Terminal file viewer/editor + per-window app-command lockdown (#60)

Clicking a file path in Claude's terminal output now opens the file in its own window with a CodeMirror 6 editor. The editor highlights the target line, live-reloads while the file changes, and saves explicitly with hash-based conflict detection. The viewer commands are gated by window label.

Every app command is now ACL-gated per window through a Tauri AppManifest. build.rs checks the handler list against the capability files and fails the build on any mismatch.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

app/src/viewer/ViewerApp.tsx

@@ -0,0 +1,54 @@
+import { useEffect, useState } from "react";
+import Button from "../components/ui/Button";
+import { viewerChooseFile, viewerGetState } from "../lib/tauri-commands";
+import type { ViewerState } from "../lib/types";
+import EditorPane from "./EditorPane";
+
+const errorText = (e: unknown) => (e instanceof Error ? e.message : String(e));
+
+export default function ViewerApp() {
+  const [state, setState] = useState<ViewerState | { error: string } | null>(null);
+  const [chooseError, setChooseError] = useState<string | null>(null);
+
+  useEffect(() => {
+    viewerGetState().then(setState, (e) => setState({ error: errorText(e) }));
+  }, []);
+
+  if (state === null) return <p className="p-4 text-sm text-[var(--text-secondary)]">Loading…</p>;
+  if ("error" in state) return <p className="p-4 text-sm">{state.error}</p>;
+
+  const choose = (index: number) => {
+    setChooseError(null);
+    viewerChooseFile(index).then(setState, (e) => setChooseError(errorText(e)));
+  };
+
+  switch (state.state.kind) {
+    case "resolved":
+      return <EditorPane state={state} />;
+    case "not_found":
+      return (
+        <div className="p-4 text-sm">
+          <p>Could not find <span className="font-mono">{state.raw_path}</span> in the container. Looked in:</p>
+          <ul className="mt-2 list-disc pl-6 font-mono text-xs text-[var(--text-secondary)]">
+            {state.state.tried.map((p) => <li key={p}>{p}</li>)}
+          </ul>
+        </div>
+      );
+    case "choose":
+      return (
+        <div className="p-4 text-sm">
+          <p>Several files match <span className="font-mono">{state.raw_path}</span>. Open which?</p>
+          <ul className="mt-2 flex flex-col items-start gap-1">
+            {state.state.candidates.map((p, i) => (
+              <li key={p}>
+                <Button size="sm" onClick={() => choose(i)}>
+                  <span className="font-mono">{p}</span>
+                </Button>
+              </li>
+            ))}
+          </ul>
+          {chooseError && <p role="alert" className="mt-2">{chooseError}</p>}
+        </div>
+      );
+  }
+}