feat(tui): design revamp of diff viewer (#28728)

packages/opencode/test/cli/tui/diff-viewer-file-tree-utils.test.ts

@@ -4,7 +4,9 @@ import {
   buildFileTree,
   flattenFileTree,
   moveFileTreeSelection,
+  moveFileTreeSelectionToFirstChild,
   moveFileTreeSelectionToFile,
+  moveFileTreeSelectionToParent,
   setFileTreeDirectoryExpanded,
   toggleFileTreeDirectory,
 } from "../../../src/cli/cmd/tui/feature-plugins/system/diff-viewer-file-tree-utils"
@@ -177,6 +179,47 @@ describe("diff viewer file tree utilities", () => {
     expect(moveFileTreeSelection([], undefined, 1)).toBeUndefined()
   })
 
+  test("moves directory selection to first visible child", () => {
+    const rows = flattenFileTree(buildFileTree([{ file: "src/config/tui.ts" }, { file: "src/session/index.ts" }]))
+    const src = rows.find((row) => row.kind === "directory" && row.name === "src")!
+    const config = rows.find((row) => row.kind === "directory" && row.name === "config")!
+    const tui = rows.find((row) => row.name === "tui.ts")!
+
+    expect(moveFileTreeSelectionToFirstChild(rows, src.id)).toBe(config.id)
+    expect(moveFileTreeSelectionToFirstChild(rows, tui.id)).toBe(tui.id)
+    expect(moveFileTreeSelectionToFirstChild(rows, undefined)).toBeUndefined()
+  })
+
+  test("moves collapsed chain selection to first visible child", () => {
+    const rows = flattenFileTree(
+      buildFileTree([
+        { file: "packages/opencode/src/cli/app.ts" },
+        { file: "packages/opencode/src/server/server.ts" },
+      ]),
+    )
+    const packages = rows.find((row) => row.kind === "directory" && row.name === "packages/opencode/src")!
+    const cli = rows.find((row) => row.kind === "directory" && row.name === "cli")!
+
+    expect(moveFileTreeSelectionToFirstChild(rows, packages.id)).toBe(cli.id)
+  })
+
+  test("moves file and collapsed directory selection to visible parent", () => {
+    const rows = flattenFileTree(
+      buildFileTree([
+        { file: "packages/opencode/src/cli/app.ts" },
+        { file: "packages/opencode/src/server/server.ts" },
+      ]),
+    )
+    const root = rows.find((row) => row.kind === "directory" && row.name === "packages/opencode/src")!
+    const cli = rows.find((row) => row.kind === "directory" && row.name === "cli")!
+    const app = rows.find((row) => row.name === "app.ts")!
+
+    expect(moveFileTreeSelectionToParent(rows, app.id)).toBe(cli.id)
+    expect(moveFileTreeSelectionToParent(rows, cli.id)).toBe(root.id)
+    expect(moveFileTreeSelectionToParent(rows, root.id)).toBe(root.id)
+    expect(moveFileTreeSelectionToParent(rows, undefined)).toBeUndefined()
+  })
+
   test("moves file selection relative to the highlighted row", () => {
     const rows = flattenFileTree(
       buildFileTree([{ file: "src/config/tui.ts" }, { file: "src/session/index.ts" }, { file: "README.md" }]),