Sandbox brand agent fails to resolve demo.example.com during certification module C2

[rockey5520]

Issue

During certification module C2 (Brand Protocol), the sandbox training agent at https://test-agent.adcontextprotocol.org/brand/mcp consistently fails to resolve demo.example.com, causing the live demo to break mid-session.

Observed behavior

The teaching flow hits this sequence:

1. Sage attempts a live get_brand_identity demo using brand domain demo.example.com
2. The sandbox fails to resolve the domain
3. Sage attempts to check available brands as a fallback
4. The sandbox fails again
5. Sage gives up and pivots to spec-only teaching, skipping the live demo entirely

The exact message learners see:

"Let me run a live demo so you can see this in action. The sandbox isn't resolving demo.example.com — let me check what brands are available. The brand agent sandbox isn't resolving domains

[bokelley]

Triage

Classification: Bug
Bucket(s): addie, training / certification
Status: drafting-pr

What the experts said:

• education-expert: root cause confirmed — unconditional buyer-domain hint caused Sage to pass demo.example.com as brand_id to get_brand_identity; daan_janssen is the correct C2 example per curriculum design
• prompt-engineer: three blockers: unconditional line 557, same issue in get_certification_module render path, and hardcoded get_products in generic teaching rules — all fixed in the PR

My take: The system prompt appended "Use brand domain demo.example.com for the account." unconditionally for every active module. In C2 (Brand Protocol), Sage conflated it with the brand_id parameter for get_brand_identity (which expects roster IDs like daan_janssen), getting REFERENCE_NOT_FOUND and falling back to spec-only teaching. Draft PR #4075 removes the unconditional instruction and replaces both demo-scenario render paths with tool-aware guidance.

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Thanks for filing! This was a clear, reproducible bug with a precise repro sequence — exactly what makes a good report.

Triaged by Claude Code. Session: https://claude.ai/code/session_019qaFNRgQ5bht7PNJpgHmiR

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Generated by Claude Code