Arrange LaunchSpineCompiler state at configuration time

[alexander-yevsyukov]

What

Eliminates two Gradle deprecation warnings that consumer builds (observed in delivery-server on Gradle 9.6.1) receive from every executed launchSpineCompiler task:

• "Changing property value of task ':…:launchSpineCompiler' property 'mainClass' at execution time" — becomes an error in Gradle 11;
• "Invocation of Task.dependsOn at execution time" — becomes an error in Gradle 10 and is incompatible with the configuration cache.

How

All task state is now arranged at configuration time:

• The constant mainClass is set in the task init block.
• The classpath (two lazy Configurations) is added in applyDefaults().
• The --params <file> pair is registered via argumentProviders, so it is evaluated only when the command line is built and — as before — the absolute path stays out of the build-cache key, keeping cached outputs relocatable.
• A new protoSourceDirs: ConfigurableFileCollection property, wired by consumeProtoFrom() from handleLaunchTaskDependency(), replaces the execution-time dependsOn.first { it is GenerateProtoTask } traversal.
• compileCommandLine() is deleted; a name-collision on the reserved task name now fails fast with a curated check message instead of a silent misconfiguration.

Deliberately unchanged: writing the parameters file stays a doFirst action. Serializing PipelineParameters loads Spine KnownTypes through the thread context classloader, which Gradle sets to the plugin classloader only around doFirst/doLast actions — from the @TaskAction method the desc.ref lookup fails. The constraint is documented at the call site. A file write is a side effect, not task-state mutation, so it triggers no deprecation.

Verification

• Full ./gradlew build dokkaGenerate is green.
• A new functional test (PluginSpec."not mutate the launch task state at execution time") runs a consumer fixture with --warning-mode=all and asserts both messages are absent.
• The test's sensitivity is proven by an A/B run of a standalone consumer project on Gradle 9.6.1: plugin 2.0.0-SNAPSHOT.060 (pre-fix) emits both warnings exactly once each; this branch's plugin emits none, with the launch task executing in both runs.
• Pre-PR checklist passed: version gate (2.0.0-SNAPSHOT.061 → .062 with regenerated dependency reports), spine-code-review, kotlin-engineer, and review-docs reviewers (all feedback applied).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the Spine Compiler Gradle plugin to avoid Gradle 9.6+ “execution-time mutation” deprecations by moving LaunchSpineCompiler task state setup fully into configuration time, keeping the task compatible with configuration cache and upcoming Gradle 10/11 behavior.

Changes:

• Configure LaunchSpineCompiler’s constant mainClass, classpath, and CLI --params <file> argument at configuration time (using argumentProviders) and remove the execution-time command-line assembly.
• Replace execution-time dependsOn traversal with an explicit protoSourceDirs carrier populated via consumeProtoFrom(generateProto), and fail fast on reserved task-name collisions.
• Add a functional regression test asserting the deprecation warnings are absent under --warning-mode=all, plus version/report bumps.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
version.gradle.kts	Bumps the compiler version snapshot used by builds/tests.
gradle-plugin/src/main/kotlin/io/spine/tools/compiler/gradle/plugin/Plugin.kt	Wires GenerateProtoTask → LaunchSpineCompiler relationship via consumeProtoFrom() and adds a guarded fast-fail for task-name collisions.
gradle-plugin/src/main/kotlin/io/spine/tools/compiler/gradle/plugin/LaunchSpineCompiler.kt	Moves task state setup to configuration time; introduces protoSourceDirs and argumentProviders; removes execution-time command-line mutation.
gradle-plugin/src/functionalTest/kotlin/io/spine/tools/compiler/gradle/plugin/PluginSpec.kt	Adds a functional test ensuring Gradle deprecation warnings are not emitted.
docs/dependencies/pom.xml	Updates docs dependency metadata version to the new snapshot.
docs/dependencies/dependencies.md	Regenerates dependency report for the new snapshot/version.
.agents/tasks/fix-launch-task-exec-time-config.md	Adds an agent task log/plan document (non-functional project metadata).

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[codecov]

Codecov Report

❌ Patch coverage is 63.33333% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.87%. Comparing base (eeceb4b) to head (a4ab3b2).

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #81      +/-   ##
============================================
+ Coverage     76.60%   76.87%   +0.27%     
- Complexity      687      688       +1     
============================================
  Files           205      205              
  Lines          4018     4026       +8     
  Branches        400      402       +2     
============================================
+ Hits           3078     3095      +17     
+ Misses          810      801       -9     
  Partials        130      130              

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[armiol]

@alexander-yevsyukov fingers crossed, LGTM.