feat: add shared metric contract for scorer functions

Expose MetricInput -> MetricResult types and adapt decorated scorers via to_metric() so Evaluator OSS scorers can share a runtime contract with platform integrations while preserving BYOB scorer compatibility.

Author: SandyChapman

CHANGELOG.md

@@ -2,6 +2,13 @@
 
 ## 0.13.0 (unreleased)
 
+### Shared Metric Contract
+
+- Added public `MetricInput -> MetricResult` scorer/metric runtime types and `ScorerFunctionMetric`.
+- Extended BYOB `@scorer` with typed scorer metadata and `to_metric()` while preserving current dict scorer behavior.
+- Added optional `config_schema` support for typed scorer configs while keeping raw dict configs as the default.
+- Split typed scorer config binding into strict `bind(config=ConfigModel(...))` and coercive `bind_raw_config(config={...})` paths.
+
 ### Adapter Proxy (Breaking — replaces LiteLLM)
 
 - **LiteLLM removed**: The `litellm` dependency, `proxy` and `proxy-full` extras, and `litellm_settings` config field are all removed. The adapter proxy is now built-in with zero external proxy dependencies.

src/nemo_evaluator/__init__.py

@@ -31,7 +31,22 @@
     VLMSolver,
 )
 from nemo_evaluator.scoring import (
+    AnnotationOutputSpec,
+    CandidateOutput,
+    DatasetRow,
+    Metric,
+    MetricDescriptor,
+    MetricInput,
+    MetricOutputSpec,
+    MetricResult,
+    MetricScorerFunction,
     ScorerInput,
+    ScorerCallable,
+    ScorerConfig,
+    ScorerFunctionMetric,
+    ScorerReturn,
+    ScoreOutputSpec,
+    ScoreValue,
     answer_line,
     code_sandbox,
     code_sandbox_async,
@@ -65,6 +80,21 @@
     "benchmark",
     "scorer",
     "ScorerInput",
+    "Metric",
+    "DatasetRow",
+    "CandidateOutput",
+    "MetricInput",
+    "ScoreOutputSpec",
+    "AnnotationOutputSpec",
+    "MetricOutputSpec",
+    "MetricDescriptor",
+    "ScoreValue",
+    "MetricResult",
+    "MetricScorerFunction",
+    "ScorerCallable",
+    "ScorerConfig",
+    "ScorerFunctionMetric",
+    "ScorerReturn",
     # Scoring primitives
     "exact_match",
     "multichoice_regex",