fix(explorer): satisfy the mypy gate on the explorer surface [roadmap:v0.8.9]

Annotates the parameters mypy flagged (schema reference, palette row,
editor launcher widget, lookup state) and corrects the view-history
annotation to the (view, path) tuples it has stored since v0.8.7.
No behaviour change; CI lint gate is the driver.

Author: tcballard

src/rac/explorer/adapter.py

@@ -15,7 +15,7 @@
 from rac.core.frontmatter import split_frontmatter
 from rac.core.fs import find_markdown_files
 from rac.core.operations import CancelToken, OperationCancelled, Progress
-from rac.core.schema import available_schemas, schema_reference
+from rac.core.schema import SchemaReference, available_schemas, schema_reference
 from rac.services.improve import improve_file
 from rac.services.ingest import ConversionError, UnsupportedDocument, ingest
 from rac.services.repository import Artifact, Repository, load_repository
@@ -479,7 +479,7 @@ def schema_detail(self, name: str) -> str | None:
         return "\n".join(lines)
 
     @staticmethod
-    def _schema_section(ref, section: str) -> str:
+    def _schema_section(ref: SchemaReference, section: str) -> str:
         description = ref.descriptions.get(section)
         values = ref.metadata.get(section)
         line = f"  {section.title()}"

src/rac/explorer/screens/main.py

@@ -23,7 +23,12 @@
 
 from rac.explorer import commands, mascot
 from rac.explorer.adapter import ExplorerAdapter
-from rac.explorer.state import LoadErrorState, LoadProgressState, RepositorySummaryState
+from rac.explorer.state import (
+    LoadErrorState,
+    LoadProgressState,
+    LookupState,
+    RepositorySummaryState,
+)
 from rac.explorer.widgets.appbar import AppBar
 from rac.explorer.widgets.palette import CommandPalette
 from rac.explorer.widgets.sidebar import NavigationSidebar
@@ -86,7 +91,7 @@ class MainScreen(Screen[None]):
     def __init__(self, adapter: ExplorerAdapter) -> None:
         super().__init__()
         self.adapter = adapter
-        self._history: list[str] = []
+        self._history: list[tuple[str, str | None]] = []
         self._last_focus: Widget | None = None
         # Live reload (v0.8.9): the corpus snapshot the last load saw. None
         # means "do not watch" — before the first successful load, after a
@@ -461,7 +466,7 @@ def _show_examples(self) -> None:
         options.extend(Option(f"  {example}", disabled=True) for example in commands.EXAMPLES)
         self._show_results(options)
 
-    def _show_lookup(self, lookup) -> None:
+    def _show_lookup(self, lookup: LookupState) -> None:
         if lookup.rows:
             # Artifact rows render through the filterable path (v0.8.9).
             self.query_one(ResultsView).show_lookup(lookup.rows, lookup.message)

src/rac/explorer/widgets/palette.py

@@ -20,6 +20,7 @@
 
 from rac.explorer import commands
 from rac.explorer.adapter import ExplorerAdapter
+from rac.explorer.state import ArtifactRow
 from rac.explorer.widgets.sidebar import type_tag
 
 # Quick-open shows at most this many artifact matches; full result sets
@@ -38,7 +39,7 @@ def _command_option(spec: commands.CommandSpec) -> Option:
     return Option(label, id=f"cmd:{spec.name}")
 
 
-def _artifact_option(row) -> Option:
+def _artifact_option(row: ArtifactRow) -> Option:
     tag, colour = type_tag(row.type)
     label = Text()
     label.append(tag, style=f"bold {colour}")

src/rac/explorer/widgets/views.py

@@ -16,6 +16,7 @@
 from textual.binding import Binding
 from textual.containers import Vertical, VerticalScroll
 from textual.message import Message
+from textual.widget import Widget
 from textual.widgets import Input, Markdown, OptionList, Static, TabbedContent, TabPane, Tabs
 from textual.widgets.option_list import Option
 from textual.worker import Worker, WorkerState, get_current_worker
@@ -66,7 +67,7 @@ def __init__(self, key: str) -> None:
         self.key = key
 
 
-def launch_editor(widget, adapter: ExplorerAdapter, path: str) -> editor_mod.EditorOutcome:
+def launch_editor(widget: Widget, adapter: ExplorerAdapter, path: str) -> editor_mod.EditorOutcome:
     """Open ``path`` in the configured editor from any widget (ADR-024).
 
     Terminal editors run with the application suspended and resumed;