feat: gate session cleanup by runtime capabilities

src/client/src/api.ts

@@ -1,3 +1,3 @@
 export { activityApi, api, configApi, filesApi, gitApi, machinesApi, piWebApi, pluginsApi, projectsApi, sessionsApi, terminalsApi, workspacesApi } from "./api/clients";
 export { globalSessionEvents, realtimeEvents, sessionEvents, terminalSocket } from "./api/sockets";
-export type { ArchiveSessionsResponse, AuthProviderOption, AuthProviderStatus, AuthProvidersResponse, AuthStatusSource, AuthType, CommandOption, CommandResult, FileContentMediaType, FileContentResponse, FileSuggestion, FileTreeEntry, FileTreeResponse, GitDiffResponse, GitFileState, GitStatusFile, GitStatusResponse, Machine, MachineHealth, MachineKind, MachineStatus, MessagePage, ModelSelectionResponse, OAuthFlowState, PiWebComponentStatus, PiWebConfigEnvOverrides, PiWebConfigResponse, PiWebConfigValues, PiWebInstallationInfo, PiWebPluginConfig, PiWebPluginConfigMap, PiWebPluginInfo, PiWebPluginsResponse, PiWebPluginScope, PiWebPluginSettings, PiWebReleaseStatus, PiWebShortcutConfig, PiWebStatusMessage, PiWebStatusResponse, Project, QueuedSessionMessage, RealtimeEvent, RunTerminalCommandInput, SessionActivity, SessionInfo, SessionModel, SessionStatus, SlashCommand, SessionUiEvent, TerminalCommandRun, TerminalCommandRunFilter, TerminalCommandRunHandle, TerminalCommandRunStatus, TerminalInfo, TerminalUiEvent, ThinkingLevel, ThinkingLevelsResponse, Workspace, WorkspaceActivity, WorkspaceActivityResponse, WorkspaceActivityUiEvent } from "../../shared/apiTypes";
+export type { ArchiveSessionsResponse, AuthProviderOption, AuthProviderStatus, AuthProvidersResponse, AuthStatusSource, AuthType, CommandOption, CommandResult, FileContentMediaType, FileContentResponse, FileSuggestion, FileTreeEntry, FileTreeResponse, GitDiffResponse, GitFileState, GitStatusFile, GitStatusResponse, Machine, MachineHealth, MachineKind, MachineRuntime, MachineStatus, MessagePage, ModelSelectionResponse, OAuthFlowState, PiWebCapability, PiWebComponentStatus, PiWebConfigEnvOverrides, PiWebConfigResponse, PiWebConfigValues, PiWebInstallationInfo, PiWebPluginConfig, PiWebPluginConfigMap, PiWebPluginInfo, PiWebPluginsResponse, PiWebPluginScope, PiWebPluginSettings, PiWebReleaseStatus, PiWebRuntimeComponent, PiWebRuntimeResponse, PiWebShortcutConfig, PiWebStatusMessage, PiWebStatusResponse, Project, QueuedSessionMessage, RealtimeEvent, RunTerminalCommandInput, SessionActivity, SessionInfo, SessionModel, SessionStatus, SlashCommand, SessionUiEvent, TerminalCommandRun, TerminalCommandRunFilter, TerminalCommandRunHandle, TerminalCommandRunStatus, TerminalInfo, TerminalUiEvent, ThinkingLevel, ThinkingLevelsResponse, Workspace, WorkspaceActivity, WorkspaceActivityResponse, WorkspaceActivityUiEvent } from "../../shared/apiTypes";

src/client/src/api/clients.test.ts

@@ -1,6 +1,7 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { PI_WEB_CAPABILITIES } from "../../../shared/capabilities";
 import type { TerminalCommandRun, Workspace } from "../../../shared/apiTypes";
-import { terminalsApi, workspacesApi } from "./clients";
+import { machinesApi, terminalsApi, workspacesApi } from "./clients";
 
 const workspace: Workspace = {
   id: "w/1",
@@ -29,6 +30,17 @@ afterEach(() => {
   vi.unstubAllGlobals();
 });
 
+describe("machine-scoped runtime API", () => {
+  it("reads machine runtime through the gateway route", async () => {
+    const fetchMock = stubJsonFetch({ machineId: "remote a", ok: true, checkedAt: "now", capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived] });
+
+    await machinesApi.runtime("remote a");
+
+    expect(fetchMock).toHaveBeenCalledOnce();
+    expect(fetchCall(fetchMock, 0)[0]).toBe("/api/machines/remote%20a/runtime");
+  });
+});
+
 describe("machine-scoped terminal command-run API", () => {
   it("deletes workspaces through the selected machine scope", async () => {
     const fetchMock = stubJsonFetch(commandRun);

src/client/src/api/clients.ts

@@ -17,12 +17,14 @@ import {
   parseGitStatusResponse,
   parseMachine,
   parseMachineHealth,
+  parseMachineRuntime,
   parseMachinesResponse,
   parseMessagePage,
   parseModelSelectionResponse,
   parseOAuthFlowState,
   parsePiWebConfigResponse,
   parsePiWebPluginsResponse,
+  parsePiWebRuntimeResponse,
   parsePiWebStatusResponse,
   parseProject,
   parseRestored,
@@ -42,6 +44,7 @@ const machinePrefix = (machineId = "local") => `/api/machines/${encodeURICompone
 
 export const piWebApi = {
   piWebStatus: () => request("/api/pi-web/status", parsePiWebStatusResponse),
+  piWebRuntime: () => request("/api/pi-web/runtime", parsePiWebRuntimeResponse),
 };
 
 export const machinesApi = {
@@ -49,6 +52,7 @@ export const machinesApi = {
   addMachine: (input: { name: string; baseUrl: string; token?: string }) => request("/api/machines", parseMachine, { method: "POST", body: JSON.stringify(input) }),
   deleteMachine: (machineId: string) => request(`/api/machines/${encodeURIComponent(machineId)}`, (value) => value, { method: "DELETE" }),
   health: (machineId: string) => request(`/api/machines/${encodeURIComponent(machineId)}/health`, parseMachineHealth),
+  runtime: (machineId: string) => request(`/api/machines/${encodeURIComponent(machineId)}/runtime`, parseMachineRuntime),
 };
 
 export const configApi = {

src/client/src/api/parsers.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
-import { parseCommandResult, parseFileContentResponse, parseFileSuggestion, parseGitStatusResponse, parseMessagePage, parsePiWebConfigResponse, parsePiWebPluginsResponse, parseSessionStatus, parseSlashCommand, parseTerminalCommandRun, parseTerminalInfo, parseWorkspaceActivityResponse } from "./parsers";
+import { PI_WEB_CAPABILITIES } from "../../../shared/capabilities";
+import { parseCommandResult, parseFileContentResponse, parseFileSuggestion, parseGitStatusResponse, parseMessagePage, parsePiWebConfigResponse, parsePiWebPluginsResponse, parsePiWebRuntimeResponse, parseSessionStatus, parseSlashCommand, parseTerminalCommandRun, parseTerminalInfo, parseWorkspaceActivityResponse } from "./parsers";
 
 describe("API parsers", () => {
   it("parses PI WEB config responses", () => {
@@ -18,6 +19,18 @@ describe("API parsers", () => {
     });
   });
 
+  it("parses PI WEB runtime responses", () => {
+    expect(parsePiWebRuntimeResponse({
+      packageName: "@jmfederico/pi-web",
+      generatedAt: "now",
+      components: {
+        web: { component: "web", label: "Web/UI", runtimeVersion: "1.0.0", available: true, capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived] },
+        sessiond: { component: "sessiond", label: "Session daemon", runtimeVersion: "1.0.0", available: true, capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived] },
+      },
+      capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived],
+    })).toMatchObject({ capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived] });
+  });
+
   it("parses PI WEB plugin status responses", () => {
     expect(parsePiWebPluginsResponse({
       plugins: [{ id: "info", module: "/pi-web-plugins/info/pi-web-plugin.js?v=1", source: "bundled", scope: "bundled", enabled: false }],

src/client/src/api/parsers.ts

@@ -1,4 +1,5 @@
-import type { ArchiveSessionsResponse, AuthProviderOption, AuthProviderStatus, AuthProvidersResponse, AuthStatusSource, AuthType, CommandOption, CommandResult, FileContentResponse, FileSuggestion, FileTreeEntry, FileTreeResponse, GitDiffResponse, GitFileState, GitStatusFile, GitStatusResponse, Machine, MachineHealth, MachineKind, MachineStatus, MessagePage, ModelSelectionResponse, OAuthFlowState, PiWebComponentStatus, PiWebConfigEnvOverrides, PiWebConfigResponse, PiWebConfigValues, PiWebInstallationInfo, PiWebPluginConfigMap, PiWebPluginInfo, PiWebPluginsResponse, PiWebPluginScope, PiWebReleaseStatus, PiWebServiceComponent, PiWebShortcutConfig, PiWebStatusMessage, PiWebStatusResponse, PiWebStatusSeverity, Project, QueuedSessionMessage, SessionInfo, SessionModel, SessionStatus, SlashCommand, TerminalCommandRun, TerminalCommandRunStatus, TerminalInfo, ThinkingLevel, ThinkingLevelsResponse, Workspace, WorkspaceActivity, WorkspaceActivityResponse } from "../../../shared/apiTypes";
+import type { ArchiveSessionsResponse, AuthProviderOption, AuthProviderStatus, AuthProvidersResponse, AuthStatusSource, AuthType, CommandOption, CommandResult, FileContentResponse, FileSuggestion, FileTreeEntry, FileTreeResponse, GitDiffResponse, GitFileState, GitStatusFile, GitStatusResponse, Machine, MachineHealth, MachineKind, MachineRuntime, MachineStatus, MessagePage, ModelSelectionResponse, OAuthFlowState, PiWebCapability, PiWebComponentStatus, PiWebConfigEnvOverrides, PiWebConfigResponse, PiWebConfigValues, PiWebInstallationInfo, PiWebPluginConfigMap, PiWebPluginInfo, PiWebPluginsResponse, PiWebPluginScope, PiWebReleaseStatus, PiWebRuntimeComponent, PiWebRuntimeResponse, PiWebServiceComponent, PiWebShortcutConfig, PiWebStatusMessage, PiWebStatusResponse, PiWebStatusSeverity, Project, QueuedSessionMessage, SessionInfo, SessionModel, SessionStatus, SlashCommand, TerminalCommandRun, TerminalCommandRunStatus, TerminalInfo, ThinkingLevel, ThinkingLevelsResponse, Workspace, WorkspaceActivity, WorkspaceActivityResponse } from "../../../shared/apiTypes";
+import { isPiWebCapability } from "../../../shared/capabilities";
 
 function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === "object" && value !== null;
@@ -95,6 +96,21 @@ export function parseMachineHealth(value: unknown): MachineHealth {
   };
 }
 
+export function parseMachineRuntime(value: unknown): MachineRuntime {
+  const record = requireRecord(value);
+  const error = optionalString(record, "error");
+  return {
+    machineId: requireString(record, "machineId"),
+    ok: requireBoolean(record, "ok"),
+    checkedAt: requireString(record, "checkedAt"),
+    ...optionalField("packageName", optionalString(record, "packageName")),
+    ...optionalField("generatedAt", optionalString(record, "generatedAt")),
+    ...(record["components"] === undefined ? {} : { components: parsePiWebRuntimeComponents(record["components"]) }),
+    ...(record["capabilities"] === undefined ? {} : { capabilities: parsePiWebCapabilities(record["capabilities"]) }),
+    ...(error === undefined ? {} : { error }),
+  };
+}
+
 function requireMachineKind(record: Record<string, unknown>, key: string): MachineKind {
   const value = requireString(record, key);
   if (value !== "local" && value !== "remote") throw new Error(`Expected machine kind field: ${key}`);
@@ -497,11 +513,38 @@ export function parsePiWebStatusResponse(value: unknown): PiWebStatusResponse {
   };
 }
 
+export function parsePiWebRuntimeResponse(value: unknown): PiWebRuntimeResponse {
+  const record = requireRecord(value);
+  return {
+    packageName: requireString(record, "packageName"),
+    generatedAt: requireString(record, "generatedAt"),
+    components: parsePiWebRuntimeComponents(record["components"]),
+    capabilities: parsePiWebCapabilities(record["capabilities"]),
+  };
+}
+
 function parsePiWebComponents(value: unknown): PiWebStatusResponse["components"] {
   const record = requireRecord(value);
   return { web: parsePiWebComponentStatus(record["web"]), sessiond: parsePiWebComponentStatus(record["sessiond"]) };
 }
 
+function parsePiWebRuntimeComponents(value: unknown): PiWebRuntimeResponse["components"] {
+  const record = requireRecord(value);
+  return { web: parsePiWebRuntimeComponent(record["web"]), sessiond: parsePiWebRuntimeComponent(record["sessiond"]) };
+}
+
+function parsePiWebRuntimeComponent(value: unknown): PiWebRuntimeComponent {
+  const record = requireRecord(value);
+  return {
+    component: parsePiWebServiceComponent(record["component"]),
+    label: requireString(record, "label"),
+    ...optionalField("runtimeVersion", optionalString(record, "runtimeVersion")),
+    available: requireBoolean(record, "available"),
+    capabilities: parsePiWebCapabilities(record["capabilities"]),
+    ...optionalField("error", optionalString(record, "error")),
+  };
+}
+
 function parsePiWebComponentStatus(value: unknown): PiWebComponentStatus {
   const record = requireRecord(value);
   return {
@@ -571,6 +614,11 @@ function parsePiWebServiceComponent(value: unknown): PiWebServiceComponent {
   return value;
 }
 
+function parsePiWebCapabilities(value: unknown): PiWebCapability[] {
+  if (!Array.isArray(value) || !value.every(isPiWebCapability)) throw new Error("Invalid PI WEB capabilities");
+  return value;
+}
+
 function parsePiWebStatusSeverity(value: unknown): PiWebStatusSeverity {
   if (value !== "info" && value !== "warning" && value !== "error") throw new Error("Invalid PI WEB status severity");
   return value;

src/client/src/appState.ts

@@ -1,4 +1,4 @@
-import type { AuthProviderOption, CommandOption, CommandResult, FileContentResponse, FileTreeEntry, GitDiffResponse, GitStatusResponse, Machine, MachineHealth, OAuthFlowState, PiWebStatusResponse, Project, SessionActivity, SessionInfo, SessionStatus, TerminalCommandRun, Workspace, WorkspaceActivity } from "./api";
+import type { AuthProviderOption, CommandOption, CommandResult, FileContentResponse, FileTreeEntry, GitDiffResponse, GitStatusResponse, Machine, MachineHealth, MachineRuntime, OAuthFlowState, PiWebStatusResponse, Project, SessionActivity, SessionInfo, SessionStatus, TerminalCommandRun, Workspace, WorkspaceActivity } from "./api";
 import type { ChatLine } from "./components/shared";
 import type { QualifiedContributionId } from "./plugins/ids";
 
@@ -7,6 +7,7 @@ export interface AppState {
   selectedMachine: Machine | undefined;
   isLoadingMachines: boolean;
   machineStatuses: Record<string, MachineHealth>;
+  machineRuntimes: Record<string, MachineRuntime>;
   projects: Project[];
   workspaces: Workspace[];
   sessions: SessionInfo[];
@@ -102,6 +103,7 @@ export function initialAppState(): AppState {
     selectedMachine: undefined,
     isLoadingMachines: false,
     machineStatuses: {},
+    machineRuntimes: {},
     projects: [],
     workspaces: [],
     sessions: [],

src/client/src/components/PiWebApp.ts

@@ -4,6 +4,7 @@ import { configApi, piWebApi, terminalsApi, workspacesApi, type Machine, type Ma
 import type { AppAction } from "../actions";
 import { initialAppState, type AppState } from "../appState";
 import { isSessionActive } from "../../../shared/activity";
+import { PI_WEB_CAPABILITIES, supportsPiWebCapability } from "../../../shared/capabilities";
 import { ActivityController } from "../controllers/activityController";
 import { AuthController } from "../controllers/authController";
 import { FileExplorerController } from "../controllers/fileExplorerController";
@@ -847,6 +848,22 @@ export class PiWebApp extends LitElement {
     this.panelResize.resetPanels();
   }
 
+  private canDeleteArchivedSessions(): boolean {
+    const runtime = this.selectedMachineRuntime();
+    return runtime?.ok === true && supportsPiWebCapability(runtime, PI_WEB_CAPABILITIES.sessionsDeleteArchived);
+  }
+
+  private archivedDeleteUnavailableMessage(): string {
+    const machineName = this.state.selectedMachine?.name ?? "this machine";
+    const runtime = this.selectedMachineRuntime();
+    if (runtime?.ok === false && runtime.error !== undefined) return `Update and restart Pi-Web on ${machineName} to delete archived sessions. Runtime check failed: ${runtime.error}`;
+    return `Update and restart Pi-Web on ${machineName} to delete archived sessions.`;
+  }
+
+  private selectedMachineRuntime() {
+    return this.state.machineRuntimes[selectedMachineId(this.state)];
+  }
+
   private renderNavigationPanel() {
     return html`
       <app-navigation-panel
@@ -870,6 +887,8 @@ export class PiWebApp extends LitElement {
         .sessionActivities=${this.state.sessionActivities}
         .selectedSession=${this.state.selectedSession}
         .canStartSession=${!!this.state.selectedWorkspace}
+        .canDeleteArchivedSessions=${this.canDeleteArchivedSessions()}
+        .archivedDeleteUnavailableMessage=${this.archivedDeleteUnavailableMessage()}
         .collapsible=${true}
         .compact=${this.appShell.isMobileNavigationLayout}
         .projectsCollapsed=${this.navigationSections.isCollapsed("projects")}
@@ -1206,7 +1225,9 @@ export class PiWebApp extends LitElement {
       focusPrompt: () => { void this.focusChatComposer(); },
       addProject: () => { this.setState({ projectDialogOpen: true }); },
       addMachine: () => { this.openMachineDialog(); },
-      refreshSelectedMachine: () => this.machines.refreshMachineHealth(),
+      refreshSelectedMachine: async () => {
+        await Promise.all([this.machines.refreshMachineHealth(), this.machines.refreshMachineRuntime()]);
+      },
       removeSelectedMachine: () => this.removeMachine(),
       openSelectedMachine: () => { this.openSelectedMachine(); },
       configureAuth: () => this.auth.openLogin(),

src/client/src/components/SessionList.ts

@@ -29,6 +29,8 @@ export class SessionList extends LitElement implements KeyboardNavigableSection
   @property({ attribute: false }) activities: Record<string, SessionActivity> = {};
   @property({ attribute: false }) selected?: SessionInfo;
   @property({ type: Boolean }) canStart = false;
+  @property({ type: Boolean }) canDeleteArchived = false;
+  @property({ type: String }) archivedDeleteUnavailableMessage = "Update and restart Pi-Web on this machine to delete archived sessions.";
   @property({ type: Boolean, reflect: true }) collapsible = false;
   @property({ type: Boolean, reflect: true }) collapsed = false;
   @property({ attribute: false }) onSelect?: (session: SessionInfo) => void;
@@ -180,7 +182,7 @@ export class SessionList extends LitElement implements KeyboardNavigableSection
       <div class="bulk-row selecting">
         <button ?disabled=${visibleSessions.length === 0} @click=${() => { this.toggleVisibleSelection(visibleSessions, !allVisibleSelected); }}>${allVisibleSelected ? "Clear visible" : "Select visible"}</button>
         <small>${selectedSessions.length} selected${visibleSelectedCount !== selectedSessions.length ? html` · ${visibleSelectedCount} visible` : null}</small>
-        <button class="danger" ?disabled=${selectedSessions.length === 0} @click=${() => { this.confirmDeleteSelectedArchived(); }}>Delete selected</button>
+        <button class="danger" title=${this.canDeleteArchived ? "Permanently delete selected archived sessions" : this.archivedDeleteUnavailableMessage} ?disabled=${selectedSessions.length === 0 || !this.canDeleteArchived} @click=${() => { this.confirmDeleteSelectedArchived(); }}>Delete selected</button>
         <button @click=${() => { this.clearSelection("archived"); }}>Clear</button>
         <button @click=${() => { this.closeSelection("archived"); }}>Done</button>
       </div>
@@ -215,7 +217,7 @@ export class SessionList extends LitElement implements KeyboardNavigableSection
                 : session.archived === true
                   ? html`
                     <button title="Restore session" @click=${() => { this.openMenuSessionId = undefined; this.onRestore?.(session); }}>Restore</button>
-                    <button class="danger" title="Permanently delete archived session" @click=${() => { this.openMenuSessionId = undefined; this.confirmDeleteArchived(session); }}>Delete archived session</button>
+                    <button class="danger" title=${this.canDeleteArchived ? "Permanently delete archived session" : this.archivedDeleteUnavailableMessage} ?disabled=${!this.canDeleteArchived} @click=${() => { this.openMenuSessionId = undefined; this.confirmDeleteArchived(session); }}>Delete archived session</button>
                   `
                   : html`
                     ${session.parentSessionPath !== undefined ? html`<button title="Detach from parent" @click=${() => { this.openMenuSessionId = undefined; this.onDetachParent?.(session); }}>Detach from parent</button>` : null}
@@ -252,10 +254,12 @@ export class SessionList extends LitElement implements KeyboardNavigableSection
   }
 
   private confirmDeleteArchived(session: SessionInfo): void {
+    if (!this.canDeleteArchived) return;
     if (confirm(`Permanently delete archived session “${sessionLabel(session)}”? This cannot be undone.`)) void this.onDeleteArchived?.(session);
   }
 
   private confirmDeleteSelectedArchived(): void {
+    if (!this.canDeleteArchived) return;
     const archived = this.selectedSessions("archived");
     if (archived.length === 0) return;
     const noun = archived.length === 1 ? "archived session" : "archived sessions";

src/client/src/components/appShell/AppNavigationPanel.ts

@@ -39,6 +39,8 @@ export class AppNavigationPanel extends LitElement {
   @property({ type: Boolean }) workspacesCollapsed = false;
   @property({ type: Boolean }) sessionsCollapsed = false;
   @property({ type: Boolean }) canStartSession = false;
+  @property({ type: Boolean }) canDeleteArchivedSessions = false;
+  @property({ type: String }) archivedDeleteUnavailableMessage = "Update and restart Pi-Web on this machine to delete archived sessions.";
   @property({ attribute: false }) onShowActions?: () => void;
   @property({ attribute: false }) onToggleMachines?: () => void;
   @property({ attribute: false }) onToggleProjects?: () => void;
@@ -151,6 +153,8 @@ export class AppNavigationPanel extends LitElement {
         .activities=${this.sessionActivities}
         .selected=${this.selectedSession}
         .canStart=${this.canStartSession}
+        .canDeleteArchived=${this.canDeleteArchivedSessions}
+        .archivedDeleteUnavailableMessage=${this.archivedDeleteUnavailableMessage}
         .collapsible=${this.collapsible}
         .collapsed=${this.sessionsCollapsed}
         .onToggleCollapsed=${() => { this.onToggleSessions?.(); }}

src/client/src/controllers/machineController.ts

@@ -12,8 +12,9 @@ export class MachineController {
       const machines = await api.machines();
       const selectedMachine = await this.selectInitialMachine(machines, routeMachineId);
       const machineIds = new Set(machines.map((machine) => machine.id));
-      this.setState({ machines, selectedMachine, machineActivities: filterKeys(this.getState().machineActivities, machineIds) });
+      this.setState({ machines, selectedMachine, machineActivities: filterKeys(this.getState().machineActivities, machineIds), machineRuntimes: filterKeys(this.getState().machineRuntimes, machineIds) });
       void this.refreshMachineHealthFor(machines);
+      void this.refreshMachineRuntimeFor(machines);
     } catch (error) {
       this.setState({ error: String(error) });
     } finally {
@@ -47,6 +48,7 @@ export class MachineController {
     if (options.updateUrl !== false) this.updateUrl();
     await this.projects.loadProjects();
     void this.refreshMachineHealth(machine.id);
+    void this.refreshMachineRuntime(machine.id);
   }
 
   async addMachine(input: { name: string; baseUrl: string; token?: string }): Promise<Machine | undefined> {
@@ -73,7 +75,7 @@ export class MachineController {
       await api.deleteMachine(machine.id);
       const machines = this.getState().machines.filter((candidate) => candidate.id !== machine.id);
       const local = machines.find((candidate) => candidate.id === "local") ?? machines[0];
-      this.setState({ machines, machineStatuses: omitKey(this.getState().machineStatuses, machine.id), machineActivities: omitKey(this.getState().machineActivities, machine.id) });
+      this.setState({ machines, machineStatuses: omitKey(this.getState().machineStatuses, machine.id), machineRuntimes: omitKey(this.getState().machineRuntimes, machine.id), machineActivities: omitKey(this.getState().machineActivities, machine.id) });
       if (wasSelected && local !== undefined) {
         if (options.selectFallback === false) return local;
         await this.selectMachine(local);
@@ -95,6 +97,15 @@ export class MachineController {
     }
   }
 
+  async refreshMachineRuntime(machineId = this.getState().selectedMachine?.id ?? "local"): Promise<void> {
+    try {
+      const runtime = await api.runtime(machineId);
+      this.setState({ machineRuntimes: { ...this.getState().machineRuntimes, [runtime.machineId]: runtime } });
+    } catch (error) {
+      this.setState({ error: String(error) });
+    }
+  }
+
   private async selectInitialMachine(machines: Machine[], routeMachineId?: string): Promise<Machine | undefined> {
     const requestedMachine = machines.find((machine) => machine.id === (routeMachineId ?? "local"));
     if (requestedMachine?.kind !== "remote") return requestedMachine ?? this.localMachine(machines);
@@ -133,6 +144,12 @@ export class MachineController {
     const health = Object.fromEntries(results.flatMap((result) => result.status === "fulfilled" ? [[result.value.machineId, result.value] as const] : []));
     if (Object.keys(health).length > 0) this.setState({ machineStatuses: { ...this.getState().machineStatuses, ...health } });
   }
+
+  private async refreshMachineRuntimeFor(machines: Machine[]): Promise<void> {
+    const results = await Promise.allSettled(machines.map((machine) => api.runtime(machine.id)));
+    const runtimes = Object.fromEntries(results.flatMap((result) => result.status === "fulfilled" ? [[result.value.machineId, result.value] as const] : []));
+    if (Object.keys(runtimes).length > 0) this.setState({ machineRuntimes: { ...this.getState().machineRuntimes, ...runtimes } });
+  }
 }
 
 function omitKey<T>(record: Record<string, T>, keyToOmit: string): Record<string, T> {

src/client/src/controllers/sessionController.test.ts

@@ -3,6 +3,7 @@ import { api as defaultApi, type MessagePage, type SessionActivity, type Session
 import { isCachedNewSessionInfo, loadCachedNewSessions, markCachedNewSessionInfo, rememberCachedNewSession } from "../cachedNewSessions";
 import { initialAppState, type AppState } from "../appState";
 import { machineSessionKey } from "../machineKeys";
+import { PI_WEB_CAPABILITIES } from "../../../shared/capabilities";
 import { loadDraft, saveDraft } from "../promptDraftStorage";
 import { SessionController, type SessionEventSocket } from "./sessionController";
 import { InMemorySessionSelectionMemory } from "./sessionSelection";
@@ -325,7 +326,13 @@ describe("SessionController", () => {
     const archivedSession = { ...oldSession, archived: true, archivedAt: "later" };
     const nextSession = { ...oldSession, id: "next-session", path: "/tmp/next-session.jsonl" };
     const deletedIds: string[] = [];
-    let state: AppState = { ...initialAppState(), selectedWorkspace: workspace, selectedSession: archivedSession, sessions: [archivedSession, nextSession] };
+    let state: AppState = {
+      ...initialAppState(),
+      selectedWorkspace: workspace,
+      selectedSession: archivedSession,
+      sessions: [archivedSession, nextSession],
+      machineRuntimes: { local: { machineId: "local", ok: true, checkedAt: "now", capabilities: [PI_WEB_CAPABILITIES.sessionsDeleteArchived] } },
+    };
     const api: typeof defaultApi = {
       ...defaultApi,
       deleteArchived: (sessionId) => {
@@ -350,6 +357,32 @@ describe("SessionController", () => {
     expect(state.selectedSession?.id).toBe(nextSession.id);
   });
 
+  it("does not delete archived sessions when the selected machine runtime does not support it", async () => {
+    const archivedSession = { ...oldSession, archived: true, archivedAt: "later" };
+    const deletedIds: string[] = [];
+    let state: AppState = { ...initialAppState(), selectedWorkspace: workspace, sessions: [archivedSession] };
+    const api: typeof defaultApi = {
+      ...defaultApi,
+      deleteArchived: (sessionId) => {
+        deletedIds.push(sessionId);
+        return Promise.resolve({ deleted: true });
+      },
+    };
+    const controller = new SessionController(
+      () => state,
+      (patch) => { state = { ...state, ...patch }; },
+      () => undefined,
+      new InMemorySessionSelectionMemory(),
+      { api, socket: new FakeSocket() },
+    );
+
+    await controller.deleteArchivedSessions([archivedSession]);
+
+    expect(deletedIds).toEqual([]);
+    expect(state.sessions).toEqual([archivedSession]);
+    expect(state.error).toContain("requires an updated Pi-Web runtime");
+  });
+
   it("forgets archived selections when the archived section collapse clears selection", async () => {
     const archivedSession = { ...oldSession, archived: true, archivedAt: "later" };
     let state: AppState = { ...initialAppState(), selectedWorkspace: workspace, sessions: [archivedSession] };

src/client/src/controllers/sessionController.ts

@@ -8,6 +8,7 @@ import { ChatTranscriptStore } from "../chatTranscriptStore";
 import { isShellInput } from "../inputModes";
 import { SessionSocket, type GlobalSessionEvent, type SessionUiEvent } from "../sessionSocket";
 import { isSessionActive } from "../../../shared/activity";
+import { PI_WEB_CAPABILITIES, supportsPiWebCapability } from "../../../shared/capabilities";
 import { InMemorySessionSelectionMemory, markSessionArchived, markSessionsArchived, selectPreferredSession, selectionAfterArchivingSession, selectionAfterArchivingSessions, shouldDeselectAfterArchivedCollapse, type SessionSelectionMemory } from "./sessionSelection";
 import { selectedMachineId, type GetState, type SetState, type UpdateUrl } from "./types";
 
@@ -288,6 +289,11 @@ export class SessionController {
     if (candidates.length === 0) return;
 
     const machineId = selectedMachineId(this.getState());
+    const runtime = this.getState().machineRuntimes[machineId];
+    if (runtime?.ok !== true || !supportsPiWebCapability(runtime, PI_WEB_CAPABILITIES.sessionsDeleteArchived)) {
+      this.setState({ error: "Deleting archived sessions requires an updated Pi-Web runtime on this machine." });
+      return;
+    }
     const results = await Promise.allSettled(candidates.map(async (session) => {
       await this.api.deleteArchived(session.id, machineId);
       return session.id;