Add SemanticCache vector index config

[omribz156]

Summary

Addresses #602.

• Add vector_index_config to SemanticCache so the cache vector field can be created with HNSW or other supported vector index options instead of always using FLAT.
• Keep the default FLAT schema unchanged, and keep dims, datatype, and distance_metric derived from the vectorizer / semantic-cache COSINE behavior.
• Document the HNSW configuration path in the LLM cache user guide.

Verification

• .venv\Scripts\python.exe -m pytest --noconftest tests/unit/test_llmcache_schema.py
• .venv\Scripts\python.exe -m black --check redisvl/extensions/cache/llm/schema.py redisvl/extensions/cache/llm/semantic.py tests/unit/test_llmcache_schema.py
• .venv\Scripts\python.exe -m compileall redisvl/extensions/cache/llm/schema.py redisvl/extensions/cache/llm/semantic.py tests/unit/test_llmcache_schema.py
• .venv\Scripts\python.exe -c "import json; json.load(open('docs/user_guide/03_llmcache.ipynb', encoding='utf-8')); print('notebook json ok')"
• git diff --check

I also tried the normal pytest command first, but local execution without --noconftest is blocked on this Windows machine because the repo autouse fixture invokes Docker Compose and the Docker CLI is not available here.

This was implemented with Codex assistance, with the patch kept focused on the cache schema/config path and docs.

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Note

^{Cursor Bugbot is generating a summary for commit 40297d2. Configure here.}

[Copilot]

Pull request overview

Adds a configurable vector-index configuration path for SemanticCache, allowing the cache’s vector field to be created with HNSW (or other supported RedisVL vector algorithms) instead of being hardcoded to FLAT, and documents the new configuration in the LLM cache user guide.

Changes:

• Extend SemanticCacheIndexSchema.from_params to accept vector_index_config and merge it into the vector field attrs while protecting vectorizer-derived attrs (dims, datatype, distance_metric).
• Add vector_index_config plumbing to SemanticCache constructor so the schema/index can be created with a non-FLAT algorithm (e.g., HNSW).
• Add unit tests for default FLAT behavior, HNSW config acceptance, and invalid config rejection; update the LLM cache notebook with a configuration example.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
redisvl/extensions/cache/llm/schema.py	Adds vector_index_config support to the semantic cache index schema builder while preventing overrides of derived attrs.
redisvl/extensions/cache/llm/semantic.py	Wires vector_index_config through SemanticCache initialization into schema/index creation.
tests/unit/test_llmcache_schema.py	Adds unit coverage for FLAT default, HNSW config, and invalid algorithm/override behavior.
docs/user_guide/03_llmcache.ipynb	Documents how to configure the semantic cache’s vector index algorithm (example: HNSW).

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[omribz156]

Thanks, fixed in 40297d2. I moved vector_index_config after overwrite in SemanticCache.init and kept the docstring in the same order, so existing positional redis_client/redis_url calls stay compatible. Verified with pytest --noconftest tests/unit/test_llmcache_schema.py, black --check, compileall, and git diff --check.