Summary

• add first-class voyage dense embedding support
• resolve Voyage model defaults when deriving embedding dimension from config
• document the Voyage configuration surface and add focused tests

Problem

OpenViking's embedding configuration currently supports a fixed set of providers and does not expose Voyage AI as a first-class dense embedding backend.

That creates two concrete issues for Voyage usage:

• there is no supported provider path for Voyage text embedding models
• when no explicit dimension is configured, schema creation falls back to a generic default instead of the Voyage model's actual output dimension

For Voyage, that second point is important because collection schema creation happens from configuration before embeddings are written. If the configured dimension does not match the vectors returned by the provider, writes fail later with a vector dimension mismatch.

What This PR Changes

1. Add a dedicated Voyage dense embedder

This PR adds VoyageDenseEmbedder and wires it into the embedding factory as a new provider: "voyage" option.

The embedder uses Voyage's embeddings API shape and supports provider-specific request fields:

• input_type
• output_dtype
• output_dimension (mapped from dimension in config)

2. Resolve Voyage dimensions from config

This PR adds provider-specific effective dimension resolution for Voyage so that:

• an explicit dimension is honored when provided
• otherwise, the configured Voyage model's default output dimension is used

That keeps vector schema creation aligned with the actual vectors returned by Voyage models.

3. Document the supported config shape

The configuration guide now includes:

• provider: "voyage"
• Voyage-specific embedding fields
• a concrete dense embedding example
• supported Voyage text embedding models

Why This Design

This PR keeps the change narrow and provider-specific.

Instead of broadening existing providers, it introduces Voyage support only where Voyage behavior is materially different:

• provider validation
• embedder construction
• Voyage-specific request payload fields
• Voyage-specific default dimension resolution

That keeps existing provider behavior unchanged while making Voyage configuration explicit and maintainable.

Verification

Ran:

.venv/bin/python -m pytest tests/unit/test_voyage_embedder.py tests/unit/test_embedding_config_voyage.py --noconftest -q

Result:

• 14 passed

Coverage of the added tests includes:

• provider validation for voyage
• default and explicit dimension handling
• embedder factory wiring
• Voyage request payload construction
• batch behavior and API error handling

Scope

This PR is intentionally limited to Voyage text embedding support.
It does not change sparse embeddings, hybrid embeddings, reranking, or non-Voyage providers.