docs: record WAL schema v12 in the staging contract

[FeathBow]

Summary

• docs/safety.md still said new staging transactions use WAL schema v11; SealWal's VERSION has been 12 since feat(core): bind held-tree sidecars to WAL recovery #87.
• State what v12 adds over v11 — binding a completed tree manifest to the exact sidecar that carries it — and correct the compatibility range: both schema-v10 and schema-v11 transactions remain readable.
• Extend the downgrade note: v12 frames, not only proof-schema-v3 records, are unreadable by older binaries.

Validation

Every claim in the edited paragraphs was checked against the code on main. The inventory bounds in the same section still match HeldTreeLimits::default() exactly and were left unchanged.

Safety

None. Documentation only; no runtime, authority, or filesystem behaviour changes.

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Team

Run ID: c6ee96c3-64c8-47db-8281-105bd7b88bfe

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}