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/highlightLine.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it } from "vitest";
+import { EditorState, Text } from "@codemirror/state";
+import { highlightExtension, highlightLineField, lineRangeToPositions, setHighlight } from "./highlightLine";
+
+describe("lineRangeToPositions", () => {
+  const doc = Text.of(["one", "two", "three"]);
+  it("maps 1-based inclusive lines to document offsets", () => {
+    expect(lineRangeToPositions(doc, 2, 2)).toEqual({ from: 4, to: 4 });
+    expect(lineRangeToPositions(doc, 1, 3)).toEqual({ from: 0, to: 8 });
+  });
+  it("clamps past the end and refuses nonsense", () => {
+    expect(lineRangeToPositions(doc, 2, 99)).toEqual({ from: 4, to: 8 });
+    expect(lineRangeToPositions(doc, 99, 100)).toEqual({ from: 8, to: 8 });
+    expect(lineRangeToPositions(doc, 0, 1)).toEqual({ from: 0, to: 0 });
+    expect(lineRangeToPositions(doc, 3, 1)).toEqual({ from: 8, to: 8 });
+  });
+});
+
+describe("highlightLineField", () => {
+  it("decorates every line in the range and clears on null", () => {
+    let state = EditorState.create({ doc: "a\nb\nc\nd", extensions: [highlightExtension()] });
+    state = state.update({ effects: setHighlight.of({ from: 2, to: 3 }) }).state;
+    let count = 0;
+    state.field(highlightLineField).between(0, state.doc.length, () => { count++; });
+    expect(count).toBe(2);
+    state = state.update({ effects: setHighlight.of(null) }).state;
+    count = 0;
+    state.field(highlightLineField).between(0, state.doc.length, () => { count++; });
+    expect(count).toBe(0);
+  });
+});