plans/prompts/wave_6/pr_c2_version_preview.md
Implement the version_preview wave of C2 in plans/cleanup-state-machines.md. The plan wins. Prereq: github_ops wave landed (it establishes the git-adjacent migration patterns; reuse them).
Pre-code artifacts per the plan: lifecycle matrix row verified (active checkout/recovery retained; reattach on reload; continue on window close; preserve/enter recovery contract on quit; reconcile branch/checkout state on restart; dispose after safe return/settlement on entity deletion — the mid-checkout recovery semantics are the heart of this machine, they must survive the move exactly); serializability audit (checkout intents, originBranch retention, recovery state — all data; the navigate/toast effects become presentation events routed per decision 5 with the N=1 identity rule); safe projection; deletion budget (renderer controller + manager, per-command-class dispatch plumbing).
Key semantics to preserve verbatim (from the machine's review history): epoch-keyed reads with mutations never dropped; semantic checkout intent (preview/return); recovery-required capability gating (restore buttons disabled — the capability selectors from the hardening work port to the remote projection); return-branch preservation until preview checkout completes; Neon uncached-app restart on return; bulk-delete ordering (entity deletion disposes the actor without firing APP_CHANGED into a deleted app — the A-phase fix must hold across the process boundary).
Tests: existing version_preview transition/recovery suites unchanged; mid-checkout window close + reattach from a second window; app deletion during checkout; restart reconciliation; ChatHeader mutation indicator (A2's selector) reads the remote projection identically. Golden suite green. /deep-review. Branch c2-version-preview; /pr-push; update plan status + matrix.
Trailing deletion (part of this wave, per the plan's rolling Phase D): land the wave's adapter/channel deletion as a SEPARATE PR immediately behind the cutover (same day is fine — no bake, no soak; per the plan's recorded corrections: no update window, no runtime toggle, stragglers are compile-time-detectable, and dead-code deletion cannot regress runtime once typecheck/CI pass). The separation exists ONLY to keep the high-scrutiny cutover diff pure for review; a later cutover revert simply reverts both PRs. The wave is not complete until it lands.
Rebatch note (see DEPENDENCIES.md): after github_ops sets the pattern, version_preview and image_generation PREP runs in parallel (disjoint domains); only the cutovers stagger through the single cutover slot.