v0.18.0

[vic]

Den v0.18 Release Notes

✨ Major Features

1. Gen-schema entity port + resolver/delivery unification (#563)

Five-part stabilization reaching 1023/1023 tests (from 825 at branch start):

• Entity schema refactor: den.schema migrates to gen-schema's mkSchemaOption/mkSchemaEntryType. Entities own id_hash via mkInstanceType. Flat declaration forms (den.hosts.igloo = {}, den.homes."tux@igloo" = {}) coexist with legacy two-level nesting.
• Isolation + delivered-child host: microvm guests. Kind-level isolated marker, re-instantiating payload delivery, projected hasAspect re-keyed by entity id_hash (fixes nested host false-negatives).
• Resolver decoupling: Pure arg classifier over schema entity DAG. Removes host/user-specific machinery from fx resolver core. Fixes host-scope { user } homeManager aspects leaking to all users (Bug: homeManager content on host-included aspects is silently dropped unless the aspect is user-parametric #609).
• Delivery-edge unification: Nine ad-hoc mechanisms collapse to one (S, T, P, M) edge algebra. New deliver { from; to; at ?[]; mode ? "merge" } primitive; route and provides retained as thin shims. One toposorted edge-fold per root.
• Constraint registry unification + sibling-exclusion fixes: sibling excludes no longer leak across entities. Unified scope+ancestor constraint lookup; late-policy dispatch scopes to emitting sibling.

Breaking change: Entity-arg binding now scoped (inert if not in-context). Cross-entity delivery via provides/policy only. Documented in explanation/parametric.mdx.

2. Synthesize host identity for standalone user@host homes (#605)

Standalone home user@host now resolves host-keyed config (provides.<host>, policy.when ({ host })) without declaring the host or instantiating platform builder. Minimal { name = hostName } identity synthesized; declared host still wins.

Fixes crash in related include-return path: aspects returning include-effect lists (e.g. lib.optional cond (policy.include {...})) now normalized (lists flattened, effects pass through).

3. In-context hasAspect honors projected scope state (#602)

.hasAspect inside parametric bodies now answers projected membership ("delivered into this scope") vs structural tree. Registry query (den.hosts.….users.tux.hasAspect) stays structural. Per-scope pathSetByScope recorded; zero extra pipeline runs.

🐛 Major Fixes

Resolver & delivery pipeline

• Sibling policy.when guard dedup collision (fix: sibling policy.when guard dedup collision; spawn subtree routes; multi-def forwarded identity #603): Guards compile to anonymous aspects; dedup now indices synthetic names and chains payloads, preventing second guard's content vanishing.
• Spawn subtree routes (fix: sibling policy.when guard dedup collision; spawn subtree routes; multi-def forwarded identity #603): Parent pipeline routes now apply to spawned resolution; user-scope route no longer skipped in spawn re-entry.
• Multi-def forwarded identity (fix: sibling policy.when guard dedup collision; spawn subtree routes; multi-def forwarded identity #603): Multi-def namespace children now tagged with __provider, fixing double-emission from multi-path inclusion.
• Guarded route crashes (fix: guarded empty-path route skips cleanly; honor intoPath alias #600): intoPath alias honored; guarded empty-path routes now skip cleanly with optionalAttrs (not mkIf).
• Positional context functions in includes (fix: resolve positional functions in includes with scope context #578): ctx: ... functions (empty args) now routed to parametric compile and called with full scope context, not silently dropped.

Forward routing & class merging

• Forwarded content overwritten across scopes (BUG: Forwarding can overwrite each other #583): Root content in complex forwards no longer filtered to @default-only when not an entity-owned class. Fixes cross-scope aggregation (e.g. atuin flags merging).
• Route wrapping merge semantics (fix: route wrapping merge semantics and forward ordering #574): Multiple aspects defining same flake class no longer clobber. Routes toposorted (producers before consumers); mergeableType deep-merges instead of shallow //.
• Order simple routes before forwards (fix: order simple routes before forwards that consume their class #584): Routes applied in correct order; custom forwards consume class content correctly.

Config & module handling

• Don't force aspect content during key classification (BUG: Recursion error when consuming self.outputs.overlays #580): Lazy instantiation preserved in compile-static; no forced evaluation during structural key walk.
• Resolve positional functions with scope context (fix: resolve positional functions in includes with scope context #578): Direct lambda detection + ctxFromHandlers call instead of fx.bind.fn.
• Null coercion in warning messages (fix: null coercion in disambiguate warning message #576): Explicit if check replaces or; no more cannot coerce null on multi-system homes with null system.

Entity & output handling

• Disambiguate multi-system homes (fix: disambiguate multi-system homes targeting same homeConfigurations output #565): Same user on multiple systems auto-qualified @system (homeConfigurations."ben@x86_64-linux" / homeConfigurations."ben@aarch64-darwin"). Single-system homes keep plain name.
• Correct flake output include schema kind (fix: correct flake output include to flake-system schema kind #587): Example corrected to flake-system (not non-existent flake-packages).
• Remove __denTest hack (fix: remove __denTest hack #571): Test harness cleanup.
• Missing host class in batteries (fix: missing host class in batteries #606): host ? class check prevents unfree battery crash when host lacks class.

Schema & validation

• Flattening default den.schema (fix: flattening default den.schema #616): Fixes Lix runtime (other nix runtimes) unable to merge multiple attrs same name in different brackets.

🎨 Refactors & Chores

• Extract diagram library to sini/den-diagram (refactor: Extract diagram library to sini/den-diagram #564): nix/lib/diag/ → den-diagram repo. Den keeps only capture.nix (fx tracing). Templates (diagram-demo, fleet-demo) use two-step pattern. Den CI has zero den-diagram dependency.
• Organize tests: public-api/internal-api/deadbugs (improve: organize tests public-api/internal-api/deadbugs #592): Test suite restructured; CI test org documented.
• Backport aspect-pipeline fixes (fix: backport aspect-pipeline fixes from entity-gen-schema-port #589): Cherry-picks + one net-new (namespace root _ bundle). Namespace-root _ exposes container-level aspects (flat map, no recursion).
• Performance: break closure chains and lazy instantiation (perf: break closure chains and lazy instantiation backport #579): Backport; reduced evaluation overhead.
• CI: bump nix-effects to den branch (ci: bump nix-effects to den branch #529): Dependency update.

📖 Documentation

• Remove deprecated link (fix(docs): Remove deprecated link #612): Archived repository pattern removed.
• Update links & README (docs: update links #595, docs: update README remove extensive code examples #594): Examples simplified, links corrected.
• Update docs from source (docs: update docs from source #593): Docs refreshed.
• Fix typos (docs: fix some typos #597).
• GH-pages robustness (fix: gh-pages dont fail if no cached versioned docs exist #591): Artifact listing paginates; no longer caps at 30 (silent truncation).

✅ CI & Testing

• Live label queries, real allow-ci gating (fix(ci): live label queries, real allow-ci gating, dead triggers #607): Label checks now query API (see re-run labels); ci-deep/flake-check actually gated; main builds never cancelled; non-draft skip cleanly on docs-only PRs; approved reviews only re-trigger CI.

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What's Changed

• fix: disambiguate multi-system homes targeting same homeConfigurations output by @sini in fix: disambiguate multi-system homes targeting same homeConfigurations output #565
• fix: remove __denTest hack by @vic in fix: remove __denTest hack #571
• ci: bump nix-effects to den branch by @vic in ci: bump nix-effects to den branch #529
• fix: route wrapping merge semantics and forward ordering by @sini in fix: route wrapping merge semantics and forward ordering #574
• fix: null coercion in disambiguate warning message by @sini in fix: null coercion in disambiguate warning message #576
• fix: don't force aspect content during key classification (BUG: Recursion error when consuming self.outputs.overlays #580) by @sini in fix: don't force aspect content during key classification (#580) #581
• perf: break closure chains and lazy instantiation backport by @sini in perf: break closure chains and lazy instantiation backport #579
• fix: resolve positional functions in includes with scope context by @sini in fix: resolve positional functions in includes with scope context #578
• fix: forwarded content overwritten across scopes (BUG: Forwarding can overwrite each other #583) by @sini in fix: forwarded content overwritten across scopes (#583) #585
• fix: correct flake output include to flake-system schema kind by @sini in fix: correct flake output include to flake-system schema kind #587
• fix: backport aspect-pipeline fixes from entity-gen-schema-port by @sini in fix: backport aspect-pipeline fixes from entity-gen-schema-port #589
• fix: order simple routes before forwards that consume their class by @sini in fix: order simple routes before forwards that consume their class #584
• fix: gh-pages dont fail if no cached versioned docs exist by @vic in fix: gh-pages dont fail if no cached versioned docs exist #591
• improve: organize tests public-api/internal-api/deadbugs by @vic in improve: organize tests public-api/internal-api/deadbugs #592
• docs: update docs from source by @vic in docs: update docs from source #593
• docs: update README remove extensive code examples by @vic in docs: update README remove extensive code examples #594
• docs: update links by @vic in docs: update links #595
• refactor: Extract diagram library to sini/den-diagram by @sini in refactor: Extract diagram library to sini/den-diagram #564
• docs: fix some typos by @quokkbit in docs: fix some typos #597
• fix: guarded empty-path route skips cleanly; honor intoPath alias by @sini in fix: guarded empty-path route skips cleanly; honor intoPath alias #600
• feat: in-context hasAspect honors projected (delivered) scope state by @sini in feat: in-context hasAspect honors projected (delivered) scope state #602
• fix: sibling policy.when guard dedup collision; spawn subtree routes; multi-def forwarded identity by @sini in fix: sibling policy.when guard dedup collision; spawn subtree routes; multi-def forwarded identity #603
• fix: move deadbug to proper location by @vic in fix: move deadbug to proper location #604
• feat: synthesize host identity for standalone user@host homes by @sini in feat: synthesize host identity for standalone user@host homes #605
• fix: missing host class in batteries by @KP64 in fix: missing host class in batteries #606
• fix(ci): live label queries, real allow-ci gating, dead triggers by @sini in fix(ci): live label queries, real allow-ci gating, dead triggers #607
• fix(docs): Remove deprecated link by @Adda0 in fix(docs): Remove deprecated link #612
• feat: gen-schema entity port + resolver decoupling + delivery-edge unification by @sini in feat: gen-schema entity port + resolver decoupling + delivery-edge unification #563
• fix: flattening default den.schema by @fmway in fix: flattening default den.schema #616

New Contributors

• @quokkbit made their first contribution in docs: fix some typos #597
• @KP64 made their first contribution in fix: missing host class in batteries #606
• @fmway made their first contribution in fix: flattening default den.schema #616

Full Changelog: v0.17.0...v0.18.0

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This discussion was created from the release v0.18.0.

[musjj]

I've just gotten around to updating and I had to do ZERO den-related changes this time! Thank you so much for keeping den stable!

[AnonymousRand]

Cross-entity delivery via provides/policy only

Does this mean that if a host aspect includes a schema with both nixos and homeManager class modules, the homeManager modules are no longer automatically passed down to users on that host (reverting the "Cross-Aspect Contributions" change from v0.3.0)? So for those aspects, will I have to explicitly put a provides.to-users before their homeManager class modules if I expect them to be included by host aspects, and a provides.to-host before their nixos class modules if I expect them to be included by user aspects?

I'm probably missing something, because that feels like it defeats the whole point of having multiple class modules in an aspect...but I have found that this indeed no longer works:

den.aspects.host1 = {
  homeManager = { host, ... }: {
    home.stateVersion = host.stateVersion; # `stateVersion` is a custom option in host schema
  };
}

And that this does work:

den.aspects.host1 = {
  provides.to-users.homeManager = { host, ... }: {
    home.stateVersion = host.stateVersion;
  };
}

Edit: looking at the diagram on the mutual config docs page, it seems like maybe homeManager class modules from hosts are not automatically shared to users, but nixos class modules from users are automatically shared with hosts ("request nixos class" during user resolution)? So all the aspects that have any homeManager class module (including ones with both homeManager and nixos) don't need any provides if they are included by a user aspect?

[sini]

This is likely the behavior you want:
https://den.denful.dev/reference/batteries/#denbatterieshost-aspects

[AnonymousRand]

Oh perfect, thank you! Sorry I missed this