Adding MCP endpoint for finding ref guide URLs

[jzonthemtn]

Creating a PR because it's easier to understand to see the code.

Closes #85

[jzonthemtn]

Converting back to draft for a bit.

[adityamparikh]

Hi! A new PR-validation CI workflow recently landed on main (#117). To get this PR's tests evaluated against the new pipeline, could you rebase your branch onto current main and push? That will trigger the new ci.yml (build / unit / integration). Thanks!

[adityamparikh]

Heads-up: this branch currently shows as conflicting against main, but the conflict surface is much smaller than the 53-commit gap suggests. I rebased it locally onto main (a57f4d9) to check, and it comes out clean — sharing what I found in case it saves you time.

The two conflicts, and how they resolve:

1. config/SolrConfig.java — import-block collision only. main added org.springframework.util.StringUtils; this branch added org.springframework.web.client.RestClient. Keep both.
2. McpToolRegistrationTest.java — SchemaService moved from org.apache.solr.mcp.server.metadata to org.apache.solr.mcp.server.schema on main. Switch the import to the new package and keep the refguide.RefGuideService one.

That's the whole manual resolution — two import lines.

The metadata → schema package split doesn't bite. It was a pure rename in git history and this branch never touched those files, so git replays it automatically. No duplicate SchemaService, no stale metadata/ package left behind.

Result after rebase: +293 / -0 across the 4 files, and ./gradlew build is green — 359 tests, 0 failures, 0 errors (RefGuideServiceTest 6/6). RefGuideService is self-contained enough (Spring + MCP annotations + RestClient) that none of the upstream churn reached it.

One thing that will block the native path: RefGuideServiceTest is Mockito-based (@ExtendWith(MockitoExtension.class)), but doesn't carry @DisabledInNativeImage. Every other Mockito test in the repo does, because ByteBuddy proxies don't survive GraalVM's closed-world assumption — so ./gradlew nativeTest -Pnative will fail on it. One-line fix:

import org.junit.jupiter.api.condition.DisabledInNativeImage;

@DisabledInNativeImage
@ExtendWith(MockitoExtension.class)
class RefGuideServiceTest {

Two smaller review notes, take or leave:

• The RestClient @Bean is added to SolrConfig, which is otherwise scoped to SolrJ client wiring. It works, but it might sit more naturally in the refguide package's own config.
• getRefGuideUrl fetches https://solr.apache.org/guide/sitemap.xml on every invocation, with no caching and no explicit timeout. Might be worth a cache and a connect/read timeout given it's a remote call on a hot path.

Happy to send the rebased commits as a patch if that's useful — they preserve your authorship and sign-off.

[adityamparikh]

Updating my earlier comment — it's gone stale, and I'd rather not have you work from it.

Back then I said this branch rebased onto main cleanly with only an import-block collision in SolrConfig.java. That is no longer true as of a84033b. Re-running the rebase now gives two conflicts, one of which is structural:

1. McpToolRegistrationTest.java — this branch imports org.apache.solr.mcp.server.metadata.SchemaService. That package no longer exists; it was split into collection/ and schema/, so the import is now org.apache.solr.mcp.server.schema.SchemaService. RefGuideService slots in alongside it fine.

2. SolrConfig.java — no longer just imports. buildSolrClient was rewritten in fix: correct indexing, collection-name and service defects #176 to normalise the Solr path via URI (parsing the URL's path rather than searching the whole string, so a host literally named solr stops matching the /solr/ in its own authority). Your RestClient @Bean and that rewrite land in the same region, so it needs a real resolution rather than taking one side — keep the new URI-based buildSolrClient and add the RestClient bean next to it.

No rush given this is a draft — flagging it mainly so the "it's just imports" read doesn't cost you time when you pick it back up. Happy to push a rebased branch to your fork if that's easier; just say so.