feat(sqlitevec): add sqlite-vec vector store components

[Lonliet]

What

Add pure-Go sqlite-vec Vector Store support for Eino:

• components/indexer/sqlitevec
• components/retriever/sqlitevec

Why

This provides an embedded vector store for local RAG, examples, tests, and small-scale applications.
It uses modernc.org/sqlite and modernc.org/sqlite/vec, so it does not require CGO or an external vector database service.

Scope

• Store Eino documents and dense vectors into SQLite/sqlite-vec.
• Retrieve TopK similar documents by query embedding.
• Preserve document ID, content, metadata, Eino score, and raw sqlite-vec distance.
• Include unit tests using in-memory SQLite.

Notes

• modernc.org/sqlite/vec currently requires modernc.org/sqlite versions that require Go 1.25 or newer; the new component modules currently use Go 1.25.10.
• sqlite-vec KNN queries require MATCH ? AND k = ?; parameterized LIMIT ? was not accepted by vec0 during testing.
• Raw SQL filters are intentionally not supported in this first version.
• I am willing to maintain these sqlitevec components and follow up on review feedback and future compatibility updates.
• The contributing guide mentions develop, but the upstream repository currently has main as its default branch and no develop branch.

Tests

Docker Linux, golang:1.25-bookworm:

• go test ./... under components/indexer/sqlitevec
• go test -race ./... under components/indexer/sqlitevec
• go vet ./... under components/indexer/sqlitevec
• go test ./... under components/retriever/sqlitevec
• go test -race ./... under components/retriever/sqlitevec
• go vet ./... under components/retriever/sqlitevec
• golangci-lint run under components/indexer/sqlitevec using golangci-lint v1.64.8
• golangci-lint run under components/retriever/sqlitevec using golangci-lint v1.64.8

Additional compatibility check:

• golang:1.22-bookworm with GOTOOLCHAIN=auto selects Go 1.25.10 for the sqlitevec modules and passes go test ./... for both modules.

Local Windows:

• go test ./... passed for both modules.
• go vet ./... passed for both modules.
• go test -race ./... failed with Windows exit status 0xc0000139; Docker Linux race tests passed.

Pre-submit Checks

• git diff --check origin/main..HEAD passed.
• GitHub search found no existing cloudwego/eino-ext issues/PRs matching sqlitevec, sqlite-vec, or "sqlite vec".

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

Adds a pure-Go embedded SQLite + sqlite-vec vector store implementation for Eino by introducing a paired SQLiteVec Indexer (store docs + embeddings) and SQLiteVec Retriever (TopK similarity search), along with docs, examples, and unit tests. This expands eino-ext with a local/embedded RAG option without CGO or external vector DB services.

Changes:

• Introduce components/indexer/sqlitevec to upsert documents + vectors into SQLite/vec0 (optionally auto-creating schema).
• Introduce components/retriever/sqlitevec to query vec0 KNN results and return Eino Document objects with score + raw distance metadata.
• Add module scaffolding (go.mod/go.sum with Go 1.25), README/README_zh, examples, and in-memory unit tests for both modules.

Reviewed changes

Copilot reviewed 17 out of 19 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
components/retriever/sqlitevec/retriever.go	Implements SQLiteVec retriever (embed query, vec0 KNN query, score + metadata handling, callbacks).
components/retriever/sqlitevec/retriever_test.go	In-memory SQLite tests covering validation, retrieval, options, and corrupt metadata.
components/retriever/sqlitevec/README.md	English documentation for retriever usage/config/options.
components/retriever/sqlitevec/README_zh.md	Chinese documentation for retriever usage/config/options.
components/retriever/sqlitevec/options.go	Adds retriever impl-specific option WithMaxDistance.
components/retriever/sqlitevec/consts.go	Defines component constants/defaults + metadata key name.
components/retriever/sqlitevec/codec.go	Table-name validation + vector/metadata JSON helpers for retriever.
components/retriever/sqlitevec/examples/retriever/main.go	Minimal runnable retriever example with in-memory DB seeding.
components/retriever/sqlitevec/go.mod	New retriever module (Go 1.25) + dependencies.
components/retriever/sqlitevec/go.sum	Dependency checksums for retriever module.
components/indexer/sqlitevec/indexer.go	Implements SQLiteVec indexer (batch embedding, upsert docs, write vec0 rows, callbacks, optional auto-create).
components/indexer/sqlitevec/indexer_test.go	In-memory SQLite tests covering validation, store/upsert behavior, and embedding error paths.
components/indexer/sqlitevec/README.md	English documentation for indexer usage/config/schema/notes.
components/indexer/sqlitevec/README_zh.md	Chinese documentation for indexer usage/config/schema/notes.
components/indexer/sqlitevec/consts.go	Defines component constants/defaults.
components/indexer/sqlitevec/codec.go	Table-name validation + metadata/vector JSON helpers for indexer.
components/indexer/sqlitevec/examples/indexer/main.go	Minimal runnable indexer example.
components/indexer/sqlitevec/go.mod	New indexer module (Go 1.25) + dependencies.
components/indexer/sqlitevec/go.sum	Dependency checksums for indexer module.

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[Copilot]

Pull request overview

Copilot reviewed 17 out of 19 changed files in this pull request and generated 3 comments.

[Lonliet]

Addressed the latest Copilot review comments in 4d0de07:

• Wrapped tx.Commit() failures with [Store] commit failed for consistent Store error context.
• Renamed WithMaxDistance's parameter to maxDistance and updated its GoDoc.

Verification after the change:

• go test ./... and go vet ./... passed for both sqlitevec modules locally.
• go test -race ./... passed for both sqlitevec modules in Docker Linux (golang:1.25-bookworm).