Python: PR #2328 Issue: `index_name` Required for Knowledge Base Scenarios

[farzad528]

PR #2328 Issue: index_name Required for Knowledge Base Scenarios

1. Scenario

Azure AI Search customers using Knowledge Bases with native retrieval sources (web, remoteSharePoint) that don't create underlying indexes.

2. Issue

AzureAISearchContextProvider requires index_name even in agentic mode. However, Knowledge Bases using native retrieval sources have no underlying index - these primitives are mutually exclusive.

# ❌ Fails - no index exists for remoteSharePoint knowledge source
provider = AzureAISearchContextProvider(
    knowledge_base_name="my-sharepoint-kb",
    index_name=???  # Nothing to provide
)

3. Proposal

Make index_name and knowledge_base_name mutually exclusive. Infer mode from which parameter is provided:

# Semantic mode (direct search)
provider = AzureAISearchContextProvider(index_name="my-index")

# Agentic mode (KB retrieval - no index needed)
provider = AzureAISearchContextProvider(knowledge_base_name="my-kb")

The Knowledge Base retrieve API (/knowledgebases/{kb-name}/retrieve) doesn't require an index name - only the KB name.