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CHANGELOG.md

@@ -4,11 +4,21 @@ Reader-facing changes to the articles, architecture decisions, diagrams, and pra
 
 When adding or revising material, add a short entry under the relevant date with links to the affected files and any related issue or commit.
 
+## 2026-10-24
+
+- Added [chapter 07: Rollback and Recovery](docs/07-rollback-and-recovery.md), covering recovery target eligibility, shared-data compatibility, approved restore and data loss, restart rules, bounded recovery, failed-release blocks, and the rollback window.
+- Added [ADR-020: Define Rollback Eligibility and Retention](adr/ADR-020-define-rollback-eligibility-and-retention.md), [ADR-021: Preserve Data Compatibility During Trial](adr/ADR-021-preserve-data-compatibility-during-trial.md), and [ADR-022: Bound Recovery and Block Failed System Releases](adr/ADR-022-bound-recovery-and-block-failed-system-releases.md).
+- Added a [C++17 rollback policy simulation](examples/simulations/rollback-policy/readme.md) with nine scenarios and CMake/CTest checks. It models completed durable transitions and supplied eligibility and health outcomes, not real storage, backup restoration, bootloader integration, or a rescue environment.
+- Added PlantUML sources for [rollback policy](diagrams/plantuml/rollback-policy.puml), [recovery coordination](diagrams/plantuml/rollback-recovery-sequence.puml), and the [rollback window](diagrams/plantuml/rollback-window.puml). Added PNG previews for [rollback policy](diagrams/rendered/rollback-policy.png), [recovery coordination](diagrams/rendered/rollback-recovery-sequence.png), and the [rollback window](diagrams/rendered/rollback-window.png), rendered from those sources.
+- Updated the [README](readme.md), [series overview](docs/00-series-overview.md), [chapter 06 continuation](docs/06-atomic-updates.md), and [diagram index](diagrams/readme.md). Linked the existing chapter 06 PNG previews and corrected the outdated source-only descriptions.
+
 ## 2026-10-20
 
+- Added PNG previews for the [installation sequence](diagrams/rendered/ab-installation-sequence.png) and [restart decisions](diagrams/rendered/ab-installation-recovery.png) after the initial chapter 06 addition. History: [9385583](https://git.himro.ca/deeaitch/ota-reference-design/commit/9385583).
+
 - Added [chapter 06: Atomic Updates](docs/06-atomic-updates.md), covering preparation before activation, durable state, gaps between records, restart decisions, and the limits of package recovery.
 - Added [ADR-018: Prepare and Verify Before Activation](adr/ADR-018-prepare-and-verify-before-activation.md) and [ADR-019: Recover Interrupted Updates From Durable State](adr/ADR-019-recover-interrupted-updates-from-durable-state.md).
-- Added PlantUML sources for the [installation sequence](diagrams/plantuml/ab-installation-sequence.puml) and [restart decisions](diagrams/plantuml/ab-installation-recovery.puml). No new image previews are included.
+- Added PlantUML sources for the [installation sequence](diagrams/plantuml/ab-installation-sequence.puml) and [restart decisions](diagrams/plantuml/ab-installation-recovery.puml). The initial chapter addition included sources only; previews were added in the follow-up above.
 - Added a [C++17 interrupted installation model](examples/simulations/interrupted-installation/readme.md), with reset points, three supplied boot-record write outcomes, recovery checks, and CMake/CTest support. It models completed durable operations in memory, not real power-loss-safe storage.
 - Applied the root [.clang-format](.clang-format) to the new model and the existing [A/B trial boot example](examples/simulations/ab-trial-boot/readme.md). Existing C++ changes are formatting only.
 - Updated the [README](readme.md), [series overview](docs/00-series-overview.md), [chapter 05 continuation](docs/05-storage-layout.md), and [diagram index](diagrams/readme.md).