Pretensor OSS

Pretensor OSS introspects PostgreSQL and Snowflake, with optional BigQuery connector support, builds a Kuzu knowledge graph of tables, columns, foreign keys, inferred joins, and related metadata, and exposes that graph to AI tools through an MCP (Model Context Protocol) server. Agents query schema context and search without issuing raw SQL against your graph store.

Status: Alpha. Pretensor is on PyPI as pretensor and currently in alpha. CLI flags, MCP tools, and graph schema can still change between alpha versions — pin exact versions until 1.0.0. See docs/releases.md for the versioning policy.

Who is this for

• Data analysts using AI to explore warehouses.
• Data engineers tired of copy-pasting DDLs into chat.
• Data architects who need grounded schema context for agents.
• Anyone feeding database schemas to an LLM by hand.

Prerequisites

• Python 3.11 or 3.12 (3.13 not yet tested).
• A reachable database for pretensor index. PostgreSQL is the fastest local path; Snowflake and BigQuery are supported via the pretensor[snowflake] and pretensor[bigquery] extras.

Install

pip install pretensor
# or, inside a uv-managed environment:
uv pip install pretensor

Optional features are exposed as extras:

Extra	Adds	Use when
pretensor[snowflake]	snowflake-sqlalchemy	You're indexing a Snowflake warehouse.
pretensor[bigquery]	google-cloud-bigquery	You're indexing BigQuery.
pretensor[clustering]	leidenalg	You want Leiden community detection during indexing. Without this, Pretensor falls back to igraph Louvain (works, but no resolution tuning).

Combine extras with comma separation, e.g. pip install 'pretensor[snowflake,clustering]'.

Try it without installing:

uvx --from pretensor pretensor --help

A note on alpha versions. Pretensor is in alpha. The plain pip install pretensor command picks up the latest alpha because PyPI has no stable release yet. Once 1.0.0 ships, future alphas will require --pre (e.g. pip install --pre pretensor); pin to a specific version (e.g. pretensor==<version>) if you want a deterministic install today — see the PyPI badge above for the latest.

If you want to hack on Pretensor itself rather than use it, see the contributor setup in CONTRIBUTING.md for the git clone + make install flow.

Quickstart

pretensor index postgresql://USER:PASSWORD@HOST:5432/DBNAME
pretensor serve --config-only   # prints mcpServers JSON for Claude / Cursor

serve --config-only prints the mcpServers JSON to stdout. Merge the pretensor entry into your Claude or Cursor MCP settings — the IDE starts the server automatically. Run pretensor serve directly if you prefer a long-running terminal process (config hints go to stderr, keeping stdout clean for JSON-RPC).

Use --state-dir on index / reindex and --graph-dir on serve when overriding the default state directory (.pretensor).

Full guide — install, tools, visibility, reindexing, graph visualization: guides/quickstart.md

MCP tools

Name	Role
list_databases	List indexed database connections with table counts and staleness.
schema	Inspect node labels, edge types, and available properties before writing Cypher.
query	BM25 keyword search over table and entity metadata.
cypher	Read-only Kuzu Cypher for one indexed database; mutating clauses are rejected.
context	Full context for one physical table, including columns, joins, lineage, and cluster metadata.
traverse	Join paths between two physical tables, including confirmed cross-database paths.
impact	Downstream tables reachable from a table via FK and inferred-join edges.
detect_changes	Compare the live database schema to the last indexed snapshot without mutating the graph.
compile_metric	Compile semantic-layer YAML into validated SQL for one indexed database.
validate_sql	Validate SQL against the indexed graph before execution.

Architecture

src/pretensor/ is organized by subsystem:

• connectors/ — database-specific introspection (PostgreSQL, Snowflake, BigQuery)
• core/ — Kuzu graph store, schema writing, relationship discovery
• intelligence/ — deterministic graph intelligence (classification, clustering, join-path precomputation; metric-template code exists but is not part of the default OSS indexing flow)
• mcp/ — MCP server, tools, resources
• cli/ — Typer CLI (index, reindex, serve, list, quickstart, export, validate, sync-grants, add, remove, plus the semantic subcommand group)

Status

Pretensor is in pre-release development. Before the first packaged release:

• The package on PyPI is named pretensor. The first stable release will be 1.0.0; everything before that is alpha. pip install pretensor works today because no stable version exists yet — --pre will be required once 1.0.0 ships and future alphas resume.
• There is no SemVer stability guarantee yet, so CLI flags, MCP tools, and graph schema may change between alphas. Pin exact versions.
• Treat current builds as evaluation software and test upgrades in a staging environment before production use.

Progress and release notes: CHANGELOG.md.

Contributing

See CONTRIBUTING.md. Security issues: see SECURITY.md.

Tests

make verify

Individual commands are also available:

make test      # pytest
make lint      # ruff check
make typecheck # pyright

License

MIT — see LICENSE.