Maven Silent Extension (MSE)

A Maven core extension that replaces Maven's verbose output with a dense, machine-readable format. Designed for AI coding agents that operate within finite context windows, where thousands of lines of lifecycle ceremony waste tokens and bury actionable errors.

How it works

MSE implements Maven's EventSpy API. When activated, it:

1. Suppresses Maven's default SLF4J logging (lifecycle banners, download progress, plugin headers).
2. Parses Surefire/Failsafe XML reports after test execution to extract structured failure details -- regardless of JVM forking.
3. Emits all output as MSE:-prefixed lines for unambiguous machine parsing.

Requirements

• Java 11+
• Maven 3.6.x through 3.9.x

Installation

Run the installer plugin in your project root:

mvn info.jerrinot:mse-maven-plugin:install

This creates .mvn/extensions.xml with the MSE extension entry. Maven downloads it automatically on the next build.

Alternatively, create .mvn/extensions.xml manually:

<extensions>
    <extension>
        <groupId>info.jerrinot</groupId>
        <artifactId>maven-silent-extension</artifactId>
        <version>0.1.0</version>
    </extension>
</extensions>

To uninstall:

mvn info.jerrinot:mse-maven-plugin:uninstall

Usage

Activate with a system property or environment variable. Both accept modes:

mvn -Dmse clean verify              # strict: logger=off + stdio redirected to build log
mvn -Dmse=relaxed clean verify      # relaxed: logger=error + stdio restored after session end
MSE_ACTIVE=relaxed mvn clean verify # same mode via env var

Mode values:

• strict, true, empty value (-Dmse) => strict mode (org.slf4j.simpleLogger.defaultLogLevel=off)
• relaxed => relaxed mode (org.slf4j.simpleLogger.defaultLogLevel=error)
• off, false, 0 => disabled

If both are set, -Dmse takes precedence over MSE_ACTIVE.

Without activation (or with off) the extension is inert: Maven behaves as if it were not installed.

Output format

All lines are prefixed with MSE:.

Successful build:

MSE:SESSION_START modules=12 goals=clean,verify
MSE:OK modules=12 passed=342 failed=0 errors=0 skipped=0 time=47s

Test failure:

MSE:FAIL maven-surefire-plugin:test @ my-module
MSE:TESTS total=342 passed=339 failed=2 errors=1 skipped=0
MSE:TEST_FAIL com.example.AppTest#testParseInput
  expected:<42> but was:<0>
  at com.example.AppTest.testParseInput(AppTest.java:27)
MSE:TEST_ERROR com.example.ServiceTest#testConnection
  java.net.ConnectException: Connection refused
  at com.example.ServiceTest.testConnection(ServiceTest.java:18)
MSE:BUILD_FAILED failed=1 modules=12 passed=339 failed=2 errors=1 skipped=0 time=52s

Compiler error:

MSE:FAIL maven-compiler-plugin:compile @ my-module
MSE:ERR /src/main/java/com/example/App.java:10:15 cannot find symbol
MSE:ERR /src/main/java/com/example/App.java:20:1 ';' expected
MSE:BUILD_FAILED failed=1 modules=12 passed=0 failed=0 errors=0 skipped=0 compiler_errors=2 time=8s

Internal error (falls back to passthrough):

MSE:PASSTHROUGH <reason>

Limitations

• Output from non-compiler, non-test plugins (exec-maven-plugin, frontend-maven-plugin) is not yet captured.
• Maven 4.x compatibility is untested.
• Plugins that fork arbitrary OS processes are out of scope.

License

Apache License, Version 2.0