Bundle Visual C++ Redistributable in Windows NSIS installer

[JosephMcEvoy]

Summary

On fresh Windows installations without the Visual C++ Redistributable, Tabby shows the splash screen but the terminal never loads. This is because native modules (node-pty) require vcruntime140.dll and msvcp140.dll, which are not bundled with Tabby and not installed by the NSIS installer.

Changes

build/installer.nsh — Added a customInstall macro that:

1. Checks if vcruntime140.dll exists in the system directory
2. If missing, extracts and silently installs the bundled VC++ Redistributable
3. Logs the result via DetailPrint

.github/workflows/build.yml — Added a CI step to download the correct VC++ Redistributable (x64 or arm64 based on build matrix) into the build/ directory before packaging. This makes it available to the NSIS ${BUILD_RESOURCES_DIR} at installer build time.

How it works

• electron-builder's NSIS integration exposes ${BUILD_RESOURCES_DIR} pointing to the build/ directory
• The customInstall macro uses the NSIS File directive to embed vc_redist.exe from that directory into the installer
• At install time, if vcruntime140.dll is already present, the step is skipped entirely (no extraction, no execution)
• If missing, the redistributable is extracted to $PLUGINSDIR (temp) and run with /install /quiet /norestart
• The VC++ redistributable installer is idempotent and handles upgrades gracefully

Impact

• Adds ~14MB to the NSIS installer size (the redistributable binary)
• No impact on portable builds (zip)
• No impact on macOS or Linux builds

Test results

All tests run on fresh Windows 11 VMs (Vagrant + Hyper-V, gusztavvargadr/windows-11 box) with no prior software installed.

Baseline: official v1.0.230 on fresh Windows 11

The official installer does not install the VC++ Redistributable. On a fresh Windows 11 VM, Electron starts and discovers all 12 plugins, but three plugins with native module dependencies fail to load:

"Could not load ssh: Error: The specified module could not be found."
"Could not load electron: Error: The specified module could not be found."
"Could not load auto-sudo-password: Error: The specified module could not be found."

Without the electron and ssh plugins, the terminal cannot function. Tabby remains stuck on the splash screen indefinitely:

=== Pre-install VC++ Check ===
vcruntime140.dll present: False

=== Post-install VC++ Check ===
vcruntime140.dll present: False

=== Process status ===
Process alive (PID: 5924)
  Process: Tabby PID=672  CPU=0.2 Handles=387 WS=54MB  Title=''
  Process: Tabby PID=2108 CPU=0   Handles=197 WS=30MB  Title=''
  Process: Tabby PID=4516 CPU=1   Handles=338 WS=223MB Title=''
  Process: Tabby PID=5916 CPU=0   Handles=337 WS=51MB  Title=''
  Process: Tabby PID=5924 CPU=0.6 Handles=756 WS=124MB Title=''

All processes alive but no window title — splash screen only, no terminal.

With this PR: custom build on fresh Windows 11

=== Pre-install VC++ Check ===
vcruntime140.dll present: False
VC++ registry key:

=== Installing Tabby ===

=== Post-install VC++ Check ===
vcruntime140.dll present: True
msvcp140.dll present: True
VC++ registry Installed: 1

=== Plugin Check ===
tabby-auto-sudo-password: dist=True
tabby-community-color-schemes: dist=True
tabby-core: dist=True
tabby-electron: dist=True
tabby-linkifier: dist=True
tabby-local: dist=True
tabby-plugin-manager: dist=True
tabby-serial: dist=True
tabby-settings: dist=True
tabby-ssh: dist=True
tabby-telnet: dist=True
tabby-terminal: dist=True

=== Launch Test ===
SUCCESS - Tabby is running (PID: 6656)

The NSIS macro detected the missing VC++ runtime, installed it silently during setup, and Tabby launched successfully.

Test checklist

• Build Windows x64 NSIS installer and verify vc_redist.exe is embedded (installer size increased from ~127MB to ~152MB)
• Install on a fresh Windows 11 VM without VC++ Redistributable — VC++ auto-installed, Tabby launches successfully
• Install on a system with VC++ already present — redistributable step is skipped
• Baseline: confirmed official v1.0.230 fails on fresh Windows 11 — native plugin modules can't load without VC++ runtime
• Build Windows arm64 NSIS installer and verify correct arm64 redistributable is bundled

Related issues

Fixes #10734, #10782, #10450, #10284