Shannon Now Runs on the Pi Harness (Beta)

[ezl-keygraph]

A few weeks ago in #348 we said the big June effort was rewriting Shannon's agent runtime onto the Pi harness and moving off claude-agent-sdk. That work is now done and available for beta testing.

You can run it today:

npx @keygraph/shannon@beta start -u <url> -r /path/to/repo

(or check out the feat/pi-harness-migration branch for a source build).

This is a beta. The pipeline, phases, and reports are unchanged. What changed is the engine underneath them. We'd love feedback before it lands on latest.

Why we did this

The number one request from this community has been multi-model support. Earlier workarounds (claude-code-router, then a custom base URL override) helped, but they were patches on top of a runtime (@anthropic-ai/claude-agent-sdk) that was fundamentally built around a single provider.

Pi (@earendil-works/pi-coding-agent) gives us a real foundation for this. Provider and model now resolve through pi-ai's model registry, with the same three-tier override contract working across Anthropic, AWS Bedrock, and any Anthropic-compatible base URL:

ANTHROPIC_SMALL_MODEL=...
ANTHROPIC_MEDIUM_MODEL=...
ANTHROPIC_LARGE_MODEL=...

For now, only Anthropic (Claude) models are supported. The Pi harness gives us the foundation to go broader, and we're actively testing other models. More on that soon.

Breaking changes / migration notes

• Google Vertex AI support has been removed. The Pi harness does not support Anthropic models via Vertex, so we dropped it. Anthropic, AWS Bedrock, and custom base URL remain. Vertex users can run npx @keygraph/shannon@beta setup to configure one of these alternatives.
• CLAUDE_CODE_MAX_OUTPUT_TOKENS is gone. Remove it from your .env/config; pi manages output limits.

What we want from you

• Run a scan on npx @keygraph/shannon@beta and tell us if results, cost, or runtime feel different from latest.
• Anything that feels off in the new runtime like agent behavior, tool errors, auth flows.

More multi-model news to come on this foundation.