agent: ConnectTarget type for connection link or SimpleX name

Adds `ConnectTarget = CTLink AConnectionLink | CTName SimplexNameInfo`
in Agent/Protocol.hs next to AConnectionLink. The StrEncoding parser
gates the CTName branch on a `@`/`#`/`simplex:/name` discriminator so
that bare tokens (which SimplexNameInfo accepts for Markdown's sake)
cannot ambiguously match at this layer. JSON is a plain string via
strToJEncoding, mirroring AConnectionLink. No consumers yet.

Author: shumvgolove

simplexmq.cabal

@@ -500,6 +500,7 @@ test-suite simplexmq-test
       AgentTests.ShortLinkTests
       CLITests
       CoreTests.BatchingTests
+      CoreTests.ConnectTargetTests
       CoreTests.CryptoFileTests
       CoreTests.CryptoTests
       CoreTests.EncodingTests

src/Simplex/Messaging/Agent/Protocol.hs

@@ -122,6 +122,7 @@ module Simplex.Messaging.Agent.Protocol
     OwnerId,
     ConnectionLink (..),
     AConnectionLink (..),
+    ConnectTarget (..),
     SimplexNameInfo (..),
     SimplexNameDomain (..),
     SimplexTLD (..),
@@ -195,6 +196,7 @@ import qualified Data.Aeson.TH as J
 import qualified Data.Aeson.Types as JT
 import Data.Attoparsec.ByteString.Char8 (Parser)
 import qualified Data.Attoparsec.ByteString.Char8 as A
+import Data.Attoparsec.Combinator (lookAhead)
 import qualified Data.ByteString.Base64.URL as B64
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
@@ -1596,6 +1598,26 @@ instance ToJSON AConnectionLink where
 instance FromJSON AConnectionLink where
   parseJSON = strParseJSON "AConnectionLink"
 
+data ConnectTarget = CTLink AConnectionLink | CTName SimplexNameInfo
+  deriving (Eq, Show)
+
+instance StrEncoding ConnectTarget where
+  strEncode = \case
+    CTLink l -> strEncode l
+    CTName n -> strEncode n
+  strP = CTName <$> (lookAhead nameStart *> strP) <|> CTLink <$> strP
+    where
+      nameStart =
+        () <$ A.satisfy (\c -> c == '@' || c == '#')
+          <|> () <$ "simplex:/name"
+
+instance ToJSON ConnectTarget where
+  toEncoding = strToJEncoding
+  toJSON = strToJSON
+
+instance FromJSON ConnectTarget where
+  parseJSON = strParseJSON "ConnectTarget"
+
 instance ConnectionModeI m => StrEncoding (ConnShortLink m) where
   strEncode = \case
     CSLInvitation sch srv (SMP.EntityId lnkId) (LinkKey k) -> slEncode sch srv 'i' lnkId k

tests/CoreTests/ConnectTargetTests.hs

@@ -0,0 +1,59 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeApplications #-}
+
+module CoreTests.ConnectTargetTests where
+
+import AgentTests.ConnectionRequestTests (contactConnRequest, invConnRequest)
+import qualified Data.Aeson as J
+import Simplex.Messaging.Agent.Protocol (AConnectionLink (..), ConnectTarget (..), ConnectionLink (..), SConnectionMode (..))
+import Simplex.Messaging.Encoding.String (strDecode, strEncode)
+import Test.Hspec hiding (fit, it)
+import Util (it)
+
+connectTargetTests :: Spec
+connectTargetTests = describe "ConnectTarget" $ do
+  describe "CTName (SimpleX name) — canonical wire form prefixes simplex:/name" $ do
+    it "@alice.simplex encodes as simplex:/name@alice.simplex" $
+      "@alice.simplex" `encodesAs` "simplex:/name@alice.simplex"
+    it "#privacy (bare TLD-less channel) encodes as simplex:/name#privacy.simplex" $
+      "#privacy" `encodesAs` "simplex:/name#privacy.simplex"
+    it "#privacy.simplex encodes as simplex:/name#privacy.simplex" $
+      "#privacy.simplex" `encodesAs` "simplex:/name#privacy.simplex"
+    it "#support.acme.simplex preserves subdomain" $
+      "#support.acme.simplex" `encodesAs` "simplex:/name#support.acme.simplex"
+    it "simplex:/name@alice.simplex round-trips" $
+      "simplex:/name@alice.simplex" `encodesAs` "simplex:/name@alice.simplex"
+    it "simplex:/name#privacy.simplex round-trips" $
+      "simplex:/name#privacy.simplex" `encodesAs` "simplex:/name#privacy.simplex"
+
+  describe "CTLink (connection link) round-trips" $ do
+    it "parses simplex:/contact#… as CTLink and round-trips" $ do
+      let s = strEncode (ACL SCMContact (CLFull contactConnRequest))
+      s `decodesSuccessfully` ()
+      s `encodesAs` s
+    it "parses simplex:/invitation#… as CTLink" $ do
+      let s = strEncode (ACL SCMInvitation (CLFull invConnRequest))
+      s `decodesSuccessfully` ()
+
+  describe "rejects ambiguous bare input at this layer" $ do
+    it "rejects bare 'alice' — no @, no #, no simplex:/name prefix" $
+      strDecode @ConnectTarget "alice" `shouldSatisfy` isLeft
+    it "rejects empty input" $
+      strDecode @ConnectTarget "" `shouldSatisfy` isLeft
+    it "rejects whitespace input" $
+      strDecode @ConnectTarget " " `shouldSatisfy` isLeft
+
+  describe "JSON shape mirrors AConnectionLink (plain string, not tagged sum)" $ do
+    it "encodes @alice.simplex as a JSON string" $
+      case strDecode @ConnectTarget "@alice.simplex" of
+        Right ct -> J.toJSON ct `shouldBe` J.String "simplex:/name@alice.simplex"
+        Left e -> expectationFailure $ "strDecode failed: " <> e
+    it "parses JSON string back to ConnectTarget" $
+      J.eitherDecode @ConnectTarget "\"@alice.simplex\""
+        `shouldSatisfy` either (const False) (const True)
+  where
+    encodesAs input canonical =
+      (strEncode <$> strDecode @ConnectTarget input) `shouldBe` Right canonical
+    decodesSuccessfully s () =
+      strDecode @ConnectTarget s `shouldSatisfy` either (const False) (const True)
+    isLeft = either (const True) (const False)

tests/Test.hs

@@ -8,6 +8,7 @@ import Control.Concurrent (threadDelay)
 import qualified Control.Exception as E
 import Control.Logger.Simple
 import CoreTests.BatchingTests
+import CoreTests.ConnectTargetTests
 import CoreTests.CryptoFileTests
 import CoreTests.CryptoTests
 import CoreTests.EncodingTests
@@ -83,6 +84,7 @@ main = do
       $ do
         describe "Core tests" $ do
           describe "Batching tests" batchingTests
+          describe "ConnectTarget tests" connectTargetTests
           describe "Encoding tests" encodingTests
           describe "Version range" versionRangeTests
           describe "Encryption tests" cryptoTests