course,tasklist,task and completed validation

Signed-off-by: rgrgogu <obsequio.rus@gmail.com>

src/components/generic/Blocks/Client/AudioBlock.jsx

@@ -2,6 +2,7 @@ import { useRef, useState, useEffect, useCallback } from "react";
 import { Music2, RotateCcw, RotateCw, Play, Pause, VolumeOff, Volume2 } from "lucide-react";
 import api from "@/utils/api.util";
 import { MediaFallback } from "@/components/generic/MediaFallback";
+import { useMediaWatchGuard } from "@/hooks/useMediaWatchGuard";
 
 // ─── Helpers ──────────────────────────────────────────────────────────────────
 
@@ -16,11 +17,6 @@ const SPEEDS = [0.5, 0.75, 1, 1.25, 1.5, 2];
 
 const API_BASE = (import.meta.env.VITE_API_URL ?? "http://localhost:3024").replace(/\/$/, "");
 
-// How often onWatchProgress may fire while playing (ms) — keeps the watch-progress
-// endpoint from getting hit on every timeupdate tick. onEnded still always reports
-// a final 100% immediately regardless of this window, so completion never lags.
-const WATCH_PROGRESS_THROTTLE_MS = 10000;
-
 // ─── AudioBlock (Client — secure) ────────────────────────────────────────────
 //
 // S3/Garage:
@@ -39,9 +35,10 @@ const WATCH_PROGRESS_THROTTLE_MS = 10000;
 
 // onWatchProgress(percent) — optional, called (throttled) as playback advances and
 // immediately at 100% on end. Backing the watch_percent completion requirement type.
-export function AudioBlock({ content, onWatchProgress }) {
+export function AudioBlock({ content, onWatchProgress, resumePercent, antiSkipEnabled }) {
     const audioRef = useRef(null);
-    const lastReportRef = useRef(0);
+    const guard     = useMediaWatchGuard({ onWatchProgress, antiSkipEnabled });
+    const resumedRef = useRef(false);
 
     // ── Stream state ──────────────────────────────────────────────────────────
     const [blobUrl,       setBlobUrl]       = useState(null);
@@ -76,6 +73,8 @@ export function AudioBlock({ content, onWatchProgress }) {
         setPlaying(false);
         setCurrentTime(0);
         setDuration(0);
+        guard.reset();
+        resumedRef.current = false;
 
         // Legacy direct URL — no asset_id
         if (!assetId && directUrl) {
@@ -127,17 +126,40 @@ export function AudioBlock({ content, onWatchProgress }) {
     const onTimeUpdate = useCallback(() => {
         const el = audioRef.current;
         setCurrentTime(el?.currentTime ?? 0);
-        if (onWatchProgress && el?.duration) {
+        guard.trackTimeUpdate(el?.currentTime ?? 0, el?.duration);
+        if (el?.duration) {
             const pct = (el.currentTime / el.duration) * 100;
-            const now = Date.now();
-            if (now - lastReportRef.current > WATCH_PROGRESS_THROTTLE_MS) {
-                lastReportRef.current = now;
-                onWatchProgress(pct);
-            }
+            guard.maybeReport(pct);
         }
-    }, [onWatchProgress]);
-    const onLoadedMeta = useCallback(() => setDuration(audioRef.current?.duration ?? 0), []);
+    }, [guard]);
+    const onLoadedMeta = useCallback(() => {
+        const el = audioRef.current;
+        const d  = el?.duration ?? 0;
+        setDuration(d);
+        guard.setDuration(d);
+        // Resume from the last position reached, once per asset. Left alone once
+        // fully watched (>=99%) — restarting reads better than resuming at the end.
+        if (el && !resumedRef.current && resumePercent > 0 && resumePercent < 99 && d) {
+            resumedRef.current = true;
+            const resumeSeconds = Math.min((resumePercent / 100) * d, d - 0.25);
+            el.currentTime = resumeSeconds;
+            setCurrentTime(resumeSeconds);
+            // Seeds the seek-cap so forward-seeking within already-watched territory
+            // works immediately, instead of clamping back to 0 until the next tick.
+            guard.trackTimeUpdate(resumeSeconds, d);
+        }
+    }, [guard, resumePercent]);
     const onEnded      = useCallback(() => { setPlaying(false); onWatchProgress?.(100); }, [onWatchProgress]);
+    const onPlay       = useCallback(() => {
+        const el = audioRef.current;
+        if (el?.duration) guard.reportPlayStart((el.currentTime / el.duration) * 100);
+    }, [guard]);
+    const onPause      = useCallback(() => {
+        const el = audioRef.current;
+        if (el?.duration) guard.flush((el.currentTime / el.duration) * 100);
+    }, [guard]);
+    const onSeeking    = useCallback(() => guard.markSeeking(), [guard]);
+    const onSeeked     = useCallback(() => guard.markSeeked(), [guard]);
     const onProgress   = useCallback(() => {
         const el = audioRef.current;
         if (el?.buffered.length && el.duration) {
@@ -158,13 +180,13 @@ export function AudioBlock({ content, onWatchProgress }) {
         const el  = audioRef.current;
         const bar = e.currentTarget;
         const pct = (e.clientX - bar.getBoundingClientRect().left) / bar.offsetWidth;
-        el.currentTime = pct * duration;
+        el.currentTime = guard.clampSeekTarget(pct * duration);
     };
 
     const skip = (secs) => {
         const el = audioRef.current;
         if (!el) return;
-        el.currentTime = Math.min(Math.max(0, el.currentTime + secs), duration);
+        el.currentTime = guard.clampSeekTarget(Math.min(Math.max(0, el.currentTime + secs), duration));
     };
 
     const handleVolume = (e) => {
@@ -215,6 +237,10 @@ export function AudioBlock({ content, onWatchProgress }) {
                 onTimeUpdate={onTimeUpdate}
                 onLoadedMetadata={onLoadedMeta}
                 onEnded={onEnded}
+                onPlay={onPlay}
+                onPause={onPause}
+                onSeeking={onSeeking}
+                onSeeked={onSeeked}
                 onProgress={onProgress}
                 preload="auto"
             />

src/components/generic/Blocks/Client/TextVideoBlock.jsx

@@ -1,17 +1,17 @@
 import { VideoBlock } from "./VideoBlock";
 
-export function TextVideoBlock({ content, onWatchProgress }) {
+export function TextVideoBlock({ content, onWatchProgress, resumePercent, antiSkipEnabled }) {
     const vidLeft = content.video_position === "left";
     return (
         <div className="flex flex-col gap-6 items-start sm:grid sm:grid-cols-2 sm:gap-6">
-            {vidLeft && <VideoBlock content={content} onWatchProgress={onWatchProgress} />}
+            {vidLeft && <VideoBlock content={content} onWatchProgress={onWatchProgress} resumePercent={resumePercent} antiSkipEnabled={antiSkipEnabled} />}
             <div
                 className="typeset text-sm w-full"
                 dangerouslySetInnerHTML={{
                     __html: content.body || "<p class='text-muted-foreground italic'>Empty text</p>",
                 }}
             />
-            {!vidLeft && <VideoBlock content={content} onWatchProgress={onWatchProgress} />}
+            {!vidLeft && <VideoBlock content={content} onWatchProgress={onWatchProgress} resumePercent={resumePercent} antiSkipEnabled={antiSkipEnabled} />}
         </div>
     );
 }

src/components/generic/Blocks/Client/VideoBlock.jsx

@@ -9,6 +9,7 @@ import {
 import { ChevronLeft, ChevronRight } from "lucide-react";
 import api from "@/utils/api.util";
 import { MediaFallback } from "@/components/generic/MediaFallback";
+import { useMediaWatchGuard } from "@/hooks/useMediaWatchGuard";
 
 // ─── Helpers ──────────────────────────────────────────────────────────────────
 
@@ -23,11 +24,6 @@ const PLAYBACK_SPEEDS = ["0.5", "0.75", "Normal", "1.25", "1.5", "2"];
 
 const API_BASE = (import.meta.env.VITE_API_URL ?? "http://localhost:3024").replace(/\/$/, "");
 
-// How often onWatchProgress may fire while playing (ms) — keeps the watch-progress
-// endpoint from getting hit on every timeupdate tick. onEnded still always reports
-// a final 100% immediately regardless of this window, so completion never lags.
-const WATCH_PROGRESS_THROTTLE_MS = 10000;
-
 // ─── Tooltip control button ───────────────────────────────────────────────────
 
 function CtrlBtn({ label, onClick, children, className = "" }) {
@@ -167,10 +163,11 @@ function SettingsPanel({ speed, onSpeed, onClose }) {
 // onWatchProgress(percent) — optional, called (throttled) as playback advances and
 // immediately at 100% on end. Backing the watch_percent completion requirement type;
 // harmless/unused when the lesson isn't configured for it (caller just won't pass it).
-export function VideoBlock({ content, onWatchProgress }) {
+export function VideoBlock({ content, onWatchProgress, resumePercent, antiSkipEnabled }) {
     const wrapRef = useRef(null);
     const vidRef  = useRef(null);
-    const lastReportRef = useRef(0);
+    const guard   = useMediaWatchGuard({ onWatchProgress, antiSkipEnabled });
+    const resumedRef = useRef(false);
 
     // ── Stream state ──────────────────────────────────────────────────────────
     const [blobUrl,      setBlobUrl]      = useState(null);
@@ -229,6 +226,8 @@ export function VideoBlock({ content, onWatchProgress }) {
         setOverlayVisible(true);
         setSettingsOpen(false);
         setEnded(false);
+        guard.reset();
+        resumedRef.current = false;
 
         let cancelled = false;
 
@@ -275,23 +274,41 @@ export function VideoBlock({ content, onWatchProgress }) {
 
         const onTimeUpdate = () => {
             setCurrentTime(v.currentTime);
+            guard.trackTimeUpdate(v.currentTime, v.duration);
             if (v.duration) {
                 const pct = (v.currentTime / v.duration) * 100;
                 setProgress(pct);
-                if (onWatchProgress) {
-                    const now = Date.now();
-                    if (now - lastReportRef.current > WATCH_PROGRESS_THROTTLE_MS) {
-                        lastReportRef.current = now;
-                        onWatchProgress(pct);
-                    }
-                }
+                guard.maybeReport(pct);
+            }
+        };
+        const onLoaded   = () => {
+            setTotalDuration(v.duration);
+            guard.setDuration(v.duration);
+            // Resume from the last position reached, once per asset. Left alone once
+            // fully watched (>=99%) — restarting reads better than resuming at the end.
+            if (!resumedRef.current && resumePercent > 0 && resumePercent < 99 && v.duration) {
+                resumedRef.current = true;
+                const resumeSeconds = Math.min((resumePercent / 100) * v.duration, v.duration - 0.25);
+                v.currentTime = resumeSeconds;
+                setCurrentTime(resumeSeconds);
+                setProgress(resumePercent);
+                // Seeds the seek-cap so forward-seeking within already-watched territory
+                // works immediately, instead of clamping back to 0 until the next tick.
+                guard.trackTimeUpdate(resumeSeconds, v.duration);
             }
         };
-        const onLoaded   = () => setTotalDuration(v.duration);
         const onEnded    = () => {
             setPlaying(false); setOverlayVisible(false); setEnded(true);
             onWatchProgress?.(100);
         };
+        const onPlay     = () => {
+            if (v.duration) guard.reportPlayStart((v.currentTime / v.duration) * 100);
+        };
+        const onPause    = () => {
+            if (v.duration) guard.flush((v.currentTime / v.duration) * 100);
+        };
+        const onSeeking  = () => guard.markSeeking();
+        const onSeeked   = () => guard.markSeeked();
         const onWaiting  = () => setBuffering(true);
         const onCanPlay  = () => setBuffering(false);
         const onProgress = () => {
@@ -305,9 +322,13 @@ export function VideoBlock({ content, onWatchProgress }) {
         v.addEventListener("timeupdate",     onTimeUpdate);
         v.addEventListener("loadedmetadata", onLoaded);
         v.addEventListener("ended",          onEnded);
+        v.addEventListener("play",           onPlay);
+        v.addEventListener("pause",          onPause);
+        v.addEventListener("seeking",        onSeeking);
+        v.addEventListener("seeked",         onSeeked);
         v.addEventListener("progress",       onProgress);
 
-        if (v.readyState >= 1 && v.duration) setTotalDuration(v.duration);
+        if (v.readyState >= 1 && v.duration) onLoaded();
 
         return () => {
             v.removeEventListener("waiting",        onWaiting);
@@ -315,6 +336,10 @@ export function VideoBlock({ content, onWatchProgress }) {
             v.removeEventListener("timeupdate",     onTimeUpdate);
             v.removeEventListener("loadedmetadata", onLoaded);
             v.removeEventListener("ended",          onEnded);
+            v.removeEventListener("play",           onPlay);
+            v.removeEventListener("pause",          onPause);
+            v.removeEventListener("seeking",        onSeeking);
+            v.removeEventListener("seeked",         onSeeked);
             v.removeEventListener("progress",       onProgress);
         };
     }, [blobUrl]);
@@ -372,7 +397,7 @@ export function VideoBlock({ content, onWatchProgress }) {
     const handleSeek = (e) => {
         const v = vidRef.current;
         if (!v || !v.duration) return;
-        v.currentTime = (parseFloat(e.target.value) / 100) * v.duration;
+        v.currentTime = guard.clampSeekTarget((parseFloat(e.target.value) / 100) * v.duration);
     };
 
     const handleVolumeChange = (e) => {
@@ -407,7 +432,7 @@ export function VideoBlock({ content, onWatchProgress }) {
                 break;
             case "ArrowRight":
                 e.preventDefault();
-                if (vidRef.current) vidRef.current.currentTime = Math.min(vidRef.current.currentTime + 5, vidRef.current.duration);
+                if (vidRef.current) vidRef.current.currentTime = guard.clampSeekTarget(Math.min(vidRef.current.currentTime + 5, vidRef.current.duration));
                 showFeedback(<SkipForward className="size-7 text-white" />, "+5s");
                 resetHideTimer();
                 break;
@@ -445,7 +470,7 @@ export function VideoBlock({ content, onWatchProgress }) {
                 break;
             default: break;
         }
-    }, [togglePlay, toggleMute, toggleFullscreen, resetHideTimer, volume, muted, isFullscreen, playing, showFeedback]);
+    }, [togglePlay, toggleMute, toggleFullscreen, resetHideTimer, volume, muted, isFullscreen, playing, showFeedback, guard]);
 
     // ── States ────────────────────────────────────────────────────────────────
 

src/components/generic/TaskMultiSelect.jsx

@@ -0,0 +1,241 @@
+/***********************************************************************************************************************************************************************
+ * File Name    : TaskMultiSelect.jsx
+ * Type         : Reusable Component
+ * Description  : Searchable multi-select dropdown for sibling Tasks (used to pick
+ *                a task's prerequisite tasks). Cloned from GroupMultiSelect.jsx's
+ *                UI/UX — portal dropdown, badge + "+N" overflow, select all/clear —
+ *                but takes `tasks` directly from the caller instead of fetching its
+ *                own endpoint, since the parent page already has the sibling task
+ *                list loaded.
+ *
+ * Props:
+ *   value       : string[]                    — selected task_ids
+ *   onChange    : (ids: string[]) => void
+ *   tasks       : { task_id, name }[]          — candidate tasks (already excludes self)
+ *   disabled?   : boolean
+ *   placeholder?: string
+ ***********************************************************************************************************************************************************************/
+import { useEffect, useLayoutEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
+import { Badge } from '@/components/ui/badge';
+import { Input } from '@/components/ui/input';
+import { cn } from '@/lib/utils';
+import { Check, ChevronsUpDown, X, ListChecks } from 'lucide-react';
+
+export default function TaskMultiSelect({
+    value = [],
+    onChange,
+    tasks = [],
+    disabled = false,
+    placeholder = 'Select tasks…',
+}) {
+    const [open, setOpen] = useState(false);
+    const [search, setSearch] = useState('');
+    const [dropdownStyle, setDropdownStyle] = useState({});
+
+    const triggerRef  = useRef(null);
+    const dropdownRef = useRef(null);
+
+    // ── Position portal dropdown under trigger ────────────────────────────────
+    useLayoutEffect(() => {
+        if (!open || !triggerRef.current) return;
+
+        const reposition = () => {
+            const rect = triggerRef.current.getBoundingClientRect();
+            setDropdownStyle({
+                position: 'fixed',
+                top:   rect.bottom + 4,
+                left:  rect.left,
+                width: rect.width,
+                zIndex: 9999,
+            });
+        };
+
+        reposition();
+        window.addEventListener('scroll', reposition, true);
+        window.addEventListener('resize', reposition);
+        return () => {
+            window.removeEventListener('scroll', reposition, true);
+            window.removeEventListener('resize', reposition);
+        };
+    }, [open]);
+
+    // ── Close on outside click ────────────────────────────────────────────────
+    useEffect(() => {
+        if (!open) return;
+        const handler = (e) => {
+            if (
+                triggerRef.current?.contains(e.target) ||
+                dropdownRef.current?.contains(e.target)
+            ) return;
+            setOpen(false);
+            setSearch('');
+        };
+        document.addEventListener('mousedown', handler);
+        return () => document.removeEventListener('mousedown', handler);
+    }, [open]);
+
+    // ── Helpers ───────────────────────────────────────────────────────────────
+    const filtered = tasks.filter((t) =>
+        t.name.toLowerCase().includes(search.toLowerCase())
+    );
+    const selectedTasks  = tasks.filter((t) => value.includes(t.task_id));
+    const overflowCount  = selectedTasks.length - 1;
+
+    // All currently visible (filtered) IDs — used for select-all scope
+    const filteredIds    = filtered.map((t) => t.task_id);
+    const allFilteredSelected = filteredIds.length > 0 && filteredIds.every((id) => value.includes(id));
+
+    const toggle = (taskId) =>
+        onChange(value.includes(taskId)
+            ? value.filter((id) => id !== taskId)
+            : [...value, taskId]
+        );
+
+    const remove = (e, taskId) => {
+        e.stopPropagation();
+        onChange(value.filter((id) => id !== taskId));
+    };
+
+    // Select all visible (filtered) tasks
+    const handleSelectAll = () => {
+        const merged = Array.from(new Set([...value, ...filteredIds]));
+        onChange(merged);
+    };
+
+    // Clear all selections
+    const handleClear = () => onChange([]);
+
+    // ── Portal dropdown ───────────────────────────────────────────────────────
+    const dropdown = open && createPortal(
+        <div
+            ref={dropdownRef}
+            style={dropdownStyle}
+            className="rounded-md border border-border bg-popover shadow-lg"
+        >
+            {/* Search row */}
+            <div className="p-2 border-b border-border">
+                <Input
+                    autoFocus
+                    value={search}
+                    onChange={(e) => setSearch(e.target.value)}
+                    placeholder="Search tasks…"
+                    className="h-8 text-sm"
+                />
+            </div>
+
+            {/* Select all / Clear row */}
+            {tasks.length > 0 && (
+                <div className="flex items-center justify-between px-3 py-1.5 border-b border-border bg-muted/40">
+                    <button
+                        type="button"
+                        onMouseDown={(e) => e.preventDefault()}
+                        onClick={allFilteredSelected ? handleClear : handleSelectAll}
+                        className="text-xs text-primary hover:underline underline-offset-2 font-medium"
+                    >
+                        {allFilteredSelected ? 'Deselect all' : 'Select all'}
+                        {search && ` (${filteredIds.length})`}
+                    </button>
+                    {value.length > 0 && (
+                        <button
+                            type="button"
+                            onMouseDown={(e) => e.preventDefault()}
+                            onClick={handleClear}
+                            className="text-xs text-muted-foreground hover:text-destructive transition-colors"
+                        >
+                            Clear ({value.length})
+                        </button>
+                    )}
+                </div>
+            )}
+
+            {/* Options */}
+            <ul className="max-h-52 overflow-y-auto py-1">
+                {filtered.length === 0 ? (
+                    <li className="px-3 py-6 text-center text-xs text-muted-foreground">
+                        No tasks found.
+                    </li>
+                ) : (
+                    filtered.map((t) => {
+                        const selected = value.includes(t.task_id);
+                        return (
+                            <li
+                                key={t.task_id}
+                                onMouseDown={(e) => e.preventDefault()}
+                                onClick={() => toggle(t.task_id)}
+                                className={cn(
+                                    'flex items-center gap-2 px-3 py-2 text-sm cursor-pointer select-none',
+                                    'hover:bg-accent hover:text-accent-foreground',
+                                    selected && 'bg-accent/50'
+                                )}
+                            >
+                                <div className={cn(
+                                    'h-4 w-4 rounded border flex items-center justify-center shrink-0',
+                                    selected
+                                        ? 'bg-primary border-primary text-primary-foreground'
+                                        : 'border-input'
+                                )}>
+                                    {selected && <Check className="h-3 w-3" />}
+                                </div>
+                                <ListChecks className="h-3.5 w-3.5 text-muted-foreground shrink-0" />
+                                <span className="truncate">{t.name}</span>
+                            </li>
+                        );
+                    })
+                )}
+            </ul>
+        </div>,
+        document.body
+    );
+
+    return (
+        <>
+            {/* ── Trigger button ───────────────────────────────────────────── */}
+            <button
+                ref={triggerRef}
+                type="button"
+                disabled={disabled}
+                onClick={() => { setOpen((o) => !o); setSearch(''); }}
+                className={cn(
+                    'w-full min-h-9 px-3 py-1.5 rounded-md border border-input bg-background text-sm',
+                    'flex items-center gap-1.5 text-left',
+                    'focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-1',
+                    'disabled:opacity-50 disabled:cursor-not-allowed',
+                    open && 'ring-2 ring-ring ring-offset-1'
+                )}
+            >
+                {selectedTasks.length === 0 ? (
+                    <span className="text-muted-foreground flex-1">{placeholder}</span>
+                ) : (
+                    <span className="flex items-center gap-1 flex-1 min-w-0">
+                        {/* Always show only the first selected task */}
+                        <Badge variant="secondary" className="gap-1 text-xs pr-1 shrink-0 max-w-[180px]">
+                            <ListChecks className="h-3 w-3 shrink-0" />
+                            <span className="truncate">{selectedTasks[0].name}</span>
+                            <span
+                                role="button"
+                                tabIndex={0}
+                                onClick={(e) => remove(e, selectedTasks[0].task_id)}
+                                onKeyDown={(e) => e.key === 'Enter' && remove(e, selectedTasks[0].task_id)}
+                                className="ml-0.5 rounded-full hover:bg-muted-foreground/20 p-0.5 cursor-pointer shrink-0"
+                            >
+                                <X className="h-2.5 w-2.5" />
+                            </span>
+                        </Badge>
+
+                        {/* +N overflow chip */}
+                        {overflowCount > 0 && (
+                            <Badge variant="outline" className="text-xs px-1.5 shrink-0">
+                                +{overflowCount}
+                            </Badge>
+                        )}
+                    </span>
+                )}
+                <ChevronsUpDown className="h-3.5 w-3.5 text-muted-foreground shrink-0 ml-auto" />
+            </button>
+
+            {/* ── Portalled dropdown ────────────────────────────────────────── */}
+            {dropdown}
+        </>
+    );
+}

src/contexts/AdminCoursesContext.jsx

@@ -295,6 +295,32 @@ export function CoursesProvider({ children }) {
     [request],
   );
 
+  // Flat lists for the prerequisite picker's Course/Unit/Lesson selectors —
+  // same endpoints AdminTaskContext uses for the Task requirement picker.
+  const fetchCoursesFlat = useCallback(
+    () => request(async () => {
+      const { data } = await api.get(`${BASE}/flat`);
+      return data?.data ?? [];
+    }),
+    [request],
+  );
+
+  const fetchUnitsFlat = useCallback(
+    () => request(async () => {
+      const { data } = await api.get(`${BASE}/units-flat`);
+      return data?.data ?? [];
+    }),
+    [request],
+  );
+
+  const fetchLessonsFlat = useCallback(
+    () => request(async () => {
+      const { data } = await api.get(`${BASE}/lessons-flat`);
+      return data?.data ?? [];
+    }),
+    [request],
+  );
+
   // =========================================================================
   // UNITS
   // =========================================================================
@@ -1273,6 +1299,9 @@ export function CoursesProvider({ children }) {
       // ── prerequisites ──────────────────────────────────────────────────────
       fetchPrerequisites,
       syncPrerequisites,
+      fetchCoursesFlat,
+      fetchUnitsFlat,
+      fetchLessonsFlat,
 
       // ── completion requirements ────────────────────────────────────────────
       fetchCourseRequirements,

src/contexts/AdminTaskContext.jsx

@@ -276,6 +276,21 @@ export function AdminTaskProvider({ children }) {
         [request]
     );
 
+    // Replaces the full assigned-group set in one call — used when editing a task
+    // list's groups so an add+remove edit only costs one sensitiveOpsLimiter hit.
+    const syncGroups = useCallback(
+        (taskListId, groupIds) =>
+            request(async () => {
+                const res = await api.put(`${BASE}/${taskListId}/groups`, {
+                    group_ids: groupIds,
+                });
+                const result = res.data?.data ?? {};
+                toast('Assigned groups updated.');
+                return result;
+            }),
+        [request]
+    );
+
     // ══════════════════════════════════════════════════════════════════════════
     // TASKS
     // ══════════════════════════════════════════════════════════════════════════
@@ -298,6 +313,19 @@ export function AdminTaskProvider({ children }) {
         [request]
     );
 
+    // Flat, unpaginated sibling-task list — used by the prerequisite picker.
+    // Deliberately does not touch tasks/pagination/attributes state (unlike
+    // fetchTasks) so it can be called from a page that isn't the tasks table.
+    const fetchTasksFlat = useCallback(
+        (taskListId) =>
+            request(async () => {
+                const res = await api.get(`${BASE}/${taskListId}/tasks`, { params: { limit: 1000 } });
+                const { data } = res.data?.data ?? {};
+                return data ?? [];
+            }),
+        [request]
+    );
+
     const fetchArchivedTasks = useCallback(
         (taskListId, { page = 1, limit = 10, filters = [], sort = [] } = {}) =>
             request(async () => {
@@ -633,9 +661,10 @@ export function AdminTaskProvider({ children }) {
             fetchTaskListGroups,
             assignGroups,
             unassignGroups,
+            syncGroups,
 
             // ── Task actions ──────────────────────────────────────────────────
-            fetchTasks, fetchTask, fetchArchivedTasks,
+            fetchTasks, fetchTask, fetchTasksFlat, fetchArchivedTasks,
             createTask, updateTask,
             archiveTask, restoreTask,
             bulkArchiveTasks, bulkRestoreTasks,

src/hooks/useMediaWatchGuard.js

@@ -0,0 +1,125 @@
+import { useRef, useCallback, useMemo, useEffect } from "react";
+
+// How many progress checkpoints we aim to spread across a clip's duration,
+// clamped between a floor (never chattier than this even for tiny clips) and
+// a ceiling (routine polling shouldn't exceed roughly once a minute).
+const MIN_INTERVAL_MS    = 8000;
+const MAX_INTERVAL_MS    = 60000;
+const CHECKPOINTS_TARGET = 4;
+
+function computeThrottleMs(durationSeconds) {
+    if (!durationSeconds) return MIN_INTERVAL_MS; // duration not known yet — stay conservative
+    return Math.min(MAX_INTERVAL_MS, Math.max(MIN_INTERVAL_MS, (durationSeconds * 1000) / CHECKPOINTS_TARGET));
+}
+
+// Shared anti-skip guard for VideoBlock/AudioBlock's watch-progress tracking.
+//
+// Tracks the furthest point actually reached during normal forward playback
+// (never during a seek) so seek targets can be clamped to "rewind only, never
+// skip ahead" — a scrub/keyboard-seek/programmatic currentTime write past that
+// point snaps back instead of landing. This is a client-side UX deterrent only;
+// the server independently re-validates elapsed wall-clock time per sample
+// (see recordWatchProgress) since a direct API call bypasses this entirely.
+//
+// The seek-cap only applies when `antiSkipEnabled` is true — the caller passes
+// this based on whether the lesson actually has a watch_percent/watch_video/
+// listen_audio completion requirement configured. Without one there's nothing
+// being enforced, so seeking is left completely free (default: disabled).
+//
+// Routine progress reports are throttled at an interval scaled to the clip's
+// own duration (~4 checkpoints across it, capped at once a minute) rather than
+// a flat interval, so short clips still get meaningful checkpoints while long
+// ones don't spam the endpoint. Pausing or backgrounding the tab immediately
+// flushes the last-known percent regardless of the throttle, so genuine
+// partial progress is never silently lost just because a short clip ended
+// before its first scheduled checkpoint. This reporting (and the resume-seed
+// it feeds) stays unconditional regardless of antiSkipEnabled, since it also
+// backs the always-on resume-position feature.
+export function useMediaWatchGuard({ onWatchProgress, antiSkipEnabled = false } = {}) {
+    const lastReportRef = useRef(0);
+    const maxReachedRef = useRef(0);
+    const lastPctRef    = useRef(0);
+    const durationRef   = useRef(0);
+    const seekingRef    = useRef(false);
+    const playSeededRef = useRef(false);
+
+    // Call on asset change (new src) to drop all guard state for the new media.
+    const reset = useCallback(() => {
+        lastReportRef.current = 0;
+        maxReachedRef.current = 0;
+        lastPctRef.current    = 0;
+        durationRef.current   = 0;
+        seekingRef.current    = false;
+        playSeededRef.current = false;
+    }, []);
+
+    // A tiny epsilon tolerates scrubber rounding / re-clicking the current spot.
+    const EPSILON = 0.75;
+    const clampSeekTarget = useCallback((target) => (
+        !antiSkipEnabled || target <= maxReachedRef.current + EPSILON ? target : maxReachedRef.current
+    ), [antiSkipEnabled]);
+
+    const markSeeking = useCallback(() => { seekingRef.current = true; }, []);
+    const markSeeked  = useCallback(() => { seekingRef.current = false; }, []);
+
+    // Call once metadata resolves — drives the adaptive throttle interval.
+    const setDuration = useCallback((durationSeconds) => {
+        durationRef.current = durationSeconds || 0;
+    }, []);
+
+    // Wire into the timeupdate handler — only advances the furthest-reached
+    // marker while actually playing forward, not mid-seek. Always records the
+    // latest percent (regardless of seek state) so pause/hidden flushes have
+    // an honest "last known position" to report even mid-seek.
+    const trackTimeUpdate = useCallback((currentTime, duration) => {
+        if (!seekingRef.current) maxReachedRef.current = Math.max(maxReachedRef.current, currentTime);
+        if (duration) lastPctRef.current = (currentTime / duration) * 100;
+    }, []);
+
+    // Unconditionally reports and resets the throttle window — used for
+    // pause/tab-hidden flushes and the initial play-start baseline, where
+    // waiting for the routine throttle would risk losing the sample entirely.
+    const flush = useCallback((pct) => {
+        if (!onWatchProgress) return;
+        lastReportRef.current = Date.now();
+        onWatchProgress(pct);
+    }, [onWatchProgress]);
+
+    const maybeReport = useCallback((pct) => {
+        if (!onWatchProgress) return;
+        const now = Date.now();
+        if (now - lastReportRef.current > computeThrottleMs(durationRef.current)) {
+            lastReportRef.current = now;
+            onWatchProgress(pct);
+        }
+    }, [onWatchProgress]);
+
+    // Seeds the server's wall-clock baseline the moment playback first starts,
+    // so the first real throttled sample has an honest elapsed-time reference
+    // rather than being compared against a progress row created lazily on
+    // whatever percent happens to be reported first.
+    const reportPlayStart = useCallback((pct) => {
+        if (playSeededRef.current) return;
+        playSeededRef.current = true;
+        flush(pct);
+    }, [flush]);
+
+    // Tab backgrounded (switched away, minimized, etc.) — flush the last known
+    // position immediately rather than risk it never being reported at all,
+    // since 'visibilitychange' → hidden reliably fires before actual unload
+    // (unlike beforeunload/unload, which browsers may cancel requests around).
+    useEffect(() => {
+        const onVisibilityChange = () => {
+            if (document.visibilityState === "hidden") flush(lastPctRef.current);
+        };
+        document.addEventListener("visibilitychange", onVisibilityChange);
+        return () => document.removeEventListener("visibilitychange", onVisibilityChange);
+    }, [flush]);
+
+    // Memoized so the returned object itself is referentially stable (all of the
+    // functions inside are already useCallback-stable) — lets callers safely list
+    // `guard` in effect/useCallback dependency arrays without re-running on every render.
+    return useMemo(() => (
+        { clampSeekTarget, trackTimeUpdate, markSeeking, markSeeked, maybeReport, flush, reportPlayStart, setDuration, reset }
+    ), [clampSeekTarget, trackTimeUpdate, markSeeking, markSeeked, maybeReport, flush, reportPlayStart, setDuration, reset]);
+}

src/modules/admin/components/courses/CoursePrerequisiteBuilder.jsx

@@ -0,0 +1,217 @@
+import { useState } from 'react';
+import { Plus, Trash2, GripVertical, ChevronsUpDown, BookOpen, Layers, FileText, Link2, Unlink } from 'lucide-react';
+
+import { Button } from '@/components/ui/button';
+import { Badge } from '@/components/ui/badge';
+import { Card, CardContent } from '@/components/ui/card';
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
+import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/ui/dialog';
+import { Command, CommandInput, CommandList, CommandEmpty, CommandGroup, CommandItem } from '@/components/ui/command';
+
+// ─── Prerequisite type config ──────────────────────────────────────────────────
+// idKey is the numeric FK field each flat list carries (course_id/unit_id/
+// lesson_id) — CoursePrerequisite.ref_id is a BIGINT FK, not a uuid, so the
+// picker must select on the numeric id even though the list is keyed/searched
+// by uuid for React purposes.
+const REF_TYPES = [
+    { value: 'course', label: 'Course', icon: BookOpen, idKey: 'course_id' },
+    { value: 'unit',   label: 'Unit',   icon: Layers,   idKey: 'unit_id' },
+    { value: 'lesson', label: 'Lesson', icon: FileText, idKey: 'lesson_id' },
+];
+const TYPE_MAP = Object.fromEntries(REF_TYPES.map((t) => [t.value, t]));
+
+// ─── Course binding indicator (units/lessons may sit under 0..N courses) ──────
+function BindingLine({ courses = [] }) {
+    if (!courses.length) {
+        return (
+            <span className="flex items-center gap-1 text-xs italic text-muted-foreground truncate">
+                <Unlink className="size-3 shrink-0" />
+                Standalone
+            </span>
+        );
+    }
+    return (
+        <span className="flex items-center gap-1 text-xs text-muted-foreground truncate">
+            <Link2 className="size-3 shrink-0" />
+            <span className="truncate">{courses.map((c) => c.title).join(', ')}</span>
+        </span>
+    );
+}
+
+// ─── Custom content picker — own Dialog rather than an anchored Popover ───────
+function ContentPicker({ value, options, idKey, placeholder = 'Select…', dialogTitle, onSelect, renderTrigger, renderItem }) {
+    const [open, setOpen] = useState(false);
+    const selected = options.find((o) => String(o[idKey]) === String(value));
+
+    const searchValue = (o) => {
+        const courseNames = (o.courses ?? []).map((c) => c.title).join(' ');
+        return `${o.title ?? ''} ${courseNames}`.trim() || String(o[idKey]);
+    };
+
+    return (
+        <>
+            <Button
+                type="button"
+                variant="outline"
+                role="combobox"
+                aria-expanded={open}
+                className="h-auto min-h-8 w-full justify-between text-sm font-normal py-1.5 px-3"
+                onClick={() => setOpen(true)}
+            >
+                {selected
+                    ? renderTrigger(selected)
+                    : <span className="text-muted-foreground">{placeholder}</span>}
+                <ChevronsUpDown className="ml-2 h-4 w-4 shrink-0 opacity-50" />
+            </Button>
+
+            <Dialog open={open} onOpenChange={setOpen}>
+                <DialogContent className="top-[15%] translate-y-0 flex flex-col max-h-[70vh] overflow-hidden rounded-xl! p-0 gap-0 sm:max-w-md">
+                    <DialogHeader className="px-4 pt-4 pb-3 border-b pr-10">
+                        <DialogTitle className="text-sm">{dialogTitle ?? placeholder}</DialogTitle>
+                    </DialogHeader>
+                    <Command className="flex-1 min-h-0 rounded-none! bg-transparent p-0" loop>
+                        <CommandInput placeholder="Search…" />
+                        <CommandList className="max-h-[50vh]">
+                            <CommandEmpty>No results found.</CommandEmpty>
+                            <CommandGroup>
+                                {options.map((o) => (
+                                    <CommandItem
+                                        key={o[idKey]}
+                                        value={searchValue(o)}
+                                        onSelect={() => { onSelect(o); setOpen(false); }}
+                                        className="p-0"
+                                    >
+                                        {renderItem(o)}
+                                    </CommandItem>
+                                ))}
+                            </CommandGroup>
+                        </CommandList>
+                    </Command>
+                </DialogContent>
+            </Dialog>
+        </>
+    );
+}
+
+function createPrereq(type = 'course') {
+    return { _key: crypto.randomUUID(), ref_type: type, ref_id: '', title: '' };
+}
+
+// ─── CoursePrerequisiteBuilder ─────────────────────────────────────────────────
+// value: [{ prereq_id?, ref_type, ref_id, title? }]
+export default function CoursePrerequisiteBuilder({ value = [], onChange, courses = [], units = [], lessons = [], excludeCourseId }) {
+    const [items, setItems] = useState(
+        value.length > 0
+            ? value.map((v) => ({ _key: crypto.randomUUID(), ...v }))
+            : []
+    );
+
+    const filteredCourses = courses.filter((c) => String(c.course_id) !== String(excludeCourseId));
+    const optionsFor = { course: filteredCourses, unit: units, lesson: lessons };
+
+    const emit = (next) => {
+        setItems(next);
+        onChange?.(next.map(({ _key, ...r }) => r));
+    };
+
+    const addItem = () => emit([...items, createPrereq('course')]);
+    const removeItem = (key) => emit(items.filter((i) => i._key !== key));
+    const updateItem = (key, patch) =>
+        emit(items.map((i) => (i._key === key ? { ...i, ...patch } : i)));
+
+    return (
+        <div className="space-y-3">
+            {items.length === 0 && (
+                <p className="text-sm text-muted-foreground text-center py-6 border border-dashed rounded-lg">
+                    No prerequisites added. Learners can start this course freely.
+                </p>
+            )}
+
+            {items.map((item, idx) => {
+                const typeDef = TYPE_MAP[item.ref_type];
+                const Icon = typeDef?.icon ?? BookOpen;
+                const options = optionsFor[item.ref_type] ?? [];
+
+                return (
+                    <Card key={item._key}>
+                        <CardContent className="pt-4 pb-4 space-y-3">
+                            <div className="flex items-center gap-2">
+                                <GripVertical className="h-4 w-4 text-muted-foreground shrink-0" />
+                                <Badge variant="outline" className="text-xs gap-1 shrink-0">
+                                    <Icon className="h-3 w-3" />
+                                    {idx + 1}
+                                </Badge>
+
+                                <Select
+                                    value={item.ref_type}
+                                    onValueChange={(v) => updateItem(item._key, { ref_type: v, ref_id: '', title: '' })}
+                                >
+                                    <SelectTrigger className="h-8 text-sm w-32 shrink-0">
+                                        <SelectValue />
+                                    </SelectTrigger>
+                                    <SelectContent>
+                                        {REF_TYPES.map((t) => (
+                                            <SelectItem key={t.value} value={t.value}>
+                                                <span className="flex items-center gap-2">
+                                                    <t.icon className="h-3.5 w-3.5" />
+                                                    {t.label}
+                                                </span>
+                                            </SelectItem>
+                                        ))}
+                                    </SelectContent>
+                                </Select>
+
+                                <div className="flex-1 min-w-0">
+                                    <ContentPicker
+                                        value={item.ref_id}
+                                        options={options}
+                                        idKey={typeDef.idKey}
+                                        placeholder={`Select a ${typeDef.label.toLowerCase()}`}
+                                        dialogTitle={`Select a ${typeDef.label.toLowerCase()}`}
+                                        onSelect={(o) => updateItem(item._key, { ref_id: o[typeDef.idKey], title: o.title })}
+                                        renderTrigger={(o) => (
+                                            <div className="flex items-center gap-2 min-w-0 flex-1">
+                                                {item.ref_type !== 'course' && (
+                                                    <div className="flex flex-col items-start flex-1 min-w-0">
+                                                        <BindingLine courses={o.courses} />
+                                                        <span className="text-sm leading-tight truncate">{o.title}</span>
+                                                    </div>
+                                                )}
+                                                {item.ref_type === 'course' && (
+                                                    <span className="flex-1 truncate text-sm">{o.title}</span>
+                                                )}
+                                            </div>
+                                        )}
+                                        renderItem={(o) => (
+                                            <div className="flex items-center gap-2 px-3 py-2 w-full">
+                                                <div className="flex flex-col flex-1 min-w-0">
+                                                    <span className="text-sm leading-tight truncate">{o.title}</span>
+                                                    {item.ref_type !== 'course' && <BindingLine courses={o.courses} />}
+                                                </div>
+                                            </div>
+                                        )}
+                                    />
+                                </div>
+
+                                <Button
+                                    type="button"
+                                    variant="ghost"
+                                    size="icon"
+                                    className="h-8 w-8 shrink-0 text-destructive hover:text-destructive"
+                                    onClick={() => removeItem(item._key)}
+                                >
+                                    <Trash2 className="h-4 w-4" />
+                                </Button>
+                            </div>
+                        </CardContent>
+                    </Card>
+                );
+            })}
+
+            <Button type="button" variant="outline" size="sm" className="w-full gap-2" onClick={addItem}>
+                <Plus className="h-4 w-4" />
+                Add Prerequisite
+            </Button>
+        </div>
+    );
+}

src/modules/admin/components/courses/LessonsPreview.jsx

@@ -135,11 +135,12 @@ export function PreviewVideo({ url, thumb }) {
 // AudioBlock themselves) attaches the block's own id/type to each call, since a lesson
 // can have several blocks of the same type and watch_video/listen_audio need to know
 // which specific one just reported progress.
-export function PreviewBlock({ block, onWatchProgress }) {
+export function PreviewBlock({ block, onWatchProgress, resumeMap, antiSkipEnabled }) {
     const { id, type, content } = block;
     const withBlockMeta = onWatchProgress
         ? (percent) => onWatchProgress(percent, { blockId: id, blockType: type })
         : undefined;
+    const resumePercent = resumeMap?.[id];
 
     switch (type) {
         case "text":
@@ -149,11 +150,11 @@ export function PreviewBlock({ block, onWatchProgress }) {
         case "text-image":
             return <TextImageBlock blockId={id} content={content} readOnly />;
         case "video":
-            return <VideoBlock content={content} readOnly onWatchProgress={withBlockMeta} />;
+            return <VideoBlock content={content} readOnly onWatchProgress={withBlockMeta} resumePercent={resumePercent} antiSkipEnabled={antiSkipEnabled} />;
         case "text-video":
-            return <TextVideoBlock blockId={id} content={content} readOnly onWatchProgress={withBlockMeta} />;
+            return <TextVideoBlock blockId={id} content={content} readOnly onWatchProgress={withBlockMeta} resumePercent={resumePercent} antiSkipEnabled={antiSkipEnabled} />;
         case "audio":
-            return <AudioBlock content={content} onWatchProgress={withBlockMeta} />;
+            return <AudioBlock content={content} onWatchProgress={withBlockMeta} resumePercent={resumePercent} antiSkipEnabled={antiSkipEnabled} />;
         case "code":
             return <CodeBlock content={content} />;
         case "markdown":
@@ -167,7 +168,13 @@ export function PreviewBlock({ block, onWatchProgress }) {
 // PhotoProvider wraps ALL blocks so images across the whole lesson share
 // one lightbox session — users can swipe between them naturally.
 
+// Only these completion-requirement types gate video/audio behind the anti-skip
+// seek-cap — everything else (or no requirement configured) allows free seeking.
+const WATCH_TYPE_REQUIREMENTS = ["watch_percent", "watch_video", "listen_audio"];
+
 export function PreviewContent({ lesson, blocks, empty = "No content yet.", showHeader = true, onWatchProgress }) {
+    const resumeMap = lesson?.resume_positions;
+    const antiSkipEnabled = WATCH_TYPE_REQUIREMENTS.includes(lesson?.completion?.type);
     return (
         <PhotoProvider
             speed={() => 300}
@@ -194,7 +201,7 @@ export function PreviewContent({ lesson, blocks, empty = "No content yet.", show
                 <div className="space-y-4 sm:space-y-5">
                     {blocks.map((block) => (
                         <div key={block.id}>
-                            <PreviewBlock block={block} onWatchProgress={onWatchProgress} />
+                            <PreviewBlock block={block} onWatchProgress={onWatchProgress} resumeMap={resumeMap} antiSkipEnabled={antiSkipEnabled} />
                         </div>
                     ))}
                 </div>

src/modules/admin/pages/courses/AddCourse.jsx

@@ -24,6 +24,7 @@ import {
 import CourseBadge from "@/modules/admin/components/courses/CourseBadge";
 import RoadmapBuilder from "@/modules/admin/components/courses/RoadmapBuilder";
 import AchievementsBuilder from "@/modules/admin/components/courses/AchievementsBuilder";
+import CoursePrerequisiteBuilder from "@/modules/admin/components/courses/CoursePrerequisiteBuilder";
 import { TIER_COLOR_OPTIONS } from "@/utils/tierColors";
 import { AssetPickerSheet } from "@/components/generic/AssetPickerSheet";
 import { useUnsavedChangesGuard } from "@/hooks/useUnsavedChangesGuard";
@@ -40,6 +41,7 @@ const schema = z.object({
   status: z.enum(["draft", "published", "unpublished"]).default("draft"),
   objectives: z.array(z.object({ text: z.string().min(1, "Objective cannot be empty.") }))
     .min(1, "At least one learning objective is required."),
+  roles: z.array(z.object({ text: z.string().min(1, "Role cannot be empty.") })).default([]),
   achievement_keys: z.array(z.string()).max(1).default([]),
 });
 
@@ -47,7 +49,7 @@ const schema = z.object({
 
 const STEPS = [
   { label: "Basic Info", description: "Title, level & objectives" },
-  { label: "Roadmap",    description: "Units & lessons"           },
+  { label: "Roadmap",    description: "Units, lessons & prerequisites" },
   { label: "Rewards",    description: "Badge & achievements"      },
   { label: "Review",     description: "Confirm & create"          },
 ];
@@ -127,11 +129,12 @@ function StepIndicator({ steps, current, onStepClick }) {
 
 export default function AddCourse() {
   const navigate = useNavigate();
-  const { createCourseFull, loading } = useCourses();
+  const { createCourseFull, loading, fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat } = useCourses();
   const { user } = useAuth();
 
   const [currentStep, setCurrentStep] = useState(0);
   const [roadmapUnits, setRoadmapUnits] = useState([]);
+  const [prerequisites, setPrerequisites] = useState([]);
   const [tierCategories, setTierCategories] = useState([]);
   useEffect(() => {
     api.get("/admin/tiers/categories")
@@ -139,6 +142,18 @@ export default function AddCourse() {
       .catch(() => {});
   }, []);
 
+  const [flatCourses, setFlatCourses] = useState([]);
+  const [flatUnits, setFlatUnits] = useState([]);
+  const [flatLessons, setFlatLessons] = useState([]);
+  useEffect(() => {
+    (async () => {
+      const [c, u, l] = await Promise.all([fetchCoursesFlat(), fetchUnitsFlat(), fetchLessonsFlat()]);
+      setFlatCourses(c ?? []);
+      setFlatUnits(u ?? []);
+      setFlatLessons(l ?? []);
+    })();
+  }, []);
+
   const [badgeColor, setBadgeColor] = useState("purple");
   const [badgeImageUrl, setBadgeImageUrl] = useState(null);
   const [badgeAssetId, setBadgeAssetId] = useState(null);
@@ -163,12 +178,15 @@ export default function AddCourse() {
       subscription: "free",
       status: "draft",
       objectives: [],
+      roles: [],
       achievement_keys: [],
     },
   });
 
   const { fields: objectiveFields, append: appendObjective, remove: removeObjective } =
     useFieldArray({ control, name: "objectives" });
+  const { fields: roleFields, append: appendRole, remove: removeRole } =
+    useFieldArray({ control, name: "roles" });
 
   const currentAchKeys   = useWatch({ control, name: "achievement_keys" });
   const watchedTitle     = useWatch({ control, name: "title" });
@@ -179,6 +197,7 @@ export default function AddCourse() {
   const watchedSubscr    = useWatch({ control, name: "subscription" });
   const watchedStatus    = useWatch({ control, name: "status" });
   const watchedObjectives = useWatch({ control, name: "objectives" });
+  const watchedRoles      = useWatch({ control, name: "roles" });
 
   const [achievementRegistry, setAchievementRegistry] = useState([]);
   useEffect(() => {
@@ -198,6 +217,7 @@ export default function AddCourse() {
   const hasUnsavedChanges =
     isDirty ||
     roadmapUnits.length > 0 ||
+    prerequisites.length > 0 ||
     currentAchKeys.length > 0 ||
     !!badgeImageUrl ||
     badgeColor !== "purple";
@@ -237,6 +257,12 @@ export default function AddCourse() {
       subscription: values.subscription,
       status: values.status,
       objectives: values.objectives.map((o) => o.text),
+      roles: values.roles.map((r) => r.text),
+      // Drop rows where a type was picked but no item was actually selected —
+      // sending an empty ref_id fails at the DB level.
+      prerequisites: prerequisites
+        .filter((p) => p.ref_id !== "" && p.ref_id != null)
+        .map(({ ref_type, ref_id }) => ({ ref_type, ref_id })),
       achievement_keys: currentAchKeys,
       badge_color: badgeColor,
       badge_asset_id: badgeAssetId ?? null,
@@ -426,12 +452,66 @@ export default function AddCourse() {
                     </Button>
                   </div>
                 </SectionCard>
+
+                <SectionCard
+                  title="Course Roles"
+                  description="Who is this course intended for? e.g. Sales Agent, Property Manager."
+                >
+                  <div className="space-y-2">
+                    {roleFields.map((field, index) => (
+                      <div key={field.id} className="flex items-start gap-2">
+                        <div className="flex-1 space-y-1">
+                          <Input
+                            placeholder={`Role ${index + 1}`}
+                            {...register(`roles.${index}.text`)}
+                          />
+                          <FieldError message={errors.roles?.[index]?.text?.message} />
+                        </div>
+                        <Button
+                          type="button"
+                          variant="ghost"
+                          size="icon"
+                          className="mt-0.5 text-muted-foreground hover:text-destructive"
+                          onClick={() => removeRole(index)}
+                        >
+                          <Trash2 className="h-4 w-4" />
+                        </Button>
+                      </div>
+                    ))}
+
+                    <Button
+                      type="button"
+                      variant="outline"
+                      size="sm"
+                      className="w-full mt-1"
+                      onClick={() => appendRole({ text: "" })}
+                    >
+                      <Plus className="h-4 w-4 mr-2" />
+                      Add Role
+                    </Button>
+                  </div>
+                </SectionCard>
               </>
             )}
 
             {/* ── Step 1: Roadmap ── */}
             {currentStep === 1 && (
-              <RoadmapBuilder units={roadmapUnits} onUnitsChange={setRoadmapUnits} />
+              <>
+                <RoadmapBuilder units={roadmapUnits} onUnitsChange={setRoadmapUnits} />
+
+                <SectionCard
+                  title="Prerequisites"
+                  description="What a learner must complete before starting this course."
+                >
+                  <CoursePrerequisiteBuilder
+                    value={prerequisites}
+                    onChange={setPrerequisites}
+                    courses={flatCourses}
+                    units={flatUnits}
+                    lessons={flatLessons}
+                  />
+                </SectionCard>
+              </>
             )}
 
             {/* ── Step 2: Rewards ── */}
@@ -587,11 +667,26 @@ export default function AddCourse() {
                       </ul>
                     )}
                   </div>
+
+                  <div className="border-t pt-4">
+                    <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide mb-2">
+                      Course Roles
+                    </p>
+                    {!watchedRoles?.length ? (
+                      <p className="text-sm text-muted-foreground">None added.</p>
+                    ) : (
+                      <div className="flex flex-wrap gap-1.5">
+                        {watchedRoles.map((r, i) => (
+                          <Badge key={i} variant="secondary">{r.text}</Badge>
+                        ))}
+                      </div>
+                    )}
+                  </div>
                 </SectionCard>
 
                 <SectionCard
                   title="Roadmap"
-                  description={`${roadmapUnits.length} unit${roadmapUnits.length === 1 ? "" : "s"} · ${totalLessons} lesson${totalLessons === 1 ? "" : "s"} added.`}
+                  description={`${roadmapUnits.length} unit${roadmapUnits.length === 1 ? "" : "s"} · ${totalLessons} lesson${totalLessons === 1 ? "" : "s"} added · ${prerequisites.length} prerequisite${prerequisites.length === 1 ? "" : "s"}.`}
                 >
                   {roadmapUnits.length === 0 ? (
                     <p className="text-sm text-muted-foreground">No units added.</p>
@@ -614,6 +709,21 @@ export default function AddCourse() {
                       })}
                     </div>
                   )}
+
+                  {prerequisites.length > 0 && (
+                    <div className="border-t pt-3 mt-1">
+                      <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide mb-2">
+                        Prerequisites
+                      </p>
+                      <div className="flex flex-wrap gap-1.5">
+                        {prerequisites.map((p, i) => (
+                          <Badge key={i} variant="outline" className="capitalize gap-1">
+                            {p.ref_type}: {p.title || `#${p.ref_id}`}
+                          </Badge>
+                        ))}
+                      </div>
+                    </div>
+                  )}
                 </SectionCard>
 
                 <SectionCard title="Rewards">

src/modules/admin/pages/courses/EditCourse.jsx

@@ -14,6 +14,7 @@ import { TIER_COLOR_OPTIONS } from "@/utils/tierColors";
 import { AssetPickerSheet } from "@/components/generic/AssetPickerSheet";
 import { PageMeta } from "@/contexts/MetadataContext";
 import CourseInstructorPicker from "@/modules/admin/components/courses/CourseInstructorPicker";
+import CoursePrerequisiteBuilder from "@/modules/admin/components/courses/CoursePrerequisiteBuilder";
 import { useCategories } from "@/contexts/AdminCategoriesContext";
 import { useAuth } from "@/contexts/AuthContext";
 import api from "@/utils/api.util";
@@ -51,6 +52,9 @@ const schema = z.object({
   objectives: z
     .array(z.object({ text: z.string().min(1, "Objective cannot be empty.") }))
     .default([]),
+  roles: z
+    .array(z.object({ text: z.string().min(1, "Role cannot be empty.") }))
+    .default([]),
 });
 
 // ─── Steps config ─────────────────────────────────────────────────────────────
@@ -59,7 +63,7 @@ const STEPS = [
   { label: "Basic Info",     description: "Title, level & objectives" },
   { label: "Categories",     description: "Tags & instructors"         },
   { label: "Rewards",        description: "Badge & achievements"       },
-  { label: "Requirements",   description: "What counts as complete"    },
+  { label: "Requirements",   description: "Prerequisites & completion"  },
   { label: "Pricing",        description: "Product listing"            },
 ];
 
@@ -146,6 +150,8 @@ export default function EditCourse() {
     fetchInstructors, syncInstructors,
     fetchCourseAchievements, syncCourseAchievements,
     fetchCourseRequirements, syncCourseRequirements,
+    fetchPrerequisites, syncPrerequisites,
+    fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat,
     loading, course,
   } = useCourses();
   const { categories: allCategories, fetchCategories } = useCategories();
@@ -172,6 +178,22 @@ export default function EditCourse() {
   const [instructorsDirty, setInstructorsDirty] = useState(false);
   const [instructorsLoading, setInstructorsLoading] = useState(false);
 
+  // ─── Prerequisites state ──────────────────────────────────────────────────
+  const [prerequisites, setPrerequisites] = useState([]);
+  const [prereqDirty, setPrereqDirty] = useState(false);
+  const [prereqLoading, setPrereqLoading] = useState(false);
+  const [flatCourses, setFlatCourses] = useState([]);
+  const [flatUnits, setFlatUnits] = useState([]);
+  const [flatLessons, setFlatLessons] = useState([]);
+  useEffect(() => {
+    (async () => {
+      const [c, u, l] = await Promise.all([fetchCoursesFlat(), fetchUnitsFlat(), fetchLessonsFlat()]);
+      setFlatCourses(c ?? []);
+      setFlatUnits(u ?? []);
+      setFlatLessons(l ?? []);
+    })();
+  }, []);
+
   // ─── Achievements state ───────────────────────────────────────────────────
   const [selectedAchievementKeys, setSelectedAchievementKeys] = useState([]);
   const [achievementsDirty, setAchievementsDirty] = useState(false);
@@ -207,12 +229,14 @@ export default function EditCourse() {
     resolver: zodResolver(schema),
     defaultValues: {
       title: "", description: "", course_code: "",
-      order_index: 0, level: undefined, subscription: "free", status: "draft", objectives: [],
+      order_index: 0, level: undefined, subscription: "free", status: "draft", objectives: [], roles: [],
     },
   });
 
   const { fields: objectiveFields, append: appendObjective, remove: removeObjective } =
     useFieldArray({ control, name: "objectives" });
+  const { fields: roleFields, append: appendRole, remove: removeRole } =
+    useFieldArray({ control, name: "roles" });
 
   // Each section (Categories, Instructors, Badge, Achievements, Product) tracks
   // its own dirty flag already (see handleDone below) — fold them in here too
@@ -224,7 +248,8 @@ export default function EditCourse() {
     instructorsDirty ||
     badgeDirty ||
     achievementsDirty ||
-    productDirty;
+    productDirty ||
+    prereqDirty;
 
   const { bypassOnce, dialog: unsavedChangesDialog } = useUnsavedChangesGuard(hasUnsavedChanges);
 
@@ -252,6 +277,10 @@ export default function EditCourse() {
           objective_id: o.objective_id ?? null,
           text: o.text ?? "",
         })),
+        roles: (c.roles ?? []).map((r) => ({
+          role_id: r.role_id ?? null,
+          text: r.text ?? "",
+        })),
       });
       setBadgeColor(c.badge_color ?? "purple");
       setBadgeAssetId(c.badge_asset_id ?? null);
@@ -272,13 +301,15 @@ export default function EditCourse() {
 
     (async () => {
       await fetchCategories();
-      const [cats, prod, insts, achKeys] = await Promise.all([
+      const [cats, prod, insts, achKeys, prereqRes] = await Promise.all([
         fetchCourseCategories(courseId),
         fetchCourseProduct(courseId),
         fetchInstructors(courseId),
         fetchCourseAchievements(courseId),
+        fetchPrerequisites(courseId),
       ]);
       setSelectedCategoryIds((cats ?? []).map((c) => String(c.id)));
+      setPrerequisites(prereqRes?.data?.data ?? []);
       if (prod) {
         setProduct(prod);
         setProductForm({
@@ -414,6 +445,24 @@ export default function EditCourse() {
     setAchievementsLoading(false);
   };
 
+  // ─── Prerequisite handlers ────────────────────────────────────────────────
+  const handlePrerequisitesChange = useCallback((next) => {
+    setPrerequisites(next);
+    setPrereqDirty(true);
+  }, []);
+
+  const handleSavePrerequisites = async () => {
+    setPrereqLoading(true);
+    // Drop rows where the admin picked a type but never actually selected an
+    // item from the picker — sending an empty ref_id fails at the DB level.
+    const complete = prerequisites
+      .filter((p) => p.ref_id !== "" && p.ref_id != null)
+      .map(({ ref_type, ref_id }) => ({ ref_type, ref_id }));
+    await syncPrerequisites(courseId, complete);
+    setPrereqDirty(false);
+    setPrereqLoading(false);
+  };
+
   // ─── Form submit (step 0 → step 1) ───────────────────────────────────────
   const saveBasicInfo = async (values) => {
     const payload = {
@@ -423,6 +472,11 @@ export default function EditCourse() {
         text: o.text,
         order_index: i,
       })) ?? [],
+      roles: values.roles?.map((r, i) => ({
+        role_id: r.role_id ?? null,
+        text: r.text,
+        order_index: i,
+      })) ?? [],
       level: values.level || null,
       course_code: values.course_code || null,
       updatedBy: user?.user_id ?? null,
@@ -462,6 +516,7 @@ export default function EditCourse() {
       if (badgeDirty)        await handleSaveBadge();
       if (achievementsDirty) await handleSaveAchievements();
       if (productDirty && productForm.price) await handleSaveProduct();
+      if (prereqDirty) await handleSavePrerequisites();
 
       bypassOnce();
       navigate(`/admin/courses/${courseId}/view`);
@@ -654,6 +709,45 @@ export default function EditCourse() {
                     </Button>
                   </div>
                 </SectionCard>
+
+                <SectionCard
+                  title="Course Roles"
+                  description="Who is this course intended for? e.g. Sales Agent, Property Manager."
+                >
+                  <div className="space-y-2">
+                    {roleFields.map((field, index) => (
+                      <div key={field.id} className="flex items-start gap-2">
+                        <div className="flex-1 space-y-1">
+                          <Input
+                            placeholder={`Role ${index + 1}`}
+                            {...register(`roles.${index}.text`)}
+                          />
+                          <FieldError message={errors.roles?.[index]?.text?.message} />
+                        </div>
+                        <Button
+                          type="button"
+                          variant="ghost"
+                          size="icon"
+                          className="mt-0.5 text-muted-foreground hover:text-destructive"
+                          onClick={() => removeRole(index)}
+                        >
+                          <Trash2 className="h-4 w-4" />
+                        </Button>
+                      </div>
+                    ))}
+
+                    <Button
+                      type="button"
+                      variant="outline"
+                      size="sm"
+                      className="w-full mt-1"
+                      onClick={() => appendRole({ text: "" })}
+                    >
+                      <Plus className="h-4 w-4 mr-2" />
+                      Add Role
+                    </Button>
+                  </div>
+                </SectionCard>
               </>
             )}
 
@@ -1015,19 +1109,48 @@ export default function EditCourse() {
               </SectionCard>
             )}
 
-            {/* ── Step 3: Completion Requirements ── */}
+            {/* ── Step 3: Prerequisites & Completion Requirements ── */}
             {currentStep === 3 && (
-              <SectionCard
-                title="Completion Requirements"
-                description="What a learner must do for this course to count as complete."
-              >
-                <CompletionRequirementBuilder
-                  entityType="course"
-                  fetchFn={fetchCourseRequirements}
-                  syncFn={syncCourseRequirements}
-                  args={[courseId]}
-                />
-              </SectionCard>
+              <>
+                <SectionCard
+                  title="Prerequisites"
+                  description="What a learner must complete before starting this course."
+                >
+                  <CoursePrerequisiteBuilder
+                    value={prerequisites}
+                    onChange={handlePrerequisitesChange}
+                    courses={flatCourses}
+                    units={flatUnits}
+                    lessons={flatLessons}
+                    excludeCourseId={courseId}
+                  />
+
+                  <div className="flex justify-end pt-2 border-t">
+                    <Button
+                      type="button"
+                      size="sm"
+                      disabled={!prereqDirty || prereqLoading}
+                      onClick={handleSavePrerequisites}
+                    >
+                      {prereqLoading && <Spinner className="h-3 w-3 mr-1.5" />}
+                      <Save className="h-3 w-3 mr-1.5" />
+                      Save Prerequisites
+                    </Button>
+                  </div>
+                </SectionCard>
+
+                <SectionCard
+                  title="Completion Requirements"
+                  description="What a learner must do for this course to count as complete."
+                >
+                  <CompletionRequirementBuilder
+                    entityType="course"
+                    fetchFn={fetchCourseRequirements}
+                    syncFn={syncCourseRequirements}
+                    args={[courseId]}
+                  />
+                </SectionCard>
+              </>
             )}
 
             {/* ── Step 4: Pricing ── */}

src/modules/admin/pages/courses/ViewCourse.jsx

@@ -244,13 +244,23 @@ function CourseDetailsTab({ course, loading, instructors, achievementKeys, achie
             {course.prerequisites.map((p, i) => (
               <li key={p.prereq_id ?? i} className="flex items-center gap-2 text-sm">
                 <Badge variant="outline" className="capitalize text-xs">{p.ref_type}</Badge>
-                <span className="text-muted-foreground">ID: {p.ref_id}</span>
+                <span>{p.title ?? `Untitled (ID: ${p.ref_id})`}</span>
               </li>
             ))}
           </ul>
         </SectionCard>
       )}
 
+      {course.roles?.length > 0 && (
+        <SectionCard icon={Users} title="Course Roles">
+          <div className="flex flex-wrap gap-1.5">
+            {course.roles.map((r, i) => (
+              <Badge key={r.role_id ?? i} variant="secondary">{r.text}</Badge>
+            ))}
+          </div>
+        </SectionCard>
+      )}
+
       {course.assessment && (
         <SectionCard icon={Lock} title="Final Assessment">
           <div className="grid grid-cols-2 gap-4">

src/modules/admin/pages/task_list/EditTaskList.jsx

@@ -15,7 +15,7 @@ import { ArrowLeft } from 'lucide-react';
 export default function EditTaskList() {
     const navigate = useNavigate();
     const { taskListId } = useParams();
-    const { fetchTaskList, updateTaskList, assignGroups, unassignGroups, loading } = useAdminTask();
+    const { fetchTaskList, updateTaskList, syncGroups, loading } = useAdminTask();
 
     const [form, setForm] = useState(null);
     const [errors, setErrors] = useState({});
@@ -77,14 +77,14 @@ export default function EditTaskList() {
 
         if (!updated) return;
 
-        // ── 2. Diff groups ────────────────────────────────────────────────────
-        const toAssign = selectedGroupIds.filter((id) => !originalGroupIds.includes(id));
-        const toUnassign = originalGroupIds.filter((id) => !selectedGroupIds.includes(id));
+        // ── 2. Sync groups (single call — avoids burning two sensitive-op hits) ──
+        const groupsChanged =
+            selectedGroupIds.length !== originalGroupIds.length ||
+            selectedGroupIds.some((id) => !originalGroupIds.includes(id));
 
-        await Promise.all([
-            toAssign.length ? assignGroups(taskListId, toAssign) : Promise.resolve(),
-            toUnassign.length ? unassignGroups(taskListId, toUnassign) : Promise.resolve(),
-        ]);
+        if (groupsChanged) {
+            await syncGroups(taskListId, selectedGroupIds);
+        }
 
         navigate(`/admin/taskList`);
     };

src/modules/admin/pages/task_list/ViewTaskList.jsx

@@ -16,7 +16,7 @@ import {
 import {
     ArrowLeft, Pencil, Users, ClipboardList, FileText,
     Link2, Upload, BookOpen, BookMarked, FileCheck2,
-    CalendarClock, Equal, Tag, Globe, Copy, File, Bookmark,
+    CalendarClock, Equal, Tag, Globe, Copy, File, Bookmark, GitBranch,
 } from 'lucide-react';
 
 // ─── All styling uses shadcn tokens — only label/icon differs per type
@@ -281,6 +281,18 @@ export default function ViewTaskList() {
                                                         </div>
                                                     )}
 
+                                                    {task.prerequisites?.length > 0 && (
+                                                        <div className="flex items-center gap-2 text-muted-foreground">
+                                                            <GitBranch className="size-4 shrink-0" />
+                                                            <span className="text-sm">
+                                                                Requires:{' '}
+                                                                <span className="text-foreground font-medium">
+                                                                    {task.prerequisites.map((p) => p.name).join(', ')}
+                                                                </span>
+                                                            </span>
+                                                        </div>
+                                                    )}
+
                                                     <TaskRequirementsSection requirements={task.requirements} />
 
                                                 </div>

src/modules/admin/pages/task_list/task/CreateTask.jsx

@@ -8,6 +8,7 @@ import { cn } from '@/lib/utils';
 import RequirementBuilder from './RequirementBuilder';
 import { taskSchema, REQUIREMENT_TYPE_META, requirementSummaryText } from './task.schema';
 
+import TaskMultiSelect from '@/components/generic/TaskMultiSelect';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Textarea } from '@/components/ui/textarea';
@@ -39,7 +40,7 @@ function SummaryRow({ label, value }) {
 export default function CreateTask() {
     const navigate = useNavigate();
     const { taskListId } = useParams();
-    const { createTask, fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat, fetchQuizzesFlat, loading } = useAdminTask();
+    const { createTask, fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat, fetchQuizzesFlat, fetchTasksFlat, loading } = useAdminTask();
 
     const [step, setStep] = useState(0);
     const [form, setForm] = useState({
@@ -48,18 +49,21 @@ export default function CreateTask() {
         deadline: '',
         is_required: true,
         requirements: [],
+        prerequisite_task_ids: [],
     });
     const [errors, setErrors] = useState({});
     const [courses, setCourses] = useState([]);
     const [units, setUnits]     = useState([]);
     const [lessons, setLessons] = useState([]);
     const [quizzes, setQuizzes] = useState([]);
+    const [siblingTasks, setSiblingTasks] = useState([]);
 
     useEffect(() => {
         fetchCoursesFlat().then((d) => d && setCourses(d));
         fetchUnitsFlat().then((d) => d && setUnits(d));
         fetchLessonsFlat().then((d) => d && setLessons(d));
         fetchQuizzesFlat().then((d) => d && setQuizzes(d));
+        fetchTasksFlat(taskListId).then((d) => d && setSiblingTasks(d));
     }, []);
 
     const validateStep = (s) => {
@@ -113,6 +117,7 @@ export default function CreateTask() {
                 delete req.duration_seconds;
                 return req;
             }),
+            prerequisite_task_ids: form.prerequisite_task_ids,
         });
 
         if (created) navigate(`/admin/taskList/${taskListId}/tasks`);
@@ -221,6 +226,25 @@ export default function CreateTask() {
                                     onCheckedChange={(v) => setForm({ ...form, is_required: v })}
                                 />
                             </div>
+
+                            <div className="space-y-1">
+                                <Label>
+                                    Prerequisite Tasks
+                                    <span className="ml-1.5 text-xs text-muted-foreground font-normal">
+                                        (optional)
+                                    </span>
+                                </Label>
+                                <TaskMultiSelect
+                                    value={form.prerequisite_task_ids}
+                                    onChange={(ids) => setForm({ ...form, prerequisite_task_ids: ids })}
+                                    tasks={siblingTasks}
+                                    disabled={loading}
+                                    placeholder="Select tasks that must be completed first…"
+                                />
+                                <p className="text-xs text-muted-foreground">
+                                    This task stays locked until every selected task is complete. Leave empty to use the default order-based lock instead.
+                                </p>
+                            </div>
                         </CardContent>
                     </Card>
                 )}
@@ -267,6 +291,15 @@ export default function CreateTask() {
                                         ? <span className="inline-flex items-center gap-1"><Clock className="h-3.5 w-3.5" />{formattedDeadline}</span>
                                         : 'No deadline'}
                                 />
+                                <SummaryRow
+                                    label="Prerequisites"
+                                    value={form.prerequisite_task_ids.length
+                                        ? siblingTasks
+                                            .filter((t) => form.prerequisite_task_ids.includes(t.task_id))
+                                            .map((t) => t.name)
+                                            .join(', ')
+                                        : null}
+                                />
                             </CardContent>
                         </Card>
 

src/modules/admin/pages/task_list/task/EditTask.jsx

@@ -6,6 +6,7 @@ import { useAdminTask } from '@/contexts/AdminTaskContext';
 import RequirementBuilder from './RequirementBuilder';
 import { taskSchema } from './task.schema';
 
+import TaskMultiSelect from '@/components/generic/TaskMultiSelect';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Textarea } from '@/components/ui/textarea';
@@ -33,7 +34,7 @@ const STATUS_OPTIONS = [
 export default function EditTask() {
     const navigate = useNavigate();
     const { taskListId, taskId } = useParams();
-    const { fetchTask, updateTask, fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat, fetchQuizzesFlat, loading } = useAdminTask();
+    const { fetchTask, updateTask, fetchTasksFlat, fetchCoursesFlat, fetchUnitsFlat, fetchLessonsFlat, fetchQuizzesFlat, loading } = useAdminTask();
 
     const [form, setForm] = useState(null);
     const [errors, setErrors] = useState({});
@@ -41,6 +42,7 @@ export default function EditTask() {
     const [units, setUnits] = useState([]);
     const [lessons, setLessons] = useState([]);
     const [quizzes, setQuizzes] = useState([]);
+    const [siblingTasks, setSiblingTasks] = useState([]);
     const [confirmOpen, setConfirmOpen] = useState(false);
     const initialRequirementsRef = useRef(null);
 
@@ -56,12 +58,14 @@ export default function EditTask() {
                 status: data.status ?? 'pending',
                 is_required: data.is_required ?? true,
                 requirements: reqs,
+                prerequisite_task_ids: (data.prerequisites ?? []).map((p) => p.task_id),
             });
         });
         fetchCoursesFlat().then((d) => d && setCourses(d));
         fetchUnitsFlat().then((d) => d && setUnits(d));
         fetchLessonsFlat().then((d) => d && setLessons(d));
         fetchQuizzesFlat().then((d) => d && setQuizzes(d));
+        fetchTasksFlat(taskListId).then((d) => d && setSiblingTasks(d.filter((t) => t.task_id !== taskId)));
     }, [taskListId, taskId]);
 
     const requirementsChanged = () =>
@@ -100,6 +104,7 @@ export default function EditTask() {
             status:      form.status,
             is_required: form.is_required,
             requirements,
+            prerequisite_task_ids: form.prerequisite_task_ids ?? [],
         });
         if (updated) navigate(`/admin/taskList/${taskListId}/tasks`);
     };
@@ -222,6 +227,25 @@ export default function EditTask() {
                                     onCheckedChange={(v) => setForm({ ...form, is_required: v })}
                                 />
                             </div>
+
+                            <div className="space-y-1">
+                                <Label>
+                                    Prerequisite Tasks
+                                    <span className="ml-1.5 text-xs text-muted-foreground font-normal">
+                                        (optional)
+                                    </span>
+                                </Label>
+                                <TaskMultiSelect
+                                    value={form.prerequisite_task_ids ?? []}
+                                    onChange={(ids) => setForm({ ...form, prerequisite_task_ids: ids })}
+                                    tasks={siblingTasks}
+                                    disabled={loading}
+                                    placeholder="Select tasks that must be completed first…"
+                                />
+                                <p className="text-xs text-muted-foreground">
+                                    This task stays locked until every selected task is complete. Leave empty to use the default order-based lock instead.
+                                </p>
+                            </div>
                         </CardContent>
                     </Card>
 

src/modules/client/components/blocks/ReadLesson.jsx

@@ -148,13 +148,24 @@ const ReadLesson = ({ title = "Read Lessons", lessons = [], groupId, taskListId,
                             <div
                                 key={lesson.id}
                                 onClick={() => {
-                                    if (isFetching || !info?.unit?.course?.course_id) return;
-                                    navigate(`/course/${info.unit.course.course_id}/unit`, {
-                                        state: {
-                                            lessonId: info.lesson_id,
-                                            unitId: info.unit.unit_id,
-                                            ...(taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {}),
-                                        },
+                                    if (isFetching || !info) return;
+                                    // Course-attached lesson — jump straight to it within the
+                                    // course's unit reader (existing behavior).
+                                    if (info.unit?.course?.course_id) {
+                                        navigate(`/course/${info.unit.course.course_id}/unit`, {
+                                            state: {
+                                                lessonId: info.lesson_id,
+                                                unitId: info.unit.unit_id,
+                                                ...(taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {}),
+                                            },
+                                        });
+                                        return;
+                                    }
+                                    // Standalone lesson (junction revamp — no parent course, or no
+                                    // parent unit at all) — the course-scoped route can't resolve,
+                                    // so fall back to the standalone lesson page instead.
+                                    navigate(`/lessons/${lesson.reference_id}`, {
+                                        state: taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {},
                                     });
                                 }}
                                 className={`bg-card rounded-2xl border p-4 flex flex-col gap-3 transition-all w-96 shrink-0 ${

src/modules/client/components/blocks/ReadUnit.jsx

@@ -194,9 +194,18 @@ const ReadUnit = ({ title = "Read Units", units = [], groupId, taskListId, taskI
                                     <div>
                                         <h1
                                             onClick={(e) => {
-                                                if (!info?.course?.course_id) return;
+                                                if (!info) return;
                                                 e.stopPropagation();
-                                                navigate(`/course/${info.course.course_id}/unit`, {
+                                                if (info.course?.course_id) {
+                                                    navigate(`/course/${info.course.course_id}/unit`, {
+                                                        state: taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {},
+                                                    });
+                                                    return;
+                                                }
+                                                // Standalone unit (junction revamp — no parent course) —
+                                                // the course-scoped route can't resolve, fall back to
+                                                // the standalone unit reader instead.
+                                                navigate(`/units/${unit.reference_id}/read`, {
                                                     state: taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {},
                                                 });
                                             }}
@@ -248,8 +257,14 @@ const ReadUnit = ({ title = "Read Units", units = [], groupId, taskListId, taskI
                         <Button
                             onClick={() => {
                                 const info = details[selected?.reference_id];
-                                if (!info?.course?.course_id) return;
-                                navigate(`/course/${info.course.course_id}/unit`, {
+                                if (!info) return;
+                                if (info.course?.course_id) {
+                                    navigate(`/course/${info.course.course_id}/unit`, {
+                                        state: taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {},
+                                    });
+                                    return;
+                                }
+                                navigate(`/units/${selected.reference_id}/read`, {
                                     state: taskId ? { taskCtx: { has_task: true, groupId, taskListId, taskId } } : {},
                                 });
                             }}

src/modules/client/pages/CourseDetails.jsx

@@ -28,6 +28,7 @@ import { useCourseReadingProgress } from "@/contexts/ClientCourseReadingProgress
 import { PageMeta } from "@/contexts/MetadataContext";
 import { toast } from "sonner";
 import { resolveTierBadge } from "@/utils/tierBadge.util";
+import { getTierColor, getContrastText } from "@/utils/tierColors";
 import { useClientAdvertisements } from "@/contexts/ClientAdvertisementContext";
 import { Banner, BannerSkeleton } from "@/components/generic/Blocks/Client/Advertisements/Banner";
 import { Tags } from "lucide-react";
@@ -681,8 +682,8 @@ const CourseDetails = () => {
                                             )}
                                         </div>
                                         {progressSummary && progressSummary.lessons_total > 0 && (
-                                            <div className="flex flex-col gap-1.5 max-w-md">
-                                                <div className="flex items-center justify-between text-xs xs:text-white/80 lg:text-muted-foreground">
+                                            <div className="flex flex-col gap-1.5 max-w-xl">
+                                                <div className="flex items-center justify-between text-sm text-white mb-1">
                                                     <span>{progressSummary.lessons_completed} of {progressSummary.lessons_total} lessons complete</span>
                                                     <span>{progressSummary.percent}%</span>
                                                 </div>
@@ -725,7 +726,7 @@ const CourseDetails = () => {
                         <div className="lg:container lg:mx-auto flex flex-col gap-6 xs:px-3 xs:-mt-5 lg:-mt-0">
                             <div className="flex flex-col xs:gap-12 lg:gap-12 flex-1 min-w-0">
                                 <div className="space-y-4">
-                                    <div className="font-bold text-2xl">About this course</div>
+                                    <div className="font-bold text-2xl">About</div>
                                     <div className="max-w-3xl space-y-4 text-muted-foreground lg:text-lg">
                                         <p>{course?.description ?? ""}</p>
                                     </div>
@@ -736,7 +737,7 @@ const CourseDetails = () => {
                                 <div className="space-y-4">
                                     {course?.objectives?.length > 0 && (
                                         <div className="space-y-4">
-                                            <div className="font-bold text-2xl">What you will learn</div>
+                                            <div className="font-bold text-2xl">Learning Outcomes</div>
                                             <ul className="max-w-3xl list-disc list-inside space-y-1 lg:text-lg text-muted-foreground">
                                                 {course.objectives.map((obj) => (
                                                     <li key={obj.objective_id}>{obj.text}</li>
@@ -746,6 +747,104 @@ const CourseDetails = () => {
                                     )}
                                 </div>
 
+                                {/* Roles + Prerequisites */}
+                                <div className="max-w-3xl space-y-6">
+                                    {/* Roles */}
+                                    <div className=" space-y-4">
+                                        <div className="space-y-2">
+                                            <div className="font-bold text-xl">Roles</div>
+                                            <p className="text-sm text-muted-foreground">Job roles this course qualifies you for</p>
+                                        </div>
+                                        {course?.roles?.length > 0 ? (
+                                            <div className="flex flex-wrap gap-2">
+                                                {course.roles.map((r) => (
+                                                    <Badge key={r.role_id} variant="secondary" className="text-sm">
+                                                        {r.text}
+                                                    </Badge>
+                                                ))}
+                                            </div>
+                                        ) : (
+                                            <div className="rounded-lg border border-dashed p-6 text-center text-sm text-muted-foreground">
+                                                No specific roles are required for this course.
+                                            </div>
+                                        )}
+                                    </div>
+
+                                    {/* Prerequisites */}
+                                    <div className="rounded-xl border bg-card p-6 space-y-4">
+                                        <div>
+                                            <div className="font-bold text-xl">Prerequisites</div>
+                                            <p className="text-sm text-muted-foreground">Complete these courses first</p>
+                                        </div>
+                                        {course?.prerequisites?.length > 0 ? (
+                                            <div className="space-y-2">
+                                                {course.prerequisites.map((p) => {
+                                                    // Guarded = the prerequisite itself sits behind a paid tier —
+                                                    // paint the whole row with that tier's actual admin-configured
+                                                    // color (Tier Categories → Color) instead of a plain gray row.
+                                                    // Uses the swatch hex directly (inline style) rather than a
+                                                    // dynamic Tailwind class, since the color key is admin-defined
+                                                    // at runtime and arbitrary bg-{key}-500 classes aren't
+                                                    // guaranteed to survive Tailwind's build-time purge.
+                                                    const tierInfo  = p.subscription ? tierMap[p.subscription] : null;
+                                                    const guarded   = (tierInfo?.rank ?? 0) > 0 && !p.completed;
+                                                    const tierColor = guarded ? getTierColor(tierInfo.color) : null;
+                                                    const textColor = tierColor ? getContrastText(tierColor.swatch, tierInfo.color) : null;
+
+                                                    return (
+                                                        <div
+                                                            key={p.prereq_id}
+                                                            className={cn(
+                                                                "flex items-center justify-between gap-3 py-3 px-3 rounded-lg",
+                                                                p.completed && "bg-emerald-50 dark:bg-emerald-950/20",
+                                                                !p.completed && !guarded && "bg-muted/40"
+                                                            )}
+                                                            style={guarded ? { backgroundColor: tierColor.swatch } : undefined}
+                                                        >
+                                                            <div className="flex items-center gap-3 min-w-0">
+                                                                {p.completed ? (
+                                                                    <div className="w-6 h-6 rounded-full bg-emerald-500 flex items-center justify-center shrink-0">
+                                                                        <Check className="w-3.5 h-3.5 text-white" />
+                                                                    </div>
+                                                                ) : (
+                                                                    <div
+                                                                        className="size-4 rounded-full border-2 shrink-0"
+                                                                        style={{ borderColor: guarded ? textColor : undefined }}
+                                                                    />
+                                                                )}
+                                                                <span
+                                                                    className={cn("font-medium truncate", !p.completed && !guarded && "text-muted-foreground")}
+                                                                    style={{ color: guarded ? textColor : undefined }}
+                                                                >
+                                                                    {p.title ?? "—"}
+                                                                </span>
+                                                            </div>
+                                                            <Badge
+                                                                variant="secondary"
+                                                                className={cn(
+                                                                    "shrink-0 border-0 gap-1",
+                                                                    p.completed
+                                                                        ? "bg-emerald-100 text-emerald-700 dark:bg-emerald-900/40 dark:text-emerald-400"
+                                                                        : !guarded && "text-muted-foreground"
+                                                                )}
+                                                                style={guarded ? { backgroundColor: `${textColor}1a`, color: textColor } : undefined}
+                                                            >
+                                                                {p.completed
+                                                                    ? <><CheckCheck className="size-3.5" /> Completed</>
+                                                                    : <><LockIcon className="size-3.5" /> Locked</>}
+                                                            </Badge>
+                                                        </div>
+                                                    );
+                                                })}
+                                            </div>
+                                        ) : (
+                                            <div className="rounded-lg border border-dashed p-6 text-center text-sm text-muted-foreground">
+                                                No prerequisites — this is a great course to start with.
+                                            </div>
+                                        )}
+                                    </div>
+                                </div>
+
 
                                 {/* Units — while content isn't ready, only Rewards is shown */}
                                 <div className="space-y-4">

src/modules/client/pages/LessonDetails.jsx

@@ -1,17 +1,18 @@
 import AppBreadcrumb from "@/components/generic/Breadcrumb/AppBreadcrumb";
-import { useParams, useNavigate } from "react-router-dom";
+import { useParams, useNavigate, useLocation } from "react-router-dom";
 import {
-    House, SendHorizonal, CheckCheck, Check, Hourglass, Clock, Video,
+    House, SendHorizonal, CheckCheck, Check, Hourglass, Clock, Video, ListChecks,
 } from "lucide-react";
 import { Skeleton } from "@/components/ui/skeleton";
 import { Button } from "@/components/ui/button";
-import { useCallback, useEffect } from "react";
+import { useCallback, useEffect, useState } from "react";
 import { useLibrary } from "@/contexts/ClientLibraryContext";
 import { useClientTiers } from "@/contexts/ClientTiersProvider";
 import { PageMeta } from "@/contexts/MetadataContext";
 import LockedContentPanel from "@/modules/client/components/LockedContentPanel";
 import LessonBlock from "../components/LessonBlock.jsx";
 import { TYPE_DEFS } from "@/modules/admin/components/courses/completionRequirementTypes";
+import api from "@/utils/api.util";
 
 // ─── Helpers ──────────────────────────────────────────────────────────────────
 
@@ -28,6 +29,20 @@ function formatDuration(seconds = 0) {
 const LessonDetails = () => {
     const { uuid } = useParams();
     const navigate = useNavigate();
+    const location = useLocation();
+
+    // Task context: state-first, endpoint fallback — same pattern as UnitList.jsx.
+    // If navigated here from a task's requirement card, taskCtx is in location.state;
+    // if the user opened this lesson directly (e.g. from /lessons), fetch it instead,
+    // so the "Task mode" banner still shows up when this lesson is a task requirement.
+    const [taskCtx, setTaskCtx] = useState(null);
+    useEffect(() => {
+        const stateCtx = location.state?.taskCtx;
+        if (stateCtx) { setTaskCtx(stateCtx); return; }
+        api.get(`/client/courses/lesson/uuid/${uuid}/task-context`)
+            .then(({ data }) => { if (data?.data?.has_task) setTaskCtx(data.data); })
+            .catch(() => {}); // non-critical — silently swallow
+    }, [uuid]); // eslint-disable-line react-hooks/exhaustive-deps
 
     const {
         getLesson, lesson, lessonLoading, unitBlocked, unitBlockedInfo, resetLesson,
@@ -104,6 +119,20 @@ const LessonDetails = () => {
                 <div className="flex flex-col gap-6 flex-1 min-w-0 xs:px-4 xs:py-8 lg:px-16 lg:py-10">
                     <AppBreadcrumb items={items} />
 
+                    {taskCtx?.has_task && (
+                        <div className={`flex items-center gap-2 text-white text-xs font-medium px-4 py-1.5 rounded-md shadow-sm w-fit transition-colors ${
+                            hasCompleted ? 'bg-green-600' : 'bg-blue-600'
+                        }`}>
+                            <ListChecks className="size-3.5 shrink-0" />
+                            <span>
+                                {hasCompleted
+                                    ? 'Lesson complete — tracking finished'
+                                    : 'Task mode — progress is being tracked automatically'
+                                }
+                            </span>
+                        </div>
+                    )}
+
                     <div className="flex flex-col gap-3 max-w-2xl">
                         <h1 className="font-bold xs:text-2xl lg:text-3xl">{lesson.title}</h1>
                         <p className="text-muted-foreground">{lesson.description ?? ""}</p>

src/modules/client/pages/UnitReader.jsx

@@ -1,7 +1,7 @@
 import { useState, useCallback, useEffect, useRef } from "react";
 import AppBreadcrumb from "@/components/generic/Breadcrumb/AppBreadcrumb";
 import { useParams, useNavigate, useLocation, useBlocker } from "react-router-dom";
-import { House, TableOfContents, ArrowRight, ClipboardList, Lock, CheckCircle2, Circle, Zap, ChevronsLeft, ChevronsRight, Hourglass } from "lucide-react";
+import { House, TableOfContents, ArrowRight, ClipboardList, Lock, CheckCircle2, Circle, Zap, ChevronsLeft, ChevronsRight, Hourglass, ListChecks } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { ScrollArea, ScrollBar } from "@/components/ui/scroll-area";
 import { Sheet, SheetContent, SheetTrigger } from "@/components/ui/sheet";
@@ -12,6 +12,7 @@ import { useLibrary } from "@/contexts/ClientLibraryContext";
 import { PageMeta } from "@/contexts/MetadataContext";
 import { Skeleton } from "@/components/ui/skeleton";
 import { toast } from "sonner";
+import api from "@/utils/api.util";
 
 // ─── Sidebar (single unit — flat lessons + quiz, no unit-accordion nesting) ──
 
@@ -87,6 +88,19 @@ const UnitReader = () => {
     // Tracks which lessons have been marked completed this session to avoid duplicate calls
     const completedSessionRef = useRef(new Set());
 
+    // ── Task context: state-first, endpoint fallback — same pattern as UnitList.jsx.
+    // If navigated here from a task's requirement card, taskCtx is in location.state;
+    // if the user opened this unit directly (e.g. from /units), fetch it instead, so
+    // the "Task mode" banner still shows up when this unit is a task requirement.
+    const [taskCtx, setTaskCtx] = useState(null);
+    useEffect(() => {
+        const stateCtx = location.state?.taskCtx;
+        if (stateCtx) { setTaskCtx(stateCtx); return; }
+        api.get(`/client/courses/unit/uuid/${uuid}/task-context`)
+            .then(({ data }) => { if (data?.data?.has_task) setTaskCtx(data.data); })
+            .catch(() => {}); // non-critical — silently swallow
+    }, [uuid]); // eslint-disable-line react-hooks/exhaustive-deps
+
     // ── Local UI state ──────────────────────────────────────────────────────
     const [selectedLessonId, setSelectedLessonId] = useState(null);
     const [selectedQuizId, setSelectedQuizId] = useState(null);
@@ -440,8 +454,23 @@ const UnitReader = () => {
                 )}
             </div>
 
+            {/* ── Task-mode banner ─────────────────────────────────────────── */}
+            {taskCtx?.has_task && (
+                <div className={`fixed xs:top-[124px] lg:top-[112px] left-0 right-0 z-30 flex items-center gap-2 text-white text-xs font-medium px-4 py-1.5 shadow-sm transition-colors ${
+                    unitDetail?.is_completed ? 'bg-green-600' : 'bg-blue-600'
+                }`}>
+                    <ListChecks className="size-3.5 shrink-0" />
+                    <span>
+                        {unitDetail?.is_completed
+                            ? 'Unit complete — tracking finished'
+                            : 'Task mode — progress is being tracked automatically'
+                        }
+                    </span>
+                </div>
+            )}
+
             {/* ── Desktop sidebar ── */}
-            <div className="hidden lg:flex flex-row fixed top-[112px] bottom-0 left-0 z-30 bg-muted border-r">
+            <div className={`hidden lg:flex flex-row fixed ${taskCtx?.has_task ? "top-[140px]" : "top-[112px]"} bottom-0 left-0 z-30 bg-muted border-r`}>
                 <div className="w-14 shrink-0 flex flex-col items-center pt-3">
                     <Button
                         variant="ghost"
@@ -471,7 +500,7 @@ const UnitReader = () => {
             </div>
 
             {/* ── Main content ── */}
-            <div className={`mt-32 ${showSidebarContent ? "lg:ml-80" : "lg:ml-14"} p-4 md:p-6 min-h-screen`}>
+            <div className={`${taskCtx?.has_task ? "xs:mt-42 lg:mt-36" : "mt-32"} ${showSidebarContent ? "lg:ml-80" : "lg:ml-14"} p-4 md:p-6 min-h-screen`}>
                 <div className="relative w-full h-full">
                     {selectedQuizId ? (
                         <QuizBlock

src/modules/client/pages/ViewTaskDetails.jsx

@@ -18,6 +18,9 @@ import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 import { Skeleton } from '@/components/ui/skeleton';
 import { Progress } from '@/components/ui/progress';
+import {
+    Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription,
+} from '@/components/ui/dialog';
 import {
     House, Calendar, AlertTriangle, Check, ArrowRight, ListChecks, LayoutList,
     LaptopMinimal, Table, Lock,
@@ -75,17 +78,17 @@ const TaskStatusBadge = ({ task }) => {
 };
 
 // ─── Task card ────────────────────────────────────────────────────────────────
-const TaskCard = ({ task, onClick, locked }) => {
+const TaskCard = ({ task, onClick, locked, lockedBy, onLockedClick }) => {
     const reqCount = task.requirements?.length ?? 0;
 
     return (
         <div
-            onClick={() => !locked && onClick()}
+            onClick={() => (locked ? onLockedClick(lockedBy) : onClick())}
             className={cn(
-                'border bg-card rounded-lg flex flex-col transition-colors',
+                'border bg-card rounded-lg flex flex-col transition-colors cursor-pointer',
                 locked
-                    ? 'opacity-60 cursor-not-allowed'
-                    : 'cursor-pointer hover:border-blue-400 dark:hover:border-blue-500',
+                    ? 'opacity-60 hover:border-muted-foreground/30'
+                    : 'hover:border-blue-400 dark:hover:border-blue-500',
                 task.has_completed && 'opacity-90',
             )}
         >
@@ -101,17 +104,15 @@ const TaskCard = ({ task, onClick, locked }) => {
                         : <TaskStatusBadge task={task} />
                     }
                 </div>
-                {task.description && (
-                    <p className="text-sm text-muted-foreground leading-relaxed line-clamp-2">
-                        {task.description}
-                    </p>
-                )}
+                <p className="text-sm text-muted-foreground leading-relaxed line-clamp-2">
+                    {task.description || 'No information details provided'}
+                </p>
                 <div className="flex items-center gap-1.5 text-xs text-muted-foreground mt-auto pt-1 [&_svg]:size-3.5">
                     <Calendar />
                     {task.deadline ? `Due ${formatDate(task.deadline)}` : 'No due date'}
                 </div>
                 {locked && (
-                    <p className="text-xs text-muted-foreground">Complete the earlier required tasks to unlock.</p>
+                    <p className="text-xs text-muted-foreground">Tap to see what's required to unlock this task.</p>
                 )}
             </div>
             <div className="px-4 py-2.5 border-t flex items-center justify-between">
@@ -167,9 +168,10 @@ const ViewTaskDetails = () => {
     const { taskList, loading, fetchTaskList } = useTask();
     const { group, fetchGroup } = useGroup();
 
-    const [view,      setView]      = useState('grid');
-    const [activeTab, setActiveTab] = useState('tab-ongoing');
-    const [allTasks,  setAllTasks]  = useState([]);
+    const [view,       setView]       = useState('grid');
+    const [activeTab,  setActiveTab]  = useState('tab-ongoing');
+    const [allTasks,   setAllTasks]   = useState([]);
+    const [lockedInfo, setLockedInfo] = useState(null); // task names blocking the last-clicked locked card
 
     // ── Fetch group info once ─────────────────────────────────────────────────
     useEffect(() => {
@@ -193,12 +195,13 @@ const ViewTaskDetails = () => {
             .catch(() => {});
     }, [groupId, taskListId]);
 
-    // ── Sequencing lock — same pattern as UnitList.jsx's quiz lock ───────────
+    // ── Sequencing/prerequisite lock — computed server-side (task.locked,
+    // task.lockedBy), since an explicit prerequisite graph can't be expressed
+    // as a one-line client-side scan the way the old order_index-only rule could.
     const lockedTaskIds = new Set(
-        allTasks
-            .filter((t, i, arr) => arr.slice(0, i).some((prev) => prev.is_required && !prev.has_completed))
-            .map((t) => t.task_id)
+        allTasks.filter((t) => t.locked).map((t) => t.task_id)
     );
+    const lockedByById = new Map(allTasks.map((t) => [t.task_id, t.lockedBy ?? []]));
 
     const completedCount = allTasks.filter((t) => t.has_completed).length;
 
@@ -250,6 +253,8 @@ const ViewTaskDetails = () => {
                         key={task.task_id}
                         task={task}
                         locked={lockedTaskIds.has(task.task_id)}
+                        lockedBy={lockedByById.get(task.task_id) ?? []}
+                        onLockedClick={setLockedInfo}
                         onClick={() => navigate(`task/${task.task_id}`)}
                     />
                 ))}
@@ -351,6 +356,35 @@ const ViewTaskDetails = () => {
                 </div>
 
             </div>
+
+            {/* ── Locked task requirement dialog ── */}
+            <Dialog open={!!lockedInfo} onOpenChange={(open) => !open && setLockedInfo(null)}>
+                <DialogContent className="sm:max-w-md">
+                    <DialogHeader>
+                        <DialogTitle className="flex items-center gap-2">
+                            <Lock className="size-4" /> Task locked
+                        </DialogTitle>
+                        <DialogDescription>
+                            {lockedInfo?.length
+                                ? `Complete the following task${lockedInfo.length !== 1 ? 's' : ''} first to unlock this one:`
+                                : 'Complete the earlier required tasks first to unlock this one.'}
+                        </DialogDescription>
+                    </DialogHeader>
+                    {!!lockedInfo?.length && (
+                        <ul className="flex flex-col gap-2">
+                            {lockedInfo.map((t) => (
+                                <li
+                                    key={t.task_id}
+                                    className="flex items-center gap-2 text-sm bg-muted rounded-md px-3 py-2"
+                                >
+                                    <ListChecks className="size-3.5 text-muted-foreground shrink-0" />
+                                    {t.name}
+                                </li>
+                            ))}
+                        </ul>
+                    )}
+                </DialogContent>
+            </Dialog>
         </div>
     );
 };