Model Name: Playbox-Time-Hammer
Architecture: Qwen3.5-0.8B-Base (initialized from Playbox_RFT_Checkpoint)
Parameters: ~0.8B
Developers: Epoch AI Labs
Intended Use: Domain-specific exact-arithmetic specialist exclusively for schedule and elapsed-time calculations.
Tool Integration: Trained to emit exact-arithmetic tool calls and consume results for the time_add(hhmm, [minutes...]) tool, bypassing unreliable internal time arithmetic.
Training Pipeline: Multi-turn Tool-Integrated Reasoning (TIR) SFT using selective label masking (learning to emit tools and process tool responses, but ignoring prompts/tool injections during loss calculation). Max 80 updates.
Performance:
Schedule Elapsed OOD Family: 100.0% accuracy (up from 0.0% with the direct RFT).
Limitations: Hyper-specialized. Suffers from complete catastrophic forgetting on general math distribution. Must only be invoked via a high-precision router for appropriate problems.
