den.ctx (Compatibility Shim)

Legacy API — Scheduled for Removal

den.ctx is a compatibility shim. It forwards entries to den.aspects and den.schema.<kind>.includes with deprecation warnings at evaluation time. It will be removed after the first stable release.

Migrate to:

• den.aspects for aspect definitions
• den.schema.<kind>.includes for entity inclusion
• den.policies for entity topology and routing

See Migrating from den.ctx for step-by-step instructions.

What it does

den.ctx was the original API for declaring aspects and binding them to entity resolution stages. It combined aspect definitions, cross-entity providers, and pipeline transitions in a single namespace.

The compatibility shim in modules/compat/ctx-shim.nix accepts den.ctx.* entries and forwards them:

den.ctx.<name> = { ... }
  ↓
den.schema.<name>.includes = [ <value with deprecation warning> ]

Each forwarded value emits a lib.warn at evaluation time telling you exactly what to change.

What replaced it

The den.ctx namespace was split into three independent concerns:

Old (den.ctx)	New	Purpose
den.ctx.<name> = { ... }	den.aspects.<name> = { ... }	Aspect definitions
den.ctx.<name>.into.<other>	den.policies.<name>	Entity topology (fan-out, routing)
den.ctx.<name>.provides.<other>	den.schema.<kind>.includes	Cross-entity inclusion
Implicit activation	den.schema.<kind>.includes = [ ... ]	Explicit activation via includes

Example migration

Before:

den.ctx.host = {
  provides.host = { host }: den.aspects.${host.aspect};
  into.user = { host }:
    map (user: { inherit host user; }) (lib.attrValues host.users);
};

After:

# Aspect definition
den.aspects.my-aspect = { host }: {
  nixos.services.foo.enable = true;
};

# Entity topology via policy
den.policies.host-to-users = { host, ... }:
  map (user: policy.resolve.to "user" { inherit host user; })
    (lib.attrValues host.users);

# Activation
den.schema.host.includes = [ den.aspects.my-aspect ];