kotlin-ls: JetBrains LSP initialization timeout on large Android projects; user command override ineffective #28289

Problem

The built-in kotlin-ls (JetBrains Kotlin LSP) fails to initialize within the configured timeout on large Android/Gradle projects. The LSP requires a full Gradle project sync before responding to the initialize request, which takes 2-5 minutes on projects with many dependencies.

Environment

• opencode v1.15.4
• Linux x86_64 (Nobara 43 / Fedora-based)
• Android project: AGP 8.11.0, ~760 source files, 50+ Gradle dependencies
• JDK 21 available

Observed Behavior

1. lsp_status shows kotlin-ls: installed; source=builtin
2. Any lsp_diagnostics call on .kt files returns: LSP request timeout (method: initialize)
3. stderr shows macOS-specific --add-opens warnings (harmless on Linux but indicates cross-platform script issues)
4. Even with "timeout": 300000 (5 minutes) in project config, initialization still times out

Attempted Workarounds (all failed)

1. Project config command override — Setting "command": ["kotlin-language-server"] in .opencode/opencode.json under lsp.kotlin-ls does NOT override the built-in binary. The JetBrains version at ~/.cache/opencode/bin/kotlin-ls/kotlin-lsp.sh is always used.

2. Project config disabled: true — Setting "disabled": true on kotlin-ls does not prevent it from being used.

3. Custom LSP name — Adding a new LSP entry like "kotlin-community" with custom command and .kt/.kts extensions does not appear in lsp_status and is never activated.

4. Increased timeout — "timeout": 300000 in project config has no observable effect.

Working Workaround (hacky)

Replacing the installed script at ~/.cache/opencode/bin/kotlin-ls/kotlin-lsp.sh with a wrapper that calls the community kotlin-language-server binary:

#!/bin/bash
export JAVA_HOME=/usr/lib/jvm/java-21-openjdk
exec /path/to/kotlin-language-server "$@"

After pre-warming the Gradle cache (./gradlew dependencies), the community version initializes within the timeout and provides diagnostics successfully.

Root Causes

1. No user override path: The built-in LSP command cannot be overridden via project or global config. The source=builtin installation takes absolute precedence.

2. JetBrains LSP requires Gradle sync: Unlike the community kotlin-language-server (which can start incrementally), the JetBrains version blocks on full project model resolution before responding to initialize.

3. Timeout config may not propagate: The timeout field in project config appears to have no effect on the actual LSP initialization timeout.

Suggested Fixes (any of these would help)

1. Allow command override in user/project config — If a user specifies lsp.kotlin-ls.command, use that instead of the built-in binary.

2. Support disabled: true — Allow users to disable built-in LSP servers that do not work in their environment.

3. Increase default timeout for kotlin-ls — The JetBrains version legitimately needs 2-5 minutes on large projects. Consider a longer default or async initialization.

4. Offer community kotlin-language-server as alternative — The fwcd/kotlin-language-server initializes much faster and provides sufficient diagnostics for most use cases.

5. Pre-warm Gradle on first LSP start — Run ./gradlew dependencies in background before attempting LSP initialization.

Additional Context

• The JetBrains kotlin-lsp.sh script contains macOS-specific --add-opens flags that produce warnings on Linux (cosmetic issue)
• The script bundles its own JRE 21, ignoring user-configured JAVA_HOME
• Community kotlin-language-server v1.3.13 works correctly as a drop-in replacement after Gradle cache warm-up
• opencode was started from / (root directory), not the project directory — project-level .opencode/opencode.json config was not loaded, which may explain why config overrides had no effect. However, even when the config IS loaded, the builtin binary still takes precedence based on source=builtin behavior.