diff --git a/.github/actions/setup/action.yml b/.github/actions/setup/action.yml
index 14a1535004..cdf847ba7f 100644
--- a/.github/actions/setup/action.yml
+++ b/.github/actions/setup/action.yml
@@ -9,9 +9,9 @@ runs:
   using: composite
   steps:
     - name: Setup pnpm
-      uses: pnpm/action-setup@v2
+      uses: pnpm/action-setup@v3
       with:
-        version: 8.3.1
+        version: 9
 
     - name: Setup Node (${{ inputs.node }})
       uses: actions/setup-node@v3
diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index b684715292..ad15a2ef48 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -24,12 +24,6 @@ jobs:
       - name: prChecks
         run: pnpm prChecks
 
-      - name: TSC Diagnostics Diff
-        uses: beerose/tsc-diff-action@v0.0.1
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          leave-comment: true
-
   compatibility:
     needs: core
     timeout-minutes: 20
diff --git a/ark/attest/__tests__/demo.test.ts b/ark/attest/__tests__/demo.test.ts
index c4e5aba0aa..bd718e701b 100644
--- a/ark/attest/__tests__/demo.test.ts
+++ b/ark/attest/__tests__/demo.test.ts
@@ -1,8 +1,4 @@
-import {
-	attest,
-	contextualize,
-	getPrimaryTsVersionUnderTest
-} from "@arktype/attest"
+import { attest, contextualize } from "@arktype/attest"
 import { type } from "arktype"
 
 const o = { ark: "type" } as const
diff --git a/ark/attest/__tests__/utils.ts b/ark/attest/__tests__/utils.ts
index 0e1bd2dd7c..1339c8c6a9 100644
--- a/ark/attest/__tests__/utils.ts
+++ b/ark/attest/__tests__/utils.ts
@@ -1,11 +1,11 @@
-import { readFile, shell } from "@arktype/fs"
+import { dirName, readFile, shell } from "@arktype/fs"
 import { copyFileSync, rmSync } from "node:fs"
 
 export const runThenGetContents = (templatePath: string): string => {
 	const tempPath = templatePath + ".temp.ts"
 	copyFileSync(templatePath, tempPath)
 	try {
-		shell(`pnpm tsx ${tempPath}`)
+		shell(`node --import=tsx ${tempPath}`, { cwd: dirName() })
 	} catch (e) {
 		console.error(e)
 	}
diff --git a/ark/attest/bench/baseline.ts b/ark/attest/bench/baseline.ts
index 1c081625d3..f48afaf2e6 100644
--- a/ark/attest/bench/baseline.ts
+++ b/ark/attest/bench/baseline.ts
@@ -1,6 +1,9 @@
 import { snapshot } from "@arktype/util"
 import process from "node:process"
-import { queueSnapshotUpdate } from "../cache/snapshots.js"
+import {
+	queueSnapshotUpdate,
+	writeSnapshotUpdatesOnExit
+} from "../cache/snapshots.js"
 import type { BenchAssertionContext, BenchContext } from "./bench.js"
 import {
 	stringifyMeasure,
@@ -29,6 +32,8 @@ export const queueBaselineUpdateIfNeeded = (
 		snapFunctionName: ctx.kind,
 		baselinePath: ctx.qualifiedPath
 	})
+
+	if (ctx.kind === "types") writeSnapshotUpdatesOnExit()
 }
 
 /** Pretty print comparison and set the process.exitCode to 1 if delta threshold is exceeded */
@@ -69,4 +74,4 @@ const handleNegativeDelta = (formattedDelta: string, ctx: BenchContext) => {
 			1
 		)}! Consider setting a new baseline.`
 	)
-}
\ No newline at end of file
+}
diff --git a/ark/attest/cache/snapshots.ts b/ark/attest/cache/snapshots.ts
index 5be8c08dc0..0f7b837be1 100644
--- a/ark/attest/cache/snapshots.ts
+++ b/ark/attest/cache/snapshots.ts
@@ -51,8 +51,15 @@ export const getSnapshotByName = (
  */
 export const queueSnapshotUpdate = (args: SnapshotArgs): void => {
 	const config = getConfig()
-	writeSnapUpdate(config.defaultAssertionCachePath, args)
-	writeSnapshotUpdatesOnExit()
+	const path = config.defaultAssertionCachePath
+	if (existsSync(path)) {
+		const existing = readJson(path)
+		writeJson(path, {
+			...existing,
+			updates:
+				Array.isArray(existing.updates) ? [...existing.updates, args] : [args]
+		})
+	} else writeJson(path, { updates: [args] })
 }
 
 export type QueuedUpdate = {
@@ -112,38 +119,23 @@ export const writeSnapshotUpdatesOnExit = (): void => {
 
 const writeCachedInlineSnapshotUpdates = () => {
 	const config = getConfig()
-	const updates: QueuedUpdate[] = []
 
-	if (existsSync(config.assertionCacheDir))
-		updates.push(...getQueuedUpdates(config.defaultAssertionCachePath))
-
-	writeUpdates(updates)
-	writeSnapUpdate(config.defaultAssertionCachePath)
-}
-
-const writeSnapUpdate = (path: string, update?: SnapshotArgs) => {
-	const assertions =
-		existsSync(path) ? readJson(path) : { updates: [] as SnapshotArgs[] }
+	let snapshotData: SnapshotArgs[] | undefined
 
-	assertions.updates =
-		update !== undefined ? [...(assertions.updates ?? []), update] : []
+	if (!existsSync(config.defaultAssertionCachePath)) return
 
-	writeJson(path, assertions)
-}
-const updateQueue = (queue: QueuedUpdate[], path: string) => {
-	let snapshotData: SnapshotArgs[] | undefined
 	try {
-		snapshotData = readJson(path).updates
+		snapshotData = readJson(config.defaultAssertionCachePath).updates
 	} catch {
 		// If we can't read the snapshot, log an error and move onto the next update
 		console.error(
-			`Unable to read snapshot data from expected location ${path}.`
+			`Unable to read snapshot data from expected location ${config.defaultAssertionCachePath}.`
 		)
 	}
 	if (snapshotData) {
 		try {
-			snapshotData.forEach(snapshot =>
-				queue.push(snapshotArgsToQueuedUpdate(snapshot))
+			writeUpdates(
+				snapshotData.map(snapshot => snapshotArgsToQueuedUpdate(snapshot))
 			)
 		} catch (error) {
 			// If writeInlineSnapshotToFile throws an error, log it and move on to the next update
@@ -152,12 +144,6 @@ const updateQueue = (queue: QueuedUpdate[], path: string) => {
 	}
 }
 
-const getQueuedUpdates = (path: string) => {
-	const queuedUpdates: QueuedUpdate[] = []
-	updateQueue(queuedUpdates, path)
-	return queuedUpdates
-}
-
 const snapshotArgsToQueuedUpdate = ({
 	position,
 	serializedValue,
diff --git a/ark/attest/main.ts b/ark/attest/main.ts
index 557abdbd53..14557f43c4 100644
--- a/ark/attest/main.ts
+++ b/ark/attest/main.ts
@@ -2,8 +2,8 @@ export { caller, type CallerOfOptions } from "@arktype/fs"
 export { attest } from "./assert/attest.js"
 export { bench } from "./bench/bench.js"
 export {
-	getBenchAssertionsAtPosition as getTypeBenchAssertionsAtPosition,
-	getTypeAssertionsAtPosition as getTypeRelationshipAssertionsAtPosition
+	getBenchAssertionsAtPosition,
+	getTypeAssertionsAtPosition
 } from "./cache/getCachedAssertions.js"
 export type {
 	ArgAssertionData,
diff --git a/ark/attest/package.json b/ark/attest/package.json
index 4b29c1e8ea..a4c3a69495 100644
--- a/ark/attest/package.json
+++ b/ark/attest/package.json
@@ -39,7 +39,7 @@
 		"@typescript/analyze-trace": "0.10.1"
 	},
 	"devDependencies": {
-		"typescript": "5.5.0-beta"
+		"typescript": "5.4.5"
 	},
 	"peerDependencies": {
 		"typescript": "*"
diff --git a/ark/repo/.eslintrc.cjs b/ark/repo/.eslintrc.cjs
index a15354cf04..8142b92e02 100644
--- a/ark/repo/.eslintrc.cjs
+++ b/ark/repo/.eslintrc.cjs
@@ -118,7 +118,13 @@ module.exports = defineConfig({
 		"no-case-declarations": "off",
 		/** In tests we use expect-error constantly, but in src if we
 		 * ever have to there should be an explanation */
-		"@typescript-eslint/ban-ts-comment": "warn"
+		"@typescript-eslint/ban-ts-comment": [
+			"warn",
+			{
+				// some errors are environment dependent or e.g. don't appear in build output
+				"ts-ignore": "allow-with-description"
+			}
+		]
 	},
 	overrides: [
 		{
diff --git a/ark/repo/mocha.globalSetup.ts b/ark/repo/mocha.globalSetup.ts
index b73626e38a..70d2e57425 100644
--- a/ark/repo/mocha.globalSetup.ts
+++ b/ark/repo/mocha.globalSetup.ts
@@ -1,5 +1,7 @@
 import { cleanup, setup } from "@arktype/attest"
 
+process.env.TZ = "America/New_York"
+
 export const mochaGlobalSetup = setup
 
 export const mochaGlobalTeardown = cleanup
diff --git a/ark/schema/constraints/constraint.ts b/ark/schema/constraints/constraint.ts
index ac599bb226..2088092f24 100644
--- a/ark/schema/constraints/constraint.ts
+++ b/ark/schema/constraints/constraint.ts
@@ -17,7 +17,8 @@ export interface BaseConstraintDeclaration extends RawNodeDeclaration {
 }
 
 export abstract class RawConstraint<
-	/** @ts-expect-error allow instantiation assignment to the base type */
+	/** uses -ignore rather than -expect-error because this is not an error in .d.ts
+	 * @ts-ignore allow instantiation assignment to the base type */
 	out d extends BaseConstraintDeclaration = BaseConstraintDeclaration
 > extends RawNode<d> {
 	readonly [arkKind] = "constraint"
diff --git a/ark/schema/constraints/props/index.ts b/ark/schema/constraints/props/index.ts
index d7681505fd..f3dfb10528 100644
--- a/ark/schema/constraints/props/index.ts
+++ b/ark/schema/constraints/props/index.ts
@@ -5,6 +5,7 @@ import {
 } from "@arktype/util"
 import type { Node, SchemaDef } from "../../node.js"
 import type { RawSchema } from "../../schema.js"
+import type { UnitNode } from "../../schemas/unit.js"
 import type { BaseMeta, declareNode } from "../../shared/declare.js"
 import { Disjoint } from "../../shared/disjoint.js"
 import { implementNode, type SchemaKind } from "../../shared/implement.js"
@@ -47,7 +48,10 @@ export const indexImplementation = implementNode<IndexDeclaration>({
 				const key = ctx.$.schema(def)
 				if (!key.extends(ctx.$.keywords.propertyKey))
 					return throwParseError(writeInvalidPropertyKeyMessage(key.expression))
-				const enumerableBranches = key.branches.filter(b => b.hasKind("unit"))
+				// TODO: explicit manual annotation once we can upgrade to 5.5
+				const enumerableBranches = key.branches.filter((b): b is UnitNode =>
+					b.hasKind("unit")
+				)
 				if (enumerableBranches.length) {
 					return throwParseError(
 						writeEnumerableIndexBranches(
diff --git a/ark/schema/node.ts b/ark/schema/node.ts
index 58c9861ab6..e263d38e0a 100644
--- a/ark/schema/node.ts
+++ b/ark/schema/node.ts
@@ -1,15 +1,15 @@
 import {
 	Callable,
-	type Dict,
-	type Guardable,
-	type Json,
-	type conform,
 	flatMorph,
 	includes,
 	isArray,
-	type listable,
 	shallowClone,
-	throwError
+	throwError,
+	type Dict,
+	type Guardable,
+	type Json,
+	type conform,
+	type listable
 } from "@arktype/util"
 import type { RawConstraint } from "./constraints/constraint.js"
 import type { PredicateNode } from "./constraints/predicate.js"
@@ -36,19 +36,19 @@ import type {
 	attachmentsOf
 } from "./shared/declare.js"
 import {
+	basisKinds,
+	constraintKinds,
+	precedenceOfKind,
+	propKinds,
+	refinementKinds,
+	schemaKinds,
 	type BasisKind,
 	type NodeKind,
 	type OpenNodeKind,
 	type PropKind,
 	type RefinementKind,
 	type SchemaKind,
-	type UnknownAttachments,
-	basisKinds,
-	constraintKinds,
-	precedenceOfKind,
-	propKinds,
-	refinementKinds,
-	schemaKinds
+	type UnknownAttachments
 } from "./shared/implement.js"
 import {
 	TraversalContext,
@@ -59,7 +59,8 @@ import {
 export type UnknownNode = RawNode | Schema
 
 export abstract class RawNode<
-	/** @ts-expect-error allow instantiation assignment to the base type */
+	/** uses -ignore rather than -expect-error because this is not an error in .d.ts
+	 * @ts-ignore allow instantiation assignment to the base type */
 	out d extends RawNodeDeclaration = RawNodeDeclaration
 > extends Callable<(data: d["prerequisite"]) => unknown, attachmentsOf<d>> {
 	constructor(public attachments: UnknownAttachments) {
diff --git a/ark/schema/schema.ts b/ark/schema/schema.ts
index 9c0eb549d9..254e35bff3 100644
--- a/ark/schema/schema.ts
+++ b/ark/schema/schema.ts
@@ -1,17 +1,17 @@
 import {
+	throwParseError,
 	type Callable,
 	type Json,
-	type conform,
-	throwParseError
+	type conform
 } from "@arktype/util"
 import type { constrain } from "./constraints/ast.js"
 import type { Predicate } from "./constraints/predicate.js"
 import {
-	type PrimitiveConstraintKind,
-	throwInvalidOperandError
+	throwInvalidOperandError,
+	type PrimitiveConstraintKind
 } from "./constraints/util.js"
 import type { NodeDef, reducibleKindOf } from "./kinds.js"
-import { type Node, RawNode } from "./node.js"
+import { RawNode, type Node } from "./node.js"
 import type { constraintKindOf } from "./schemas/intersection.js"
 import type {
 	Morph,
@@ -29,9 +29,9 @@ import { Disjoint } from "./shared/disjoint.js"
 import { ArkErrors } from "./shared/errors.js"
 import type { NodeKind, SchemaKind, kindRightOf } from "./shared/implement.js"
 import {
-	type inferIntersection,
 	intersectNodesRoot,
-	pipeNodesRoot
+	pipeNodesRoot,
+	type inferIntersection
 } from "./shared/intersections.js"
 import {
 	arkKind,
@@ -55,7 +55,8 @@ export type TypeOnlySchemaKey =
 	| "tOut"
 
 export abstract class RawSchema<
-		/** @ts-expect-error allow instantiation assignment to the base type */
+		/** uses -ignore rather than -expect-error because this is not an error in .d.ts
+		 * @ts-ignore allow instantiation assignment to the base type */
 		out d extends RawSchemaDeclaration = RawSchemaDeclaration
 	>
 	extends RawNode<d>
diff --git a/ark/schema/shared/errors.ts b/ark/schema/shared/errors.ts
index 87407a3702..1a2ef56ddc 100644
--- a/ark/schema/shared/errors.ts
+++ b/ark/schema/shared/errors.ts
@@ -9,10 +9,8 @@ import type { NodeKind } from "./implement.js"
 import type { TraversalContext } from "./traversal.js"
 import { arkKind, pathToPropString, type TraversalPath } from "./utils.js"
 
-export const throwArkError = (
-	...args: ConstructorParameters<typeof ArkError>
-): never => {
-	throw new ArkError(...args)
+export const throwArkError = (message: string): never => {
+	throw new ArkError(message)
 }
 
 export class ArkError extends TypeError {
diff --git a/ark/type/parser/objectLiteral.ts b/ark/type/parser/objectLiteral.ts
index 92d13e5d31..b6367b558e 100644
--- a/ark/type/parser/objectLiteral.ts
+++ b/ark/type/parser/objectLiteral.ts
@@ -1,19 +1,20 @@
 import {
+	tsKeywords,
 	type NodeDef,
 	type RawSchema,
-	tsKeywords,
+	type UnitNode,
 	type writeInvalidPropertyKeyMessage
 } from "@arktype/schema"
 import {
+	printable,
+	spliterate,
+	stringAndSymbolicEntriesOf,
+	throwParseError,
 	type Dict,
 	type ErrorMessage,
 	type Key,
 	type merge,
-	printable,
-	type show,
-	spliterate,
-	stringAndSymbolicEntriesOf,
-	throwParseError
+	type show
 } from "@arktype/util"
 import type { ParseContext } from "../scope.js"
 import type { inferDefinition, validateDefinition } from "./definition.js"
@@ -62,8 +63,10 @@ export const parseObjectLiteral = (def: Dict, ctx: ParseContext): RawSchema => {
 			const value = ctx.$.parse(entry.value, ctx)
 
 			// extract enumerable named props from the index signature
-			const [enumerable, nonEnumerable] = spliterate(key.branches, k =>
-				k.hasKind("unit")
+			// TODO: remove explicit annotation once we can use TS 5.5
+			const [enumerable, nonEnumerable] = spliterate(
+				key.branches,
+				(k): k is UnitNode => k.hasKind("unit")
 			)
 
 			if (enumerable.length) {
diff --git a/ark/type/parser/tuple.ts b/ark/type/parser/tuple.ts
index c3d1b026a9..433083d3bf 100644
--- a/ark/type/parser/tuple.ts
+++ b/ark/type/parser/tuple.ts
@@ -1,4 +1,7 @@
 import {
+	jsObjects,
+	makeRootAndArrayPropertiesMutable,
+	tsKeywords,
 	type BaseMeta,
 	type Morph,
 	type MutableInner,
@@ -12,22 +15,19 @@ import {
 	type distillConstrainableOut,
 	type inferIntersection,
 	type inferMorphOut,
-	type inferNarrow,
-	jsObjects,
-	makeRootAndArrayPropertiesMutable,
-	tsKeywords
+	type inferNarrow
 } from "@arktype/schema"
 import {
+	append,
+	objectKindOrDomainOf,
+	throwParseError,
 	type BuiltinObjectKind,
 	type Constructor,
 	type Domain,
 	type ErrorMessage,
-	append,
 	type array,
 	type conform,
-	objectKindOrDomainOf,
-	type show,
-	throwParseError
+	type show
 } from "@arktype/util"
 import type { ParseContext } from "../scope.js"
 import type { inferDefinition, validateDefinition } from "./definition.js"
@@ -194,15 +194,15 @@ export type validateTuple<def extends array, $, args> =
 		]
 	:	validateTupleLiteral<def, $, args>
 
-export type validateTupleLiteral<def extends array, $, args> = Readonly<
-	parseSequence<def, $, args>["validated"]
->
+export type validateTupleLiteral<def extends array, $, args> =
+	parseSequence<def, $, args> extends infer s extends SequenceParseState ?
+		Readonly<s["validated"]>
+	:	never
 
-type inferTupleLiteral<def extends array, $, args> = parseSequence<
-	def,
-	$,
-	args
->["inferred"]
+type inferTupleLiteral<def extends array, $, args> =
+	parseSequence<def, $, args> extends infer s extends SequenceParseState ?
+		s["inferred"]
+	:	never
 
 type SequenceParseState = {
 	unscanned: array
diff --git a/package.json b/package.json
index ae5b630053..c12ea81959 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,7 @@
 		"c8": "9.1.0",
 		"knip": "5.9.4",
 		"tsx": "4.7.2",
-		"typescript": "5.5.0-beta",
+		"typescript": "5.4.5",
 		"mocha": "10.4.0",
 		"@types/mocha": "10.0.6"
 	},
diff --git a/tsconfig.json b/tsconfig.json
index 224f4d7dc3..05cc6df32b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -23,5 +23,5 @@
 		},
 		"types": ["mocha", "node"]
 	},
-	"exclude": ["**/out", "node_modules", "./ark/docs", "./ark/repo"]
+	"exclude": ["**/out", "**/node_modules", "./ark/docs", "./ark/repo"]
 }