Use Spoolman spool purchase cost in Cost & Pricing Doctor

[jdkluck]

Snapmaker Studio already integrates with Spoolman for filament inventory tracking. It would be very useful if the Cost & Pricing Doctor could optionally use the purchase-cost data associated with the selected Spoolman spool, instead of relying only on a manually entered, generic Spool Price and Spool Weight.

Current behavior
The Cost & Pricing Doctor appears to calculate material cost using local assumptions:

Spool Price

Spool Weight (g)

Grams Used, or Studio’s geometry estimate

Material

Markup / Margin

For example, the material calculation shown in the interface is essentially:
material cost = grams used × (spool price / spool weight)

This is useful as a quick estimate, but it does not necessarily reflect what was actually paid for the particular spool being used.

Why this would help
Many users have multiple spools of the same material with very different real costs:

Discounted spools purchased during sales

Premium or specialty filaments

Different quantities or net weights

The same filament purchased at different prices over time

Spools with shipping, tax, bulk discounts, or other different effective costs

When a print is associated with a particular Spoolman spool, Spoolman should be the most relevant source of truth for that spool’s inventory information and purchase cost. Importing that data into Cost & Pricing Doctor would make cost, suggested selling price, and profit estimates much more accurate, while avoiding duplicate manual data entry.

Suggested implementation
Add a pricing-source option in Cost & Pricing Doctor:

Manual spool assumptions — current behavior and fallback

Use selected Spoolman spool cost

When a Spoolman spool is selected and has usable cost and weight information, Studio could calculate:
cost per gram = actual spool purchase price / spool net weight in grams
material cost = estimated grams used × cost per gram

It would also be helpful to clearly show the pricing source and calculation, for example:
Pricing source: Spoolman
Selected spool: PLA Black — Spool #123
Purchase price: $17.99
Net spool weight: 1,000 g
Effective material rate: $0.0180/g
Estimated material cost for this print: $2.70

That transparency would make it clear which spool is being used and let users verify the calculation.

Fallback behavior
If the selected Spoolman spool has no usable purchase-cost or weight data, Studio could simply fall back to the existing manual Spool Price and Spool Weight values, with a non-blocking notice such as:
Selected Spoolman spool has no usable cost/weight data; using manual assumptions.

Users should still be able to manually override the price for a one-off estimate without having to edit the Spoolman record.

Example
For a print using 153.91 g of PLA:

Spool Actual cost Accurate material cost
Sale PLA, 1 kg spool $12.00 about $1.85
Premium PLA, 1 kg spool $29.00 about $4.46

With a generic $20 / 1 kg local assumption, both would show about $3.08 in material cost. That is inaccurate in opposite directions and can meaningfully affect the recommended marketplace price and projected profit.

Acceptance criteria
When a print has a selected Spoolman spool with valid cost and net-weight data, Cost & Pricing Doctor can use it to calculate material cost.

The UI clearly indicates whether pricing comes from Spoolman, manual assumptions, or a local override.

The current manual Spool Price / Spool Weight workflow remains available.

Missing Spoolman price or weight data does not prevent calculation; Studio falls back to manual values.

The UI displays the calculated cost-per-gram and the source spool for verification.

This would make the Spoolman integration more complete by connecting real inventory data with actual per-spool print cost and profitability data.

The Markdown file is ready in the file panel as spoolman-cost-pricing-feature-request.md.