feat(go): implement TCP/TLS connection in Go SDK

[saie-ch]

Which issue does this PR close?

This unblocks issue #2807 so TCP/TLS integration tests and examples can now be written for the Go
SDK.

Rationale

The Go SDK had TLS configuration fields (tlsEnabled, tlsDomain, tlsCAFile, tlsValidateCertificate)
and TLS error types generated, but the handshake was stubbed out at line 329 with return
errors.New("TLS connection is not implemented yet"). This blocked writing integration tests and
examples for TCP/TLS connections.

What changed?

Before: Line 329 returned a stub error preventing any TLS connections.

After: Full TLS implementation with:

• Added 4 TLS configuration option functions: WithTLS(), ### WithTLSDomain(), WithTLSCAFile(),
  WithTLSValidateCertificate()
• Implemented createTLSConfig() helper method that:
  • Configures certificate validation (InsecureSkipVerify)
  • Extracts server name from address for SNI (if tlsDomain not provided)
  • Loads custom CA certificates from file
  • Returns appropriate TLS error types (ErrInvalidTlsDomain, ErrInvalidTlsCertificatePath,
    ErrInvalidTlsCertificate)
• Replaced stub with actual TLS handshake using crypto/tls (lines 360-373):
  • Creates TLS config
  • Wraps TCP connection with tls.Client()
  • Performs TLS handshake with proper error handling

Implementation follows the same patterns as Rust (tcp_tls_connection_stream.rs), Java
(InternalTcpClient.java), C# (TcpMessageStream.cs), and Node.js (client.connection.ts) SDKs.

AI Usage

Claude Sonnet 4.5

• Guided by existing Rust, Java, Node.js, and C# TLS implementations
• Followed Go SDK patterns and used existing error types
• All pre-merge checks passed locally

[codecov]

Codecov Report

❌ Patch coverage is 0% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.55%. Comparing base (13ff0f5) to head (14c4cb8).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
foreign/go/client/tcp/tcp_core.go	0.00%	42 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2834      +/-   ##
============================================
- Coverage     68.43%   67.55%   -0.88%     
  Complexity      739      739              
============================================
  Files          1052     1049       -3     
  Lines         84635    84117     -518     
  Branches      61214    60653     -561     
============================================
- Hits          57917    56825    -1092     
- Misses        24347    24942     +595     
+ Partials       2371     2350      -21     

Flag	Coverage Δ
go	6.27% <0.00%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
foreign/go/client/tcp/tcp_core.go	0.00% <0.00%> (ø)

... and 41 files with indirect coverage changes

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[hubcio]

where are tests?

[saie-ch]

Hi @hubcio This PR implements the TLS handshake functionality that was previously stubbed out (line 329). It does NOT include tests - those will be added in issue #2807.

[atharvalade]

Hi @hubcio This PR implements the TLS handshake functionality that was previously stubbed out (line 329). It does NOT include tests - those will be added in issue #2807.

I can confirm. @hubcio Test issue was created and assigned to me but implementation itself was pending so I went ahead and created implementation issue.

@saie-ch if it's easier, do you want to take up tests for this since you did implementation? I don't mind either. Once I get some time, I'll do a quick review as well. Currently I am assigned for #2807.

[mmodzelewski]

Looks good, @saie-ch. @saie-ch @atharvalade could you please coordinate on who will be proceeding with the tests/examples issue? Feel free to hop on Discord to discuss it if that’s easier.

[saie-ch]

Hi @hubcio This PR implements the TLS handshake functionality that was previously stubbed out (line 329). It does NOT include tests - those will be added in issue #2807.

I can confirm. @hubcio Test issue was created and assigned to me but implementation itself was pending so I went ahead and created implementation issue.

@saie-ch if it's easier, do you want to take up tests for this since you did implementation? I don't mind either. Once I get some time, I'll do a quick review as well. Currently I am assigned for #2807.

Hi @atharvalade, happy to take on the test task; I'll work on #2807. thanks:)