docs: add v1.2.3 release documentation

Add CHANGELOG and release notes for v1.2.3 release with:
- Configurable MySQL session timeout feature
- C API for parsing web-style search expressions

Author: libraz

CHANGELOG.md

@@ -7,6 +7,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.2.3] - 2025-11-20
+
+### Added
+
+- Configurable MySQL session timeout to prevent disconnection during long operations
+  - New configuration option: `replication.session_timeout_sec` (default: 28800 seconds / 8 hours)
+  - Automatically sets `wait_timeout` and `interactive_timeout` on MySQL connection
+  - Prevents timeout issues during large table synchronization or slow binlog processing
+- C API for parsing web-style search expressions
+  - New public API: `mygram_parse_search_expr()` for parsing search queries
+  - Enables integration with other C/C++ applications
+  - Supports all existing query syntax (SEARCH, FILTER, SORT, LIMIT)
+
 ## [1.2.2] - 2025-11-20
 
 ### Fixed
@@ -180,7 +193,8 @@ Initial release of MygramDB with core search engine functionality and MySQL repl
 
 ---
 
-[Unreleased]: https://github.com/libraz/mygram-db/compare/v1.2.2...HEAD
+[Unreleased]: https://github.com/libraz/mygram-db/compare/v1.2.3...HEAD
+[1.2.3]: https://github.com/libraz/mygram-db/compare/v1.2.2...v1.2.3
 [1.2.2]: https://github.com/libraz/mygram-db/compare/v1.2.1...v1.2.2
 [1.2.1]: https://github.com/libraz/mygram-db/compare/v1.2.0...v1.2.1
 [1.2.0]: https://github.com/libraz/mygram-db/compare/v1.1.0...v1.2.0

docs/releases/v1.2.3.md

@@ -0,0 +1,231 @@
+# MygramDB v1.2.3 Release Notes
+
+**Release Date:** 2025-11-20
+**Type:** Minor Release (Feature Addition)
+
+---
+
+## Overview
+
+Version 1.2.3 adds two important features: configurable MySQL session timeout to prevent disconnection during long operations, and a C API for parsing web-style search expressions. This release enables better integration with external applications and improves stability for large-scale data synchronization.
+
+## What's New
+
+### 1. Configurable MySQL Session Timeout
+
+**Problem:** During long-running operations like large table synchronization or slow binlog processing, MySQL connections would timeout and disconnect, causing synchronization failures.
+
+**Solution:** Added configurable session timeout settings that automatically configure MySQL's `wait_timeout` and `interactive_timeout` on connection.
+
+**Configuration:**
+
+```yaml
+replication:
+  session_timeout_sec: 28800  # 8 hours (default)
+```
+
+**Benefits:**
+
+- Prevents unexpected disconnections during large table sync operations
+- Configurable timeout value to match your workload requirements
+- Automatically applies to both initial connection and reconnections
+- Default value (8 hours) suitable for most production scenarios
+
+**Use Cases:**
+
+- Syncing tables with millions of rows
+- Slow network environments where binlog processing takes time
+- Batch processing scenarios requiring long-lived connections
+
+**Example:**
+
+```yaml
+# For very large tables requiring 24-hour sync operations
+replication:
+  session_timeout_sec: 86400  # 24 hours
+
+# For faster environments with frequent reconnections
+replication:
+  session_timeout_sec: 3600   # 1 hour
+```
+
+### 2. C API for Parsing Web-Style Search Expressions
+
+**Feature:** New public C API for parsing MygramDB search query syntax, enabling integration with other C/C++ applications.
+
+**API Function:**
+
+```c
+/**
+ * Parse web-style search expression into structured query
+ * @param expr Search expression string
+ * @param table_name Target table name
+ * @param out_query Output query structure (caller must free)
+ * @return 0 on success, error code on failure
+ */
+int mygram_parse_search_expr(
+    const char* expr,
+    const char* table_name,
+    mygram_query_t** out_query
+);
+```
+
+**Supported Syntax:**
+
+- `SEARCH "keywords"` - Full-text search
+- `FILTER col:value` - Column filtering
+- `SORT [-]field` - Sort by field (- for descending)
+- `LIMIT offset,count` - Result pagination
+
+**Example Usage:**
+
+```c
+#include "mygram_api.h"
+
+mygram_query_t* query = NULL;
+int ret = mygram_parse_search_expr(
+    "SEARCH \"hello world\" FILTER status:active SORT -created_at LIMIT 10",
+    "articles",
+    &query
+);
+
+if (ret == 0) {
+    // Use parsed query structure
+    // ...
+    mygram_query_free(query);
+}
+```
+
+**Use Cases:**
+
+- Integrating MygramDB search into existing C/C++ applications
+- Building custom search interfaces
+- Embedding MygramDB query parser in other systems
+- Query validation and preprocessing
+
+## Migration Guide
+
+### From v1.2.2
+
+**No breaking changes.** This is a backward-compatible feature release.
+
+**Optional Configuration:**
+
+```yaml
+# Add to config.yaml if you need custom session timeout
+replication:
+  session_timeout_sec: 28800  # Default value, can be omitted
+```
+
+**For C API Users:**
+
+```c
+// New header to include
+#include "mygram_api.h"
+
+// Link against libmygram when building
+gcc your_app.c -lmygram -o your_app
+```
+
+### Upgrade Steps
+
+**Docker users:**
+
+```bash
+# Pull the new image
+docker pull ghcr.io/libraz/mygram-db:v1.2.3
+
+# Or update docker-compose.yml
+services:
+  mygramdb:
+    image: ghcr.io/libraz/mygram-db:v1.2.3
+```
+
+**RPM users:**
+
+```bash
+# Download and install new RPM
+sudo rpm -Uvh mygram-db-1.2.3-1.el9.x86_64.rpm
+```
+
+**Source build:**
+
+```bash
+git checkout v1.2.3
+cmake -B build -DCMAKE_BUILD_TYPE=Release
+cmake --build build --parallel
+```
+
+## Technical Details
+
+### MySQL Session Timeout Implementation
+
+**Relevant Code:**
+- `src/data/mysql_connection.cpp` - Connection initialization with timeout settings
+
+**Configuration Hierarchy:**
+
+1. User-specified `replication.session_timeout_sec`
+2. Default: 28800 seconds (8 hours)
+3. Applied via `SET SESSION wait_timeout=X, interactive_timeout=X`
+
+**Behavior:**
+
+- Setting is applied immediately after connection establishment
+- Applies to both initial connection and automatic reconnections
+- MySQL server must support session variable modification
+- Compatible with MySQL 5.7+ and MariaDB 10.2+
+
+### C API Architecture
+
+**Header File:** `include/mygram_api.h`
+**Implementation:** `src/api/mygram_api.cpp`
+
+**Design Principles:**
+
+- Pure C interface for maximum compatibility
+- No C++ exceptions crossing API boundary
+- Caller-owned memory with explicit free functions
+- Error codes for all failure modes
+
+**Error Codes:**
+
+```c
+#define MYGRAM_OK              0
+#define MYGRAM_ERR_PARSE       1  // Query syntax error
+#define MYGRAM_ERR_INVALID_ARG 2  // NULL pointer or invalid argument
+#define MYGRAM_ERR_NOMEM       3  // Memory allocation failure
+```
+
+## Performance Impact
+
+**Negligible overhead:**
+
+- Session timeout: One-time `SET SESSION` command per connection
+- C API: Zero overhead (direct calls to existing parser)
+
+**No changes to:**
+
+- Query execution performance
+- Binlog processing throughput
+- Memory usage patterns
+
+## Known Issues
+
+None.
+
+## Contributors
+
+- @libraz
+
+## Links
+
+- [Full Changelog](https://github.com/libraz/mygram-db/compare/v1.2.2...v1.2.3)
+- [Docker Image](https://github.com/libraz/mygram-db/pkgs/container/mygram-db)
+- [Configuration Reference](../en/configuration.md)
+- [API Documentation](../en/api.md)
+
+---
+
+**Questions or Issues?**
+Please open an issue on [GitHub Issues](https://github.com/libraz/mygram-db/issues)