> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bensevern.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# v1 vs v2 at a glance

> One-screen comparison of GoldenMatch 1.0 and 2.0: what breaks in the 2.0 major, and the capability deltas that accumulated across the 1.x line.

The scannable version. For the narrative, see [What changed from 1.0 to 2.0](/docs/goldenmatch/v1-to-v2); for the upgrade steps, see [Migrating to v2](/docs/goldenmatch/migrating-to-v2).

<Note>
  The 2.0 major is a **small, clean break** (four removed legacy paths, output unchanged). The big delta is the 1.x capability accumulation in the second table.
</Note>

## What breaks in 2.0

| Removed in 2.0                                                   | Replacement                                    | Action needed                                                                                                                     |
| ---------------------------------------------------------------- | ---------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------- |
| `GOLDENMATCH_IDENTITY_ID_SCHEME` + legacy `:hash:` lookup bridge | Canonical `:h1:` scheme (only scheme)          | Run `goldenmatch identity migrate-ids` **before** upgrading if you persist an identity DB. Un-fingerprintable rows keep `:hash:`. |
| `GOLDENMATCH_CLUSTER_FRAMES_OUT`                                 | Arrow frames-out path (the only path now)      | Remove the env var; it is silently ignored. Output is unchanged.                                                                  |
| `RunHistory.cheapest_healthy()`                                  | `pick_committed()`                             | Rename the call.                                                                                                                  |
| `_scale_aware_backend` (internal shim)                           | `auto_configure_df` / `dedupe_df` (v3 planner) | Switch to the public API if you imported it directly.                                                                             |

Nothing else in the public API changed. `dedupe()`, `match()`, `pprl_link()`, `evaluate()` behave identically.

## Capabilities: 1.0 vs 2.0

| Area                   | GoldenMatch 1.0 (2026-03-23)                                                           | GoldenMatch 2.0 (2026-06-14)                                                                                    |
| ---------------------- | -------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- |
| Core API               | `dedupe` / `match` / `pprl_link` / `evaluate`, 96 exports, 21 CLI commands, REST + MCP | Same surface, unchanged                                                                                         |
| Config                 | Zero-config + YAML schema                                                              | Zero-config + the **v3 introspective planner** (auto backend/plan, refuses low-confidence at scale)             |
| Identity               | Run-local cluster IDs only                                                             | **Durable Identity Graph** (v1.15): stable `entity_id`s, evidence edges, event log, 6 surfaces                  |
| Single-box scale       | Polars in-memory                                                                       | Planner-selected `bucket` path + signed-off **native Rust kernels** (`GOLDENMATCH_NATIVE=auto`)                 |
| Distributed            | Ray backend (basic)                                                                    | **Phase-5 streaming pipeline**: 100M rows end-to-end, \~0.3 GB driver RSS; validated on a real 5-node cluster   |
| Probabilistic matching | Scorer-level                                                                           | **Splink-class Fellegi-Sunter** that beats hand-rolled Splink on every shared-evaluator dataset (zero training) |
| Acceleration           | Pure Python / Polars                                                                   | Optional `goldenmatch[native]` Rust/Arrow kernels; bit-parity to the Python reference                           |
| SQL                    | —                                                                                      | **In-database UDFs** for DuckDB / Postgres / DataFusion                                                         |
| Other engines          | Ray only                                                                               | Opt-in **Sail (Spark Connect)** tier; opt-in **WASM** acceleration for the TypeScript port                      |

## See also

* [What changed from 1.0 to 2.0](/docs/goldenmatch/v1-to-v2) — the full story behind this table.
* [Migrating to v2](/docs/goldenmatch/migrating-to-v2) — the upgrade steps.
* [Tuning & opt-ins](/docs/goldenmatch/tuning) — every `GOLDENMATCH_*` knob in 2.0.