diff --git a/packages/convert/src/gramjs/convert.test.ts b/packages/convert/src/gramjs/convert.test.ts
index 0555957d..e61e60e8 100644
--- a/packages/convert/src/gramjs/convert.test.ts
+++ b/packages/convert/src/gramjs/convert.test.ts
@@ -23,15 +23,16 @@ describe('gramjs/convert', () => {
                     ipAddress: '149.154.167.40',
                     ipv6: false,
                     port: 443,
+                    testMode: true,
                 },
                 media: {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     ipv6: false,
                     port: 443,
+                    testMode: true,
                 },
             },
-            testMode: true,
             version: 3,
         })
     })
diff --git a/packages/convert/src/mtkruto/convert.test.ts b/packages/convert/src/mtkruto/convert.test.ts
index 5c63474c..eb26e27a 100644
--- a/packages/convert/src/mtkruto/convert.test.ts
+++ b/packages/convert/src/mtkruto/convert.test.ts
@@ -22,14 +22,15 @@ describe('mtkruto/convert', () => {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     port: 443,
+                    testMode: true,
                 },
                 media: {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     port: 443,
+                    testMode: true,
                 },
             },
-            testMode: true,
             version: 3,
         })
     })
diff --git a/packages/convert/src/pyrogram/convert.test.ts b/packages/convert/src/pyrogram/convert.test.ts
index 9c36d62d..cc3f1ef6 100644
--- a/packages/convert/src/pyrogram/convert.test.ts
+++ b/packages/convert/src/pyrogram/convert.test.ts
@@ -22,11 +22,13 @@ describe('pyrogram/convert', () => {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     port: 443,
+                    testMode: true,
                 },
                 media: {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     port: 443,
+                    testMode: true,
                 },
             },
             self: {
@@ -35,7 +37,6 @@ describe('pyrogram/convert', () => {
                 userId: 5000801609,
                 usernames: [],
             },
-            testMode: true,
             version: 3,
         })
     })
diff --git a/packages/convert/src/telethon/convert.test.ts b/packages/convert/src/telethon/convert.test.ts
index caa57bd1..10997fd7 100644
--- a/packages/convert/src/telethon/convert.test.ts
+++ b/packages/convert/src/telethon/convert.test.ts
@@ -23,15 +23,16 @@ describe('telethon/convert', () => {
                     ipAddress: '149.154.167.40',
                     ipv6: false,
                     port: 80,
+                    testMode: true,
                 },
                 media: {
                     id: 2,
                     ipAddress: '149.154.167.40',
                     ipv6: false,
                     port: 80,
+                    testMode: true,
                 },
             },
-            testMode: true,
             version: 3,
         })
     })
diff --git a/packages/convert/src/telethon/parse.test.ts b/packages/convert/src/telethon/parse.test.ts
index dd525c8e..22e6f3fc 100644
--- a/packages/convert/src/telethon/parse.test.ts
+++ b/packages/convert/src/telethon/parse.test.ts
@@ -28,7 +28,7 @@ describe('telethon/parse', () => {
     it('should correctly parse ipv6 sessions', () => {
         expect(parseTelethonSession(TELETHON_TEST_SESSION_V6)).toEqual({
             dcId: 1,
-            ipAddress: '2001:0b28:f23d:f001:0000:0000:0000:000e',
+            ipAddress: '2001:b28:f23d:f001::e',
             port: 443,
             ipv6: true,
             authKey: hex.decode(
diff --git a/packages/core/src/highlevel/utils/inline-utils.ts b/packages/core/src/highlevel/utils/inline-utils.ts
index fb57f448..22c3f960 100644
--- a/packages/core/src/highlevel/utils/inline-utils.ts
+++ b/packages/core/src/highlevel/utils/inline-utils.ts
@@ -1,7 +1,7 @@
 import type { tl } from '@mtcute/tl'
 import { TlBinaryReader, TlBinaryWriter } from '@mtcute/tl-runtime'
+import { base64 } from '@fuman/utils'
 
-import { getPlatform } from '../../platform.js'
 import { assertNever } from '../../types/utils.js'
 
 /**
@@ -10,7 +10,7 @@ import { assertNever } from '../../types/utils.js'
  * @param id  Inline message ID
  */
 export function parseInlineMessageId(id: string): tl.TypeInputBotInlineMessageID {
-    const buf = getPlatform().base64Decode(id, true)
+    const buf = base64.decode(id, true)
     const reader = TlBinaryReader.manual(buf)
 
     if (buf.length === 20) {
@@ -57,7 +57,7 @@ export function encodeInlineMessageId(id: tl.TypeInputBotInlineMessageID): strin
             assertNever(id)
     }
 
-    return getPlatform().base64Encode(writer.result(), true)
+    return base64.encode(writer.result(), true)
 }
 
 export function normalizeInlineId(id: string | tl.TypeInputBotInlineMessageID): tl.TypeInputBotInlineMessageID {
diff --git a/packages/core/src/highlevel/utils/inspectable.ts b/packages/core/src/highlevel/utils/inspectable.ts
index 6a16e294..d2cbeb41 100644
--- a/packages/core/src/highlevel/utils/inspectable.ts
+++ b/packages/core/src/highlevel/utils/inspectable.ts
@@ -2,8 +2,7 @@
 /* eslint-disable ts/no-unsafe-call,ts/no-unsafe-argument */
 
 import Long from 'long'
-
-import { getPlatform } from '../../platform.js'
+import { base64 } from '@fuman/utils'
 
 const customInspectSymbol = Symbol.for('nodejs.util.inspect.custom')
 
@@ -57,7 +56,7 @@ export function makeInspectable<T>(
 
                 if (val && typeof val === 'object') {
                     if (val instanceof Uint8Array) {
-                        val = getPlatform().base64Encode(val)
+                        val = base64.encode(val)
                     } else if (Long.isLong(val)) {
                         val = val.toString()
                     } else if (typeof val.toJSON === 'function') {
diff --git a/packages/core/src/highlevel/utils/string-session.test.ts b/packages/core/src/highlevel/utils/string-session.test.ts
index e96dec5c..710e13b5 100644
--- a/packages/core/src/highlevel/utils/string-session.test.ts
+++ b/packages/core/src/highlevel/utils/string-session.test.ts
@@ -17,6 +17,16 @@ const stubDcs = {
         mediaOnly: true,
     },
 }
+const stubDcsTest = {
+    main: {
+        ...stubDcs.main,
+        testMode: true,
+    },
+    media: {
+        ...stubDcs.media,
+        testMode: true,
+    },
+}
 const stubDcsBasic = {
     main: {
         id: 2,
@@ -24,6 +34,7 @@ const stubDcsBasic = {
         ipv6: false,
         mediaOnly: false,
         port: 443,
+        testMode: false,
     },
     media: {
         id: 2,
@@ -31,6 +42,17 @@ const stubDcsBasic = {
         ipv6: false,
         mediaOnly: true,
         port: 443,
+        testMode: false,
+    },
+}
+const stubDcsBasicTest = {
+    main: {
+        ...stubDcsBasic.main,
+        testMode: true,
+    },
+    media: {
+        ...stubDcsBasic.media,
+        testMode: true,
     },
 }
 const stubDcsSameMedia = {
@@ -47,24 +69,22 @@ describe('writeStringSession', () => {
         expect(
             writeStringSession({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasic,
                 authKey: stubAuthKey,
             }),
         ).toMatchInlineSnapshot(
-            '"AwQAAAAXAQIADjE0OS4xNTQuMTY3LjUwALsBAAAXAQICDzE0OS4xNTQuMTY3LjIyMrsBAAAgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
+            '"AwQAAAAXAgIADjE0OS4xNTQuMTY3LjUwALsBAAAXAgICDzE0OS4xNTQuMTY3LjIyMrsBAAAgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
         )
     })
     it('should write production string session without user with same dc for media', () => {
         expect(
             writeStringSession({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasicSameMedia,
                 authKey: stubAuthKey,
             }),
         ).toMatchInlineSnapshot(
-            '"AwAAAAAXAQIADjE0OS4xNTQuMTY3LjUwALsBAAAgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
+            '"AwAAAAAXAgIADjE0OS4xNTQuMTY3LjUwALsBAAAgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
         )
     })
 
@@ -72,7 +92,6 @@ describe('writeStringSession', () => {
         expect(
             writeStringSession({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasic,
                 authKey: stubAuthKey,
                 self: {
@@ -83,7 +102,7 @@ describe('writeStringSession', () => {
                 },
             }),
         ).toMatchInlineSnapshot(
-            '"AwUAAAAXAQIADjE0OS4xNTQuMTY3LjUwALsBAAAXAQICDzE0OS4xNTQuMTY3LjIyMrsBAAA5MAAAAAAAADeXebwgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
+            '"AwUAAAAXAgIADjE0OS4xNTQuMTY3LjUwALsBAAAXAgICDzE0OS4xNTQuMTY3LjIyMrsBAAA5MAAAAAAAADeXebwgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
         )
     })
 
@@ -91,8 +110,7 @@ describe('writeStringSession', () => {
         expect(
             writeStringSession({
                 version: 3,
-                testMode: true,
-                primaryDcs: stubDcsBasic,
+                primaryDcs: stubDcsBasicTest,
                 authKey: stubAuthKey,
                 self: {
                     userId: 12345,
@@ -102,7 +120,7 @@ describe('writeStringSession', () => {
                 },
             }),
         ).toMatchInlineSnapshot(
-            '"AwcAAAAXAQIADjE0OS4xNTQuMTY3LjUwALsBAAAXAQICDzE0OS4xNTQuMTY3LjIyMrsBAAA5MAAAAAAAADeXebwgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
+            '"AwUAAAAXAgIEDjE0OS4xNTQuMTY3LjUwALsBAAAXAgIGDzE0OS4xNTQuMTY3LjIyMrsBAAA5MAAAAAAAADeXebwgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"',
         )
     })
 })
@@ -116,7 +134,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasic,
                 authKey: stubAuthKey,
                 self: null,
@@ -130,7 +147,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasicSameMedia,
                 authKey: stubAuthKey,
                 self: null,
@@ -144,7 +160,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 3,
-                testMode: false,
                 primaryDcs: stubDcsBasic,
                 authKey: stubAuthKey,
                 self: {
@@ -163,8 +178,7 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 3,
-                testMode: true,
-                primaryDcs: stubDcsBasic,
+                primaryDcs: stubDcsBasicTest,
                 authKey: stubAuthKey,
                 self: {
                     userId: 12345,
@@ -184,7 +198,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 2,
-                testMode: false,
                 primaryDcs: stubDcs,
                 authKey: stubAuthKey,
                 self: null,
@@ -198,7 +211,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 2,
-                testMode: false,
                 primaryDcs: stubDcsSameMedia,
                 authKey: stubAuthKey,
                 self: null,
@@ -212,7 +224,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 2,
-                testMode: false,
                 primaryDcs: stubDcs,
                 authKey: stubAuthKey,
                 self: {
@@ -231,8 +242,7 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 2,
-                testMode: true,
-                primaryDcs: stubDcs,
+                primaryDcs: stubDcsTest,
                 authKey: stubAuthKey,
                 self: {
                     userId: 12345,
@@ -252,7 +262,6 @@ describe('readStringSession', () => {
                 ),
             ).toEqual({
                 version: 1,
-                testMode: false,
                 // v1 didn't have separate media dc
                 primaryDcs: stubDcsSameMedia,
                 authKey: stubAuthKey,
diff --git a/packages/core/src/highlevel/utils/string-session.ts b/packages/core/src/highlevel/utils/string-session.ts
index c1fc1415..8bec69a2 100644
--- a/packages/core/src/highlevel/utils/string-session.ts
+++ b/packages/core/src/highlevel/utils/string-session.ts
@@ -1,6 +1,6 @@
 import { TlBinaryReader, TlBinaryWriter } from '@mtcute/tl-runtime'
+import { base64 } from '@fuman/utils'
 
-import { getPlatform } from '../../platform.js'
 import { MtArgumentError } from '../../types/index.js'
 import type { BasicDcOption, DcOptions } from '../../utils/dcs.js'
 import { parseBasicDcOption, serializeBasicDcOption } from '../../utils/dcs.js'
@@ -74,11 +74,11 @@ export function writeStringSession(data: StringSessionData): string {
 
     writer.bytes(data.authKey)
 
-    return getPlatform().base64Encode(writer.result(), true)
+    return base64.encode(writer.result(), true)
 }
 
 export function readStringSession(data: string): StringSessionData {
-    const buf = getPlatform().base64Decode(data, true)
+    const buf = base64.decode(data, true)
 
     const version = buf[0]
 
diff --git a/packages/core/src/network/transports/intermediate.test.ts b/packages/core/src/network/transports/intermediate.test.ts
index d5b79814..4ef9924c 100644
--- a/packages/core/src/network/transports/intermediate.test.ts
+++ b/packages/core/src/network/transports/intermediate.test.ts
@@ -1,109 +1,87 @@
 // todo: fix test
-// import { describe, expect, it } from 'vitest'
-// import { defaultTestCryptoProvider, useFakeMathRandom } from '@mtcute/test'
+import { describe, expect, it } from 'vitest'
+import { defaultTestCryptoProvider, useFakeMathRandom } from '@mtcute/test'
+import { hex } from '@fuman/utils'
+import { Bytes, write } from '@fuman/io'
 
-// import { IntermediatePacketCodec, PaddedIntermediatePacketCodec, TransportError } from '../../index.js'
-// import { getPlatform } from '../../platform.js'
+import { IntermediatePacketCodec, PaddedIntermediatePacketCodec } from './intermediate'
+import { TransportError } from './abstract'
 
-// const p = getPlatform()
+describe('IntermediatePacketCodec', () => {
+    it('should return correct tag', () => {
+        expect(hex.encode(new IntermediatePacketCodec().tag())).eq('eeeeeeee')
+    })
 
-// describe('IntermediatePacketCodec', () => {
-//     it('should return correct tag', () => {
-//         expect(p.hexEncode(new IntermediatePacketCodec().tag())).eq('eeeeeeee')
-//     })
+    it('should correctly parse immediate framing', async () => {
+        const codec = new IntermediatePacketCodec()
+        expect(codec.decode(Bytes.from(hex.decode('050000000501020304')), false)).eql(new Uint8Array([5, 1, 2, 3, 4]))
+    })
 
-//     it('should correctly parse immediate framing', () =>
-//         new Promise<void>((done) => {
-//             const codec = new IntermediatePacketCodec()
-//             codec.on('packet', (data: Uint8Array) => {
-//                 expect([...data]).eql([5, 1, 2, 3, 4])
-//                 done()
-//             })
-//             codec.feed(p.hexDecode('050000000501020304'))
-//         }))
+    it('should correctly parse incomplete framing', () => {
+        const codec = new IntermediatePacketCodec()
+        const buf = Bytes.alloc()
 
-//     it('should correctly parse incomplete framing', () =>
-//         new Promise<void>((done) => {
-//             const codec = new IntermediatePacketCodec()
-//             codec.on('packet', (data: Uint8Array) => {
-//                 expect([...data]).eql([5, 1, 2, 3, 4])
-//                 done()
-//             })
-//             codec.feed(p.hexDecode('050000000501'))
-//             codec.feed(p.hexDecode('020304'))
-//         }))
+        write.bytes(buf, hex.decode('050000000501'))
+        expect(codec.decode(buf, false)).toEqual(null)
 
-//     it('should correctly parse multiple streamed packets', () =>
-//         new Promise<void>((done) => {
-//             const codec = new IntermediatePacketCodec()
+        write.bytes(buf, hex.decode('020304'))
+        expect(codec.decode(buf, false)).eql(new Uint8Array([5, 1, 2, 3, 4]))
+        expect(codec.decode(buf, false)).toEqual(null)
+    })
 
-//             let number = 0
+    it('should correctly parse multiple streamed packets', () => {
+        const codec = new IntermediatePacketCodec()
+        const buf = Bytes.alloc()
 
-//             codec.on('packet', (data: Uint8Array) => {
-//                 if (number === 0) {
-//                     expect([...data]).eql([5, 1, 2, 3, 4])
-//                     number = 1
-//                 } else {
-//                     expect([...data]).eql([3, 1, 2, 3, 1])
-//                     done()
-//                 }
-//             })
-//             codec.feed(p.hexDecode('050000000501'))
-//             codec.feed(p.hexDecode('020304050000'))
-//             codec.feed(p.hexDecode('000301020301'))
-//         }))
+        write.bytes(buf, hex.decode('050000000501'))
+        expect(codec.decode(buf, false)).toEqual(null)
+        write.bytes(buf, hex.decode('020304050000'))
+        expect(codec.decode(buf, false)).eql(new Uint8Array([5, 1, 2, 3, 4]))
+        expect(codec.decode(buf, false)).eql(null)
 
-//     it('should correctly parse transport errors', () =>
-//         new Promise<void>((done) => {
-//             const codec = new IntermediatePacketCodec()
+        write.bytes(buf, hex.decode('000301020301'))
+        expect(codec.decode(buf, false)).eql(new Uint8Array([3, 1, 2, 3, 1]))
+        expect(codec.decode(buf, false)).toEqual(null)
+    })
 
-//             codec.on('error', (err: TransportError) => {
-//                 expect(err).to.have.instanceOf(TransportError)
-//                 expect(err.code).eq(404)
-//                 done()
-//             })
+    it('should correctly parse transport errors', () => {
+        const codec = new IntermediatePacketCodec()
+        const buf = Bytes.alloc()
 
-//             codec.feed(p.hexDecode('040000006cfeffff'))
-//         }))
+        write.bytes(buf, hex.decode('040000006cfeffff'))
+        expect(() => codec.decode(buf, false)).toThrow(new TransportError(404))
+    })
 
-//     it('should reset when called reset()', () =>
-//         new Promise<void>((done) => {
-//             const codec = new IntermediatePacketCodec()
+    it('should correctly frame packets', () => {
+        const data = hex.decode('6cfeffff')
+        const buf = Bytes.alloc()
 
-//             codec.on('packet', (data: Uint8Array) => {
-//                 expect([...data]).eql([1, 2, 3, 4, 5])
-//                 done()
-//             })
+        new IntermediatePacketCodec().encode(data, buf)
 
-//             codec.feed(p.hexDecode('ff0000001234567812345678'))
-//             codec.reset()
-//             codec.feed(p.hexDecode('050000000102030405'))
-//         }))
+        expect(hex.encode(buf.result())).toEqual('040000006cfeffff')
+    })
+})
 
-//     it('should correctly frame packets', () => {
-//         const data = p.hexDecode('6cfeffff')
+describe('PaddedIntermediatePacketCodec', () => {
+    useFakeMathRandom()
 
-//         expect(p.hexEncode(new IntermediatePacketCodec().encode(data))).toEqual('040000006cfeffff')
-//     })
-// })
+    const create = async () => {
+        const codec = new PaddedIntermediatePacketCodec()
+        codec.setup!(await defaultTestCryptoProvider())
 
-// describe('PaddedIntermediatePacketCodec', () => {
-//     useFakeMathRandom()
+        return codec
+    }
 
-//     const create = async () => {
-//         const codec = new PaddedIntermediatePacketCodec()
-//         codec.setup!(await defaultTestCryptoProvider())
+    it('should return correct tag', async () => {
+        expect(hex.encode((await create()).tag())).eq('dddddddd')
+    })
 
-//         return codec
-//     }
+    it('should correctly frame packets', async () => {
+        const data = hex.decode('6cfeffff')
+        const buf = Bytes.alloc()
 
-//     it('should return correct tag', async () => {
-//         expect(p.hexEncode((await create()).tag())).eq('dddddddd')
-//     })
+        ;(await create()).encode(data, buf)
 
-//     it('should correctly frame packets', async () => {
-//         const data = p.hexDecode('6cfeffff')
-
-//         expect(p.hexEncode((await create()).encode(data))).toEqual('0a0000006cfeffff29afd26df40f')
-//     })
-// })
+        expect(hex.encode(buf.result())).toEqual('0a0000006cfeffff29afd26df40f')
+    })
+})
diff --git a/packages/core/src/network/transports/intermediate.ts b/packages/core/src/network/transports/intermediate.ts
index e59cb496..c60961cf 100644
--- a/packages/core/src/network/transports/intermediate.ts
+++ b/packages/core/src/network/transports/intermediate.ts
@@ -29,8 +29,8 @@ export class IntermediatePacketCodec implements IPacketCodec {
 
         if (length === 4) {
             // error
-            const code = read.uint32le(reader)
-            throw new TransportError(code)
+            const code = read.int32le(reader)
+            throw new TransportError(-code)
         }
 
         if (reader.available < length) {
diff --git a/packages/core/src/utils/binary/asn1-parser.ts b/packages/core/src/utils/binary/asn1-parser.ts
index 601ce728..702d0456 100644
--- a/packages/core/src/utils/binary/asn1-parser.ts
+++ b/packages/core/src/utils/binary/asn1-parser.ts
@@ -1,15 +1,13 @@
 // all available libraries either suck or are extremely large for the use case, so i made my own~
 
-import { hex } from '@fuman/utils'
-
-import { getPlatform } from '../../platform.js'
+import { base64, hex } from '@fuman/utils'
 
 /**
  * Parses a single PEM block to buffer.
  * In fact just strips begin/end tags and parses the rest as Base64
  */
 export function parsePemContents(pem: string): Uint8Array {
-    return getPlatform().base64Decode(pem.replace(/^-----(?:BEGIN|END)(?: RSA)? PUBLIC KEY-----$|\n/gm, ''))
+    return base64.decode(pem.replace(/^-----(?:BEGIN|END)(?: RSA)? PUBLIC KEY-----$|\n/gm, ''))
 }
 
 // based on https://git.coolaj86.com/coolaj86/asn1-parser.js/src/branch/master/asn1-parser.js
diff --git a/packages/node/src/utils.ts b/packages/node/src/utils.ts
index 70dd1c86..b084b27e 100644
--- a/packages/node/src/utils.ts
+++ b/packages/node/src/utils.ts
@@ -1,3 +1,2 @@
 export * from './utils/crypto.js'
-export * from './utils/stream-utils.js'
 export * from '@mtcute/core/utils.js'