simplify comment in UI re: locked 2D

app/web/main.py

@@ -188,7 +188,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "PCA",
         "blurb": "Principal component analysis. Linear, fast, deterministic.",
         "key": [
-            ("n_components", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_components", "int", 2, None, "Locked."),
         ],
         "advanced": [
             ("svd_solver", "str", "auto", ["auto", "full", "arpack", "randomized"], None),
@@ -201,7 +201,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "FactorAnalysis",
         "blurb": "Gaussian latent-factor model with per-feature noise.",
         "key": [
-            ("n_components", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_components", "int", 2, None, "Locked."),
             ("random_state", "int", 42, None, None),
         ],
         "advanced": [
@@ -215,7 +215,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "t-SNE",
         "blurb": "Stochastic neighbour embedding. Local structure preserved.",
         "key": [
-            ("n_components", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_components", "int", 2, None, "Locked."),
             ("perplexity", "float", 30.0, None, None),
             ("random_state", "int", 42, None, None),
         ],
@@ -232,7 +232,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "UMAP",
         "blurb": "Uniform manifold approximation. Preserves local + some global structure.",
         "key": [
-            ("n_components", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_components", "int", 2, None, "Locked."),
             ("n_neighbors", "int", 15, None, None),
             ("min_dist", "float", 0.1, None, None),
             ("random_state", "int", 42, None, None),
@@ -249,7 +249,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "PaCMAP",
         "blurb": "Pairwise-controlled manifold approximation. Balanced local/global.",
         "key": [
-            ("n_components", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_components", "int", 2, None, "Locked."),
             ("n_neighbors", "int", 10, None, None),
             ("MN_ratio", "float", 0.5, None, None),
             ("FP_ratio", "float", 2.0, None, None),
@@ -266,7 +266,7 @@ REDUCERS: Dict[str, Dict[str, Any]] = {
         "label": "TriMap",
         "blurb": "Triplet-based dimensionality reduction. Emphasises global structure.",
         "key": [
-            ("n_dims", "int", 2, None, "Locked to 2 — flow asserts 2D output."),
+            ("n_dims", "int", 2, None, "Locked."),
             ("n_inliers", "int", 10, None, None),
             ("n_outliers", "int", 5, None, None),
             ("n_random", "int", 5, None, None),

flows/embedding_flow.py

@@ -7,6 +7,18 @@ import sys
 os.environ.setdefault("PREFECT_API_URL", "http://localhost:4200/api")
 os.environ.setdefault("DO_NOT_TRACK", "1")
 
+# Pin per-process thread pools to 1 so Ray's worker parallelism doesn't
+# multiply against BLAS/numba/etc. thread pools — otherwise 4 workers × N
+# cores → thrash. Must be set before numpy/numba/sklearn import, since
+# those libs latch onto these env vars at import time. Ray manages OMP
+# per-task-CPU but does NOT manage NUMBA_NUM_THREADS, which is what
+# PaCMAP/UMAP use for their optimization loops.
+os.environ.setdefault("OMP_NUM_THREADS", "1")
+os.environ.setdefault("MKL_NUM_THREADS", "1")
+os.environ.setdefault("OPENBLAS_NUM_THREADS", "1")
+os.environ.setdefault("NUMEXPR_NUM_THREADS", "1")
+os.environ.setdefault("NUMBA_NUM_THREADS", "1")
+
 from datetime import timedelta
 import math
 from pathlib import Path