docs(tour): add live-file step and renumber tour

autotag_metadata/ui/guided_tour.py

@@ -359,13 +359,13 @@ def _build_steps(self) -> list[TourStep]:
                 [app.ledFolder, app.btnBrowse, app.btnActivate],
             ),
             TourStep(
-                "2. Filter which files",
+                "2.1 Filter which files",
                 "Restrict tagging to matching files with comma-separated globs "
                 "(e.g. <code>*.csv,*.tsv</code>), and tick <b>Recursive</b> to include sub-folders.",
                 [app._patterns_label, app.ledFilePatterns, app.cbRecursiveWatch],
             ),
             TourStep(
-                "2.5 Sidecar suffix",
+                "2.2 Sidecar suffix",
                 "The <b>Suffix</b> field controls the sidecar file name. Leave it empty for the "
                 "default <code>.metadata.yaml</code>, or type a custom extension "
                 "(e.g. <code>.ec-lab.metadata.yaml</code>) to distinguish sidecar families.",
@@ -459,15 +459,29 @@ def _build_steps(self) -> list[TourStep]:
                 on_enter=self._show_views,
             ),
             TourStep(
-                "5. Drop files on demand",
+                "5. The live file",
+                "The <b>Live file</b> is a YAML file kept in sync with the editor. Press "
+                "<b>Select…</b> to choose one, <b>Use</b> to watch it — then edits in your "
+                "external editor flow back into this document and vice versa — and <b>Open</b> "
+                "to launch it in your default editor.",
+                [
+                    app.ledTemporaryLoc,
+                    app.btnSelectTemporaryFile,
+                    app.btnOpenTemporaryFile,
+                    app.btnUseTemporaryFile,
+                ],
+                on_enter=self._show_form,
+            ),
+            TourStep(
+                "6. Drop files on demand",
                 "The <b>Drop files</b> toggle opens a drop zone for tagging individual files "
                 "without watching a folder. Drag files onto the zone and they are tagged with "
                 "the current metadata. The <b>Log</b> panel shows what happened.",
                 [dropzone_btn, app._dropzone_dock],
                 on_enter=self._reveal_dropzone,
             ),
             TourStep(
-                "6. The Log",
+                "7. The Log",
                 "The <b>Log</b> toggle reveals the log panel at the bottom. Every tagging event, "
                 "warning, and error is recorded here so you can see exactly what happened and "
                 "which files were processed.",

doc/usage.md

@@ -183,12 +183,26 @@ three-panel layout onto `curation`, `experimental`, and `system` at once:
 A saved view restores a multi-panel layout, each panel zoomed onto a different part of the document.
 ```
 
+### Editing in an external editor with the live file
+
+The **Live file** is a YAML file kept in sync with the editor. Press **Select…** to choose one,
+**Use** to watch it — edits made in an external, schema-aware editor then flow back into this
+document and vice versa — and **Open** to launch it in your default editor.
+
+```{figure} images/tour-15-5-the-live-file.png
+:alt: The live-file controls on the editor bar
+:width: 100%
+
+The live file mirrors the current metadata to a file so an external editor can validate it as you
+type.
+```
+
 ### Tagging on demand and watching the log
 
 Besides watching a folder, the **Drop files** toggle opens a drop zone. Drag files or folders onto
 it to tag them immediately with the current metadata, without activating a watch:
 
-```{figure} images/tour-15-5-drop-files-on-demand.png
+```{figure} images/tour-16-6-drop-files-on-demand.png
 :alt: The Drop files zone
 :width: 100%