refactor(whiteboard): address code-review feedback

W1: drop stale "prior-state image" reference from conflict-block prose
    (lib/orchestration/summarizers/whiteboard-conflicts.ts) — the image
    feature was removed; the text now says "real visible problem on the
    current board".

W3: type `thinking` on StatelessChatRequest instead of reading it through
    a cast. `app/api/chat/route.ts` now accesses `body.thinking` directly;
    frontend callers can discover the field via TS completion.

W4: unify canvas height constant to 563 (matching the actual rendered
    pixel count from capture.ts). The geometry detector's
    CANVAS_HEIGHT, the snippet's Dimensions / coordinate system /
    layout-guide text, and examples all now agree.

N6: add tests/orchestration/whiteboard-conflicts.test.ts — 17 cases
    covering empty input, bbox overlap threshold (30%, 50%, 100%, plus
    10% sub-threshold), line-crosses-bbox (through, endpoint-inside,
    path-above), canvas clipping on all 4 edges, exact-edge placement
    (not reported), malformed elements (skipped not crashed), and
    output format.

All 43 tests pass; tsc --noEmit clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/api/chat/route.ts

@@ -120,12 +120,7 @@ export async function POST(req: NextRequest) {
         // Default: thinking disabled for low-latency chat. Callers (e.g. eval
         // harness) can opt in per-request by sending `thinking: { enabled: true }`
         // in the body.
-        const requestedThinking = (body as unknown as { thinking?: ThinkingConfig })
-          .thinking;
-        const thinkingConfig: ThinkingConfig =
-          requestedThinking && typeof requestedThinking === 'object'
-            ? requestedThinking
-            : { enabled: false };
+        const thinkingConfig: ThinkingConfig = body.thinking ?? { enabled: false };
 
         const generator = statelessGenerate(
           {

lib/orchestration/summarizers/whiteboard-conflicts.ts

@@ -11,7 +11,7 @@
  */
 
 const CANVAS_WIDTH = 1000;
-const CANVAS_HEIGHT = 562;
+const CANVAS_HEIGHT = 563;
 const OVERLAP_THRESHOLD = 0.3; // intersection / min-area; flag if >= 30%
 
 interface BBox {
@@ -172,7 +172,7 @@ function shortId(id: string): string {
  * Detected conflicts:
  * - bbox overlap >= 30% of the smaller element's area
  * - line/arrow path crossing through any non-line element's bbox
- * - any element extending past the 1000×562 canvas bounds
+ * - any element extending past the 1000×563 canvas bounds
  */
 // eslint-disable-next-line @typescript-eslint/no-explicit-any -- PPTElement variants
 export function buildWhiteboardConflicts(elements: any[]): string {
@@ -236,7 +236,7 @@ export function buildWhiteboardConflicts(elements: any[]): string {
 
   const lines_out = conflicts.map((c) => `  - ${c}`).join('\n');
   return `\n## ⚠ Layout Conflicts Detected (computed from current whiteboard JSON)
-The following geometric conflicts exist on the board RIGHT NOW. Each one corresponds to a real visible problem in the prior-state image. You MUST address these before adding new content — either wb_delete one of the conflicting elements, or wb_clear and start fresh:
+The following geometric conflicts exist on the board RIGHT NOW. Each entry is a real visible problem on the current board. You MUST address these before adding new content — either wb_delete one of the conflicting elements, or wb_clear and start fresh:
 ${lines_out}
 `;
 }

lib/prompts/snippets/whiteboard-reference.md

@@ -2,15 +2,15 @@
 
 ### Canvas Specifications
 
-**Dimensions**: 1000 × 562 pixels.
+**Dimensions**: 1000 × 563 pixels.
 
-**Coordinate system**: `x = 0` at the left edge, `x = 1000` at the right edge. `y = 0` at the top, `y = 562` at the bottom. Every element has `(left, top)` at its top-left corner.
+**Coordinate system**: `x = 0` at the left edge, `x = 1000` at the right edge. `y = 0` at the top, `y = 563` at the bottom. Every element has `(left, top)` at its top-left corner.
 
-**Safe zone**: keep content within `x ∈ [20, 980]` and `y ∈ [20, 542]` to leave a 20px margin from the canvas edges.
+**Safe zone**: keep content within `x ∈ [20, 980]` and `y ∈ [20, 543]` to leave a 20px margin from the canvas edges.
 
 **Reference points**:
 - Centered horizontally: `x = (1000 - width) / 2`
-- Centered vertically: `y = (562 - height) / 2`
+- Centered vertically: `y = (563 - height) / 2`
 - Two-column layout: left column `x ∈ [20, 480]`, right column `x ∈ [520, 980]` (40px gutter)
 
 ### JSON Output Context
@@ -129,7 +129,7 @@ Render a data chart.
 | `themeColors` | string[] | no | Palette override. |
 | `elementId` | string | no | Stable ID. |
 
-**Common mistake**: placing a chart that extends past `x + width = 1000` or `y + height = 562` — charts silently clip at canvas edges.
+**Common mistake**: placing a chart that extends past `x + width = 1000` or `y + height = 563` — charts silently clip at canvas edges.
 
 #### wb_draw_table
 
@@ -268,11 +268,11 @@ The JSON parser sees `\f` (form feed), `\p` (kept as `\p`), `\s` (kept as `\s`).
 
 ### Bounds & Overlap
 
-The canvas is **1000 × 562**. Elements that extend past the edges are clipped.
+The canvas is **1000 × 563**. Elements that extend past the edges are clipped.
 
 **Hard bounds** (every element):
 - `x ≥ 0` and `x + width ≤ 1000`
-- `y ≥ 0` and `y + height ≤ 562`
+- `y ≥ 0` and `y + height ≤ 563`
 
 **Safe zone** (preferred): `20 ≤ x`, `x + width ≤ 980`, `20 ≤ y`, `y + height ≤ 542`.
 
@@ -297,7 +297,7 @@ The canvas is **1000 × 562**. Elements that extend past the edges are clipped.
 chart occupies x=100..600, y=80..280
 next safe y  = 80 + 200 + 30 = 310
 formula at (100, 310, height 80) → occupies y=310..390
-check: y + height = 390 ≤ 562  ✓
+check: y + height = 390 ≤ 563  ✓
 check: no overlap with chart (chart ends at y=280, formula starts at y=310) ✓
 ```
 
@@ -350,12 +350,12 @@ Width is auto-computed from `height × aspect_ratio`; `width` acts as a horizont
 Before emitting whiteboard actions, mentally walk through these:
 
 1. **[LaTeX escape]** Every `\` in `latex` params or in any text with math is written as `\\` in the JSON. Scan for single-backslash `\frac`, `\text`, `\theta`, `\times`, `\rightarrow`, `\circ`, `\beta`, `\varphi` — none should appear.
-2. **[Hard bounds]** For each element: `x ≥ 0`, `y ≥ 0`, `x + width ≤ 1000`, `y + height ≤ 562`.
+2. **[Hard bounds]** For each element: `x ≥ 0`, `y ≥ 0`, `x + width ≤ 1000`, `y + height ≤ 563`.
 3. **[Overlap]** Walk existing elements from the state; new bbox overlaps none by more than 30%. If tight, `wb_delete` first.
 4. **[Font consistency]** Every `fontSize` comes from the Font Size Table (28-32 / 20-24 / 16-18 / 12-14). No 8, 11, 48, 64.
 5. **[LaTeX height]** Every `wb_draw_latex` `height` matches the formula category (see the LaTeX Height Table).
 6. **[Redraw guard]** The element is not already on the whiteboard — if the state lists a formula/chart/table matching your intent, reference it instead of redrawing.
 7. **[Element type]** Math expressions use `wb_draw_latex`. Plain text uses `wb_draw_text`. Never embed LaTeX commands in text.
-8. **[Safe zone]** Where possible, stay within `x ∈ [20, 980]`, `y ∈ [20, 542]`.
+8. **[Safe zone]** Where possible, stay within `x ∈ [20, 980]`, `y ∈ [20, 543]`.
 9. **[Leave whiteboard open]** Do not call `wb_close` at the end of a drawing turn. Students need to read.
 10. **[Visual weight pairing]** Text that sits next to a LaTeX formula uses a `fontSize` matched to the LaTeX `height` per the pairing table above. No tiny 12-14px text next to height-80 formulas.

lib/types/chat.ts

@@ -6,6 +6,7 @@
  */
 
 import type { UIMessage } from 'ai';
+import type { ThinkingConfig } from './provider';
 
 // Session Types
 export type SessionType = 'qa' | 'discussion' | 'lecture';
@@ -280,6 +281,12 @@ export interface StatelessChatRequest {
   baseUrl?: string;
   model?: string;
   providerType?: string;
+  /**
+   * Opt-in: enable provider-side thinking for this request. Default is
+   * `{ enabled: false }` (low-latency chat). Eval harness sets this to
+   * `{ enabled: true }` when `EVAL_ENABLE_THINKING=1`.
+   */
+  thinking?: ThinkingConfig;
 }
 
 /**

tests/orchestration/whiteboard-conflicts.test.ts

@@ -0,0 +1,177 @@
+import { describe, expect, test } from 'vitest';
+import { buildWhiteboardConflicts } from '@/lib/orchestration/summarizers/whiteboard-conflicts';
+
+// Minimal PPTElement stand-ins — the summarizer only reads geometry fields.
+const text = (id: string, left: number, top: number, width: number, height: number) => ({
+  type: 'text',
+  id,
+  left,
+  top,
+  width,
+  height,
+  content: '<p>sample</p>',
+});
+
+const table = (id: string, left: number, top: number, width: number, height: number) => ({
+  type: 'table',
+  id,
+  left,
+  top,
+  width,
+  height,
+  data: [[{ text: 'a' }]],
+});
+
+const line = (
+  id: string,
+  left: number,
+  top: number,
+  start: [number, number],
+  end: [number, number],
+) => ({ type: 'line', id, left, top, start, end });
+
+describe('buildWhiteboardConflicts — no conflicts', () => {
+  test('empty element list returns empty string', () => {
+    expect(buildWhiteboardConflicts([])).toBe('');
+  });
+
+  test('two well-separated elements return empty string', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 20, 20, 200, 60),
+      text('t2', 400, 200, 200, 60),
+    ]);
+    expect(out).toBe('');
+  });
+
+  test('just-touching bboxes (intersection area = 0) are not reported', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 0, 0, 100, 100),
+      text('t2', 100, 0, 100, 100), // shares only the x=100 edge
+    ]);
+    expect(out).toBe('');
+  });
+
+  test('line routed clear of all elements produces no conflict', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 100, 100, 200, 60),
+      line('l1', 0, 0, [50, 50], [50, 400]),
+    ]);
+    expect(out).toBe('');
+  });
+});
+
+describe('buildWhiteboardConflicts — bbox overlap', () => {
+  test('one element fully inside another reports ~100% overlap', () => {
+    const out = buildWhiteboardConflicts([
+      table('big', 0, 0, 500, 400),
+      text('small', 50, 50, 100, 80), // entirely inside the table
+    ]);
+    expect(out).toContain('OVERLAP:');
+    expect(out).toContain('100%');
+  });
+
+  test('50% overlap is reported; 10% is not (30% threshold)', () => {
+    // Each bbox 100×100; smaller area = 10000. Overlap area = 50×100 = 5000 → 50%.
+    const overlapping = buildWhiteboardConflicts([
+      text('a', 0, 0, 100, 100),
+      text('b', 50, 0, 100, 100),
+    ]);
+    expect(overlapping).toContain('OVERLAP:');
+    expect(overlapping).toContain('50%');
+
+    // Overlap area = 10×100 = 1000 → 10% — below threshold.
+    const tiny = buildWhiteboardConflicts([
+      text('a', 0, 0, 100, 100),
+      text('b', 90, 0, 100, 100),
+    ]);
+    expect(tiny).toBe('');
+  });
+
+  test('non-line elements without width/height are skipped, not crashed', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 0, 0, 100, 100),
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      { type: 'text', id: 'broken', left: 10, top: 10 } as any, // missing width/height
+    ]);
+    // Only one valid element remaining → no overlap to report.
+    expect(out).toBe('');
+  });
+});
+
+describe('buildWhiteboardConflicts — line crossing elements', () => {
+  test('line passing through the middle of a text box is reported', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 100, 100, 200, 60), // covers x∈[100,300], y∈[100,160]
+      line('l1', 0, 0, [0, 130], [400, 130]), // horizontal line through y=130, cuts the box
+    ]);
+    expect(out).toContain('LINE CROSSES:');
+    expect(out).toContain('t1');
+  });
+
+  test('line whose endpoint is inside a bbox is reported', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 100, 100, 200, 60),
+      line('l1', 0, 0, [50, 50], [200, 130]), // endpoint (200,130) is inside t1
+    ]);
+    expect(out).toContain('LINE CROSSES:');
+  });
+
+  test('line with endpoints on opposite sides of a box but path above the box is clean', () => {
+    const out = buildWhiteboardConflicts([
+      text('t1', 100, 100, 200, 60),
+      line('l1', 0, 0, [50, 50], [400, 50]), // y=50, above the box (y∈[100,160])
+    ]);
+    expect(out).toBe('');
+  });
+});
+
+describe('buildWhiteboardConflicts — canvas edge clipping', () => {
+  test('element extending past right edge is reported', () => {
+    const out = buildWhiteboardConflicts([text('wide', 900, 100, 200, 60)]);
+    expect(out).toContain('OUT OF CANVAS:');
+    expect(out).toContain('right edge by 100px');
+  });
+
+  test('element extending past bottom edge is reported (canvas height = 563)', () => {
+    const out = buildWhiteboardConflicts([text('tall', 100, 500, 100, 80)]);
+    expect(out).toContain('OUT OF CANVAS:');
+    expect(out).toContain('bottom edge by 17px'); // 500+80-563 = 17
+  });
+
+  test('element with negative left is reported', () => {
+    const out = buildWhiteboardConflicts([text('negx', -10, 100, 50, 50)]);
+    expect(out).toContain('OUT OF CANVAS:');
+    expect(out).toContain('left edge by 10px');
+  });
+
+  test('element exactly at right edge (x+w == 1000) is NOT reported', () => {
+    const out = buildWhiteboardConflicts([text('edge', 900, 100, 100, 60)]);
+    expect(out).toBe('');
+  });
+
+  test('element exactly at bottom edge (y+h == 563) is NOT reported', () => {
+    const out = buildWhiteboardConflicts([text('edge', 100, 500, 100, 63)]);
+    expect(out).toBe('');
+  });
+});
+
+describe('buildWhiteboardConflicts — output format', () => {
+  test('renders a single markdown block with a header and bullet list', () => {
+    const out = buildWhiteboardConflicts([
+      text('a', 0, 0, 100, 100),
+      text('b', 50, 0, 100, 100),
+    ]);
+    expect(out).toMatch(/## ⚠ Layout Conflicts Detected/);
+    expect(out).toMatch(/\n {2}- OVERLAP:/);
+  });
+
+  test('lists multiple conflicts in one block', () => {
+    const out = buildWhiteboardConflicts([
+      text('a', 0, 0, 100, 100),
+      text('b', 50, 0, 100, 100), // overlap with a
+      text('outside', 950, 100, 200, 60), // out of canvas
+    ]);
+    const bullets = out.split('\n').filter((l) => l.trim().startsWith('- '));
+    expect(bullets.length).toBeGreaterThanOrEqual(2);
+  });
+});