Day 34 — Ship and Defend Mosaic

Today you ship one vertical slice and prove you can operate it.

Choose one application path

Expose Brandforge, AskDocs, Signal Room, or Cutroom through Mosaic. The path must include:

1. authenticated typed request;
2. tenant-scoped durable run;
3. bounded evidence acquisition;
4. harness release and provider route;
5. verification and terminal state;
6. content-addressed artifacts;
7. resumable events;
8. eval and operational signals.

Do not expose all four poorly. One complete path proves the platform.

Build and inspect

cd rust/rust-ai-engineering
sh scripts/ci.sh
docker build -f containers/Dockerfile -t mosaic-service:lifecycle .

The container runs as a non-root user where possible, declares health/readiness behavior, handles termination, stops admission, drains bounded work, and exits before the platform’s kill deadline.

Liveness asks whether the process should restart. Readiness asks whether it should receive traffic. A model service still loading weights may be alive but not ready.

Final drills

Prove each with artifacts:

• malformed and oversized request;
• provider timeout;
• worker crash and lease recovery;
• duplicate delivery;
• slow SSE client and reconnect;
• cross-tenant access attempt;
• prompt injection in evidence;
• quota exhaustion;
• candidate release regression and rollback;
• graceful shutdown with work in flight.

Architecture defense

Your final document answers:

• Which types make invalid states difficult to represent?
• Which queues and resources are bounded?
• Which effects require authorization and receipts?
• Which artifacts reproduce a run?
• Which evals protect releases?
• Which signals detect regressions?
• Which action restores service safely?
• What remains intentionally unsupported?

Definition of done

Mosaic is complete when another engineer can clone the repository, run the offline path, reproduce tests and evals, inspect a trace, understand a failure, operate the service, and roll back a release. An impressive one-time model answer is not the completion condition.

Finish with Project 7 Revision →.