feat: MCPStateStore — key-value state store with change tracking, transactions, TTL, namespaces, JSON serialization — 45 new tests — bump to v0.41.0

Author: Nicola Spieser

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.41.0] — 2026-02-23
+
+### Added
+- **State Store** (`MCPStateStore.h`): General-purpose key-value state store for microcontrollers. Designed for storing device state, calibration data, user preferences, and runtime config that persists across application logic (pair with NVS/EEPROM for reboot persistence).
+  - `StateStore`: Bounded or unlimited key-value store with `set()`, `get()`, `has()`, `remove()`, `clear()`.
+  - **Namespaced keys**: Use dotted keys (e.g., `"sensor.temp"`, `"config.name"`) and filter with `keys("sensor.")`.
+  - **Change listeners**: `onChange()` callback with old/new values, listener removal by ID.
+  - **Dirty tracking**: `isDirty()`, `dirtyKeys()`, `clearDirty()` for efficient persistence — only write changed keys to flash.
+  - **Bounded size**: Optional `maxEntries` with LRU-style eviction (evicts oldest-accessed entry).
+  - **TTL support**: Optional per-key expiry with `purgeExpired()`.
+  - **Transactions**: `begin()` / `commit()` / `rollback()` for atomic batch updates — changes buffered until commit, listeners fire only on commit.
+  - **JSON serialization**: `toJSON()` / `fromJSON()` for snapshot export/import, `toDetailedJSON()` with metadata, `statsJSON()`.
+  - Eviction and deletion notify listeners for consistent state tracking.
+- **45 new tests**: Full coverage of StateStore operations, namespaces, dirty tracking, listeners, eviction, TTL, transactions, JSON round-trip, and edge cases. **Total: 1457 tests**.
+
+### Fixed
+- Version sync: `library.properties` now matches `MCPD_VERSION`.
+
 ## [0.36.0] — 2026-02-22
 
 ### Added

README.md

@@ -33,7 +33,7 @@
 |---|:---:|:---:|:---:|
 | Runs on the MCU | ✅ | ✅ | ❌ CLI tool |
 | MCP spec compliant | ✅ 2025-11-25 | ❌ custom WS | ❌ |
-| Actually compiles | ✅ 1412 tests | ❌ self-described | N/A |
+| Actually compiles | ✅ 1457 tests | ❌ self-described | N/A |
 | Streamable HTTP + SSE | ✅ | ❌ | ❌ |
 | WebSocket transport | ✅ | ✅ | ❌ |
 | Claude Desktop bridge | ✅ | ❌ | ❌ |

library.json

@@ -1,6 +1,6 @@
 {
   "name": "mcpd",
-  "version": "0.40.0",
+  "version": "0.41.0",
   "description": "MCP Server SDK for Microcontrollers — Expose ESP32/RP2040/STM32 hardware as AI-accessible tools via Model Context Protocol",
   "keywords": [
     "mcp",

library.properties

@@ -1,5 +1,5 @@
 name=mcpd
-version=0.37.0
+version=0.41.0
 author=Nicola Spieser
 maintainer=Nicola Spieser <redbasecap-buiss@users.noreply.github.com>
 sentence=MCP Server SDK for Microcontrollers