fix: address CodeRabbit findings on registry-fallback search (#190 follow-up)

[getappz]

Summary

Follow-up to #190 (merged) addressing CodeRabbit review comments that weren't resolved before merge:

• Major: the MCP Registry endpoint was /v0/servers, which doesn't exist — the real endpoint is /v0.1/servers. The registry-fallback search has been hitting a dead URL and silently returning nothing since Fallback MCP registry search #190 merged.
• Remote selection now filters for remote_type == "streamable-http" instead of blindly taking the first remote (could previously surface a deprecated SSE remote this codebase can't speak to).
• skill-registry's registry-fallback hits now get source: "mcp_registry" instead of an empty string, so callers can distinguish them from local skills.
• The registry HTTP call now runs via tokio::task::spawn_blocking instead of inline on the async task — the main binary's tokio runtime only enables the rt feature (single-threaded), so the blocking ureq call was stalling every other in-flight request for up to 3s, not just ones needing the registry lock (which Fallback MCP registry search #190 already fixed).

Test plan

• cargo test --workspace — all passing, new regression tests added (select_remote_url transport filtering, endpoint URL, mcp_registry provenance)
• cargo clippy --workspace --all-targets -- -D warnings -A unsafe_code -A clippy::pedantic — clean
• cargo fmt --check — clean

Summary by CodeRabbit

• New Features
  • Enhanced fallback search reliability by switching to the stable registry endpoint.
  • Fallback results now prefer compatible streamable HTTP remotes.
  • Registry fallback results are clearly tagged with a distinct source label.
• Bug Fixes
  • Remote registry lookups no longer block other server operations.
  • Remote search failures now gracefully fall back to empty results instead of disrupting merging behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: a25b7381-a686-4fc4-8b9f-568fcf8effd7

📥 Commits

Reviewing files that changed from the base of the PR and between 802ca09 and d728b4e.

📒 Files selected for processing (1)

• src/mcp_server.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• src/mcp_server.rs

---

📝 Walkthrough

Walkthrough

The registry fallback now uses /v0.1/servers, selects streamable-http remotes, marks fallback hits with mcp_registry, and runs MCP registry searches asynchronously through spawn_blocking.

Changes

Registry fallback search

Layer / File(s)	Summary
Stable endpoint and remote selection crates/gateway-registry/src/registry_search.rs	Registry searches use /v0.1/servers and select a streamable-http remote, with tests for selection and endpoint configuration.
Fallback hit provenance crates/skill-registry/src/search.rs	Merged registry hits now set SkillHit.source to mcp_registry, with corresponding test coverage.
Asynchronous MCP searches src/mcp_server.rs	The skill tool is asynchronous, and both skill and tool registry fallbacks use awaited spawn_blocking calls; affected tests are asynchronous.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant AgentflareMcp
  participant spawn_blocking
  participant search_registry
  AgentflareMcp->>spawn_blocking: run registry search
  spawn_blocking->>search_registry: search query and result limit
  search_registry-->>spawn_blocking: registry hits or failure
  spawn_blocking-->>AgentflareMcp: awaited fallback results

Loading

Possibly related PRs

• getappz/agentflare#92: Introduced the skill-registry search types and MCP skill-search integration used by the fallback metadata change.
• getappz/agentflare#190: Introduced the fallback registry search logic updated here.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly reflects the follow-up fixes to registry-fallback search and CodeRabbit review comments.
Description check	✅ Passed	The summary and test plan are present, but the reviewer notes section is missing and the clippy command differs from the template.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/registry-fallback-coderabbit-followup

---

_{Comment @coderabbitai help to get the list of available commands.}