diff --git a/apps/desktop/src/backend/DesktopServerExposure.test.ts b/apps/desktop/src/backend/DesktopServerExposure.test.ts
index dcfee93778d1876c13546a6d87cc20c6290238c2..4a8b516cb9361021ce871afb8d59b08f7c6251b9 100644
--- a/apps/desktop/src/backend/DesktopServerExposure.test.ts
+++ b/apps/desktop/src/backend/DesktopServerExposure.test.ts
@@ -272,8 +272,6 @@ describe("DesktopServerExposure", () => {
           modeError,
           DesktopServerExposure.DesktopServerExposureModePersistenceError,
         );
-        assert.isTrue(DesktopServerExposure.isDesktopServerExposureSetModeError(modeError));
-        assert.isTrue(DesktopServerExposure.isDesktopServerExposureError(modeError));
         assert.equal(modeError.mode, "network-accessible");
         assert.strictEqual(modeError.cause, settingsFailure);
         assert.strictEqual(modeError.cause.cause, diskFailure);
@@ -290,7 +288,6 @@ describe("DesktopServerExposure", () => {
           tailscaleError,
           DesktopServerExposure.DesktopTailscaleServePersistenceError,
         );
-        assert.isTrue(DesktopServerExposure.isDesktopServerExposureError(tailscaleError));
         assert.equal(tailscaleError.enabled, true);
         assert.equal(tailscaleError.port, 8443);
         assert.strictEqual(tailscaleError.cause, settingsFailure);
diff --git a/apps/desktop/src/backend/DesktopServerExposure.ts b/apps/desktop/src/backend/DesktopServerExposure.ts
index f04d2af7b1f67f707b4ac53b567225176f09fc0f..6c3cd55527ebb3d5bd8bf757b6c6f4c25db96499 100644
--- a/apps/desktop/src/backend/DesktopServerExposure.ts
+++ b/apps/desktop/src/backend/DesktopServerExposure.ts
@@ -244,7 +244,6 @@ export const DesktopServerExposureSetModeError = Schema.Union([
   DesktopServerExposureModePersistenceError,
 ]);
 export type DesktopServerExposureSetModeError = typeof DesktopServerExposureSetModeError.Type;
-export const isDesktopServerExposureSetModeError = Schema.is(DesktopServerExposureSetModeError);
 
 export const DesktopServerExposureError = Schema.Union([
   DesktopServerExposureNoNetworkAddressError,
@@ -252,7 +251,6 @@ export const DesktopServerExposureError = Schema.Union([
   DesktopTailscaleServePersistenceError,
 ]);
 export type DesktopServerExposureError = typeof DesktopServerExposureError.Type;
-export const isDesktopServerExposureError = Schema.is(DesktopServerExposureError);
 
 export interface DesktopServerExposureBackendConfig {
   readonly port: number;
diff --git a/apps/desktop/src/ipc/DesktopIpc.test.ts b/apps/desktop/src/ipc/DesktopIpc.test.ts
index fc311877f8290ed33a0c9d8d2cc7d36874a37f4e..5533831f9b55f94522c2cc5580db1c8155b8be56 100644
--- a/apps/desktop/src/ipc/DesktopIpc.test.ts
+++ b/apps/desktop/src/ipc/DesktopIpc.test.ts
@@ -41,7 +41,6 @@ describe("DesktopIpc", () => {
       const error = yield* Effect.flip(Effect.scoped(ipc.handle(invokeMethod)));
 
       assert.instanceOf(error, DesktopIpc.DesktopIpcRegistrationError);
-      assert.isTrue(DesktopIpc.isDesktopIpcError(error));
       assert.strictEqual(error.handlerKind, "invoke");
       assert.strictEqual(error.channel, invokeMethod.channel);
       assert.strictEqual(error.cause, cause);
@@ -69,7 +68,6 @@ describe("DesktopIpc", () => {
       if (exit._tag === "Success") return;
       const error = Cause.squash(exit.cause);
       assert.instanceOf(error, DesktopIpc.DesktopIpcUnregistrationError);
-      assert.isTrue(DesktopIpc.isDesktopIpcError(error));
       assert.strictEqual(error.handlerKind, "sync");
       assert.strictEqual(error.channel, syncMethod.channel);
       assert.strictEqual(error.cause, cause);
diff --git a/apps/desktop/src/ipc/DesktopIpc.ts b/apps/desktop/src/ipc/DesktopIpc.ts
index e948571cc62871ea5248ec76c3f33cd310e42a44..643543d4ec334ead309fee1e79f758a31f81ff27 100644
--- a/apps/desktop/src/ipc/DesktopIpc.ts
+++ b/apps/desktop/src/ipc/DesktopIpc.ts
@@ -55,7 +55,6 @@ export const DesktopIpcError = Schema.Union([
   DesktopIpcUnregistrationError,
 ]);
 export type DesktopIpcError = typeof DesktopIpcError.Type;
-export const isDesktopIpcError = Schema.is(DesktopIpcError);
 
 export interface DesktopIpcMethod<E, R> {
   readonly channel: string;
diff --git a/apps/desktop/src/preview/BrowserSession.test.ts b/apps/desktop/src/preview/BrowserSession.test.ts
index ff22f3dd227262be2b5d45a2cf643d98fadb2a6f..aaf34c3578f9e51c5773122f5f362bbed7cb3d8a 100644
--- a/apps/desktop/src/preview/BrowserSession.test.ts
+++ b/apps/desktop/src/preview/BrowserSession.test.ts
@@ -172,8 +172,6 @@ describe("BrowserSession", () => {
       const error = yield* browserSessions.getPartition("environment-a").pipe(Effect.flip);
 
       assert.instanceOf(error, BrowserSession.BrowserSessionPartitionDerivationError);
-      assert.isTrue(BrowserSession.isBrowserSessionGetSessionError(error));
-      assert.isTrue(BrowserSession.isBrowserSessionError(error));
       assert.equal(error.scope, "environment-a");
       assert.strictEqual(error.cause, platformCause);
       assert.strictEqual(error.cause.reason.cause, nativeCause);
@@ -196,8 +194,6 @@ describe("BrowserSession", () => {
       const error = yield* browserSessions.getSession("environment-b").pipe(Effect.flip);
 
       assert.instanceOf(error, BrowserSession.BrowserSessionCreationError);
-      assert.isTrue(BrowserSession.isBrowserSessionGetSessionError(error));
-      assert.isTrue(BrowserSession.isBrowserSessionError(error));
       assert.equal(error.scope, "environment-b");
       assert.equal(error.partition, partition);
       assert.strictEqual(error.cause, cause);
@@ -270,7 +266,6 @@ describe("BrowserSession", () => {
       const storageError = yield* browserSessions.clearCookies().pipe(Effect.flip);
 
       assert.instanceOf(storageError, BrowserSession.BrowserSessionStorageClearError);
-      assert.isTrue(BrowserSession.isBrowserSessionError(storageError));
       assert.equal(storageError.partition, secondPartition);
       assert.strictEqual(storageError.cause, storageCause);
       assert.equal(
@@ -287,7 +282,6 @@ describe("BrowserSession", () => {
       const cacheError = yield* browserSessions.clearCache().pipe(Effect.flip);
 
       assert.instanceOf(cacheError, BrowserSession.BrowserSessionCacheClearError);
-      assert.isTrue(BrowserSession.isBrowserSessionError(cacheError));
       assert.equal(cacheError.partition, firstPartition);
       assert.strictEqual(cacheError.cause, cacheCause);
       assert.equal(
diff --git a/apps/desktop/src/preview/BrowserSession.ts b/apps/desktop/src/preview/BrowserSession.ts
index 7f3c9ec5d7acd448399d6fc9461382a922dc7190..7ff8798522834d627422738fb5c39b0ab88b3ad1 100644
--- a/apps/desktop/src/preview/BrowserSession.ts
+++ b/apps/desktop/src/preview/BrowserSession.ts
@@ -93,7 +93,6 @@ export const BrowserSessionGetSessionError = Schema.Union([
   BrowserSessionCreationError,
 ]);
 export type BrowserSessionGetSessionError = typeof BrowserSessionGetSessionError.Type;
-export const isBrowserSessionGetSessionError = Schema.is(BrowserSessionGetSessionError);
 
 export const BrowserSessionError = Schema.Union([
   BrowserSessionPartitionDerivationError,
@@ -102,7 +101,6 @@ export const BrowserSessionError = Schema.Union([
   BrowserSessionCacheClearError,
 ]);
 export type BrowserSessionError = typeof BrowserSessionError.Type;
-export const isBrowserSessionError = Schema.is(BrowserSessionError);
 
 export class BrowserSession extends Context.Service<
   BrowserSession,
diff --git a/apps/desktop/src/updates/DesktopUpdates.test.ts b/apps/desktop/src/updates/DesktopUpdates.test.ts
index 1978337df3e720f72b5809c7909f2cecac9bc0d1..5097785215112a3a50952b9d5dc0dfc8cbb3a44b 100644
--- a/apps/desktop/src/updates/DesktopUpdates.test.ts
+++ b/apps/desktop/src/updates/DesktopUpdates.test.ts
@@ -794,7 +794,6 @@ describe("DesktopUpdates", () => {
         const error = yield* updates.setChannel("nightly").pipe(Effect.flip);
 
         assert.instanceOf(error, DesktopUpdates.DesktopUpdateChannelPersistenceError);
-        assert.isTrue(DesktopUpdates.isDesktopUpdateSetChannelError(error));
         assert.equal(error.channel, "nightly");
         assert.strictEqual(error.cause, settingsFailure);
         assert.strictEqual(error.cause.cause, diskFailure);
diff --git a/apps/desktop/src/updates/DesktopUpdates.ts b/apps/desktop/src/updates/DesktopUpdates.ts
index 20f005f2ab2dbc63485ff04cfa083437715987b1..344d135a10247af394d0eb395ce4802d507ef145 100644
--- a/apps/desktop/src/updates/DesktopUpdates.ts
+++ b/apps/desktop/src/updates/DesktopUpdates.ts
@@ -155,7 +155,6 @@ export const DesktopUpdateSetChannelError = Schema.Union([
   DesktopUpdateChannelPersistenceError,
 ]);
 export type DesktopUpdateSetChannelError = typeof DesktopUpdateSetChannelError.Type;
-export const isDesktopUpdateSetChannelError = Schema.is(DesktopUpdateSetChannelError);
 
 export class DesktopUpdates extends Context.Service<
   DesktopUpdates,