feat(backend): V281.0 - Vision-First OCR, Visuals robustness (Pow fix), and Rigid Graph Identification

V280.0: Robust Math Validation Fixes & Model Lockdown (RCE Protection, Multiline Regex, Soft Fail)

QA Cycle 2.1: Data Slicing, Hotfix refinement, Firestore fix, and UI Safety updates

Force Rebuild: Updated restart trigger in main.py

Critical QA Fixes: Bug 1-4 (Data Isolation, Hotfix Sanity, History Save, Visuals Stability)

V5.10.4: History Tier Fix (admin_unlimited) & Vision Extractor Graph Descriptions

V5.10.3: History Debugging & Graph Anti-Hallucination Prompt Fix

V5.10.2: Fix kwargs collision in smart_solve - pop explicit keys before spread

FORCE RESTART - V5.10.1

Implement SymPy Algebraic Verification & Self-Correction - Resolved critical regression and auth

Fix History Save Regression & Ask Teacher Auth - Emergency Fix

Fix Digital Binder history saving - Parameter propagation & logging

Implement Digital Binder (History) - Conditional saving for premium users

V5.9.10: Inactivity Push Notifications & CMS Implementation

fix: Robust Firebase initialization with environment variable support and lazy loading

fix: Split-Brain resolved - DEV config now points to buddy-math-dev project

fix: Auto-provision dev-bypass-user with Admin roles on startup

fix: Backend crashes (AttributeError) and Quota bypass for DEV

fix: Robust server-side auth fallback for DEV environment

fix: Bug 1 & 2 - Synchronize stats and add full user deletion endpoint

feat: add /admin/stats endpoint for dashboard usage tracking

fix: Robust token parsing and additional logging for DEV bypass

debug: Add detailed environment logging to config.py

fix: Auto-detect DEV environment using Hugging Face SPACE_ID

feat: Implementation of DEV auth bypass with strict guardrails

feat: Implement Check Solution logic with score and structured mistakes

Security Hardening: Firebase Auth + Quota V2 Enforcement

feat: token pipeline and device fingerprinting

feat: Payment Page integration and Rebranding to המורה למתמטיקה

feat: Parent Report Engine (HTML to PDF) and SendGrid Delivery

feat: AI Assessment Analytics Infrastructure

feat: multi-image support for V2 endpoint

Merge user security changes

V310.0: OCR Visual Disambiguation Fix (1 vs a)

V309.6: FINAL STABILITY Restored (HOTFIX + Correct Regex + OCR Fix)

V309.5: Rollback to HOTFIX + OCR Anti-Truncation + Abs Fix

V308.0: latex2sympy2 Integration + Procedural Bypass + Abs Fix

V307.0: Polygraph Restore + Math Syntax Pre-processor + Graph Polish Sync

V306.0: SVG Pad Optimization + OCR Rigor (1 vs 3)

V305.0: Final Graph Aesthetics + Protocol Alignment

V5.8.6: Signed URLs, math improvements, and orchestrator refinements

Hotfix: SymPy Parse Error bypass

V5.8.5: Enhanced 5-unit math (3D Vectors, Solid Geom, Optimization) + Placeholder Fixes + HF Space compatibility

V5.8.5: Enhanced 5-unit math (3D Vectors, Solid Geom, Optimization) + Placeholder Fixes + HF Space compatibility

Fix: Move debug and log directories to /tmp for Hugging Face compatibility

Fix: Add Hugging Face metadata via README.md

Fresh surgical release (v1.2.3) - Code Only

Fix: Clean production deployment with sse-starlette