How does license type constrain a sharing design, and when should that be assessed?

License type gates which standard objects a user can access at all, before profiles, permission sets, and sharing are consulted. No sharing configuration overcomes a license restriction.

The examples that come up most often:

1. Salesforce Platform covers custom objects plus Accounts, Contacts, Reports, Dashboards, and Documents, but excludes core CRM objects such as Opportunity, Case, Lead, Campaign, and Forecast.
2. Customer Community is high-volume: no roles, no sharing rule participation, so sharing sets and share groups are the only mechanisms.
3. Customer Community Plus and Partner Community are role-based and do participate in the standard sharing constructs.

It should be assessed at the start of the security design, alongside the requirements gathering. The expensive failure mode is designing the sharing model first, then discovering during build that the chosen license cannot participate in it — at which point the choice is a licensing change nobody budgeted for or a redesign nobody planned.

I also verify entitlements against the current Salesforce license comparison rather than from memory, because they change.