Efficient Online Continual Foundation Model Fine-Tuning for Predictive Process Monitoring
Authors: Sjoerd van Straten, Marwan Hassani
Organizations: Department of Mathematics and Computer Science, Eindhoven University of Technology, The Netherlands · Department of Mathematics and Computer Science, University of Wuppertal, Germany
Predictive Process Monitoring (PPM) models are increasingly deployed in dynamic environments where concept drift causes the underlying process distribution to shift over time. While recent work has moved toward online continual learning, existing methods train compact, task-specific networks entirely from scratch, leaving a persistent cold-start problem. Foundation Models (FMs) offer a compelling solution to this problem, but their continual fine-tuning in the process mining domain remains unexplored. We propose COMPASS (Continual Online foundation Model-based PPM with Adaptive SubSpaces), the first framework for online continual fine-tuning of FMs for PPM. COMPASS adapts loss-plateau drift detection to autonomously identify task boundaries in event streams and maintains a unified knowledge subspace including both pre-trained and task-specific directions. We evaluate our approach on nine event streams covering synthetic and real-world concept drift scenarios, across task-free and task-aware settings with multiple backbones and with consistent hyperparameter tuning across all methods. Our approach outperforms three SOTA non-FM competitors and two update strategy baselines, with particularly strong gains on streams exhibiting recurrent drift and complex, long-running cases, while incurring acceptable computational overhead compared to the non-FM competitors.
Figures & tables
Figure 1: Comparison of an image stream and a process event stream under concept drift. In an image stream ( left ) tasks are visually distinct between TA and TB . In a process event stream ( right ), cases ( C1−C7 ) are long-running and interleaved across task boundaries, and drift is caused by organizational changes causing activities (represented as letters) and the time between them to change. Resource R1 is on maternity leave after T1 , and a policy change after T2 causes newly initiated cases to be prioritized, pushing older interleaved cases to the background. No input-space signal announces the shift, making autonomous adaptation to drift substantially harder than in image streams.
Figure 2: Overview of the COMPASS architecture. Colors indicate functional stages: LoRA fine-tuning (purple), plateau detection (blue), knowledge subspace expansion (green), and adapter reinitialization (pink), described in order below.
Symbol
Meaning
Updated
Wp
Dominant input directions of pre-trained W0
Fixed after initial SVD
Mt
Task-specific directions accumulated across tasks 1,…,t
Grows at each consolidation
Mt′=[Wp,Mt]
Unified knowledge subspace used for orthogonal projection
Grows, capped at rank R
Table 1: Summary of the subspaces used in knowledge subspace expansion.
Method
IRO5000
ORI5000
ROI5000
OIR5000
RIO5000
BPI15-REC
BPI20-RFP
BPI20-DD
BPI20-ID
DoNothing [ 13 ]
.192 ± .107
.200 ± .068
.223 ± .097
.205 ± .072
.171 ± .072
.013 ± .006
.511 ± .088
.495 ± .090
.247 ± .008
γ = LastDrift [ 12 ]
.220 ± .085
.770 ± .003
.246 ± .056
.709 ± .003
.269 ± .052
.484 ± .000
.886 ± .001
.863 ± .001
.840 ± .006
DynaTrainCDD [ 6 ]
.775 ± .005
.785 ± .006
.790 ± .001
.729 ± .004
.784 ± .004
.455 ± .008
.831 ± .010
.830 ± .011
.793 ± .003
TFCLPM [ 14 ]
.803 ± .001
.817 ± .002
.825 ± .011
.775 ± .002
.814 ± .001
.473 ± .003
.863 ± .009
.876 ± .003
.820 ± .002
CNAPwP [ 3 ]
.802 ± .002
.816 ± .005
.829 ± .002
.780 ± .001
.812 ± .006
.492 ± .015
.879 ± .001
.881 ± .008
.846 ± .003
Task-Aware
Table 2: Average accuracy for all baselines and datasets. Bold denotes the highest accuracy, italic and underlined the second and third highest. Sig. = statistically significant difference ( α = .05).
Figure 3: Accuracy at given index for the BPI15-REC and OIR5000 stream, illustrating COMPASS’ faster recovery after concept drift and mitigation of the cold-start problem.
Figure 4: Accuracy versus runtime (top) and memory consumption (bottom) over the event stream for ORI5000, BPI15-REC and BPI20-DD. COMPASS shows state-of-the-art accuracy with acceptable computational overhead.
Wp
Mt
TF
Avg.
×
×
✓
.735 ± .002
×
×
×
.758 ± .003
✓
×
✓
.721 ± .004
✓
×
×
.747 ± .002
✓
✓
✓
.802 ± .004 *
✓
✓
×
.802 ± .003 *
Table 3: Ablation study using accuracy for our components (TF = Task-Free).
Department of Mathematics and Computer Science, Eindhoven University of Technology, The Netherlands · Department of Mathematics and Computer Science, University of Wuppertal, Germany