fix(layout): reject degenerate startup snapshots

Author: Jacobinwwey

path_mode/scripts/path_renderer.gd

@@ -38,8 +38,6 @@ var _last_applied_background_path: String = "__unset__"
 const DOUBLE_CLICK_THRESHOLD := 0.5
 const MAX_INITIAL_UI_SETTINGS_RETRIES := 8
 const INITIAL_UI_SETTINGS_RETRY_DELAY := 0.15
-const BACKGROUND_MAX_DIMENSION := 2048
-const BACKGROUND_MAX_BYTES_HINT := 64 * 1024 * 1024
 
 @onready var ui: PathModeUI = $"../UI"
 
@@ -896,37 +894,8 @@ func _load_hdr_background_safely(path: String) -> Texture2D:
 		push_warning("[PathRenderer] Failed to load imported HDR background resource: %s" % path)
 		return null
 
-	var image := (imported_tex as Texture2D).get_image()
-	if image == null:
-		push_warning("[PathRenderer] Failed to extract HDR image data from imported resource: %s" % path)
-		return null
-
-	var original_size := image.get_size()
-	if original_size.x <= 0 or original_size.y <= 0:
-		push_warning("[PathRenderer] Invalid HDR background dimensions for: %s" % path)
-		return null
-
-	if image.get_format() != Image.FORMAT_RGBA8:
-		image.convert(Image.FORMAT_RGBA8)
-
-	var largest_dimension := maxi(original_size.x, original_size.y)
-	if largest_dimension > BACKGROUND_MAX_DIMENSION:
-		var scale := float(BACKGROUND_MAX_DIMENSION) / float(largest_dimension)
-		var resized_width := maxi(1, int(round(original_size.x * scale)))
-		var resized_height := maxi(1, int(round(original_size.y * scale)))
-		image.resize(resized_width, resized_height, Image.INTERPOLATE_LANCZOS)
-		print("[PathRenderer] Downscaled HDR background from %s to %s to avoid large GPU uploads." % [str(original_size), str(image.get_size())])
-
-	var estimated_bytes := image.get_width() * image.get_height() * 4
-	if estimated_bytes > BACKGROUND_MAX_BYTES_HINT:
-		push_warning("[PathRenderer] HDR background still too large after resize (%s bytes): %s" % [estimated_bytes, path])
-		return null
-
-	var texture := ImageTexture.create_from_image(image)
-	if texture == null:
-		push_warning("[PathRenderer] Failed to create ImageTexture from HDR background: %s" % path)
-	else:
-		_background_texture_cache[path] = texture
+	var texture := imported_tex as Texture2D
+	_background_texture_cache[path] = texture
 	return texture
 
 

src/frontend/app.js

@@ -457,6 +457,36 @@ async function persistStartupLayoutSnapshotRecord(record) {
     db.close();
 }
 
+async function deleteStartupLayoutSnapshotRecord(fingerprint) {
+    if (!fingerprint) {
+        return;
+    }
+
+    if (typeof localStorage !== 'undefined') {
+        try {
+            localStorage.removeItem(`${STARTUP_LAYOUT_SNAPSHOT_LS_PREFIX}${fingerprint}`);
+        } catch (_err) {
+            // Ignore localStorage cleanup failures.
+        }
+    }
+
+    const db = await openStartupLayoutSnapshotDb();
+    if (!db) {
+        return;
+    }
+
+    await new Promise((resolve, reject) => {
+        const tx = db.transaction(STARTUP_LAYOUT_SNAPSHOT_STORE_NAME, 'readwrite');
+        const store = tx.objectStore(STARTUP_LAYOUT_SNAPSHOT_STORE_NAME);
+        store.delete(fingerprint);
+        tx.oncomplete = () => resolve();
+        tx.onerror = () => reject(tx.error || new Error('indexedDB delete failed'));
+        tx.onabort = () => reject(tx.error || new Error('indexedDB delete aborted'));
+    });
+
+    db.close();
+}
+
 function collectStartupLayoutSnapshotRecord(reason = '') {
     if (!startupLayoutSnapshotState.fingerprint || !Array.isArray(nodes) || nodes.length === 0) {
         return null;
@@ -515,6 +545,44 @@ function validateStartupLayoutSnapshotRecord(record) {
         return { ok: false, reason: 'position-coverage-low', coverage: Number(coverage.toFixed(4)) };
     }
 
+    const finitePositions = record.positions.filter((item) => (
+        item &&
+        Number.isFinite(Number(item.x)) &&
+        Number.isFinite(Number(item.y))
+    ));
+    if (expectedNodeCount >= 10 && finitePositions.length > 0) {
+        let minX = Infinity;
+        let maxX = -Infinity;
+        let minY = Infinity;
+        let maxY = -Infinity;
+        const uniqueBuckets = new Set();
+
+        for (let index = 0; index < finitePositions.length; index += 1) {
+            const item = finitePositions[index];
+            const x = Number(item.x);
+            const y = Number(item.y);
+            if (x < minX) minX = x;
+            if (x > maxX) maxX = x;
+            if (y < minY) minY = y;
+            if (y > maxY) maxY = y;
+            uniqueBuckets.add(`${Math.round(x)}:${Math.round(y)}`);
+        }
+
+        const spanX = maxX - minX;
+        const spanY = maxY - minY;
+        const uniqueRatio = uniqueBuckets.size / Math.max(1, finitePositions.length);
+        if ((spanX < 48 && spanY < 48) || uniqueRatio < 0.12) {
+            return {
+                ok: false,
+                reason: 'degenerate-layout',
+                purge: true,
+                spanX: Number(spanX.toFixed(2)),
+                spanY: Number(spanY.toFixed(2)),
+                uniqueRatio: Number(uniqueRatio.toFixed(4)),
+            };
+        }
+    }
+
     return {
         ok: true,
         coverage: Number(coverage.toFixed(4)),
@@ -568,8 +636,16 @@ function maybeApplyStartupWarmSnapshot(trigger = '') {
             recordFingerprint: record.fingerprint || null,
             recordNodeCount: record.nodeCount || 0,
             recordEdgeCount: record.edgeCount || 0,
-            positionCount: Array.isArray(record.positions) ? record.positions.length : 0
+            positionCount: Array.isArray(record.positions) ? record.positions.length : 0,
+            spanX: validation.spanX,
+            spanY: validation.spanY,
+            uniqueRatio: validation.uniqueRatio,
         });
+        if (validation.purge === true && record.fingerprint) {
+            deleteStartupLayoutSnapshotRecord(record.fingerprint).catch((error) => {
+                console.warn('[Startup Warm Snapshot] Failed to purge invalid snapshot record:', error && error.message ? error.message : String(error));
+            });
+        }
         startupLayoutSnapshotState.pendingRecord = null;
         return false;
     }

src/pathmode.background.contract.test.ts

@@ -14,14 +14,12 @@ describe('pathmode background safety contract', () => {
 
   test('loads HDR backgrounds through the guarded resize-and-convert path', () => {
     const source = fs.readFileSync(pathRendererPath, 'utf8');
-    expect(source).toContain('const BACKGROUND_MAX_DIMENSION := 2048');
     expect(source).toContain('var _background_texture_cache: Dictionary = {}');
     expect(source).toContain('var _last_applied_background_path: String = "__unset__"');
     expect(source).toContain('func _load_hdr_background_safely(path: String) -> Texture2D:');
     expect(source).toContain('var imported_tex = ResourceLoader.load(path)');
-    expect(source).toContain('(imported_tex as Texture2D).get_image()');
+    expect(source).toContain('var texture := imported_tex as Texture2D');
+    expect(source).not.toContain('(imported_tex as Texture2D).get_image()');
     expect(source).not.toContain('var image_error := image.load(path)');
-    expect(source).toContain('image.convert(Image.FORMAT_RGBA8)');
-    expect(source).toContain('image.resize(resized_width, resized_height, Image.INTERPOLATE_LANCZOS)');
   });
 });

src/startup.layout.snapshot.contract.test.ts

@@ -0,0 +1,15 @@
+import * as fs from 'fs';
+import * as path from 'path';
+
+describe('startup layout snapshot contract', () => {
+  const repoRoot = path.resolve(__dirname, '..');
+  const appPath = path.join(repoRoot, 'src', 'frontend', 'app.js');
+
+  test('rejects and purges degenerate persisted layout snapshots', () => {
+    const source = fs.readFileSync(appPath, 'utf8');
+    expect(source).toContain('async function deleteStartupLayoutSnapshotRecord(fingerprint)');
+    expect(source).toContain("reason: 'degenerate-layout'");
+    expect(source).toContain('if ((spanX < 48 && spanY < 48) || uniqueRatio < 0.12)');
+    expect(source).toContain('if (validation.purge === true && record.fingerprint)');
+  });
+});