Added

• Identify boards from manually installed platforms in "Select Other Board and Port" dialog tooltip (#2270)
• Support .cc and .cxx extensions for sketch files (#2265)
• Intellisense and validation for custom_debug.json (#2281)
• Support direct modification of debugger's launch.json configuration file (#2281)
• Show progress information in the status bar when Arduino CLI is running debug --info --programmer command (#2281)
• Support selecting debug probe via "Tools > Programmer" menu (#2281)
• Disable debug widget if unsupported by board (#14)
• Advanced preference to limit thread count of Arduino Language Server (#2350)

Changed

• Use new debug -I -P CLI output (#2281)
• New debug_custom.json schema (#2281)
• Update built-in example sketches to 1.10.1 (#2322)
• Update translation files (#2216)
• Update Node.js dependency to 18 (#2199)
• Update electron dependency to 27.0.3 (#2199, #2252, 0f83a48)
• Update Theia dependency to 1.41.0 (#2211)
• Update Arduino Language Server dependency to 0.7.6 (a0bd5d0, #2350)
• Update Arduino CLI dependency to 0.35.2 (73b6dc4, b8dd39c, #2350)
• Update vscode-arduino-tools dependency to 0.1.1 (73b6dc4)

Removed

• Support for macOS Mojave (0f83a48)

Fixed

• Forward backend logging to electron (#2236)
• Arduino state data not available to extensions after IDE startup (#2233)
• "Configure and Upload" dialog not presented for uploads dependent on "user provided fields" after IDE startup (#2230)
• Custom board option selection made in one window affects other windows as well (#2240)
• "Start Debugging" button incorrectly disabled if board was pre-selected on IDE startup (#2237)
• Board-dependent menus not populated if board was pre-selected on IDE startup (#2239)
• Saving sketch fails silently when files are read-only (#1501)
• IDE window doesn't open when started via sketch file association (#2209)
• Subfolder structure of sketch lost after "Save As" operation (#2077)
• Naming collision during "Save As" causes overwrite of secondary sketch file (#827)
• Previous selection remains in "Firmware Updater" and "Certificate Uploader" menu after no longer available (#2222)
• Bundle native Arduino Firmware Uploader with Apple Silicon build (#2338)

Security

• Update electron to resolve CVE-2023-4863 and CVE-2023-39956 (#2252)
• Replace usage of shelljs package with fs and console (#2252)
• Replace usage of uuid package with @phosphor/coreutils (#2252)
• Update @babel/traverse to resolve CVE-2023-45133 (#2273)
• Update auth0-js to resolve CVE-2023-46233 (#2273)

Full Changelog: 2.2.1...2.3.0