[BUG] Git, OCI, and S3 Agent Plugin resources cannot be materialized while creating Substrate golden Actors

[supreme-gg-gg]

📋 Prerequisites

• I have searched the existing issues to avoid creating a duplicate
• By submitting this issue, you agree to follow our Code of Conduct
• I am using the latest version of the software
• I have tried to clear cache/cookies or used incognito mode (if ui-related)
• I can consistently reproduce this issue

🎯 Affected Service(s)

App Service

🚦 Impact/Severity

No impact (Default)

🐛 Bug Description

Kagent advertises Git, OCI, and S3 sources for Agent Plugin resources, but an
AgentTemplate using a network-backed source cannot currently become ready on
the Substrate runtime. Both the Go ADK runtime and the Claude harness materialize
their selected resources during process startup, before their readiness endpoint
is available. Outbound networking is not usable at that point in the golden
Actor lifecycle, so the fetch fails with a closed connection and the process
exits.

This leaves the AgentTemplate pending, the golden Actor in RESUMING, and its
worker occupied. The failure is reproduced with both a public Git repository
and a public, digest-pinned OCI artifact. It does not depend on source
credentials.

🔄 Steps To Reproduce

1. Configure a Kagent AgentTemplate using the Go ADK harness and select an
   Agent Plugin whose source is a public Git repository pinned to a commit.
2. Apply the template and wait for its generated ActorTemplate to build a
   golden Actor.
3. Observe that the template never becomes ready and the golden Actor remains
   in RESUMING.
4. Inspect the golden Actor's container logs.

Initialized empty Git repository in /plugins/plugin-0/.git/
fatal: unable to access 'https://github.com/agentplugins/agent-plugins-example.git/': Send failure: Broken pipe
Failed to materialize Agent Plugins: materialize plugin 0: exit status 128

Observed with a public OCI skill artifact pinned by digest:

materialize skill "myskill": pull ghcr.io/supreme-gg-gg/myskill@sha256:...:
Get "https://ghcr.io/v2/": EOF
Failed to materialize Agent Plugins

The same class of failure occurs in the Claude harness while materializing a
plugin-selected skill, although its Git/TLS implementation reports the closed
connection as a TLS handshake failure.

🤔 Expected Behavior

An AgentTemplate using a valid Git, OCI, or S3 Agent Plugin resource reaches
Ready, and the plugin's selected skills and MCP configuration are available
to the agent. Golden creation must support any network access that Kagent
requires to materialize declared plugin resources.

📱 Actual Behavior

The runtime process attempts the Git fetch before it serves readiness. The
connection is closed during startup, materialization fails, and the process
exits before it can ever become ready. Golden creation consequently cannot
complete.

💻 Environment

No response

🔧 CLI Bug Report

No response

🔍 Additional Context

Temporary Workarounds:

• Bake the required plugin or skill content into the harness image and avoid a
  runtime network fetch. This sacrifices normal Agent Plugin source semantics
  and requires a new image for every resource revision.
• Pre-populate the exact materialization destination in a custom image only if
  the runtime's validation and path expectations remain satisfied. This is
  brittle and should be treated as a development-only workaround.

📋 Logs

📷 Screenshots

No response

🙋 Are you willing to contribute?

• I am willing to submit a PR to fix this issue

[supreme-gg-gg]

Note that in the case of Claude I was able to ask the Agent to clone the plugin repo and setup the plugin using the bash tool so it's definitely not a wrong harness setup. The issue is the network egress limitation by Substrate during golden image build.

Codex looked into upstream code and wrote some analysis, I will paste the following core idea here for record-keeping:

cmd/ateom-gvisor/main.go implements RunWorkload in this order:

1. It explicitly deactivates Actor networking at lines 604-606.
2. It prepares the Actor's authenticated egress identity and installs the
   network redirect at lines 621-629.
3. It creates and starts every application container at lines 679-700.
4. It waits for every configured readiness endpoint at lines 702-705.
5. Only after readiness succeeds does it call activateActorNetworking at
   lines 706-708.

Preparing the redirect is not equivalent to allowing egress. In
internal/atunnel/egress.go, Egress.handle reads the current active tunnel at
lines 238-240 and immediately closes the downstream connection when it is nil at
lines 241-245. The harness therefore sees a TCP/TLS connection begin and then
close, which accounts for the Git Broken pipe, OCI EOF, and GnuTLS handshake
variants.

This produces a direct circular dependency:

Kagent readiness requires remote resource materialization
        -> materialization requires Actor egress
        -> Actor egress activation requires readiness