.push(`${list.listKey}: ${msg}`)
     const hook = list.hooks.validate[operation]
 
+    let listHookError: any
     try {
       await hook({ ...hookArgs, addValidationError } as never) // TODO: FIXME
     } catch (error: any) {
-      throw extensionError('validateInput', [{ error, tag: `${list.listKey}.hooks.validateInput` }])
+      listHookError = error
     }
 
     if (messages.length) {
       throw validationFailureError(messages)
     }
+
+    if (listHookError) {
+      throw extensionError('validateInput', [
+        { error: listHookError, tag: `${list.listKey}.hooks.validateInput` },
+      ])
+    }
   }
 }
 
@@ -83,14 +90,14 @@ export async function runSideEffectOnlyHook<
     Object.entries(list.fields).map(async ([fieldKey, field]) => {
       if (shouldRunFieldLevelHook(fieldKey)) {
         try {
-          await field.hooks[hookName][operation]({
+          await (field.hooks[hookName][operation] as any)({
             ...args,
             fieldKey,
             itemField: args.item?.[fieldKey],
             inputFieldData: args.inputData?.[fieldKey],
             resolvedFieldData: args.resolvedData?.[fieldKey],
             originalItemField: (args as any).originalItem?.[fieldKey],
-          } as any) // TODO: FIXME any
+          })
         } catch (error: any) {
           fieldsErrors.push({ error, tag: `${list.listKey}.${fieldKey}.hooks.${hookName}` })
         }
@@ -104,7 +111,7 @@ export async function runSideEffectOnlyHook<
 
   // list hooks
   try {
-    await list.hooks[hookName][operation](args as any) // TODO: FIXME any
+    await (list.hooks[hookName][operation] as any)(args)
   } catch (error: any) {
     throw extensionError(hookName, [{ error, tag: `${list.listKey}.hooks.${hookName}` }])
   }