[feat] dreamverse: main-UI steering mode switch + first-segment-only seeding

Add a user-facing Auto rollout / Steering segmented control to the main composer (not just
devtools), wired to manualContinuationMode and authoritative at session start. In steering
mode a preset seeds only its first segment and auto/loop are forced off, so the backend waits
for the user to describe each subsequent scene by hand.

apps/dreamverse/web/src/app/page.tsx

@@ -237,6 +237,7 @@ export default function Page() {
 		enhancementEnabled,
 		promptExtensionError,
 		autoExtensionEnabled,
+		manualContinuationMode,
 		autoExtensionTimeoutHint,
 		loopGenerationEnabled,
 		generationPaused,
@@ -1555,6 +1556,14 @@ export default function Page() {
 		);
 	}
 
+	// Steering (manual continuation) vs the automatic 6-segment rollout — a pre-session
+	// preference honored when the session starts.
+	function handleManualContinuationToggle(event: any) {
+		sessionStore.patch({
+			manualContinuationMode: Boolean(event.currentTarget.checked),
+		});
+	}
+
 	function handleLoopGenerationToggle(event: any) {
 		sessionStore.patch({
 			loopGenerationEnabled: Boolean(event.currentTarget.checked),
@@ -1769,7 +1778,14 @@ export default function Page() {
 	}
 
 	function buildProjectInitPayload(type: "session_init_v2" | "project_init_v1") {
-		const segmentPrompts = getSessionInitPrompts();
+		const manualMode = Boolean(sessionStore.get().manualContinuationMode);
+		let segmentPrompts = getSessionInitPrompts();
+		// Steering mode: a preset/rollout only seeds the FIRST segment; the user
+		// drives every subsequent segment by hand. Force auto/loop off so the
+		// backend waits for the user's next prompt instead of auto-continuing.
+		if (manualMode) {
+			segmentPrompts = segmentPrompts.slice(0, 1);
+		}
 		setSeedPrompts(segmentPrompts);
 		return {
 			type,
@@ -1780,9 +1796,9 @@ export default function Page() {
 			initial_image: null,
 			single_clip_mode: false,
 			enhancement_enabled: sessionStore.get().enhancementEnabled,
-			auto_extension_enabled: sessionStore.get().autoExtensionEnabled,
-			loop_generation_enabled: sessionStore.get().loopGenerationEnabled,
-			manual_continuation_mode: sessionStore.get().manualContinuationMode,
+			auto_extension_enabled: manualMode ? false : sessionStore.get().autoExtensionEnabled,
+			loop_generation_enabled: manualMode ? false : sessionStore.get().loopGenerationEnabled,
+			manual_continuation_mode: manualMode,
 		};
 	}
 
@@ -1962,7 +1978,9 @@ export default function Page() {
 		const initialPrompt = normalizeInitialPrompt(sessionStore.get().livePromptDraft as string);
 		pendingInitialPromptRef.current = initialPrompt;
 		const rCAR = !uiStore.get().devtoolsMode && !uiStore.get().demoMode;
-		const nextManualContinuationMode = Boolean(initialPrompt) && getSessionInitPrompts().length === 0;
+		// The "Steering mode" toggle is authoritative: checked = manual per-segment steering,
+		// unchecked = automatic 6-segment rollout (default).
+		const nextManualContinuationMode = Boolean(sessionStore.get().manualContinuationMode);
 		sessionStore.patch({
 			sessionNotice: "",
 			sessionExpired: false,
@@ -2513,6 +2531,7 @@ export default function Page() {
 				selectedPresetId={selectedPresetId as string}
 				enhancementEnabled={enhancementEnabled as boolean}
 				autoExtensionEnabled={autoExtensionEnabled as boolean}
+				manualContinuationEnabled={manualContinuationMode as boolean}
 				loopGenerationEnabled={loopGenerationEnabled as boolean}
 				canJoinSession={canJoinSession as boolean}
 				canSubmitContinuation={canSubmitContinuation}
@@ -2525,6 +2544,7 @@ export default function Page() {
 				onEnhancementToggle={handleEnhancementToggle}
 				onCuratedPromptLimitChange={handleCuratedPromptLimitChange}
 				onAutoExtensionToggle={handleAutoExtensionToggle}
+				onManualContinuationToggle={handleManualContinuationToggle}
 				onLoopToggle={handleLoopGenerationToggle}
 				onJoin={joinSession}
 				onLeave={leaveSession}
@@ -2794,6 +2814,8 @@ export default function Page() {
 							isGenerating={loadingAnimation as boolean}
 							storyPresets={storyPresets as any[]}
 							continuationDraft={livePromptDraft as string}
+							manualContinuationEnabled={manualContinuationMode as boolean}
+							onModeChange={(manual) => sessionStore.patch({ manualContinuationMode: manual })}
 							canJoinSession={canStartSession}
 							canSubmitContinuation={canSubmitContinuation}
 							sessionExpired={sessionExpired as boolean}

apps/dreamverse/web/src/components/ChatBar.tsx

@@ -23,6 +23,8 @@ interface Props {
 	projectResetPending?: boolean;
 	viewingReadOnly?: boolean;
 	waitingForSegmentPrompt?: boolean;
+	manualContinuationEnabled?: boolean;
+	onModeChange?: (manual: boolean) => void;
 	onPresetGenerate?: (presetId: string) => void;
 	onContinuationInput?: (e: React.ChangeEvent<HTMLTextAreaElement>) => void;
 	onContinuationKeydown?: (e: React.KeyboardEvent<HTMLTextAreaElement>) => void;
@@ -48,6 +50,8 @@ export default function ChatBar({
 	projectResetPending = false,
 	viewingReadOnly = false,
 	waitingForSegmentPrompt = false,
+	manualContinuationEnabled = false,
+	onModeChange = () => {},
 	onPresetGenerate = () => {},
 	onContinuationInput = () => {},
 	onContinuationKeydown = () => {},
@@ -356,6 +360,44 @@ export default function ChatBar({
 				</div>
 			)}
 
+			{!sessionStarted && (
+				<div className="flex flex-col items-center gap-1.5">
+					<div className="inline-flex rounded-full border border-input bg-card/65 p-0.5 shadow-sm backdrop-blur-sm">
+						<button
+							type="button"
+							onClick={() => onModeChange(false)}
+							aria-pressed={!manualContinuationEnabled}
+							className={cn(
+								"rounded-full px-4 py-1 text-xs font-medium transition-colors",
+								!manualContinuationEnabled
+									? "bg-primary text-primary-foreground shadow-sm"
+									: "text-muted-foreground hover:text-foreground",
+							)}
+						>
+							Auto rollout
+						</button>
+						<button
+							type="button"
+							onClick={() => onModeChange(true)}
+							aria-pressed={manualContinuationEnabled}
+							className={cn(
+								"rounded-full px-4 py-1 text-xs font-medium transition-colors",
+								manualContinuationEnabled
+									? "bg-primary text-primary-foreground shadow-sm"
+									: "text-muted-foreground hover:text-foreground",
+							)}
+						>
+							Steering
+						</button>
+					</div>
+					<p className="text-[11px] text-muted-foreground">
+						{manualContinuationEnabled
+							? "Drive each scene yourself — type what happens next, one segment at a time."
+							: "Automatic 6-segment story rollout."}
+					</p>
+				</div>
+			)}
+
 			<div
 				className={cn(
 					"flex min-w-0 items-center gap-1.5 rounded-4xl border py-2.5 pl-5 pr-2.5 shadow-md backdrop-blur-sm transition-all duration-200",