tui(browser): r re-scans mcp-mirror/

r calls onRescan() which re-walks the project root and rerenders the
Browser with the new tree. Optional prop so tests don't have to wire
it.

src/tui/browser/Browser.tsx

@@ -10,6 +10,7 @@ export interface BrowserProps {
   readPou: (pou: POU) => Promise<string>;
   writeSelection: (s: Selection) => void;
   onQuit: () => void;
+  onRescan?: () => void;
 }
 
 interface FlatRow {
@@ -31,7 +32,7 @@ function flatten(project: Project, expanded: Set<string>): FlatRow[] {
   return rows;
 }
 
-export function Browser({ project, readPou, writeSelection, onQuit }: BrowserProps): React.ReactElement {
+export function Browser({ project, readPou, writeSelection, onQuit, onRescan }: BrowserProps): React.ReactElement {
   const [expanded, setExpanded] = React.useState<Set<string>>(new Set());
   const [cursorIdx, setCursorIdx] = React.useState(0);
   const [text, setText] = React.useState<string | null>(null);
@@ -73,6 +74,7 @@ export function Browser({ project, readPou, writeSelection, onQuit }: BrowserPro
       return;
     }
     if (input === 'q') return onQuit();
+    if (input === 'r' && onRescan) return onRescan();
     if (input === 'j' || key.downArrow) {
       setCursorIdx((i) => Math.min(i + 1, rows.length - 1));
     } else if (input === 'k' || key.upArrow) {
@@ -116,7 +118,7 @@ export function Browser({ project, readPou, writeSelection, onQuit }: BrowserPro
           <Viewer pou={cursor?.pou ?? null} text={text} scrollTop={scrollTop} visibleRows={20} />
         </Box>
       </Box>
-      <Text>j/k nav  l expand  h collapse  ? help  q quit</Text>
+      <Text>j/k nav  l expand  h collapse  r rescan  ? help  q quit</Text>
     </Box>
   );
 }
@@ -129,6 +131,7 @@ function HelpOverlay(): React.ReactElement {
       <Text>  k / ↑     move cursor up</Text>
       <Text>  l / →     expand device</Text>
       <Text>  h / ←     collapse device</Text>
+      <Text>  r         re-scan mcp-mirror/</Text>
       <Text>  ?         toggle this help</Text>
       <Text>  Esc       close help</Text>
       <Text>  q         quit</Text>

src/tui/index.tsx

@@ -51,12 +51,29 @@ async function runBrowser(maybeRoot: string | undefined): Promise<number> {
       resolve(0);
     };
     const readPou = (pou: { absPath: string }) => fs.readFile(pou.absPath, 'utf8');
+    const onRescan = async () => {
+      try {
+        const next = await walk(root);
+        app.rerender(
+          <Browser
+            project={next}
+            readPou={readPou}
+            writeSelection={onWriteSelection}
+            onQuit={onQuit}
+            onRescan={onRescan}
+          />
+        );
+      } catch (err) {
+        process.stderr.write(`phobiCS-tui: rescan failed: ${(err as Error).message}\n`);
+      }
+    };
     const app = render(
       <Browser
         project={project!}
         readPou={readPou}
         writeSelection={onWriteSelection}
         onQuit={onQuit}
+        onRescan={onRescan}
       />
     );
   });

tests/tui/Browser.test.tsx

@@ -99,6 +99,23 @@ describe('<Browser>', () => {
     expect(lastFrame()).not.toContain('Keybindings');
   });
 
+  it('calls onRescan on r', async () => {
+    const onRescan = vi.fn();
+    const { stdin } = render(
+      <Browser
+        project={project}
+        readPou={async () => ''}
+        writeSelection={() => {}}
+        onQuit={() => {}}
+        onRescan={onRescan}
+      />
+    );
+    await flush();
+    stdin.write('r');
+    await flush();
+    expect(onRescan).toHaveBeenCalled();
+  });
+
   it('closes the help overlay on Esc', async () => {
     const { stdin, lastFrame } = render(
       <Browser