Nested ER-Based Derivative Estimates

Feature Request: Nested ER-Based Derivative Estimates

Summary:
Enable users to perform derivative estimates on other derivatives, specifically allowing Estimated Results (ERs) to be used as the basis for additional ERs. This would support multi-step calculation chains where factors such as support-to-touch and material or travel spreads can be applied sequentially to intermediate results, rather than only to base inputs.

Problem Statement:
Users cannot perform derivative estimates on other derivatives (ERs specifically). For example, if a user wants to apply a support-to-touch factor and then apply a material or travel spread on the combined result, this is not possible because ERs cannot be performed on other ERs. This limitation forces users to approximate multi-step scenarios using manual calculations or external tools, increasing effort, risk of error, and reducing the fidelity of the estimates maintained in the system.

Proposed Solution:
Allow ERs to reference other ERs as their input basis, enabling chained or nested derivative calculations.
Support configuration of multiple ER layers, such that one ER can apply a support-to-touch factor on a base value and a subsequent ER can apply additional spreads (e.g., material or travel) on the combined result.
Ensure that changes to underlying ERs automatically propagate and recalculate all dependent ERs in the chain, maintaining data consistency.
Provide safeguards to prevent circular dependencies (e.g., ER A depending on ER B while ER B also depends on ER A).
Expose clear visual indicators or dependency views so users can understand how ERs are linked and in what order calculations are applied.
Include support for these nested ER relationships in reporting and exports so downstream consumers see the fully calculated results.

Benefits:
Enables more accurate and realistic modeling of complex cost and effort scenarios within the system.
Reduces manual off-system calculations and the associated risk of inconsistencies or transcription errors.
Improves transparency by keeping multi-step calculation logic and results in a single, auditable location.
Increases flexibility for power users who need to build layered estimates (e.g., support, material, and travel adjustments) without workarounds.
Enhances user confidence that the system can represent their real-world estimation workflows end to end.