feat: session goals - server-driven goal loop with independent small-model audit (#2148)

Arm the target button in the composer and the next prompt becomes a goal:
the server keeps the session working toward it (idle tick -> small-model
audit -> continuation) until the objective is verifiably complete, blocked,
or out of budget — even with the UI closed.

Server (packages/web/server/lib/session-goal):
- event-driven loop on the global SSE hub; goal state lives in
  session.metadata.openchamber.goal (merge-safe patches, stale-write guard
  by goal id), so it survives restarts and syncs to every client for free
- the small-model audit (objective + last assistant turn only, language
  pinned to the objective) is the sole termination authority; blocked needs
  3 consecutive verdicts, audit outages tolerate one unaudited continuation
  then stop the goal as resumable-blocked
- hard stops: optional token budget, auto-continuation cap (Resume grants a
  fresh allowance), turn errors; user abort pauses the goal instead of
  blocking it, and resuming over an aborted tail nudges immediately
- token accounting as a snapshot of the latest turn (input + cache.read +
  output), goal-relative via a creation baseline and segmented across
  compactions; a compaction summary skips the audit and continues
- continuations reuse the session's own provider/model/agent/variant

UI:
- three-mode target button (arm / disarm / manage dialog), informational
  goal strip with inline pause/resume and an Evaluating indicator, sidebar
  state glyph, objective length counter (2000-char server clamp),
  read-only completed goals
- goal entry points: composer (sessions and drafts), start-new-session-
  from-answer dialog, plan implement dialog (plan content becomes the
  objective), scheduled tasks (Run as goal + budget)
- Settings -> Chat -> Goal: feature toggle + default token budget with
  three-layer parity (web server, client persistence, VS Code bridge);
  VS Code renders goal state but hides the entry points (the loop runs in
  the web server only)

Notifications: per-turn "ready" notifications are suppressed while a goal
is active; settling sends one final notification (desktop, web-push, APNs
generic titles with the session name as body) honoring the completion
toggle. Error/question/permission notifications are untouched.

Docs: user guide (session-goals) in all 9 locales + sidebar entry,
scheduled-tasks cross-reference, server module DOCUMENTATION.md.

packages/ui/src/components/session/TodoSendDialog.tsx

@@ -6,6 +6,8 @@ import {
   DialogHeader,
   DialogTitle,
 } from '@/components/ui/dialog';
+import { Checkbox } from '@/components/ui/checkbox';
+import { isVSCodeRuntime } from '@/lib/desktop';
 import { ModelSelector } from '@/components/sections/agents/ModelSelector';
 import { AgentSelector } from '@/components/sections/commands/AgentSelector';
 import { ThinkingPill } from '@/components/session/ThinkingPill';
@@ -21,6 +23,7 @@ export type TodoSendExecution = {
   modelID: string;
   variant: string;
   agent: string;
+  runAsGoal?: boolean;
 };
 
 type TodoSendDialogProps = {
@@ -29,6 +32,8 @@ type TodoSendDialogProps = {
   target: TodoSendTarget;
   projectDirectory: string | null;
   submitting?: boolean;
+  /** Offer a "Run as goal" checkbox (hidden in VS Code, where the loop does not run). */
+  allowRunAsGoal?: boolean;
   onConfirm: (execution: TodoSendExecution) => Promise<void> | void;
 };
 
@@ -46,7 +51,8 @@ const getInitialExecution = (params: {
 
 export function TodoSendDialog(props: TodoSendDialogProps) {
   const { t } = useI18n();
-  const { open, onOpenChange, target, projectDirectory, submitting = false, onConfirm } = props;
+  const { open, onOpenChange, target, projectDirectory, submitting = false, allowRunAsGoal = false, onConfirm } = props;
+  const showRunAsGoal = allowRunAsGoal && !isVSCodeRuntime();
 
   const loadProviders = useConfigStore((state) => state.loadProviders);
   const loadConfigAgents = useConfigStore((state) => state.loadAgents);
@@ -177,7 +183,26 @@ export function TodoSendDialog(props: TodoSendDialogProps) {
           </div>
         </div>
 
-        <div className="flex items-center justify-end gap-2">
+        <div className={`flex items-center gap-3 ${showRunAsGoal ? 'justify-between' : 'justify-end'}`}>
+          {showRunAsGoal ? (
+            <div className="flex min-w-0 items-center gap-2">
+              <Checkbox
+                checked={execution.runAsGoal === true}
+                onChange={(runAsGoal: boolean) => setExecution((prev) => ({ ...prev, runAsGoal }))}
+                disabled={submitting}
+                ariaLabel={t('sessions.scheduledTasks.editor.goal.aria')}
+              />
+              <button
+                type="button"
+                className="truncate typography-ui-label text-muted-foreground transition-colors hover:text-foreground disabled:cursor-not-allowed disabled:opacity-50"
+                disabled={submitting}
+                onClick={() => setExecution((prev) => ({ ...prev, runAsGoal: prev.runAsGoal !== true }))}
+              >
+                {t('sessions.scheduledTasks.editor.goal.label')}
+              </button>
+            </div>
+          ) : null}
+          <div className="flex items-center justify-end gap-2">
           <Button variant="ghost" size="sm" onClick={() => onOpenChange(false)} disabled={submitting}>
             {t('rightSidebar.contextNotesTodo.sendDialog.actions.cancel')}
           </Button>
@@ -186,6 +211,7 @@ export function TodoSendDialog(props: TodoSendDialogProps) {
               ? t('rightSidebar.contextNotesTodo.sendDialog.actions.sending')
               : t('rightSidebar.contextNotesTodo.sendDialog.actions.send')}
           </Button>
+          </div>
         </div>
       </DialogContent>
     </Dialog>