feat(harness): Initial Claude Code Support by supreme-gg-gg · Pull Request #2602 · kagent-dev/kagent

supreme-gg-gg · 2026-08-27T17:41:12Z

Basic support for running Claude Code on Substrate and add extensible interfaces for future harness like Codex.

Add a native Claude harness that runs the pinned Claude Code CLI and supports A2A streaming, cancellation, session resume, and durable state.
Add Claude template compilation for Anthropic, Amazon Bedrock, and Vertex AI, and shared local subagents
Add Claude support for remote MCP servers, standalone skills, and plugin-provided skills, with runtime-neutral resource materialization and configuration warnings.
Wire the Claude harness into the controller and build/release pipelines, including its container image and configurable controller logging.
Add comprehensive unit and E2E coverage for Claude interactions, persistence, fork and resume, cancellation, built-in tools, subagent routing, and MCP calls.
Merge adjacent streamed text parts in the UI so Claude responses render as continuous messages. (However, UI is not completely working due to ListTasks returns a task's messages and artifacts as two unordered lists, so a transcript cannot be replayed in order #2584)

supreme-gg-gg · 2026-08-27T21:20:33Z

Note to reviewer: See #2603

supreme-gg-gg · 2026-08-27T21:21:44Z

Note to reviewer: #2595 removed some functionality that the UI needs

Thanks! I added a bug issue here: #2613 that this PR should close.

Claude picked up that "FeedbackService" and "MemoryService" are not registered here - but they also don't seem to be used anywhere at the moment.

FeedbackService isn't used anywhere I think, but MemoryService is required by ADK to enable memory, I'll add it in a follow up

supreme-gg-gg · 2026-08-27T21:32:00Z

+- [x] Durable Claude session resume between turns
+- [x] Claude Code built-in tools
+- [x] Shared local subagents
+- [x] Standalone skills and plugin-provided skills


Note to reviewer: This short list summarizes what has been done and what will come next for Claude harness.
Plugin provided skills are not entirely working due to #2604

supreme-gg-gg · 2026-08-27T22:01:54Z

Codex review

[P1] Terminate the entire Claude process group — go/harness/claude/internal/driver/process.go:206-213

When a turn is canceled or parsing/event delivery fails while Claude has spawned a built-in tool process, signaling and killing only cmd.Process leaves its child processes running. Those orphaned commands can continue modifying the durable workspace or consuming resources after the task is reported canceled; start Claude in its own process group and terminate the group instead.

When I was working on #2602 I noticed some UI code was redundant after removal in #2598. This PR removes them --------- Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

Charlesthebird

I tested the UI fixes here and they are working well 🎉 - I haven't tested the claude harness parts though.

EItanya

Initial review

EItanya · 2026-08-28T15:42:23Z

Does this need to be nested inside of go/harness/claude/cmd/kagent-claude/main.go
Since it's the only main.go can't it just be go/harness/claude/cmd/main.go

This is mainly for the binary to keep the kagent-claude name instead of a generic cmd, I think it matches the Kagent CLI in go/core/cli/cmd/kagent

You can always name the binary with -o

That's true I forgot, I'll move it 😓

EItanya · 2026-08-28T15:46:23Z

-}
+// These aliases preserve the existing ADK configuration API while sharing one
+// runtime-neutral resource model with other Harness adapters.
+type AgentPluginConfig = agentplugin.Resources


Why do we need all of these aliases, can't we just use the actual types?

EItanya · 2026-08-28T15:54:01Z

Is there a more secure/lighter weight node runtime we could use so we don't have to deal with the CVEs from node:22-trixie-slim

We don't need a node runtime since it's now a native binary, I've switched to an alpine image

EItanya · 2026-08-28T15:58:55Z

+const (
+	claudeConfigDirEnv = "CLAUDE_CONFIG_DIR"
+	disableUpdaterEnv  = "DISABLE_AUTOUPDATER"
+	googleCredsEnv     = "GOOGLE_APPLICATION_CREDENTIALS"


What's this for?

The Vertex AI credentials are loaded into a /tmp file instead of the ADC default path since home directory /data is durable and snapshotted and this avoids the credentials from being persisted

EItanya · 2026-08-28T15:59:01Z

+
+const (
+	claudeConfigDirEnv = "CLAUDE_CONFIG_DIR"
+	disableUpdaterEnv  = "DISABLE_AUTOUPDATER"


Also, what's this for?

This keeps the runtime on the pinned Claude version by the image; I've changed I to DISABLE_UPDATES so both auto and manual updates are disabled. This also ensures that harness-provided env var cannot override this to re-enable update

EItanya · 2026-08-28T15:59:23Z

+// Input contains compiler output and Actor-owned locations used to construct
+// the Claude driver.
+type Input struct {
+	Context      context.Context


context shouldn't be in a struct generally, is this necessary, can we just pass it as an arg?

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

EItanya · 2026-08-28T16:26:45Z

+			// Work around upstream ADK's artifact-only event conversion: its callbacks can
+			// mutate an artifact but cannot replace it with another A2A event. Do this before
+			// a2a-go persists the update; remove when ADK exposes a general event converter.
+			if update, ok := event.(*a2atype.TaskArtifactUpdateEvent); ok && artifactContainsToolEvent(update.Artifact) {


Please swap this for #2621

EItanya · 2026-08-28T16:31:19Z

@@ -0,0 +1,18 @@
+//go:build !unix


Do we need !unix?

I've renamed this to use _windows.go suffix instead, since Claude Code can only run on either unix or windows

EItanya · 2026-08-28T16:40:53Z

+	if durableDir == "" {
+		return nil, fmt.Errorf("durable directory is required")
+	}


This is a claudism, it always checks args that it doesn't need to

Have it run through all instances like this

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

EItanya · 2026-08-29T15:05:30Z

There is too much happening in this PR for a focused review. Please split the ToolService / RemoteMCPServer / MCPServer changes into a separate PR and keep this one scoped to the Claude harness work. Those changes have their own catalog, reconciliation, lifecycle, and UI implications and need focused review and testing on their own.

github-actions Bot added the enhancement New feature or request label Aug 27, 2026

supreme-gg-gg mentioned this pull request Aug 27, 2026

[BUG] MCP servers never appear in the list — nothing writes the toolserver table since the legacy reconciler was removed #2603

Open

supreme-gg-gg commented Aug 27, 2026

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supreme-gg-gg force-pushed the feat/claude-harness branch from e59e0a4 to 312dfe6 Compare August 27, 2026 21:22

supreme-gg-gg mentioned this pull request Aug 27, 2026

chore: cleanup session paths from UI #2607

Merged

supreme-gg-gg commented Aug 27, 2026

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supreme-gg-gg marked this pull request as ready for review August 27, 2026 21:34

supreme-gg-gg requested review from a team, Charlesthebird and peterj as code owners August 27, 2026 21:34

github-actions Bot added enhancement New feature or request and removed enhancement New feature or request labels Aug 27, 2026

This was referenced Aug 28, 2026

fix: wire the system service into controller-v2 #2614

Closed

[BUG] Agents page cannot load: controller-v2 never wires the system service, so ListNamespaces always returns INTERNAL #2613

Open

fix: preserve A2A transcript order #2591

Merged

Charlesthebird approved these changes Aug 28, 2026

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Charlesthebird enabled auto-merge (squash) August 28, 2026 15:35

Charlesthebird disabled auto-merge August 28, 2026 15:36

EItanya force-pushed the main branch from 28d7572 to bf0ba9d Compare August 28, 2026 16:02

EItanya reviewed Aug 28, 2026

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supreme-gg-gg added 8 commits August 28, 2026 12:57

claude initial commit

c651efd

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

mcp, skills, plugins, fixes to claude

6622299

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

rebase and go mod

8e4e7e0

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

add claude code docs

9618f39

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

fix lint and test

793ffaa

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

add remotemcpserver back, fixes to make claude mcp work e2e

be71e96

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

fix codex review comments

91162c6

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

e2e: add fork and resume

a784320

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg added 2 commits August 28, 2026 12:59

review comments

a50cdd3

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

add timeout to claude

1a6da57

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg force-pushed the feat/claude-harness branch from 47759d9 to 1a6da57 Compare August 28, 2026 17:03

EItanya reviewed Aug 28, 2026

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supreme-gg-gg and others added 2 commits August 28, 2026 13:44

review comments

7559cf1

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

Merge branch 'main' into feat/claude-harness

88b1568

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supreme-gg-gg commented Aug 27, 2026

Codex review

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