feat(viewer): IPC types, wrappers and Rust module skeleton for the file viewer

Task 0 of the terminal file viewer plan: the shared interfaces that seven
later tasks build against in parallel. Adds ViewerLocation/ViewerTargetState/
ViewerState/ViewerFile/ViewerPoll to types.ts and their invoke() wrappers to
tauri-commands.ts, creates the file_viewer Rust module (mod.rs with
MAX_VIEWER_WINDOWS/VIEWER_LABEL_PREFIX/is_viewer_label, plus placeholder
registry/resolve/poll/write/window submodules), wires it into lib.rs, and
loosens visibility on the file_commands.rs helpers the viewer commands will
reuse (MAX_READ_BYTES, validate_container_path, validate_container_write_path,
FetchedFile, fetch_container_file, require_running, clip_container_text).

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

app/src/lib/tauri-commands.ts

@@ -1,5 +1,5 @@
 import { invoke } from "@tauri-apps/api/core";
-import type { Project, ProjectPath, ProjectRemovalReport, ProjectResetOutcome, ContainerInfo, AppSettings, SettingsImportPreview, SettingsImportOutcome, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo, UploadOutcome, Note } from "./types";
+import type { Project, ProjectPath, ProjectRemovalReport, ProjectResetOutcome, ContainerInfo, AppSettings, SettingsImportPreview, SettingsImportOutcome, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo, UploadOutcome, Note, ViewerFile, ViewerPoll, ViewerState } from "./types";
 
 // Docker
 export const checkDocker = () => invoke<boolean>("check_docker");
@@ -413,3 +413,22 @@ export const getMigrationState = (projectId: string) =>
  *  Rejects with a string already phrased for a toast. */
 export const openUrlExternal = (url: string) =>
   invoke<void>("open_url_external", { url });
+
+// ---- Terminal file viewer ----
+
+export const openFileViewer = (
+  projectId: string,
+  path: string,
+  line?: number,
+  col?: number,
+  endLine?: number,
+) => invoke<void>("open_file_viewer", { projectId, path, line, col, endLine });
+
+export const viewerGetState = () => invoke<ViewerState>("viewer_get_state");
+export const viewerReadFile = (maxBytes: number) =>
+  invoke<ViewerFile>("viewer_read_file", { maxBytes });
+export const viewerPollFile = () => invoke<ViewerPoll>("viewer_poll_file");
+export const viewerWriteFile = (contentsBase64: string, baseHash: string) =>
+  invoke<string>("viewer_write_file", { contentsBase64, baseHash });
+export const viewerChooseFile = (index: number) =>
+  invoke<ViewerState>("viewer_choose_file", { index });

app/src/lib/types.ts

@@ -954,3 +954,41 @@ export interface MigrationState {
   options: MigrationOptions;
   plan: MigrationPlan | null;
 }
+
+// ---- Terminal file viewer (commands/file_viewer_commands.rs) ----
+
+export interface ViewerLocation {
+  line: number | null;
+  col: number | null;
+  end_line: number | null;
+}
+
+export type ViewerTargetState =
+  | { kind: "resolved"; container_path: string }
+  | { kind: "choose"; candidates: string[] }
+  | { kind: "not_found"; tried: string[] };
+
+export interface ViewerState {
+  project_id: string;
+  project_name: string;
+  /** What was clicked, for the title and the not-found message. */
+  raw_path: string;
+  state: ViewerTargetState;
+  initial: ViewerLocation;
+}
+
+export interface ViewerFile {
+  contents_base64: string;
+  truncated: boolean;
+  size: number;
+  /** SHA-256 hex of the returned bytes; equals the file's hash when `truncated` is false. */
+  hash: string;
+  editable: boolean;
+  readonly_reason: string | null;
+}
+
+export interface ViewerPoll {
+  exists: boolean;
+  hash: string | null;
+  size: number | null;
+}