fix the date naming:)

Updates/daily_updates/21042026-DailyUpdate.md

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+**Daily Update — Bad Case Analysis**
+*Image embedding benchmark · Tobacco-3482*
+
+---
+
+## Completed
+
+- Fixed a result logging issue where post-processed results were overwriting the raw embedding results in the checkpoint. Separated raw and post-processed entries so both are retained independently for comparison.
+- Ran bad case analysis for both SigLIP2 SO400M and ModernVBERT Bi using top-1 kNN criterion, loading embeddings directly from cached `.npy` files.
+- Generated per-class error breakdowns for all 10 document classes across both models.
+- Sampled misclassified cases per class and retrieved top-10 nearest neighbours for each query for visual inspection.
+- Saved full error breakdown to `results/bad_case_analysis.json` and bad case report to `.txt`.
+- Created retrieval confusion heatmap and retrieval error rate summary bar chart saved to `figures\bad_cases`
+- Visualised sampled bad cases with top-10 retrieval results per query, saved to `.png` at `figures\bad_cases`.
+
+---
+
+## In Progress
+
+- Improving the visual retrieval report resolution or switching to a more readable format (HTML or PDF) for better presentation — planned for tomorrow.
+- Writing up a bad case summary covering the key failure patterns identified and potential approaches to improve embedding quality for the affected classes.
+
+---
+
+## Blockers
+
+- The visualised bad cases is non-readable.
+
+---
+
+## Key Learnings
+
+- **Per-class errors reveal more than aggregate accuracy:** SigLIP2 and ModernVBERT Bi are only ~2.6 percentage points apart in overall error rate but ModernVBERT Bi is dramatically worse on Report specifically (70.4% vs 44.4%), which aggregate accuracy alone hides. Full breakdown in the bad case report.
+- **Systematic vs random errors:** The Memo/Letter confusion is consistent across both models and almost all Memo error cases, pointing to a structural embedding space overlap rather than noise — a more actionable signal than scattered errors.
+- **Low distance does not guarantee correct retrieval:** Some Scientific and Note cases in SigLIP2 show very low cosine distances to wrong-class neighbours, meaning the model is highly confident but wrong — suggesting genuine class overlap in embedding space rather than general uncertainty.