fix(langchain): catch gRPC errors in keyword_search, add missing methods to README

[polaz]

Summary

• keyword_search() now returns [] instead of raising when server returns StatusCode.UNIMPLEMENTED (older CoordiNode without TextSearch endpoint)
• Add regression test test_returns_empty_when_text_search_raises
• Add keyword_search, similarity_search, structured_schema to API table in README (were missing after feat(langchain): add CoordinodeGraph.keyword_search() #41)

Root cause

keyword_search() checked callable(getattr(client, "text_search", None)) — this catches the case where the method doesn't exist at all (e.g. bare LocalClient). But when text_search is defined but the server doesn't implement the endpoint, a gRPC UNIMPLEMENTED error propagates uncaught.

Fix follows the same pattern as refresh_schema(): broad except Exception + logger.debug(...).

Closes #43

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 19846e7a-c5e4-4115-89cb-29fe57414e36

📥 Commits

Reviewing files that changed from the base of the PR and between 984f1f3 and b4f887f.

📒 Files selected for processing (3)

• langchain-coordinode/README.md
• langchain-coordinode/langchain_coordinode/graph.py
• tests/unit/test_langchain_graph.py

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📝 Walkthrough

Summary by CodeRabbit

• New Features
  • Added keyword_search() method to perform full-text BM25 search on graph data
  • Added similarity_search() method to perform vector nearest-neighbor search on graph data
  • Added structured_schema property to access graph schema in structured dictionary format

Walkthrough

Extended the CoordinodeGraph API documentation to include keyword_search and similarity_search methods, plus the structured_schema property. Modified keyword_search exception handling to catch all exceptions from text_search calls and return an empty list, with accompanying regression test.

Changes

Cohort / File(s)	Summary
Documentation & API Reference langchain-coordinode/README.md	Added keyword_search(), similarity_search(), and structured_schema property to the API reference table.
Exception Handling langchain-coordinode/langchain_coordinode/graph.py	Wrapped text_search() call in keyword_search() with broad try/except Exception to catch gRPC UNIMPLEMENTED and other errors, logging DEBUG and returning empty list instead of propagating exceptions.
Test Coverage tests/unit/test_langchain_graph.py	Added _ClientWithRaisingTextSearch fake client and test_returns_empty_when_text_search_raises() test to verify exception handling behavior.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• feat(langchain): add CoordinodeGraph.keyword_search() #41 — Introduced the keyword_search() method that is now having its error handling improved in this PR.
• feat: similarity_search() for LangChain + upsert_relations() idempotency test #27 — Added the similarity_search() method that is documented as part of this API reference extension.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.86% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main changes: fixing gRPC error handling in keyword_search and adding missing methods to the README.
Description check	✅ Passed	The description is well-related to the changeset, explaining the fix, test addition, and documentation updates with clear root cause analysis.
Linked Issues check	✅ Passed	All objectives from issue #43 are met: keyword_search now catches exceptions and returns empty list, regression test added, and README updated with missing API methods.
Out of Scope Changes check	✅ Passed	All changes are directly aligned with issue #43 objectives: error handling in keyword_search, regression test, and README documentation updates.

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✨ 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/#43-keyword-search-grpc-error

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud