v0.3.9 — Hybrid split-engine loops

Highlights (0.3.0 → 0.3.9)

Two new Claude Code-only skills route the existing loops across a
high-taste Claude design model and cheap Codex CLI sessions:

• /cvg-hybrid-plan-loop — the design-tier model (default: Fable) drafts and
  revises the plan; Codex CLI sessions gate it as fresh plan reviewers.
• /cvg-hybrid-build-loop — Codex implements and takes every first-pass
  review round; a clean cheap-tier review promotes to a design-tier
  final-fresh-exit review instead of ending the loop. Only a clean
  design-tier pass exits.

Every mechanic in the codex-backed specialist wrapper pattern was verified
against live runs on codex-cli 0.142.3 and hardened release by release:

• wrappers stay in-turn (a stopped background specialist is never re-invoked
  when its background command exits) with a SendMessage recovery path
• sandbox re-pinned on every resume (an unpinned resume re-resolves from
  local config and can silently escalate to full access)
• reviewers run workspace-write from a scratch working directory: repo
  OS-level read-only, /tmp audit artifacts still land (read-only blocks
  them entirely)
• workers in linked git worktrees get the git common dir via --add-dir, so
  per-slice commits work
• the -o file is the source of truth, not the codex exit code
• cross-repo plans: one loop per repo, uncovered repos are blocking known
  gaps (also applied to the base cvg-build-loop)

Three behavioral eval layers under evals/wrapper-behavior/ back these
rules: a sandbox ground-truth matrix against the real codex CLI (also the
canary for codex upgrades), wrapper-compliance scenarios against a stub codex
with per-rule ablation, and orchestrator cross-repo scoping scenarios.

Full details: README §Hybrid Loops and evals/wrapper-behavior/README.md.