diff --git a/.github/workflows/realapps.yml b/.github/workflows/realapps.yml
index e98e35c..87afe39 100644
--- a/.github/workflows/realapps.yml
+++ b/.github/workflows/realapps.yml
@@ -58,13 +58,13 @@ jobs:
       - name: Run the federation
         working-directory: ${{ runner.temp }}/${{ matrix.app }}
         run: |
-          rm -rf /tmp/flcrate_out
+          rm -rf /tmp/flwrcrate-ro-crate
           # flwr run detaches the simulation when there's no TTY, so we kick it
           # off and then poll for the crate within this same step (keeping the
           # step alive so the background sim isn't killed).
           flwr run . --run-config "num-server-rounds=2" || true
           for i in $(seq 1 90); do
-            if [ -f /tmp/flcrate_out/ro-crate/ro-crate-metadata.json ]; then
+            if [ -f /tmp/flwrcrate-ro-crate/ro-crate-metadata.json ]; then
               echo "crate appeared after ~$((i*5))s"; break
             fi
             sleep 5
@@ -82,7 +82,7 @@ jobs:
           /tmp/validator/bin/pip install -e . --no-deps
           /tmp/validator/bin/rocrate-validator cache warm -p ro-crate-1.2 -p process-run-crate-0.5
           /tmp/validator/bin/python tests/e2e/validate_crate.py \
-            /tmp/flcrate_out/ro-crate/ro-crate-metadata.json \
+            /tmp/flwrcrate-ro-crate/ro-crate-metadata.json \
             "${{ matrix.strategy }}" "${{ matrix.framework }}"
 
       - name: Upload the crate as an artifact
@@ -90,5 +90,5 @@ jobs:
         uses: actions/upload-artifact@v4
         with:
           name: crate-${{ matrix.app }}
-          path: /tmp/flcrate_out/ro-crate/
+          path: /tmp/flwrcrate-ro-crate/
           if-no-files-found: warn
diff --git a/.gitignore b/.gitignore
index 3d22253..c06a8c7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,7 +7,7 @@ dist/
 .eggs/
 
 # Tool output
-fl_crate_out/
+flwrcrate-ro-crate/
 *.tmp
 
 # Test / coverage artifacts
diff --git a/README.md b/README.md
index d479c1b..4d6369d 100644
--- a/README.md
+++ b/README.md
@@ -127,7 +127,7 @@ def main(grid: Grid, context: Context) -> None:
 
     with FLCrateTracker(
         context, strategy,
-        output_dir="/absolute/path/to/your-app/fl_crate_out",        # absolute!
+        output_dir="/absolute/path/to/your-app/flwrcrate-ro-crate",  # absolute!
         pyproject_path="/absolute/path/to/your-app/pyproject.toml",  # absolute!
         app_name="My federated run",
         author={"name": "Your Name", "orcid": "https://orcid.org/0000-0000-0000-0000"},
@@ -142,7 +142,7 @@ def main(grid: Grid, context: Context) -> None:
         )
         torch.save(result.arrays.to_torch_state_dict(), "final_model.pt")
         tracker.record_result(result, model_path="final_model.pt")
-    # On clean exit the RO-Crate is written to <output_dir>/ro-crate/
+    # On clean exit, <output_dir> is the RO-Crate
 ```
 
 That is the whole integration. On exit — **including on failure** — the crate
@@ -186,7 +186,7 @@ as absolute paths.
 |---|---|---|
 | `context` | yes | The Flower `Context` (gives access to `run_config`) |
 | `strategy` | yes | Your strategy instance (FedAvg, FedProx, …) — class, module, and hyperparameters are captured |
-| `output_dir` | recommended | Where to write outputs. **Use an absolute path.** Default: `./fl_crate_out` |
+| `output_dir` | recommended | Where to write outputs. **Use an absolute path.** Default: `./flwrcrate-ro-crate` |
 | `pyproject_path` | recommended | Path to your app's `pyproject.toml`. **Use an absolute path.** Default: `"pyproject.toml"` |
 | `app_name` | no | Human-readable name for the crate's root dataset |
 | `author` | no | `"Name"` or `{"name": ..., "orcid": ..., "affiliation": ...}` — becomes a `Person` entity (ORCID as `@id`) |
@@ -211,16 +211,21 @@ Mapped metrics get a `propertyID`; unmapped metrics still emit a plain
 
 ## Output
 
+The output folder is the RO-Crate itself:
+
 ```
-<output_dir>/
-├── captured_metadata.json   # full capture: config, frameworks, strategy, timing, final metrics
-├── metrics_log.json         # per-round metrics + federation details (referenced by the crate)
-└── ro-crate/
-    ├── ro-crate-metadata.json
-    ├── final_model.pt        # if a model_path was given
-    └── metrics_log.json
+<output_dir>/                  # default: ./flwrcrate-ro-crate
+├── ro-crate-metadata.json
+├── metrics_log.json           # per-round metrics + federation details
+└── final_model.pt             # if a model_path was given
 ```
 
+During the run, flwrCrate also keeps `captured_metadata.json` there, a record of
+everything captured so far. It is deleted once the crate is written, and kept if
+writing the crate fails. If the folder contains files flwrCrate didn't write, it
+logs a warning: they aren't described in the crate, but would travel with it if
+the folder is shared.
+
 ### What's inside `ro-crate-metadata.json`
 
 The crate's `@graph` contains, linked together:
diff --git a/examples/quickstart-pytorch/server_app.py b/examples/quickstart-pytorch/server_app.py
index 0b618ab..15a078e 100644
--- a/examples/quickstart-pytorch/server_app.py
+++ b/examples/quickstart-pytorch/server_app.py
@@ -45,7 +45,7 @@ def main(grid: Grid, context: Context) -> None:
     # relative paths resolve there, not in your project.
     with FLCrateTracker(
         context, strategy,
-        output_dir="/absolute/path/to/quickstart-pytorch/fl_crate_out",
+        output_dir="/absolute/path/to/quickstart-pytorch/flwrcrate-ro-crate",
         pyproject_path="/absolute/path/to/quickstart-pytorch/pyproject.toml",
         app_name="Quickstart PyTorch (demo)",
         author={"name": "Ali Faizollah", "orcid": "https://orcid.org/0009-0000-0000-0000"},
@@ -60,7 +60,7 @@ def main(grid: Grid, context: Context) -> None:
         )
         torch.save(result.arrays.to_torch_state_dict(), "final_model.pt")
         tracker.record_result(result, model_path="final_model.pt")  # flwrCrate (3/3b)
-    # On clean exit the RO-Crate is written to <output_dir>/ro-crate/
+    # On clean exit, <output_dir> is the RO-Crate
 
 
 def global_evaluate(server_round: int, arrays: ArrayRecord) -> MetricRecord:
diff --git a/flwrcrate/tracker.py b/flwrcrate/tracker.py
index 2d7c4eb..b40fdcb 100755
--- a/flwrcrate/tracker.py
+++ b/flwrcrate/tracker.py
@@ -6,7 +6,7 @@
 
     with FLCrateTracker(
         context, strategy,
-        output_dir="fl_crate_out",
+        output_dir="flwrcrate-ro-crate",
         author="Ali",                       
         license="http://spdx.org/licenses/MIT",
     ) as tracker:
@@ -19,7 +19,7 @@
         )
         torch.save(result.arrays.to_torch_state_dict(), "final_model.pt")
         tracker.record_result(result, model_path="final_model.pt")
-    # On clean exit, the RO-Crate is written to output_dir/ro-crate/.
+    # On clean exit, output_dir itself becomes the RO-Crate.
 """
 
 import json
@@ -47,12 +47,12 @@ class FLCrateTracker:
     def __init__(self, context, strategy, output_dir=None,
                  pyproject_path="pyproject.toml", app_name=None,
                  author=None, license=None, agent=None):
-        self.output_dir = Path(output_dir) if output_dir else (Path.cwd() / "fl_crate_out")
+        self.output_dir = Path(output_dir) if output_dir else (Path.cwd() / "flwrcrate-ro-crate")
         self.output_dir.mkdir(parents=True, exist_ok=True)
         self.pyproject_path = pyproject_path
         self.capture_path = self.output_dir / "captured_metadata.json"
         self.metrics_log_path = self.output_dir / "metrics_log.json"
-        self.crate_dir = self.output_dir / "ro-crate"
+        self.crate_dir = self.output_dir  # the output folder is the crate itself
         self.model_path = None
         self._built = False
 
@@ -200,6 +200,24 @@ def record_result(self, result, model_path=None):
         self._capture["final_metrics"] = self._final_round_metrics()
         self._save_capture()
 
+    def _warn_about_unrelated_files(self):
+        """Warn about files in the crate folder that flwrCrate didn't write.
+
+        They aren't described in the crate, but they travel with it whenever the
+        folder is shared. Hidden files such as .DS_Store are ignored.
+        """
+        ours = {"ro-crate-metadata.json", self.metrics_log_path.name}
+        if self.model_path:
+            ours.add(self.model_path.name)
+        others = sorted(p.name for p in self.crate_dir.iterdir()
+                        if p.name not in ours and not p.name.startswith("."))
+        if others:
+            logger.warning(
+                "The RO-Crate folder %s also contains files flwrCrate did not write: %s. "
+                "They are not described in the crate, but would travel with it if the "
+                "folder is shared.", self.crate_dir, ", ".join(others)
+            )
+
     def build(self):
         """Write the RO-Crate. Called automatically on clean exit."""
         if self._built:
@@ -216,6 +234,9 @@ def build(self):
             agent=self.agent,
         )
         self._built = True
+        # The capture is only a fallback record for runs whose crate can't be written.
+        self.capture_path.unlink(missing_ok=True)
+        self._warn_about_unrelated_files()
         logger.info("RO-Crate written to %s", self.crate_dir)
         return self.crate_dir
 
diff --git a/tests/e2e/sklearn_ci_server_app.py b/tests/e2e/sklearn_ci_server_app.py
index 93a464c..4ff80ba 100644
--- a/tests/e2e/sklearn_ci_server_app.py
+++ b/tests/e2e/sklearn_ci_server_app.py
@@ -38,7 +38,7 @@ def main(grid: Grid, context: Context) -> None:
 
     with FLCrateTracker(
         context, strategy,
-        output_dir="/tmp/flcrate_out",
+        output_dir="/tmp/flwrcrate-ro-crate",
         pyproject_path="/tmp/flcrate_pyproject.toml",
         app_name="Quickstart scikit-learn (CI e2e)",
         author={"name": "flwrCrate CI", "orcid": "https://orcid.org/0000-0000-0000-0000"},
diff --git a/tests/test_integration.py b/tests/test_integration.py
index af16ef4..6702b23 100644
--- a/tests/test_integration.py
+++ b/tests/test_integration.py
@@ -15,7 +15,7 @@
 
 
 def _graph(out_dir):
-    data = json.loads((out_dir / "ro-crate" / "ro-crate-metadata.json").read_text())
+    data = json.loads((out_dir / "ro-crate-metadata.json").read_text())
     return {e["@id"]: e for e in data["@graph"]}
 
 
@@ -40,6 +40,9 @@ def test_full_lifecycle_produces_complete_crate(
         tracker.record_result(fake_result, model_path=str(model))
 
     g = _graph(out)
+    # the output folder is the crate itself: no sub-folder, and the capture file is gone
+    assert sorted(p.name for p in out.iterdir()) == [
+        "final_model.pt", "metrics_log.json", "ro-crate-metadata.json"]
 
     # all five profile fixes present
     assert g["./"]["mentions"] == [{"@id": "#fl-run"}]                 # #1
@@ -119,3 +122,34 @@ def test_federation_summary_picks_up_config_hints(
     assert "fraction-evaluate" in fed
     assert "min-available-clients" in fed
     assert "learning-rate" not in fed  # not a federation key
+
+
+def test_capture_kept_when_crate_cannot_be_written(
+    tmp_path, fake_context, fake_strategy, app_pyproject, monkeypatch
+):
+    """captured_metadata.json is deleted after a successful build, so it must
+    survive as the run's only record when the build fails."""
+    def broken_build(*args, **kwargs):
+        raise OSError("disk full")
+
+    monkeypatch.setattr("flwrcrate.tracker.build_crate", broken_build)
+    out = tmp_path / "out"
+    with FLCrateTracker(fake_context, fake_strategy, output_dir=str(out),
+                        pyproject_path=str(app_pyproject)):
+        pass
+
+    assert (out / "captured_metadata.json").exists()
+
+
+def test_warns_about_files_flwrcrate_did_not_write(
+    tmp_path, fake_context, fake_strategy, app_pyproject, caplog
+):
+    """Files already in the output folder would travel with the crate, so say so."""
+    out = tmp_path / "out"
+    out.mkdir()
+    (out / "patients.csv").write_text("id,age\n1,42\n")
+    with FLCrateTracker(fake_context, fake_strategy, output_dir=str(out),
+                        pyproject_path=str(app_pyproject)):
+        pass
+    
+    assert "patients.csv" in caplog.text