docs(bench): add MLX local validation handoff

docs/benchmarks/apple-uma-mlx-exact-recall-local-validation.md

@@ -0,0 +1,45 @@
+# Gemini Local Validation Handoff — MLX Exact Recall
+
+Branch: `feat/apple-mlx-exact-cga-recall-experiment`
+
+This branch is deliberately narrow. It adds the MLX exact CGA recall experiment as an isolated benchmark module before wiring it into the main Apple UMA report.
+
+## Commands
+
+```bash
+cd /Users/kaizenpro/Projects/core
+git fetch origin --prune
+git switch feat/apple-mlx-exact-cga-recall-experiment
+git pull --ff-only origin feat/apple-mlx-exact-cga-recall-experiment
+
+uv run python -m pytest -q tests/test_apple_uma_mlx_exact_recall.py
+uv run python -m benchmarks.apple_uma_mlx_exact_recall --json
+```
+
+If MLX is available or installable locally:
+
+```bash
+CORE_BACKEND=rust uv run python -m benchmarks.apple_uma_mlx_exact_recall --json
+```
+
+## Touch-up limits
+
+Only patch:
+
+- MLX import/API mismatches
+- formatting or lint issues
+- test failure fixes directly tied to this module
+
+Do not add serving integration.
+Do not add Metal.
+Do not add CoreML/ANE.
+Do not change semantic source of truth.
+Do not use ANN or approximate recall.
+
+## Success criteria
+
+- Skip path passes when MLX is unavailable.
+- MLX-present path emits cases.
+- Every emitted case has `parity.parity_pass: true`.
+- Copy-in/copy-out fields remain explicit.
+- Non-claims remain visible.