[PM-30298] Initial documentation for OrganizationAbility pattern

src/Core/AdminConsole/OrganizationFeatures/OrganizationAbility/README.md

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+# Organization Ability Flags
+
+## Overview
+
+Many Bitwarden features are tied to specific subscription plans. For example, SCIM and SSO are Enterprise features,
+while Event Logs are available to Teams and Enterprise plans. When developing features that require plan-based access
+control, we use **Organization Ability Flags** (or simply _abilities_) — explicit boolean properties on the Organization
+entity that indicate whether an organization can use a specific feature.
+
+## The Rule
+
+**Never check plan types to control feature access.** Always use a dedicated ability flag on the Organization entity.
+
+### ❌ Don't Do This
+
+```csharp
+// Checking plan type directly
+if (organization.PlanType == PlanType.Enterprise ||
+    organization.PlanType == PlanType.Teams ||
+    organization.PlanType == PlanType.Family)
+{
+    // allow feature...
+}
+```
+
+### ❌ Don't Do This
+
+```csharp
+// Piggybacking off another feature's ability
+if (organization.PlanType == PlanType.Enterprise && organization.UseEvents)
+{
+    // assume they can use some other feature...
+}
+```
+
+### ✅ Do This Instead
+
+```csharp
+// Check the explicit ability flag
+if (organization.UseEvents)
+{
+    // allow UseEvents feature...
+}
+```
+
+## Why This Pattern Matters
+
+Using explicit ability flags instead of plan type checks provides several benefits:
+
+1. **Simplicity** — A single boolean check is cleaner and less error-prone than maintaining lists of plan types.
+
+2. **Centralized Control** — Feature access is managed in one place: the ability assignment during organization
+   creation/upgrade. No need to hunt through the codebase for scattered plan type checks.
+
+3. **Flexibility** — Abilities can be set independently of plan type, enabling:
+
+    - Early access programs for features not yet tied to a plan
+    - Trial access to help customers evaluate a feature before upgrading
+    - Custom arrangements for specific customers
+    - A/B testing of features across different cohorts
+
+4. **Safe Refactoring** — When plans change (e.g., adding a new plan tier, renaming plans, or moving features between
+   tiers), we only update the ability assignment logic—not every place the feature is used.
+
+5. **Graceful Downgrades** — When an organization downgrades, we update their abilities. All feature checks
+   automatically respect the new access level.
+
+## How It Works
+
+### Ability Assignment at Signup/Upgrade
+
+When an organization is created or changes plans, the ability flags are set based on the plan's capabilities:
+
+```csharp
+// During organization creation or plan change
+organization.UseGroups = plan.HasGroups;
+organization.UseSso = plan.HasSso;
+organization.UseScim = plan.HasScim;
+organization.UsePolicies = plan.HasPolicies;
+organization.UseEvents = plan.HasEvents;
+// ... etc
+```
+
+### Modifying Abilities for Existing Organizations
+
+To change abilities for existing organizations (e.g., rolling out a feature to a new plan tier), create a database
+migration that updates the relevant flag:
+
+```sql
+-- Example: Enable UseEvents for all Teams organizations
+UPDATE [dbo].[Organization]
+SET UseEvents = 1
+WHERE PlanType IN (17, 18) -- TeamsMonthly = 17, TeamsAnnually = 18
+```
+
+Then update the plan-to-ability assignment code so new organizations get the correct value.
+
+## Adding a New Ability
+
+When developing a new plan-gated feature:
+
+1. **Add the ability to the Organization and OrganizationAbility entities** — Create a `Use[FeatureName]` boolean
+   property.
+
+2. **Add a database migration** — Add the new column to the Organization table.
+
+3. **Update plan definitions** — Add a corresponding `Has[FeatureName]` property to the Plan model and configure which
+   plans include it.
+
+4. **Update organization creation/upgrade logic** — Ensure the ability is set based on the plan.
+
+5. **Update the organization license claims** (if applicable) - to make the feature available on self-hosted instances.
+
+6. **Implement checks throughout client and server** — Use the ability consistently everywhere the feature is accessed.
+    - Clients: get the organization object from `OrganizationService`.
+    - Server: if you already have the full `Organization` object in scope, you can use it directly. If not, use the
+      `IApplicationCacheService` to retrieve the `OrganizationAbility`, which is a simplified, cached representation
+      of the organization ability flags. Note that some older flags may be missing from `OrganizationAbility` but
+      can be added if needed.
+
+## Existing Abilities
+
+For reference, here are some current organization ability flags (not a complete list):
+
+| Ability                  | Description                   | Plans             |
+|--------------------------|-------------------------------|-------------------|
+| `UseGroups`              | Group-based collection access | Teams, Enterprise |
+| `UseDirectory`           | Directory Connector sync      | Teams, Enterprise |
+| `UseEvents`              | Event logging                 | Teams, Enterprise |
+| `UseTotp`                | Authenticator (TOTP)          | Teams, Enterprise |
+| `UseSso`                 | Single Sign-On                | Enterprise        |
+| `UseScim`                | SCIM provisioning             | Teams, Enterprise |
+| `UsePolicies`            | Enterprise policies           | Enterprise        |
+| `UseResetPassword`       | Admin password reset          | Enterprise        |
+| `UseOrganizationDomains` | Domain verification/claiming  | Enterprise        |
+
+## Questions?
+
+If you're unsure whether your feature needs a new ability or which existing ability to use, reach out to your team lead
+or members of the Admin Console or Architecture teams. When in doubt, adding an explicit ability is almost always the
+right choice—it's easy to do and keeps our access control clean and maintainable.