Add SPA build caching with folder hash detection

[PieterjanDeClippel]

Summary

• Implements intelligent build caching for Angular/React SPA projects using MintPlayer.FolderHasher.Targets
• Computes SHA-256 hash of SPA folder contents before running npm build commands
• Skips unnecessary npm run build / npm run build:ssr when hash unchanged
• Significantly reduces build times (90%+) when SPA source hasn't changed

Features

• Hash-based caching: Compares current folder hash with stored hash to determine if rebuild is needed
• .hasherignore support: Exclude files/folders from hash calculation (similar to .gitignore syntax)
• Auto-created defaults: Creates .hasherignore with sensible defaults if missing
• Configurable: New MSBuild properties EnableSpaBuildCaching, SpaHashFilePath, ForceSpaBuild, CreateDefaultHasherIgnore
• Transitive support: Works for all projects referencing the package directly or indirectly
• Fail-safe: Missing or corrupted hash files trigger a full rebuild

New MSBuild Properties

Property	Default	Description
EnableSpaBuildCaching	true	Enable/disable the caching feature
SpaHashFilePath	$(IntermediateOutputPath)spa-folder.hash	Location to store the hash file
ForceSpaBuild	false	Force rebuild even if hash unchanged
CreateDefaultHasherIgnore	true	Auto-create .hasherignore with default patterns if missing

Build Command Selection

BuildServerSideRenderer	Build Command
true (default)	npm run build:ssr:production
false	npm run build -- --configuration production

Default Ignore Patterns

The auto-created .hasherignore excludes:

• Dependencies: node_modules/
• Build outputs: dist/, dist-server/, build/, out/
• Framework caches: .angular/, .cache/, .npm/
• Test outputs: coverage/, test-results/, .nyc_output/
• IDE files: .idea/, .vscode/
• Editor temp files: *.swp, *.swo, *~
• OS files: .DS_Store, Thumbs.db

Testing Instructions

1. First publish (should run full build and create hash file):

cd Demo/Prerendering/Demo.Web
dotnet publish -c Release

Look for messages like:

• First SPA build detected (hash: xxx). Will build.
• npm install and npm run build:ssr:production should execute

2. Second publish (should skip build):

dotnet publish -c Release

Look for:

• SPA source unchanged (hash: xxx). Skipping npm build.
• Using cached SPA build output from ClientApp\dist

3. Modify a source file and publish (should rebuild):

# Make a small change to any .ts file in ClientApp/src
dotnet publish -c Release

Look for:

• SPA source changed. Will rebuild. (Previous: xxx, Current: yyy)

4. Force rebuild:

dotnet publish -c Release -p:ForceSpaBuild=true

5. Check hash file location:

cat obj/Release/net10.0/spa-folder.hash

Test plan

• First publish creates hash file and runs npm build
• Second publish (no changes) skips npm build and uses cached output
• Changing a .ts file triggers rebuild
• ForceSpaBuild=true forces rebuild even when hash unchanged
• Deleting dist/ folder triggers rebuild
• Works with transitive package references
• .hasherignore is auto-created with default patterns

🤖 Generated with Claude Code