Adopt two-lane strategy — pin known-good models on @latest, bleeding edge opt-in

[BaseInfinity]

Context

The sibling repo (BaseInfinity/claude-sdlc-harness) shipped v1.100.0 as the Reliable default:

• Opus 4.6[1m] max builder + GPT-5.5 xhigh first brain + Fable high second brain
• Published to npm @latest
• Frontier (Opus 5 + Sol + Fable) will publish to @frontier as 2.0.0-frontier.N

See the epic: BaseInfinity/claude-sdlc-harness#718

What this repo should do

1. Identify the current known-good model configuration for codex-sdlc-wizard
2. Pin it as the default install path
3. Create a frontier lane for bleeding-edge model adoption (opt-in)
4. Add a containerized baseline so future changes prove they're improvements

Key lessons from the sibling

• Never flip the default model in a docs commit with no canary run
• A new model enters behind a named dist-tag and a canary, not by changing the default
• Immutable npm versions already prevent contamination — a branch is only needed for patch releases
• The escalation ladder (builder → first brain → second brain) makes model changes surgical

Reference

• Sibling epic: Epic: Two-lane fork — Reliable (@latest) / Frontier (@frontier) claude-sdlc-harness#718
• Reliable release: v1.100.0 on claude-sdlc-harness
• GPT-5.5 CLI retirement: 2026-10-14 (affects both repos if using codex exec)