refactor(customization): accum every training metric as time series

docs/customizer/manage-customization-jobs/get-job-status.mdx

@@ -10,9 +10,13 @@ Get detailed execution status for a customization job, including step-by-step pr
 This endpoint provides granular execution details including:
 
 - **Step-level status**: `model-and-dataset-download` → `training` → `model-upload` → `model-entity-creation`
-- **Training metrics**: `step`, `epoch`, `train_loss`, `lr` (learning rate), `grad_norm`, `val_loss`
+- **Training progress**: `step`, `epoch`, `max_steps`, `num_epochs`, `percentage_done`
+- **Latest metric values**: one field per metric, named `<phase>_<metric>` — `train_loss`, `train_lr`, `train_grad_norm`, `val_loss`, and whatever else your backend reports
+- **Metric history**: `metrics`, holding each metric as a series of `{step, epoch, value}` points
 - **Progress tracking**: `downloaded_files`, `uploaded_bytes`, `progress_pct`
 
+Which metrics appear depends on the backend and the algorithm. See [Checking Your Customization Job Metrics](/documentation/customizer-reference/tutorials/metrics) for how the names are formed.
+
 To list jobs or get job definitions (model entity, hyperparameters, spec), use [List Active Jobs](/documentation/customizer-reference/manage-customization-jobs/list-active-jobs) instead.
 
 </Tip>
@@ -146,9 +150,25 @@ curl -X GET \
              "num_epochs": 2,
              "step": 8,
              "epoch": 1,
+             "percentage_done": 8,
              "train_loss": 2.8918895721435547,
-             "lr": 4.9101714686276044e-05,
-             "grad_norm": 26.0
+             "train_lr": 4.9101714686276044e-05,
+             "train_grad_norm": 26.0,
+             "metrics": {
+               "train_loss": [
+                 { "step": 4, "epoch": 1, "value": 3.2087905406951904 },
+                 { "step": 8, "epoch": 1, "value": 2.8918895721435547 }
+               ],
+               "val_loss": [],
+               "train_lr": [
+                 { "step": 4, "epoch": 1, "value": 4.9550857343138022e-05 },
+                 { "step": 8, "epoch": 1, "value": 4.9101714686276044e-05 }
+               ],
+               "train_grad_norm": [
+                 { "step": 4, "epoch": 1, "value": 31.5 },
+                 { "step": 8, "epoch": 1, "value": 26.0 }
+               ]
+             }
            }
          }
        ]
@@ -222,11 +242,30 @@ curl -X GET \
              "num_epochs": 2,
              "step": 94,
              "epoch": 2,
+             "percentage_done": 100,
              "train_loss": 0.3437718152999878,
-             "lr": 5.000000000000001e-07,
-             "grad_norm": 20.125,
+             "train_lr": 5.000000000000001e-07,
+             "train_grad_norm": 20.125,
              "val_loss": 0.5527229905128479,
-             "checkpoint_path": "/var/run/scratch/job/training/checkpoints"
+             "checkpoint_path": "/var/run/scratch/job/training/checkpoints",
+             "metrics": {
+               "train_loss": [
+                 { "step": 47, "epoch": 1, "value": 1.1204545497894287 },
+                 { "step": 94, "epoch": 2, "value": 0.3437718152999878 }
+               ],
+               "val_loss": [
+                 { "step": 47, "epoch": 1, "value": 0.9182837605476379 },
+                 { "step": 94, "epoch": 2, "value": 0.5527229905128479 }
+               ],
+               "train_lr": [
+                 { "step": 47, "epoch": 1, "value": 2.5e-05 },
+                 { "step": 94, "epoch": 2, "value": 5.000000000000001e-07 }
+               ],
+               "train_grad_norm": [
+                 { "step": 47, "epoch": 1, "value": 24.75 },
+                 { "step": 94, "epoch": 2, "value": 20.125 }
+               ]
+             }
            }
          }
        ]

docs/customizer/tutorials/metrics.mdx

@@ -27,10 +27,38 @@ The time to complete this tutorial is approximately 10 minutes.
 
 ## Available Metrics
 
-Each customization job tracks two key metrics:
+A customization job tracks every numeric metric its backend reports, not a fixed
+list. Training loss and validation loss are always among them:
 
-- **Training Loss**: Calculated during training, logged every 10 steps (default, configurable via hyperparameters)
-- **Validation Loss**: Calculated during validation, logged at each validation interval
+- **Training Loss** (`train_loss`): Calculated during training, logged every 10 steps (default, configurable via hyperparameters)
+- **Validation Loss** (`val_loss`): Calculated during validation, logged at each validation interval
+
+Alongside those you will typically see `train_lr` (learning rate) and
+`train_grad_norm`, plus whatever else the algorithm produces — a DPO job also
+reports `train_preference_loss` and `val_accuracy`, for example.
+
+### How Metrics Are Named
+
+Each metric is named `<phase>_<metric>`, where the phase is `train` or `val` and
+the metric keeps whatever name the training framework gave it. A metric reported
+during both training and validation therefore stays separate: DPO's `accuracy`
+becomes `train_accuracy` and `val_accuracy` rather than one interleaved series.
+
+`train_loss` and `val_loss` are simply what this rule produces for a metric named
+`loss`.
+
+### Where Metrics Appear
+
+Each metric shows up in two places in a training task's `status_details`:
+
+- **The latest value**, as a top-level field under its full name (`train_loss`,
+  `train_lr`, ...). Present only when the metric was actually reported, so a
+  missing field means no value rather than a zero.
+- **The full history**, under `metrics`, as a list of `{step, epoch, value}`
+  points per metric. This is what the loss curves in the UI are drawn from.
+
+Non-numeric values a framework emits alongside the scalars — histograms, tables,
+nested dictionaries — are not charted and do not appear in either place.
 
 ## Viewing Your Metrics
 
@@ -64,11 +92,20 @@ for step in status.steps or []:
             print(f"Epoch: {details.get('epoch')}/{details.get('num_epochs')}")
             print(f"Training Loss: {details.get('train_loss')}")
             print(f"Validation Loss: {details.get('val_loss')}")
-            print(f"Learning Rate: {details.get('lr')}")
-            print(f"Gradient Norm: {details.get('grad_norm')}")
+            print(f"Learning Rate: {details.get('train_lr')}")
+            print(f"Gradient Norm: {details.get('train_grad_norm')}")
 ```
 
-The response includes training progress and metrics including loss, learning rate, and validation loss.
+To read the curves rather than the latest values, use the `metrics` payload. It
+carries every metric the job reported, so iterating it picks up backend-specific
+ones without naming them in advance:
+
+```python
+for name, points in (details.get("metrics") or {}).items():
+    if not points:
+        continue
+    print(f"{name}: {len(points)} points, latest {points[-1]['value']}")
+```
 
 ### Using MLflow