docs(archive): Preserve PR #5423

docs/pr-discussions/PR-5423-feat-b-0857-p2-deferred-install-sh-becomes-universal-unix-li.md

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+---
+pr_number: 5423
+title: "feat(B-0857 P2 deferred): install.sh becomes universal Unix-like-OS entry \u2014 routes by environment; SHORTER path than B-0854 Ace migration (Aaron 2026-05-27)"
+author: "AceHack"
+state: "MERGED"
+created_at: "2026-05-27T07:49:27Z"
+merged_at: "2026-05-27T07:53:40Z"
+closed_at: "2026-05-27T07:53:40Z"
+head_ref: "backlog/b-0857-install-sh-universal-unix-entry-consolidation-2026-05-27"
+base_ref: "main"
+archived_at: "2026-05-27T12:19:58Z"
+archive_tool: "tools/pr-preservation/archive-pr.ts"
+---
+
+# PR #5423: feat(B-0857 P2 deferred): install.sh becomes universal Unix-like-OS entry — routes by environment; SHORTER path than B-0854 Ace migration (Aaron 2026-05-27)
+
+## PR description
+
+## Summary
+
+Operator-named direction: *"when are we moving to install.sh over zeta-install.sh? the universall install surface for unix like oses?"*
+
+Filed immediately per Aaron 2026-05-27 separation-of-concerns discipline. Implementation defers until current cred-persistence + cosign + self-register stack lands + next USB test validates.
+
+## Migration target
+
+\`tools/setup/install.sh\` becomes universal Unix-like-OS entry that ROUTES by environment:
+
+| Detect | Routes to |
+|---|---|
+| macOS (Darwin) | \`setup/macos.sh\` (dev env) |
+| Linux non-NixOS | \`setup/linux.sh\` (dev env) |
+| Linux NixOS live-USB | \`setup/nixos-install-from-usb.sh\` (factored zeta-install.sh body) |
+| Installed NixOS | runtime verify / update |
+
+## Shorter than B-0854 (Ace migration)
+
+| | B-0857 | B-0854 |
+|---|---|---|
+| Scope | Routing + factor zeta-install.sh | Declarative manifest + Ace CLI |
+| Dependencies | None | B-0288 + manifest design |
+| Timeline | 1-2 ISO test cycles | Multi-phase long horizon |
+
+B-0857 ships operator-facing unification at imperative-bash scope. B-0854 builds declarative substrate on top. Both compose; B-0857 doesn't block B-0854 + can ship faster.
+
+## 10 sub-rows enumerated
+
+B-0857.1 audit PR #5389 integration claim → B-0857.2 env-detection → B-0857.3 factor body → B-0857.4 route → B-0857.5-7 compose with adjacent stacks → B-0857.8 thin-wrapper back-compat → B-0857.9 retire wrapper → B-0857.10 empirical validation.
+
+## Composes with
+
+- **B-0854** (Ace migration; Phase 4 builds on top)
+- **B-0852** (cred-persistence; OS-agnostic)
+- **B-0855** (self-register fix; OS-agnostic)
+- **B-0853** (cosign verify; OS-agnostic)
+- **B-0833** (installer creds discipline)
+
+## Rule 0 preserved
+
+Install-graph carve-out stays at \`tools/setup/\`; new \`nixos-install-from-usb.sh\` joins it as Linux-NixOS-USB-mode sibling.
+
+🤖 Generated with [Claude Code](https://claude.com/claude-code)
+
+## Reviews
+
+### COMMENTED — @copilot-pull-request-reviewer (2026-05-27T07:52:29Z)
+
+## Pull request overview
+
+Docs-only PR that files a new P2 backlog row (B-0857) capturing the operator's direction to make `tools/setup/install.sh` the universal Unix-like-OS install entry, routing by environment (macOS / Linux-non-NixOS / NixOS-live-USB / installed-NixOS), and shrinking `zeta-install.sh` to a thin wrapper on a shorter path than the broader B-0854 Ace migration. Implementation is deferred; only the row and its index entry land here.
+
+**Changes:**
+- Adds `docs/backlog/P2/B-0857-...md` with framing, current state, migration target, 10 enumerated sub-rows, composition with adjacent rows (B-0854/0852/0855/0853/0833), and P2 justification.
+- Adds the corresponding open-row entry to `docs/BACKLOG.md` under the P2 section.
+
+### Reviewed changes
+
+Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
+
+| File | Description |
+| ---- | ----------- |
+| docs/backlog/P2/B-0857-...md | New backlog row defining install.sh universal-entry consolidation and 10 sub-rows |
+| docs/BACKLOG.md | Index entry pointing at the new B-0857 row |
+
+## General comments
+
+### @chatgpt-codex-connector (2026-05-27T07:49:32Z)
+
+You have reached your Codex usage limits for code reviews. You can see your limits in the [Codex usage dashboard](https://chatgpt.com/codex/cloud/settings/usage).