Make the LSP more robust against invalid projects

[hegyibalint]

Currently, the LSP breaks when opened up with an invalid project (#14).
This can simply mean a typo in a settings.gradle[.kts] file.

This is quite bad, as it's completely expected that projects could (and will be) in a transitional state.
This PR solves this problem by:

• Improving the state holder objects, and making the TAPI requests failure-free (i.e., no leaking exceptions).
• Implement a simple trigger to initiate a resync (currently modifications to any **/settings.gradle[.kts] file)
  • This mechanism can be elaborated further in the future by implementing explicit commands, but this is deemed enough to get started with.

[Copilot]

Pull Request Overview

This PR enhances the LSP’s resilience when opening invalid or broken Gradle projects by preventing unhandled exceptions in TAPI calls and enabling on-the-fly resynchronization when settings.gradle[.kts] files change.

• Introduce DeclarativeModelStore to wrap all Tooling API interactions in a failure-safe store.
• Refactor text/workspace services and tests to use the new model store and a simplified MutationRegistry.
• Add a didSave handler that triggers updateModel() on settings file saves and cover with end-to-end tests.

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
lsp/src/test/kotlin/.../VersionedDocumentStoreTest.kt	Added VersionedDocumentStore import to exercise the relocated class.
lsp/src/test/kotlin/.../AbstractDeclarativeTextDocumentServiceTest.kt	Switched test helpers to return DeclarativeModelStore and simplified MutationRegistry constructor.
lsp/src/main/kotlin/.../valueFactoryIndex.kt	Removed obsolete import now that VersionedDocumentStore lives in org.gradle.declarative.lsp.
lsp/src/main/kotlin/.../mutation/MutationRegistry.kt	Moved class to new package, dropped direct dependency on DeclarativeResourcesModel.
lsp/src/main/kotlin/.../extension/DeclarativeResourcesModelExtensions.kt	Added helper extension to build a SimpleAnalysisEvaluator from a DeclarativeResourcesModel.
lsp/src/main/kotlin/org/gradle/declarative/lsp/VersionedDocumentStore.kt	Changed package from .service to root org.gradle.declarative.lsp.
lsp/src/main/kotlin/org/gradle/declarative/lsp/ToolingApiConnector.kt	Replaced TapiConnectionHandler with a failure-safe ToolingApiConnector.withToolingApi helper.
lsp/src/main/kotlin/org/gradle/declarative/lsp/Main.kt	Extracted startDeclarativeLanguageServer for better I/O injection and testability.
lsp/src/main/kotlin/org/gradle/declarative/lsp/DeclarativeWorkspaceService.kt	Updated to accept DeclarativeModelStore and removed legacy VersionedDocumentStore imports.
lsp/src/main/kotlin/org/gradle/declarative/lsp/DeclarativeTextDocumentService.kt	Switched to use DeclarativeModelStore.ifAvailable, added settings-file didSave reload logic.
lsp/src/main/kotlin/org/gradle/declarative/lsp/DeclarativeModelStore.kt	New class managing DeclarativeResourcesModel retrieval, caching, and safe reloads.
lsp/src/main/kotlin/org/gradle/declarative/lsp/DeclarativeLanguageServer.kt	Refactored to wire up DeclarativeModelStore, defined MutationRegistry entries, and added isInitialized.
lsp/src/integTest/InvalidGradleProjectTests.kt	Two new end-to-end tests verifying server doesn’t crash on invalid settings and recovers on fix.
lsp/src/integTest/AbstractEndToEndTest.kt	New base for integration tests with project-dir init helper.
lsp/build.gradle.kts	Added Kotlin serialization plugin, switched many dependencies to api, configured integration tests.
gradle/libs.versions.toml	Bumped Kotlin and added kotlinx-serialization-json entries.

Comments suppressed due to low confidence (1)

lsp/src/main/kotlin/org/gradle/declarative/lsp/DeclarativeLanguageServer.kt:176

• [nitpick] The method isInitialized reports only model availability, which might be confused with server initialization state. Consider renaming it to isModelAvailable or similar to clarify its intent.

    fun isInitialized(): Boolean {

[hegyibalint]

ℹ️ These were moved to the api configuration, as test-suites wouldn't inherit implementation dependencies.
I think it makes sense, as all of these are exposed in our API.

[eskatos]

It's good to see some robustness!

I requested a few minor changes and asked some questions.

[eskatos]

💅 The Gradle version used in tests should probably be parameterized, eventually. I understand that this is out of scope for this PR but I think it would be nice to at least extract the version number as a prominent constant in order to make it more obvious.

[hegyibalint]

WDYT, what should be the parametrization source?

[eskatos]

There are options like:

• a list of tested Gradle versions hardcoded in the base test
• a list of tested Gradle versions passed from the build definition
• a test task per tested Gradle version

But my point was that this can actually happen later, it doesn't have to be part of this PR.

I think it would be nice to at least extract the version number as a prominent constant in order to make it more obvious.

[eskatos]

🎉