Migrate internal plumbing DEBUG statements to TRACE level

[gnodet]

Summary

• Migrates 70+ DEBUG log statements to TRACE in 6 areas that produce excessive noise under -X: lifecycle engine (reactor plan dumps, step scheduling), classrealm (realm creation/population/imports), cache internals (config resolution, access stats), resolver (descriptor filtering, relocation), model builder (cache clearing, profile activation), and plugin resolution (version/prefix tracing)
• Adds TRACE to Slf4jConfiguration.Level enum so the logging system supports -Dmaven.logger.defaultLogLevel=trace as a system property for Maven core developers
• DEBUG (-X) remains the right level for plugin development; TRACE is for Maven core developers diagnosing framework internals

Motivation

The TRACE level was added in the logging-foundation PR to separate two audiences:

• DEBUG — plugin developers and power users diagnosing plugin behavior
• TRACE — Maven core developers tracing internal framework mechanics

Without this migration, TRACE exists but nothing emits at it, making the distinction theoretical. This PR populates it with the noisiest internal plumbing output that dominates -X today and drowns out the signal plugin developers actually want.

What stays at DEBUG

• Plugin parameter resolution, mojo configuration/loading (useful for plugin devs)
• mvnup upgrade diagnostics
• CLI bootstrap messages (uses o.a.m.api.cli.Logger which doesn't have TRACE)

Files changed (18 files, +108/-105)

Area	Files	Changes
Lifecycle engine	LifecycleDebugLogger, BuildPlanExecutor, MultiThreadedBuilder	32 statements
Cache internals	DefaultRequestCache, CacheConfigurationResolver	22 statements
Classrealm	DefaultClassRealmManager	8 statements
Resolver	DefaultArtifactDescriptorReader, relocation sources, TypeDeriver	8 statements
Model builder	DefaultModelBuilder	8 statements
Plugin resolution	DefaultPluginVersionResolver, DefaultPluginPrefixResolver	6 statements
Infrastructure	Slf4jConfiguration, MavenSimpleConfiguration, CliUtils	TRACE level support
Tests	DefaultClassRealmManagerTest, LookupInvokerLoggingTest	Updated mocks

PR chain

#	PR	Feature
1	#12694	Logging foundation
2	#12695	Build report
3	#12697	Console modes
4	#12698	Warning mode + diagnostics
5	#12699	mvnlog viewer
6	#12702	Structured problems pipeline
7	This PR	TRACE level migration

Test plan

• All modified modules compile cleanly
• DefaultClassRealmManagerTest updated to verify trace() calls instead of debug()
• LookupInvokerLoggingTest updated for new TRACE enum value
• All tests pass in isolation (batch-mode flakiness in MavenInvokerTest is pre-existing)

🤖 Generated with Claude Code

[gnodet]

Clean mechanical migration of 70+ debug statements to trace level. MavenSimpleConfiguration, CliUtils, and tests are all correctly updated to handle the new Level.TRACE enum value.

Missing TRACE handling in two logging backends:

The new TRACE enum value is correctly handled in MavenSimpleConfiguration (case TRACE -> "trace"), CliUtils (case TRACE, DEBUG ->), and the test, but two other setRootLoggerLevel implementations were not updated:

• Log4j2Configuration.java (line 32-36): default -> "error" silently maps TRACE to "error" — should add case TRACE -> "trace"
• LogbackConfiguration.java (line 34-37): default -> ch.qos.logback.classic.Level.ERROR silently maps TRACE to ERROR — should add case TRACE -> ch.qos.logback.classic.Level.TRACE

Both are live code — registered in META-INF/maven/slf4j-configuration.properties as runtime-selected implementations. While Level.TRACE is not yet wired to a CLI option (limiting immediate impact), the inconsistency should be fixed to prevent a silent bug when trace-level CLI support lands.

This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of gnodet

[gnodet]

Clean mechanical migration of 70+ internal DEBUG statements to TRACE level. All switch expressions, guard conditions, and tests are correctly updated.

Non-blocking observations:

• LifecycleDebugLogger.debug(String) now calls logger.trace(), making the method name misleading. However, the class is non-public API and renaming would expand the scope unnecessarily.
• Several trace log calls use string concatenation instead of parameterized logging (pre-existing, not introduced by this PR).
• Pre-existing arithmetic bug in DefaultModelBuilder.java:2722: afterSize - beforeSize produces a negative count for removed entries. Should be beforeSize - afterSize. This PR only changed the log level.

LGTM — the migration is well-scoped: only internal plumbing is demoted to TRACE, while plugin-facing DEBUG output correctly remains at DEBUG.

This review was generated by an AI agent (Claude Code) and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of Guillaume Nodet