09 — Decide, ramp, and decouple

Epic: #520 · Behavior change: ramp · Depends on: #527, #528

Summary

Use the metrics + parity scorecard to decide whether pi replaces anthropic, then ramp it — and if so,
drop the coupled SDK.

Scope

• Review #527 dashboards + #528 scorecard; decide pi vs anthropic.
• Ramp the winner via the existing wizard-runner 25 → 50 → 100 (each step gated on metrics); revert to
  anthropic stays one flip.
• If pi wins: flip the default runner in DEFAULT_ROUTE/ROUTES to pi, remove
  @anthropic-ai/claude-agent-sdk + the anthropic runner from RUNNERS, and clean up the second SDK
  consumer (mcp-prompt-streaming.ts).
• If anthropic still wins: keep it the default runner, leave the seam + pi runner registered behind the
  flag for re-evaluation.

Acceptance criteria

• Decision recorded with the data behind it.
• Winner ramped to target, or status quo retained with rationale.
• If decoupling: dep removed, no source imports it, all programs/frameworks green on the new default.

Start by reviewing #527's dashboards and #528's scorecard, then inspect the existing wizard-runner ramp and the DEFAULT_ROUTE, ROUTES, and RUNNERS entry points. If pi wins, check the @anthropic-ai/claude-agent-sdk dependency, the anthropic runner, and mcp-prompt-streaming.ts for cleanup. Done means the decision and data are recorded, the winner reaches its target or the status quo is justified, and the acceptance checks pass.