Bump version to 0.21.1-beta and update documentation

Author: ocots

BREAKINGS.md

@@ -2,12 +2,17 @@
 
 This document outlines all breaking changes introduced in CTBase v0.18.0-beta compared to v0.17.4. Use this guide to migrate your code and understand the impact of these changes.
 
-## Non-breaking note (0.21.x)
+## Non-breaking note (0.21.1-beta)
 
 - **Module renamed**: `CTBase.Extensions` → `CTBase.DevTools`
   - The submodule previously named `Extensions` is now named `DevTools` to better reflect its purpose (internal developer tools, not a general extension system)
   - All tag types and functions are unchanged: `run_tests`, `postprocess_coverage`, `automatic_reference_documentation`, `AbstractTestRunnerTag`, `TestRunnerTag`, `AbstractDocumenterReferenceTag`, `DocumenterReferenceTag`, `AbstractCoveragePostprocessingTag`, `CoveragePostprocessingTag`
   - **Migration**: replace `CTBase.Extensions` with `CTBase.DevTools` and `import CTBase.Extensions` with `import CTBase.DevTools` at all call sites
+- **Core utilities**: Added generic building blocks to CTBase.Core for sharing across control-toolbox ecosystem
+  - `AbstractCache`: abstract base type for computation caches (e.g. prepared AD plans), exported from Core
+  - `make_coerce`: shape-matching coercion helper (`only` for scalars, `identity` for arrays), exported from Core
+  - Both moved from CTFlows to CTBase for reuse across packages
+  - No breaking changes; purely additive public API. No migration required.
 
 ## Non-breaking note (0.21.0-beta)
 

CHANGELOGS.md

@@ -5,6 +5,47 @@ All notable changes to CTBase will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.21.1-beta] - 2026-06-23
+
+### 🔄 Breaking Changes
+
+#### **Module Rename: Extensions → DevTools**
+
+- **Renamed submodule**: `CTBase.Extensions` → `CTBase.DevTools` to better reflect its purpose (internal developer tools, not a general extension system)
+- **Unchanged API**: All tag types and functions remain unchanged:
+  - `run_tests`
+  - `postprocess_coverage`
+  - `automatic_reference_documentation`
+  - `AbstractTestRunnerTag`, `TestRunnerTag`
+  - `AbstractDocumenterReferenceTag`, `DocumenterReferenceTag`
+  - `AbstractCoveragePostprocessingTag`, `CoveragePostprocessingTag`
+- **Migration**: Replace `CTBase.Extensions` with `CTBase.DevTools` and `import CTBase.Extensions` with `import CTBase.DevTools` at all call sites
+
+### ✨ New Features
+
+#### **Core Utilities**
+
+- **AbstractCache**: Added abstract base type for computation caches in `Core/caches.jl`
+  - Generic type for storing pre-allocated buffers and prepared plans (e.g. AD plans)
+  - Concrete cache subtypes defined by packages/extensions providing specific backends
+  - Exported from `CTBase.Core` for reuse across control-toolbox ecosystem
+- **make_coerce**: Added shape-matching coercion helper in `Core/function_utils.jl`
+  - Returns `only` for scalars to extract single element from 1-element vectors
+  - Returns `identity` for arrays (`AbstractVector`, `AbstractMatrix`) as no-op
+  - Used to map uniform vector-valued results back to natural input shape
+  - Exported from `CTBase.Core` for reuse across control-toolbox ecosystem
+
+### 🏗️ Architecture
+
+- **Shared infrastructure**: Moved generic, dependency-free building blocks from CTFlows to CTBase.Core
+  - Enables sharing across control-toolbox packages without duplication
+  - `AbstractCache` provides common interface for computation caches
+  - `make_coerce` provides uniform shape coercion strategy
+
+### 🧹 Maintenance
+
+- **Version bump**: Bumped to 0.21.1-beta for module rename and core utilities.
+
 ## [0.21.0-beta] - 2026-06-22
 
 ### ✨ New Features

Project.toml

@@ -1,6 +1,6 @@
 name = "CTBase"
 uuid = "54762871-cc72-4466-b8e8-f6c8b58076cd"
-version = "0.21.0-beta"
+version = "0.21.1-beta"
 authors = ["Olivier Cots <olivier.cots@irit.fr>", "Jean-Baptiste Caillau <caillau@univ-cotedazur.fr>"]
 
 [deps]