Agents Guidance

This file documents key information about the project architecture, build commands, code style, and security practices.

Project overview

A Java library providing ASCII-safe Charset SPI implementations that transliterate Unicode to ASCII subsets rather than simply rejecting non-ASCII input. Published to GitHub Packages as com.maybeitssquid:ascii-safe-charsets.

Commands

Build and test:

./gradlew build              # compile, test, spotless check
./gradlew test               # run all tests
./gradlew test --tests "*CacheTest"           # run tests by class name
./gradlew test --tests "*CacheTest.test*"     # run tests by method pattern

Code quality:

./gradlew spotlessApply           # auto-format (required before commit)
./gradlew dependencyCheckAnalyze  # OWASP vulnerability scan (slow; fails at CVSS ≥ 7)

External dependencies: Standalone library; no runtime dependencies beyond Java.

Build uses Java 25 toolchain, compiles to Java 17 bytecode (release = "17"). CI tests on Java 17, 21, and 25.

Key Entry Points

• TransliteratingASCIIProvider — main CharsetProvider SPI entry point; provides charset instances
• Charset.forName("X-Transliterating") — retrieve a charset by name (registered via SPI)

Versioning and Releases

Versions are derived from git tags using gradle-git-version:

• On a tag (e.g., v1.0.0) → version = 1.0.0
• After a tag → version = tag + distance + commit hash (e.g., 1.0.1-3-gABC1234 = 3 commits after v1.0.0)
• No tags yet → version synthesized from git history (e.g., 0.0.1-dev-88-gXYZ)

To create a release:

# Ensure all commits are pushed
git push origin main

# Create and push the tag (triggers automatic version picking in build)
git tag -a v1.0.0 -m "Release 1.0.0"
git push origin v1.0.0

# Build and publish
./gradlew clean build publish

To delete a release tag:

git tag -d v1.0.0              # Delete locally
git push origin :v1.0.0        # Delete from remote

Configuration cache is disabled (org.gradle.configuration-cache=false) to allow git invocation during the build.

Architecture

The library wires together two subsystems: a Charset implementation and a configurable transliteration pipeline.

Module and package layout

The library is a named JPMS module (module-info.java, module com.maybeitssquid.safeascii). Only the charset API package com.maybeitssquid.safeascii is exported. The transliteration pipeline lives in com.maybeitssquid.safeascii.internal, which is not exported — those classes are implementation details, not public API. The provider is declared two ways so it works on both paths: provides java.nio.charset.spi.CharsetProvider with … in module-info.java (module path) and META-INF/services/java.nio.charset.spi.CharsetProvider (classpath).

Charset layer

• TransliteratingASCIIProvider — CharsetProvider SPI entry point in the exported package, registered via src/main/resources/META-INF/services/java.nio.charset.spi.CharsetProvider (classpath) and the provides directive in module-info.java (module path). Provides four charsets lazily:
  • X-ASCII-Printable (alias ASCII-Printable) — strict printable ASCII (0x20–0x7E only, controls blocked)
  • X-ASCII-Plain (alias ASCII-Plain) — same but allows LF; CR is unmappable so CRLF normalises to LF under IGNORE
  • X-ASCII-Formatted (alias ASCII-Formatted) — same as X-ASCII-Plain but also allows TAB (0x09)
  • X-Transliterating — aggressive Unicode-to-ASCII transliteration
  • X-Transliterating-Single-Byte (alias ACH) — same but guarantees 1:1 character output
• TransliteratingASCII — extends java.nio.charset.Charset. Takes an IntFunction<CharSequence> transliterator at construction; the encoder/decoder delegate all codepoint mapping to it.

Transliterator pipeline

Pipeline classes live in the non-exported com.maybeitssquid.safeascii.internal package:

• ASCII-Printable / ASCII-Plain: Cache → ASCIIFilter
• X-Transliterating: Cache → Decompose → Name → ASCIIFilter
• X-Transliterating-Single-Byte: Cache → SingleCharacterFilter → Decompose → Name → ASCIIFilter

Code style

Spotless enforces Google Java Format. Run ./gradlew spotlessApply before committing. The formatter excludes module-info.java.

Security patches

For CVE patch management, see the gradle-security-patch skill. Use /gradle-security-patch to pin a CVE fix in the version catalog.