diff --git a/app/api/generate/scene-outlines-stream/route.ts b/app/api/generate/scene-outlines-stream/route.ts
index f0d599e8fc..b7ea020ba2 100644
--- a/app/api/generate/scene-outlines-stream/route.ts
+++ b/app/api/generate/scene-outlines-stream/route.ts
@@ -337,6 +337,8 @@ export async function POST(req: NextRequest) {
       mediaEnabled: mediaGenerationEnabled,
       teacherContext,
       userProfile: userProfileText,
+      // Design Brief mode: emit a natural-language `brief` + structured `media[]` per slide.
+      designBriefMode: requirements.designBriefMode === true,
     });
 
     if (!prompts) {
diff --git a/lib/generation/outline-generator.ts b/lib/generation/outline-generator.ts
index 1c90feab60..7e938d445c 100644
--- a/lib/generation/outline-generator.ts
+++ b/lib/generation/outline-generator.ts
@@ -100,6 +100,7 @@ export async function generateSceneOutlinesFromRequirements(
     imageEnabled,
     videoEnabled,
     mediaEnabled,
+    designBriefMode: requirements.designBriefMode === true,
     researchContext: options?.researchContext || 'None',
     // Server-side generation populates this via options; client-side populates via formatTeacherPersonaForPrompt
     teacherContext: options?.teacherContext || '',
diff --git a/lib/generation/scene-builder.ts b/lib/generation/scene-builder.ts
index 478e179fdc..309d5fb25b 100644
--- a/lib/generation/scene-builder.ts
+++ b/lib/generation/scene-builder.ts
@@ -33,10 +33,34 @@ const log = createLogger('Generation');
  * contamination on the homepage. Using nanoid-based IDs ensures global uniqueness.
  */
 export function uniquifyMediaElementIds(outlines: SceneOutline[]): SceneOutline[] {
+  // Design Brief mode bridge: the outliner emits a structured `media[]` manifest
+  // (parallel to `brief`). Derive the existing `mediaGenerations` (generate items)
+  // and `suggestedImageIds` (asset items) from it so the existing media-orchestrator
+  // dispatches generation. Skipped when mediaGenerations is already populated.
+  const bridged = outlines.map((outline) => {
+    if (!outline.media || outline.media.length === 0) return outline;
+    const gen = outline.media.filter((m) => m.source === 'generate');
+    const assetIds = outline.media.filter((m) => m.source === 'asset').map((m) => m.id);
+    const mediaGenerations =
+      outline.mediaGenerations && outline.mediaGenerations.length > 0
+        ? outline.mediaGenerations
+        : gen.map((m) => ({
+            type: m.type,
+            prompt: m.prompt ?? m.caption ?? '',
+            elementId: m.id,
+            aspectRatio: m.aspectRatio,
+          }));
+    const suggestedImageIds =
+      assetIds.length > 0
+        ? Array.from(new Set([...(outline.suggestedImageIds ?? []), ...assetIds]))
+        : outline.suggestedImageIds;
+    return { ...outline, mediaGenerations, suggestedImageIds };
+  });
+
   const idMap = new Map<string, string>();
 
   // First pass: collect all sequential media IDs and assign unique replacements
-  for (const outline of outlines) {
+  for (const outline of bridged) {
     if (!outline.mediaGenerations) continue;
     for (const mg of outline.mediaGenerations) {
       if (!idMap.has(mg.elementId)) {
@@ -46,17 +70,25 @@ export function uniquifyMediaElementIds(outlines: SceneOutline[]): SceneOutline[
     }
   }
 
-  if (idMap.size === 0) return outlines;
+  if (idMap.size === 0) return bridged;
+
+  // Rewrite a brief's inline id references (e.g. "right column shows gen_img_1") to
+  // keep them in sync with the uniquified ids. `\d+\b` captures the full number so
+  // gen_img_1 and gen_img_10 stay distinct.
+  const rewriteBrief = (brief: string | undefined): string | undefined =>
+    brief?.replace(/\b(?:gen_(?:img|vid)|img)_\d+\b/g, (token) => idMap.get(token) ?? token);
 
-  // Second pass: replace IDs in mediaGenerations
-  return outlines.map((outline) => {
-    if (!outline.mediaGenerations) return outline;
+  // Second pass: replace IDs in mediaGenerations, media[], and the brief together
+  return bridged.map((outline) => {
+    if (!outline.mediaGenerations && !outline.media && !outline.brief) return outline;
     return {
       ...outline,
-      mediaGenerations: outline.mediaGenerations.map((mg) => ({
+      mediaGenerations: outline.mediaGenerations?.map((mg) => ({
         ...mg,
-        elementId: idMap.get(mg.elementId) || mg.elementId,
+        elementId: idMap.get(mg.elementId) ?? mg.elementId,
       })),
+      media: outline.media?.map((m) => ({ ...m, id: idMap.get(m.id) ?? m.id })),
+      brief: rewriteBrief(outline.brief),
     };
   });
 }
diff --git a/lib/generation/scene-generator.ts b/lib/generation/scene-generator.ts
index 0a86a7157e..8cdd1c0b9a 100644
--- a/lib/generation/scene-generator.ts
+++ b/lib/generation/scene-generator.ts
@@ -738,6 +738,9 @@ async function generateSlideContent(
     title: outline.title,
     description: outline.description,
     keyPoints: (outline.keyPoints || []).map((p, i) => `${i + 1}. ${p}`).join('\n'),
+    // Design Brief mode: when the outline carries a natural-language `brief`, it is
+    // the authoritative layout spec (the prompt prefers it over title/keyPoints).
+    brief: outline.brief?.trim() || '',
     elements: '（根据要点自动生成）',
     assignedImages: assignedImagesText,
     canvas_width: canvasWidth,
diff --git a/lib/prompts/templates/requirements-to-outlines/system.md b/lib/prompts/templates/requirements-to-outlines/system.md
index 096dba2582..153bb029dc 100644
--- a/lib/prompts/templates/requirements-to-outlines/system.md
+++ b/lib/prompts/templates/requirements-to-outlines/system.md
@@ -279,6 +279,10 @@ Rules:
 | title             | string                   | ✅       | Scene title, concise and clear                                                                   |
 | description       | string                   | ✅       | 1-2 sentences describing teaching purpose                                                        |
 | keyPoints         | string[]                 | ✅       | 3-5 core points                                                                                  |
+{{#if designBriefMode}}
+| brief             | string                   | ✅ (for slide) | Detailed natural-language design brief for `slide` scenes — see "Slide Design Brief" below |
+| media             | SlideMediaItem[]         | ❌ (for slide) | Structured manifest of the images/videos this slide actually needs; the brief references each by id — see "Slide Design Brief" below. Omit when the slide needs no media. |
+{{/if}}
 | teachingObjective | string                   | ❌       | Corresponding learning objective                                                                 |
 | estimatedDuration | number                   | ❌       | Estimated duration (seconds)                                                                     |
 | order             | number                   | ✅       | Sort order, starting from 1                                                                      |
@@ -294,6 +298,65 @@ Rules:
 | widgetOutline     | object                   | ✅ (for interactive) | Widget-specific configuration (see Widget Type Selection)                                                               |
 | pblConfig         | object                   | ❌       | Required for pbl type, contains projectTopic/projectDescription/targetSkills/issueCount/language |
 
+{{#if designBriefMode}}
+### Slide Design Brief (required for every `slide` scene)
+
+For every scene with `"type": "slide"`, add a `brief` field: a detailed natural-language design brief that a layout designer could turn directly into a finished slide. This is the PRIMARY input to the slide renderer — write rich, specific, flowing prose (roughly 120–280 words), not a bullet list. Keep `description` and `keyPoints` short as before; invest the real detail in `brief`.
+
+Each `brief` must cover, in prose:
+
+1. **Page goal** — the single concept this one slide must land and what the viewer grasps at a glance. One slide = one idea; never cram a whole lesson.
+2. **Overall visual style** — the look plus a simple color palette in words (e.g. "white background, deep-blue title, teal accent line, light-gray table"), and whether to avoid images or use them.
+3. **Layout in regions, not pixels** — e.g. a top title band, then a left/right column split with rough proportions ("left column ~60% holds the table, right ~40% the diagram"), and grouping/spacing. NEVER give pixel coordinates, px sizes, or font sizes.
+4. **The actual content of each block, written out** — do NOT say "a table comparing X"; write the real rows, numbers, and formulas. Wrap anything that must appear exactly (formulas, numbers, proper nouns, technical terms) in double quotes, e.g. the formula `"3x + 5 = 17"`, the value `"42%"`, the term `"SYN-ACK"`. On-slide text must be in the course language from `languageDirective`.
+5. **Visual emphasis** — name the focal element and what is secondary.
+6. **Media discipline** — do NOT add decorative images or per-card icons just to fill space; **most slides need ZERO images**. Draw dividers, badges and simple icons with `shape`/`line`, and prefer `table`/`chart`/`latex` to carry information. Only request a real image/video when it carries irreplaceable visual information (an actual diagram, a photograph, an illustrative scene). When you do, put it in the structured `media` manifest below — **never just write "add an icon/picture" in the prose.**
+
+#### The `media` manifest (structured, parallel to `brief`)
+
+When — and only when — a slide genuinely needs an image or video, also output a `media` array listing each one, and have the `brief` refer to each item **by its `id`** (e.g. `right column shows gen_img_1 (a GAD-vs-human scatter plot)`) rather than vaguely saying "add a figure". Each item:
+
+- `id`: `gen_img_1`, `gen_img_2`, … for to-be-generated images (`gen_vid_1`, … for video). Use a real `img_N` id **only** when that image is listed under Available Images.
+- `source`: `"generate"` (AI will create it) or `"asset"` (a real listed `img_N` already exists).
+- `type`: `"image"` or `"video"`.
+- `prompt`: concise English description of what to generate — **REQUIRED for `source:"generate"`**, omit for `"asset"`.
+- `caption`: one short phrase for what it depicts / its role.
+- `aspectRatio`: `"16:9"` | `"4:3"` | `"1:1"` | `"9:16"` (optional, default 16:9).
+
+**Consistency is mandatory**: every id referenced in `brief` MUST appear in `media`, and every id in `media` MUST be referenced in `brief`. If the slide needs no media, omit `media` and do not mention any image id in the brief.
+
+**Example A — a content slide that needs NO media (the common case):**
+
+```json
+{
+  "id": "scene_4",
+  "type": "slide",
+  "title": "Special-Angle Trig Values",
+  "description": "Help students quickly look up trig values for special angles.",
+  "keyPoints": ["quick-reference table", "unit circle", "memory steps"],
+  "brief": "A clean reference slide titled \"Special-Angle Trig Values\". White background, deep-blue title, teal accent line, light blue-gray table; no images. Top ~12% is the title band with a small right-aligned tag \"radians · unit circle · quick table\", and a thin teal rule under it. The body is a left/right split: the left column (~62%) holds the focal table — 6 rows × 5 columns with headers \"angle, radians, sinθ, cosθ, tanθ\" and data \"0°|0|0|1|0\", \"30°|π/6|1/2|√3/2|√3/3\", \"45°|π/4|√2/2|√2/2|1\", \"60°|π/3|√3/2|1/2|√3\", \"90°|π/2|1|0|undefined\"; deep-blue header row, with a light-gray note below it: \"tanθ = sinθ / cosθ, so tanθ is undefined when cosθ = 0\". The right column (~38%) draws a simple unit circle marking the \"30°\", \"45°\", \"60°\" radii, and below it three memory-step cards \"1 convert to radians\", \"2 find the reference angle\", \"3 fix the quadrant sign\" with teal borders.",
+  "order": 4
+}
+```
+
+**Example B — a slide that genuinely needs ONE figure (structured `media` + id reference in the brief):**
+
+```json
+{
+  "id": "scene_6",
+  "type": "slide",
+  "title": "GAD: Right Density, No Overlap, No Fragmentation",
+  "description": "Use a scatter plot to show GAD correlates strongly with human ratings.",
+  "keyPoints": ["GAD=OM+FR", "correlates with human score", "RMSE/ρ"],
+  "media": [
+    { "id": "gen_img_1", "source": "generate", "type": "image", "prompt": "scatter plot showing strong positive correlation between a GAD layout metric on the x-axis and human ratings on the y-axis, clean academic style", "caption": "GAD vs human-rating scatter plot", "aspectRatio": "4:3" }
+  ],
+  "brief": "An academic slide titled \"GAD: Right Density, No Overlap, No Fragmentation\". White background, deep-blue title, teal accents, with a thin rule under the title band. Centered near the top is the formula \"GAD = OM + FR\". Below it a left/right split: the left column explains the three terms in words (Occupancy Matching OM, Fragmentation Reward FR, overall density), and the right column shows gen_img_1 (the GAD-vs-human-rating scatter plot) with a one-line caption beneath it. A centered light-yellow stat box at the bottom reads \"RMSE = 0.580   ρ = 0.820\". No other images or icons besides that scatter plot.",
+  "order": 6
+}
+```
+{{/if}}
+
 ### quizConfig Structure
 
 ```json
diff --git a/lib/prompts/templates/requirements-to-outlines/user.md b/lib/prompts/templates/requirements-to-outlines/user.md
index a00c1ff1a0..1186cf6914 100644
--- a/lib/prompts/templates/requirements-to-outlines/user.md
+++ b/lib/prompts/templates/requirements-to-outlines/user.md
@@ -86,6 +86,10 @@ Never return a bare array. Never omit `languageDirective`. Both keys are require
 {{#if hasSourceImages}}
 - **If source images are available**, add `suggestedImageIds` to relevant slide scenes. Only use image IDs listed under Available Images.
 {{/if}}
+{{#if designBriefMode}}
+- **Every `slide` scene MUST include a `brief`** — a detailed natural-language design brief (~120–280 words) following the "Slide Design Brief" section in the system prompt: page goal, visual style + color palette in words, region-based layout (no pixels), the actual written-out content (real rows/numbers/formulas, verbatim parts in quotes), and focal emphasis. `description`/`keyPoints` stay short; the real detail goes in `brief`.
+- **Media discipline**: most slides need NO images — draw icons/dividers with shapes and carry information with `table`/`chart`/`latex`. Do NOT add decorative images or per-card icons. ONLY when a slide genuinely needs a figure/photo/video, add a structured `media` array (each `{id, source, type, prompt?, caption, aspectRatio?}`) and reference each item in the `brief` by its `id` (e.g. `gen_img_1`). Every brief id ⇔ a `media` entry (both directions). No media → omit `media` and mention no image id.
+{{/if}}
 - **Interactive scenes**: If a concept benefits from hands-on simulation/visualization, use `"type": "interactive"` with `widgetType` and `widgetOutline` fields. Limit to 1-2 per course.
    - Select widgetType based on concept: simulation (physics/chem), diagram (processes), code (programming), game (practice), visualization3d (3D models)
    - Provide appropriate widgetOutline for the widget type
diff --git a/lib/prompts/templates/slide-content/user.md b/lib/prompts/templates/slide-content/user.md
index 844139b9c3..2d38fbae54 100644
--- a/lib/prompts/templates/slide-content/user.md
+++ b/lib/prompts/templates/slide-content/user.md
@@ -7,6 +7,14 @@
 - **Key Points**:
   {{keyPoints}}
 
+{{#if brief}}
+## Design Brief (authoritative)
+
+A detailed design brief is provided below. Treat it as the **authoritative** layout and content spec for this slide — the Title/Description/Key Points above are only a summary. Realize the brief faithfully: preserve its visual hierarchy, regions and proportions, and render the content it spells out (tables, formulas, lists, media). When the brief references a media id (e.g. `gen_img_1`, `img_2`), use that exact id as the element `src`.
+
+{{brief}}
+{{/if}}
+
 {{teacherContext}}
 
 ## Available Resources
diff --git a/lib/types/generation.ts b/lib/types/generation.ts
index 845846fe8b..b6bee8b63c 100644
--- a/lib/types/generation.ts
+++ b/lib/types/generation.ts
@@ -53,6 +53,7 @@ export interface UserRequirements {
   webSearch?: boolean; // Enable web search for richer context
   interactiveMode?: boolean; // Enable Interactive Mode for interactive-first generation
   taskEngineMode?: boolean; // Enable vocational task-engine generation path
+  designBriefMode?: boolean; // Outliner emits a natural-language design `brief` + structured `media[]` per slide scene
 }
 
 // ==================== Stage 1 Output: Scene Outlines (Simplified) ====================
@@ -85,6 +86,28 @@ export interface WidgetOutline {
   challengeType?: string; // code - type of coding challenge
 }
 
+/**
+ * Structured media item for a slide outline (Design Brief mode).
+ *
+ * Unifies real source images (e.g. PDF-extracted) and to-be-generated media into
+ * ONE manifest that sits parallel to `brief`. The brief references each item by
+ * `id`, so the slide-content model is told exactly which media exist (and whether
+ * each is a real asset or a placeholder) instead of inferring image intent from
+ * prose — which avoids over-emitting decorative image placeholders.
+ */
+export interface SlideMediaItem {
+  /** Id used both in the brief reference and as the slide element `src`. */
+  id: string; // 'img_1' (source asset) | 'gen_img_1' / 'gen_vid_1' (to generate)
+  /** 'asset' = a real image already available; 'generate' = AI-generated placeholder. */
+  source: 'asset' | 'generate';
+  type: 'image' | 'video';
+  /** Generation prompt — required for source:'generate'; omit for 'asset'. */
+  prompt?: string;
+  /** What it depicts / its role on the page; shown to the slide-content model. */
+  caption?: string;
+  aspectRatio?: '16:9' | '4:3' | '1:1' | '9:16';
+}
+
 /**
  * Simplified scene outline
  * Gives AI more freedom, only requiring intent description and key points
@@ -95,6 +118,12 @@ export interface SceneOutline {
   title: string;
   description: string; // 1-2 sentences describing the purpose
   keyPoints: string[]; // 3-5 core key points
+  // Design Brief mode (UserRequirements.designBriefMode): a detailed natural-language
+  // design brief for `slide` scenes, used as the primary slide-content input when present.
+  brief?: string;
+  // Design Brief mode: structured manifest of the images/videos this slide actually
+  // needs; the brief references each by id. Unifies source (asset) and generate.
+  media?: SlideMediaItem[];
   teachingObjective?: string;
   estimatedDuration?: number; // seconds
   order: number;