Reconcile the frontend with the round-1 backend contracts

Five backend branches merged and the TypeScript still compiled, because
none of this is a type error: a field that arrives `undefined`, a variant
nothing emits any more, a prompt whose loop never closes. Six things.

**Orphaned volumes are destructive now, not safe.** `ReclaimTarget::
OrphanVolume` is gone from Rust; the object is a `DestructiveTarget::
OrphanVolume { name, project_id }` confirmed against the *volume's* name,
there being no project to name. The TS union still listed it under
`ReclaimTarget`, and — worse — `DiskProjectTable` keys destructive items
off `project_id`, which an orphan's never matches. So the item existed in
the plan and appeared nowhere on screen. `DiskSettings` now splits the
plan's destructive list and gives orphans their own section with a
per-volume `TypedConfirmModal`. The copy says what a
`triple-c-claude-config-*` volume actually is — a Claude login
credential, every plugin and skill, every transcript that project had —
and keeps the sentence explaining that "no matching project" is a lookup
against the project list and is never inferred from a project being
stopped or having no image, which is the inference that once flagged two
live projects.

`TypedConfirmModal` grew a `subject` prop: asking a user for "the exact
project name" of a volume that has no project is asking for a string that
does not exist.

**Snapshot and Total reconcile.** `ProjectDiskRow.snapshot_attributed_bytes`
is the single figure `snapshot_attribution()` exists to produce. The
column rendered `snapshot_above_base_bytes` and fell back to `—` while
the Total was `size - shared` regardless — and in that branch `size -
shared` is the whole 4.7 GB base image, charged per project and then
added again as a base-image row. One field, one rule. The one branch
where the figure *is* the whole image says so rather than passing itself
off as a share.

**The overwrite loop closes.** Traced end to end: a `FILE_EXISTS:`
refusal raises the prompt, Replace re-invokes with `overwrite: true`,
Skip advances, "…all" answers the rest without asking, and picker and
host-drop both reach `uploadFileToContainer` through `uploadPaths`. Two
gaps: a second batch's `askOverwrite` overwrote the first's resolver,
leaving that batch awaiting an answer no dialog could produce; and the
backend's written refusals — a hidden host folder, a path outside the
write roots — were passed as a toast `detail`, which `ToastHost` renders
as collapsed monospace behind a "Details" button, so the only sentence
that explained anything was the part nobody saw. `readableRefusal`
promotes it to the headline when a batch failed the same way.

**The browser pane's sandbox is pinned.** `allow-same-origin` must stay
(the proxy's gate reads `Origin`/`Referer`, and an opaque origin sends
`null`); every top-navigation grant and `allow-popups-to-escape-sandbox`
must stay absent, and the test names the offending token rather than
printing a set diff.

**`@tauri-apps/plugin-store` is gone** from `package.json` — its
capability grants were removed as a host-file-write primitive and nothing
in `app/src` imports it. The lockfile was updated with
`--package-lock-only`, deliberately: `node_modules` is a symlink shared
with other worktrees and a real install would have pulled it out from
under them.

Nothing under `src-tauri/` is touched. 663 frontend tests pass (was 635),
`tsc --noEmit` clean, `npm run build` green, `cargo test` 446 unchanged.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GBq2rGum6GX7xXgsas1fDc

app/src/hooks/useFileManager.ts

@@ -4,8 +4,10 @@ import type { FileEntry } from "../lib/types";
 import * as commands from "../lib/tauri-commands";
 import { useAppState } from "../store/appState";
 import {
+  errorText,
   fileExistsPath,
   isFileExistsError,
+  readableRefusal,
   type OverwriteChoice,
 } from "../lib/uploadErrors";
 
@@ -99,8 +101,34 @@ export function useFileManager(projectId: string) {
     setCompleted(null);
   }, []);
 
-  const report = useCallback((message: string, detail?: string) => {
-    useAppState.getState().pushToast({ kind: "error", message, detail });
+  /**
+   * Report a failed operation, given the headline this hook would write and the
+   * raw failures behind it.
+   *
+   * The headline is what the *hook* knows ("Could not rename …"); it is a
+   * category, not an explanation. Some backend refusals are already a finished
+   * sentence written for the person reading it — a hidden host folder, a
+   * container path outside the roots this panel may change — and those used to
+   * arrive as the toast's `detail`, which `ToastHost` renders as collapsed
+   * monospace behind a "Details" button. So the sentence that said what was
+   * wrong and what to do about it was hidden under a headline that said
+   * neither. When every failure reduces to the *same* such sentence — which is
+   * the normal case, since these refusals are about the target directory and so
+   * fail identically for every file in a batch — it becomes the headline and
+   * there is nothing left to hide.
+   */
+  const report = useCallback((message: string, ...causes: unknown[]) => {
+    const refusals = causes.map(readableRefusal);
+    const shared =
+      causes.length > 0 && refusals.every((r) => r !== null)
+        ? [...new Set(refusals as string[])]
+        : [];
+    const promoted = shared.length === 1 ? shared[0] : null;
+    useAppState.getState().pushToast({
+      kind: "error",
+      message: promoted ?? message,
+      detail: promoted || causes.length === 0 ? undefined : causes.map(errorText).join("\n"),
+    });
   }, []);
 
   const confirm = useCallback((message: string) => {
@@ -161,7 +189,7 @@ export function useFileManager(projectId: string) {
           setBusy(null);
         }
       } catch (e) {
-        report(`Could not save "${entry.name}" to the host`, String(e));
+        report(`Could not save "${entry.name}" to the host`, e);
       }
     },
     [projectId, startWork, report, confirm],
@@ -194,6 +222,14 @@ export function useFileManager(projectId: string) {
   const askOverwrite = useCallback(
     (hostPath: string, directory: string, remaining: number, containerPath: string | null) =>
       new Promise<OverwriteChoice>((resolve) => {
+        // One batch asks one question at a time — the loop awaits each answer —
+        // so a resolver still sitting here belongs to a *different* batch (two
+        // drops in flight at once, or a drop landing while the Upload button's
+        // batch is still copying). Installing over it would leave that batch
+        // awaiting an answer no dialog can ever produce: a silent hang, with
+        // its file neither uploaded nor skipped. Skipping it is the same
+        // reading of "the dialog went away" the unmount cleanup uses.
+        conflictResolver.current?.("skip");
         conflictResolver.current = resolve;
         setConflict({
           hostPath,
@@ -221,7 +257,8 @@ export function useFileManager(projectId: string) {
       // the end, because the user is free to walk away while it copies.
       const target = currentPathRef.current;
       startWork(`Uploading ${hostPaths.length} item${hostPaths.length > 1 ? "s" : ""}…`);
-      const failures: string[] = [];
+      /** Raw failures, kept unstringified so `report` can read their shape. */
+      const failures: unknown[] = [];
       let uploaded = 0;
       let skipped = 0;
       /** A "…all" answer, applied to every remaining clash without asking. */
@@ -235,7 +272,7 @@ export function useFileManager(projectId: string) {
             continue;
           } catch (e) {
             if (!isFileExistsError(e)) {
-              failures.push(String(e));
+              failures.push(e);
               continue;
             }
             const choice: OverwriteChoice =
@@ -256,7 +293,7 @@ export function useFileManager(projectId: string) {
             await commands.uploadFileToContainer(projectId, hostPath, target, true);
             uploaded++;
           } catch (e) {
-            failures.push(String(e));
+            failures.push(e);
           }
         }
       } finally {
@@ -273,7 +310,7 @@ export function useFileManager(projectId: string) {
       if (failures.length > 0) {
         report(
           failures.length === 1 ? "A file could not be uploaded" : `${failures.length} files could not be uploaded`,
-          failures.join("\n"),
+          ...failures,
         );
       }
       // Only re-list if the user is still looking at the directory this went
@@ -331,7 +368,7 @@ export function useFileManager(projectId: string) {
         setCompleted(`"${entry.name}" is ready to drag.`);
         return { hostPath, cached: false };
       } catch (e) {
-        report(`Could not prepare "${entry.name}" for dragging`, String(e));
+        report(`Could not prepare "${entry.name}" for dragging`, e);
         return null;
       } finally {
         setBusy(null);
@@ -346,7 +383,7 @@ export function useFileManager(projectId: string) {
       if (!selected) return;
       await uploadPaths(Array.isArray(selected) ? selected : [selected as string]);
     } catch (e) {
-      report("Could not open the file picker", String(e));
+      report("Could not open the file picker", e);
     }
   }, [uploadPaths, report]);
 
@@ -366,7 +403,7 @@ export function useFileManager(projectId: string) {
         if (currentPathRef.current === target) await navigate(target);
         return true;
       } catch (e) {
-        report(`Could not rename "${entry.name}"`, String(e));
+        report(`Could not rename "${entry.name}"`, e);
         return false;
       }
     },
@@ -384,7 +421,7 @@ export function useFileManager(projectId: string) {
         if (currentPathRef.current === target) await navigate(target);
         return true;
       } catch (e) {
-        report(`Could not create "${trimmed}"`, String(e));
+        report(`Could not create "${trimmed}"`, e);
         return false;
       }
     },