fix: resolve JVM imports in multi-module Maven/Gradle projects (0 edges bug)

[sb-giithub]

Problem

Any Java/Kotlin/Scala project using a multi-module Maven or Gradle layout produces 0 dependency edges in codebase_graph_stats, making codebase_graph_query, codebase_graph_circular, and codebase_graph_visualize useless for the majority of real-world JVM codebases.

Tested on a 30-module Spring Boot monorepo (~29,000 Java files):

Total dependency edges: 0   ← before this fix

Root cause

resolveImport already had correct import parsing and FQN→path conversion for Java. The resolution failed silently because the fallback directory list was limited to three fixed prefixes:

src/main/java/
src/main/
src/

A multi-module project places sources at:

module-sso/module-sso-service/src/main/java/cn/sino/sso/UserService.java

None of the three prefixes match when resolved from the project root, so every cross-module import returned null.

Fix

Introduce buildJvmSuffixMap(fileSet) — a one-time O(n) scan that registers every JVM file by its class-path key (everything after src/main/<lang>/):

"cn/sino/sso/UserService.java" → "module-sso/module-sso-service/src/main/java/cn/sino/sso/UserService.java"

resolveImport accepts the map as an optional last argument and falls back to an O(1) map lookup when the existing prefix approach fails.

buildCodeGraph builds the map once per graph build, only when the project contains JVM files — zero overhead for non-JVM projects.

Changes

File	Change
src/services/graph-resolution.ts	Export buildJvmSuffixMap; add jvmSuffixMap? param to resolveImport; use it in Java/Kotlin/Scala case
src/services/code-graph.ts	Build suffix map once before the import analysis loop; pass to resolveImport
tests/unit/graph-resolution.test.ts	7 new unit tests covering map construction, test-source exclusion, multi-module Java/Kotlin resolution, unresolvable class, stdlib guard

Compatibility

• Fully backwards-compatible: jvmSuffixMap is optional; single-module projects continue to resolve via the existing prefix approach without reaching the suffix map.
• Windows/POSIX safe: map keys are built and looked up using path.sep.
• No new dependencies.

Testing

All 7 new unit tests pass. The 42 pre-existing test failures on Windows are unrelated path-separator issues in the test harness (/ vs \) that existed before this PR.

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Relates to issue #21 — Java dependency graph support

🤖 Co-authored with Claude Code

[giancarloerra]

Thanks merged!