Close gateway-secret desync, TOCTOU, and undisclosed custom-image gaps

Round 4 review findings:

- Disclose and warn on a custom Docker image the import would set (HIGH):
  it's the image every project container is created from, so an
  undisclosed change here was a sharper version of the redirected-base-URL
  problem round 3 already flagged for the model backends.
- Recreate a running gateway container when an import restores a new
  secret with the shape unchanged (MEDIUM): reconcile_gateway's shape
  comparison can't see a secret-only change, so the container would
  otherwise keep serving old key material indefinitely.
- Report keychain write failures back to the caller instead of only
  logging them (MEDIUM): apply_settings_import now returns
  SettingsImportOutcome with secret_restore_warnings so a partial restore
  can't read as unqualified success.
- Pin a hash of the previewed file's ciphertext and refuse to apply if it
  changed on disk (MEDIUM): closes a TOCTOU between preview and apply.
- Sanitize and cap every free-form string a preview surfaces, and move the
  warning boxes above the replace list in the UI (MEDIUM): an unbounded
  base URL or image name could otherwise push the security warnings below
  the scroll fold.
- Validate the Docker socket path on import the same as the SSH key and CA
  cert paths (LOW): it was the one mounted host path validate_settings_update
  didn't cover.
- Fix ExportedSecrets::is_empty() to treat whitespace-only as blank, like
  every other secret-presence check in this feature (LOW).
- Authenticate the file header as AEAD associated data (LOW, defense in
  depth) and correct two doc comments that overstated the password not
  being cached.

app/src/lib/settingsImportPreview.test.ts

@@ -18,6 +18,8 @@ function preview(overrides: Partial<SettingsImportPreview> = {}): SettingsImport
     llamacpp_base_url: null,
     openai_compatible_base_url: null,
     gateway_api_base: null,
+    image_source: "registry",
+    custom_image_name: null,
     ...overrides,
   };
 }
@@ -76,6 +78,18 @@ describe("describeImport", () => {
     expect(items.some((i) => i.includes("llama.cpp"))).toBe(false);
     expect(items.some((i) => i.includes("OpenAI-compatible"))).toBe(false);
   });
+
+  it("names a custom Docker image when set, falling back to a placeholder if unnamed", () => {
+    expect(
+      describeImport(preview({ image_source: "custom", custom_image_name: "ghcr.io/me/triple-c" })),
+    ).toContain("Docker image: ghcr.io/me/triple-c");
+    expect(describeImport(preview({ image_source: "custom", custom_image_name: null }))).toContain(
+      "Docker image: (no image name set)",
+    );
+    expect(describeImport(preview({ image_source: "registry" })).some((i) => i.includes("Docker image"))).toBe(
+      false,
+    );
+  });
 });
 
 describe("describeImportWarnings", () => {
@@ -101,4 +115,11 @@ describe("describeImportWarnings", () => {
       "Includes a web terminal access token that will activate the next time the web terminal is turned on.",
     ]);
   });
+
+  it("warns about a custom Docker image every time, not only when it changes", () => {
+    expect(
+      describeImportWarnings(preview({ image_source: "custom", custom_image_name: "evil:latest" })),
+    ).toEqual(["Runs every project container from a custom Docker image: evil:latest."]);
+    expect(describeImportWarnings(preview({ image_source: "registry" }))).toEqual([]);
+  });
 });

app/src/lib/settingsImportPreview.ts

@@ -25,6 +25,9 @@ export function describeImport(preview: SettingsImportPreview): string[] {
     items.push(`OpenAI-compatible server: ${preview.openai_compatible_base_url}`);
   }
   if (preview.gateway_api_base) items.push(`Gateway upstream: ${preview.gateway_api_base}`);
+  if (preview.image_source === "custom") {
+    items.push(`Docker image: ${preview.custom_image_name ?? "(no image name set)"}`);
+  }
   return items;
 }
 
@@ -41,6 +44,10 @@ export function describeImport(preview: SettingsImportPreview): string[] {
  * would silently become live the next time someone flips the terminal on
  * through the UI, with no import-time signal that it wasn't freshly
  * generated.
+ *
+ * A custom Docker image gets a warning every time, not just on change: it's
+ * the image every project container is created from, so it's worth calling
+ * out regardless of what was configured before the import.
  */
 export function describeImportWarnings(preview: SettingsImportPreview): string[] {
   const warnings: string[] = [];
@@ -51,5 +58,10 @@ export function describeImportWarnings(preview: SettingsImportPreview): string[]
       "Includes a web terminal access token that will activate the next time the web terminal is turned on.",
     );
   }
+  if (preview.image_source === "custom") {
+    warnings.push(
+      `Runs every project container from a custom Docker image: ${preview.custom_image_name ?? "(no image name set)"}.`,
+    );
+  }
   return warnings;
 }

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, 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 } 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 } from "./types";
 
 // Docker
 export const checkDocker = () => invoke<boolean>("check_docker");
@@ -49,7 +49,7 @@ export const exportSettings = (password: string) =>
 export const previewSettingsImport = (password: string) =>
   invoke<SettingsImportPreview | null>("preview_settings_import", { password });
 export const applySettingsImport = (password: string) =>
-  invoke<AppSettings>("apply_settings_import", { password });
+  invoke<SettingsImportOutcome>("apply_settings_import", { password });
 
 // AWS
 export const awsSsoRefresh = (projectId: string) =>

app/src/lib/types.ts

@@ -316,6 +316,20 @@ export interface SettingsImportPreview {
   llamacpp_base_url: string | null;
   openai_compatible_base_url: string | null;
   gateway_api_base: string | null;
+  /** Whether the import sets a custom Docker image, and its name if so —
+   *  this is the image every project container is created from, so worth
+   *  more attention than an ordinary setting. */
+  image_source: ImageSource;
+  custom_image_name: string | null;
+}
+
+/** What `apply_settings_import` returns: the settings that were actually
+ *  saved, plus a note for each keychain secret the import carried but could
+ *  not be restored (a partial keychain failure must not read as unqualified
+ *  success just because the settings half went through). */
+export interface SettingsImportOutcome {
+  settings: AppSettings;
+  secret_restore_warnings: string[];
 }
 
 /** What `inspect_ca_cert_path` reports about a corporate CA path. Errors ride