Multi-Step Cascading Allocations¶

Problem¶

Current allocation engine runs a single pass per rule. Real allocations require ordered steps where output of step N becomes input to step N+1. Example: 1. Step 1: Allocate IT costs to all departments by headcount 2. Step 2: Allocate Facilities costs (which now include some IT) by square meters 3. Step 3: Allocate shared services to business units by revenue

Requirements¶

R1: Step ordering in allocation_rules seed¶

Add column step_order (integer) to allocation_rules.csv:

allocation_rule_id,rule_name,step_order,source_account,source_cost_center,driver_type,target_account,description
ALLOC_001,IT Cost Allocation,1,7100,IT,headcount,7100,Step 1: IT by headcount
ALLOC_002,Facility Allocation,2,7200,FACILITY,sqm,7200,Step 2: Facilities by sqm
ALLOC_003,Mgmt Fee Allocation,3,7300,MGMT,revenue,7300,Step 3: Mgmt by revenue

R2: Cascading allocation macro¶

New macro allocation_engine_multistep that: 1. Reads all rules ordered by step_order 2. For step 1: source pool comes from gold_trial_balance (as today) 3. For step N>1: source pool comes from gold_trial_balance PLUS allocated amounts from steps 1..N-1 4. Each step produces allocation rows with step_order column

R3: New model `gold_allocation_results_v2`¶

Replaces gold_allocation_results
Contains all steps' results
Columns: step_order, allocation_rule_id, data_area_id, fiscal_year, fiscal_period, source_account, target_cost_center, driver_type, pool_amount, driver_weight, allocated_amount

R4: Driver seed flexibility¶

Each rule references its own driver seed via driver_seed_name column
allocation_drivers_headcount (existing), add allocation_drivers_sqm, allocation_drivers_revenue

Acceptance Tests¶

Test	Assertion
`assert_allocation_step_order`	All rows have valid step_order matching their rule
`assert_step2_pool_includes_step1`	Step 2 pool_amount > original TB amount for that account (proves cascade)
`assert_each_step_sums_to_pool`	Per step: sum(allocated_amount) = pool_amount within 0.01
`assert_no_self_allocation`	No row has target_cost_center = source_cost_center

Out of Scope¶

Circular (iterative) allocations
Reciprocal allocation method