fix: handle ABI-incompatible grammars and fix 28 test failures

[MO2k4]

Summary

Fixes all 28 test failures on the current main branch. The root cause is a combination of ABI-incompatible tree-sitter grammar bindings and stale test expectations.

Swift/Dart grammar ABI incompatibility (21 test failures)

Swift (tree-sitter-swift 0.6.0): The package fails to install on macOS arm64 (Apple Silicon) — require('tree-sitter-swift') throws MODULE_NOT_FOUND. There is no prebuilt binary for this platform and the source build fails. loadGrammar() correctly returned null, but 8 tests ran unconditionally.

Dart (@sengac/tree-sitter-dart 1.1.6): This is the more subtle failure. The npm package installs and require() succeeds, but the grammar object has an incompatible ABI with tree-sitter 0.22.4. Calling parser.setLanguage(dart) crashes with:

TypeError: Cannot read properties of undefined (reading 'length')
    at initializeLanguageNodeClasses (node_modules/tree-sitter/index.js:858:42)
    at Parser.setLanguage (node_modules/tree-sitter/index.js:355:5)

This is a two-stage failure that loadGrammar() couldn't detect:

1. loadGrammar('dart') → returns the grammar object (require worked) ✓
2. getParser('dart') → calls parser.setLanguage() → uncaught crash ✗

The grammar's internal nodeTypeNamesById array is undefined, indicating it was built against a different tree-sitter ABI version than the 0.22.4 currently installed.

Source fix (src/extraction/grammars.ts):

• Wrap parser.setLanguage() in try/catch inside getParser() so ABI-incompatible grammars degrade gracefully (return null + log warning) instead of crashing the process
• Change isLanguageSupported() and getSupportedLanguages() to call getParser() (validates full ABI compatibility) instead of loadGrammar() (only checks if require succeeds)

Test fix (__tests__/extraction.test.ts):

• Add describe.skipIf(!isLanguageSupported('swift')) / describe.skipIf(!isLanguageSupported('dart')) to all Swift/Dart test blocks
• Remove hardcoded swift/dart from "should list all supported languages" assertion — availability is platform-dependent

Schema version mismatch (1 test failure)

foundation.test.ts expected version?.version to be 1, but DatabaseConnection.initialize() now inserts version 2 directly (after the v2 migration was added). Fixed assertion to expect 2.

DB test initialization errors (4 test failures)

pr19-improvements.test.ts DB tests had two bugs:

• Called DatabaseConnection.initialize(testDir) with a directory path — better-sqlite3 cannot open a directory as a database file. Fixed to DatabaseConnection.initialize(path.join(testDir, 'test.db')).
• Called db.getDatabase() which doesn't exist — the method is db.getDb().

MCP truncation test (1 test failure)

Object.create(ToolHandler.prototype) bypasses the constructor, so the class field MAX_OUTPUT_LENGTH = 15000 is never initialized (it's undefined). The comparison text.length <= undefined is always false, causing every string — even short ones — to be truncated. Fixed by explicitly setting the property on the prototype-created handler.

Test plan

• npm run build compiles without errors
• npm test — 11 passed, 0 failed (333 passed, 21 skipped for unavailable grammars)
• Skipped tests are only Swift (8) and Dart (13) — both have unavailable native bindings
• All other languages (TypeScript, JavaScript, Python, Go, Rust, Java, C, C++, C#, PHP, Ruby, Kotlin, Svelte, Liquid) continue to pass

[MO2k4]

Closing — these fixes are included in #35 (cherry-picked + extended with Kotlin skipIf guards and Windows path normalization).