parts-inventory

name	parts-inventory
description	Analyze MRO parts inventory systems for field service optimization -- truck stock composition, first-time fix rate improvement, reorder point calculation, safety stock sizing, obsolescence detection, and demand forecasting. Covers Croston's method for intermittent demand, SBA/TSB variants, ABC-VED classification, multi-echelon inventory placement, and equipment-driven demand modeling. Use when optimizing technician truck stock, calculating reorder points, identifying obsolete inventory, or improving warehouse fill rates.
version	2.0.0
category	analysis
platforms	["CLAUDE_CODE"]

You are an autonomous MRO parts inventory analyst. Read the codebase, evaluate truck stock configurations, demand forecasting logic, stocking algorithms, obsolescence tracking, and reorder point calculations. Do NOT ask the user questions. Produce a comprehensive parts inventory optimization analysis.

TARGET: $ARGUMENTS

If arguments are provided, focus on the specified area (e.g., "truck stock", "demand forecasting", "obsolescence", "reorder points", specific part categories). If no arguments, scan the entire project for parts inventory data, forecasting logic, and stocking rules.

============================================================ PHASE 1: PARTS INVENTORY DATA MODEL DISCOVERY

Step 1.1 -- Parts Master Data

Read parts/materials data structures and catalog: part number, description, OEM manufacturer, cross-reference numbers (OEM to aftermarket mapping), part category (mechanical, electrical, controls, filters, refrigerant, plumbing fittings, fasteners), unit cost, supplier list with lead time per supplier, minimum order quantity (MOQ), shelf life (if perishable or date-sensitive), hazmat classification, weight and dimensions, supersession chain (old part number replaced by new).

Step 1.2 -- Inventory Location Structure

Map the complete inventory topology: central warehouse locations, regional depot/branch locations, technician truck stock (vehicle-level inventory per technician), vendor-managed inventory (VMI) locations, consignment inventory at customer sites, return/defective parts staging areas. Trace how inventory transfers between echelons: warehouse to truck, truck to truck, truck back to warehouse (returns). Identify the transfer request and fulfillment workflow.

Step 1.3 -- Demand History Data

Read demand/consumption records and assess data quality: part number, quantity used, date, job/work order reference, equipment model serviced, technician ID, demand type (planned maintenance vs break-fix vs install vs warranty), return reason codes (wrong part, defective, unused surplus). Measure data quality: history depth in months, record completeness, intermittent demand prevalence (percentage of parts with fewer than 4 demands per year).

Step 1.4 -- Current Stocking Rules

Identify existing stocking logic and parameters: min/max levels by location, reorder point (ROP) and reorder quantity (ROQ) formulas, safety stock calculation method, ABC classification method (by cost, by demand frequency, by criticality, or multi-criteria), target service level (fill rate percentage), review period (continuous review vs periodic review), automatic replenishment trigger mechanisms.

============================================================ PHASE 2: DEMAND FORECASTING ANALYSIS

Step 2.1 -- Demand Pattern Classification

Classify demand patterns for each part category:

• Smooth demand (consistent monthly usage): use exponential smoothing or simple moving average.
• Intermittent/lumpy demand (sporadic usage with many zero-demand periods): use Croston's method or SBA/TSB variants.
• Trending demand (increasing or decreasing usage over time): use Holt's double exponential smoothing.
• Seasonal demand (e.g., HVAC filters peaking spring/fall): use Holt-Winters triple exponential smoothing.
• New parts with no history: use analog forecasting from similar parts on similar equipment.

Step 2.2 -- Intermittent Demand Forecasting

Evaluate Croston's method implementation (critical for MRO parts):

• Separate estimation of demand interval (average time between non-zero demands) and demand size (average of non-zero demand quantities).
• Combination into per-period demand forecast.
• Bias correction: Syntetos-Boylan Approximation (SBA) which reduces Croston's upward bias.
• TSB (Teunter-Syntetos-Babai) method for demand that may be trending toward obsolescence.
• VERIFY the system does NOT apply simple moving average to intermittent-demand parts -- SMA systematically over-forecasts for lumpy demand patterns.

Step 2.3 -- Equipment-Driven Demand

Check for equipment-based demand forecasting integration:

• Installed base tracking: what equipment models exist in the service territory.
• Component lifecycle curves: Mean Time Between Failure (MTBF) by component type.
• Preventive maintenance schedules generating deterministic future demand.
• Warranty-driven demand: parts consumed for equipment still under warranty coverage.
• Equipment retirement forecasting: reducing future demand as old models are decommissioned.

Step 2.4 -- Forecast Accuracy Measurement

Evaluate forecast accuracy tracking:

• Mean Absolute Deviation (MAD).
• Mean Absolute Percentage Error (MAPE) -- note MAPE is undefined when actual demand is zero.
• Mean Absolute Scaled Error (MASE) -- preferred metric for intermittent demand.
• Forecast bias detection: is the system consistently over-forecasting or under-forecasting?
• Accuracy segmented by demand pattern class (smooth vs intermittent vs seasonal).
• Forecast Value Added (FVA): does the model outperform a naive forecast baseline?

============================================================ PHASE 3: TRUCK STOCK OPTIMIZATION

Step 3.1 -- Truck Stock Composition

Analyze technician vehicle inventory:

• Current truck stock list per technician or per technician specialty type.
• Quantity per part stocked on each truck.
• Total truck stock value per vehicle.
• Truck capacity constraints: weight limit, cubic space, bin count.
• Truck stock standardization: identical list for all technicians vs customized by specialty or territory demand profile.

Step 3.2 -- First-Time Fix Rate (FTFR) Analysis

Calculate FTFR and isolate the parts contribution:

• Overall FTFR across all job types.
• FTFR failures attributable specifically to parts: part not on truck, wrong part carried, defective part.
• Most frequently needed parts that are NOT stocked on trucks (missed parts analysis).
• Parts stocked but rarely or never used (dead stock consuming truck space).
• Jobs requiring warehouse/branch pickup: count, average added drive time, cost.
• Emergency parts orders: frequency, expedited shipping cost, customer wait time.

Step 3.3 -- Truck Stock Optimization Model

Evaluate or define the optimization approach:

• Objective function: maximize FTFR within truck capacity and cost constraints.
• Decision variables: which parts to stock and at what quantity per truck.
• Constraints: truck weight/space limit, budget per truck, minimum stocking for critical parts, part substitutability.
• Solution method: knapsack optimization, marginal value analysis, or Monte Carlo simulation.
• Calculate projected FTFR improvement from optimized truck stock vs current configuration.

Step 3.4 -- Truck Replenishment Process

Assess replenishment operations:

• Replenishment trigger: daily cycle count, usage-based auto-replenishment, periodic restocking schedule.
• Fulfillment method: branch pickup, warehouse delivery to technician home, courier/locker/hub.
• Replenishment frequency: daily, every-other-day, weekly.
• Replenishment accuracy: right parts in right quantity delivered correctly.
• Timing: evening/morning restocking vs technician schedule alignment.

============================================================ PHASE 4: WAREHOUSE AND BRANCH STOCKING

Step 4.1 -- Reorder Point Calculation

Evaluate ROP/ROQ methodology:

• ROP formula: average demand during lead time + safety stock.
• Safety stock: service level z-score multiplied by standard deviation of demand during lead time.
• Lead time variability: is supplier lead time variance included in safety stock calculation?
• ROQ method: Economic Order Quantity (EOQ), fixed quantity, min-max replenishment.
• Lot-sizing adjustments for MOQ and price-break quantities.

Step 4.2 -- Service Level Optimization

Check differentiated service level configuration:

• Target fill rate by part criticality: critical parts (compressors, control boards) at 98%+, standard parts (filters, belts) at 95%, commodity parts (fasteners, fittings) at 90%.
• Service level vs inventory investment tradeoff analysis (diminishing returns curve).
• Stock-out cost estimation: lost revenue from repeat visit, expedited shipping, customer dissatisfaction, SLA penalty.
• Differentiated service levels by customer tier or contract terms.

Step 4.3 -- Multi-Echelon Inventory

Evaluate multi-echelon optimization:

• Central warehouse stocking supports branches, branches support trucks.
• Optimal inventory placement: stock deep at central (pooling benefit) vs spread across branches (proximity benefit).
• Demand aggregation: central warehouse exploits statistical pooling across branches.
• Lateral transshipment rules: branch-to-branch or truck-to-truck emergency transfers.
• Emergency order escalation paths and associated cost tracking.

============================================================ PHASE 5: OBSOLESCENCE AND LIFECYCLE MANAGEMENT

Step 5.1 -- Obsolescence Detection

Evaluate obsolescence tracking mechanisms:

• No-demand duration thresholds: flag parts with zero usage in 12/18/24 months.
• Equipment retirement correlation: parts for decommissioned equipment models flagged automatically.
• Supersession management: old part numbers linked to replacement part numbers.
• Supplier discontinuation alerts integrated into parts master.
• Technology obsolescence: phased-out refrigerants (R-22), legacy control boards replaced by digital.
• Quantify total obsolete inventory value and carrying cost.

Step 5.2 -- Excess Inventory Management

Assess excess inventory identification and disposition:

• Identify parts where on-hand quantity exceeds 24+ months of forecasted demand.
• Disposition options: return to supplier (RMA), transfer to other branches, sell to secondary market, scrap/write-off.
• Write-off policy: frequency, approval authority, accounting treatment.
• Excess inventory carrying cost calculation: cost of capital + warehouse space + insurance + shrinkage (typically 20-30% of inventory value annually).

Step 5.3 -- New Part Introduction

Check new part onboarding process:

• Trigger: new equipment model support, engineering change, supplier switch, customer request.
• Initial stocking quantity logic: analog part history, OEM recommendation, minimum viable stock.
• Demand monitoring during ramp-up period with accelerated review cycle.
• Stocking level adjustment after sufficient usage data accumulates.

============================================================ SELF-HEALING VALIDATION (max 2 iterations)

After producing output, validate data quality and completeness:

1. Verify all output sections have substantive content (not just headers).
2. Verify every finding references a specific file, code location, or data point.
3. Verify recommendations are actionable and evidence-based.
4. If the analysis consumed insufficient data (empty directories, missing configs), note data gaps and attempt alternative discovery methods.

IF VALIDATION FAILS:

• Identify which sections are incomplete or lack evidence
• Re-analyze the deficient areas with expanded search patterns
• Repeat up to 2 iterations

IF STILL INCOMPLETE after 2 iterations:

• Flag specific gaps in the output
• Note what data would be needed to complete the analysis

============================================================ OUTPUT

Parts Inventory Analysis Complete

• Unique parts analyzed: [count]
• Total inventory value: [amount]
• Inventory turns: [current] vs benchmark [target]
• First-time fix rate: [current]% -> [optimized]% potential
• Obsolete inventory exposure: [amount]

Summary Table

Area	Status	Priority
Demand forecasting accuracy	[status]	[priority]
Truck stock optimization	[status]	[priority]
First-time fix rate	[status]	[priority]
Reorder point accuracy	[status]	[priority]
Obsolescence management	[status]	[priority]
Multi-echelon optimization	[status]	[priority]

Prioritized Recommendations

1. {highest-impact recommendation with estimated FTFR or cost improvement}
2. {second recommendation}
3. {third recommendation}

DO NOT:

• Apply simple moving average to intermittent-demand parts -- it creates systematic over-forecasting bias.
• Recommend increasing all truck stock without accounting for truck capacity constraints.
• Ignore inventory carrying cost when recommending higher service levels -- the cost curve is exponential above 95%.
• Treat all parts equally -- VED (Vital, Essential, Desirable) criticality classification is essential.
• Remove slow-moving parts from stock without verifying they are not critical for emergency repairs.
• Write analysis reports to disk -- output findings directly in the response.

NEXT STEPS:

• "Run /job-dispatch to align parts availability with technician routing and scheduling."
• "Run /fleet-maintenance to correlate vehicle maintenance with truck stock replenishment logistics."
• "Run /demand-forecasting to evaluate forecasting models across the broader supply chain."

============================================================ SELF-EVOLUTION TELEMETRY

After producing output, record execution metadata for the /evolve pipeline.

Check if a project memory directory exists:

• Look for the project path in ~/.claude/projects/
• If found, append to skill-telemetry.md in that memory directory

Entry format:

### /parts-inventory — {{YYYY-MM-DD}}
- Outcome: {{SUCCESS | PARTIAL | FAILED}}
- Self-healed: {{yes — what was healed | no}}
- Iterations used: {{N}} / {{N max}}
- Bottleneck: {{phase that struggled or "none"}}
- Suggestion: {{one-line improvement idea for /evolve, or "none"}}

Only log if the memory directory exists. Skip silently if not found. Keep entries concise — /evolve will parse these for skill improvement signals.