| name | slice-isolation |
| description | **TIMEWARP SKILL** — product slice placement and TWA0009 isolation (SliceRoot, namespaces, platform Applications, Components/contracts sharing, CrossSliceReference opt-out). Invoke before scaffolding a new feature/slice/page or when fixing TWA0009 / cross-slice references. WHEN: "Add a new clients feature page", "Where does this state live?", "TWA0009 slice references another product slice", "CrossSliceReference", "new product area under features/", greenfield slice scaffolding. |
| when-to-use | slice, slice isolation, TWA0009, CrossSliceReference, SliceRoot, TimeWarpSliceRoot, product feature folder, features/, Applications platform, cross-slice, where page/state live
|
Slice isolation (TWA0009)
Slices are independently removable vertical units. Folders organize humans; the
namespace under SliceRoot is the law. Analyzer TWA0009 is the reactive safety net;
this skill is for correct first placement so greenfield work does not couple product
areas by accident.
Enforcement ships in TimeWarp.Architecture.Analyzers (and monorepo ProjectReference). Do not
re-interpret rules here — mirror the analyzer.
Detection — when to invoke
| Signal | How to find it |
|---|
Product area under features/ | web-spa/features/…, web-contracts/features/… |
| Namespace under SliceRoot | …Features.<Id> (or nested …Features.Admin.Roles) |
TWA0009 / CrossSliceReference | diagnostic text or attribute on a type |
| “Where does this page/state live?” | any new product capability before scaffolding |
Terms
| Term | Meaning |
|---|
| Slice | Removable vertical capability; the isolation unit |
| Feature | Informal product language only — not the analyzer’s unit name |
| Module | IModule / host DI composition — not a product slice |
Prefer saying slice in diagnostics, opt-outs, and agent prose. Namespace path may still use
…Features.* (familiar VSA / contracts layout).
SliceRoot
| Setting | Value |
|---|
| Default | {RootNamespace}.Features (from MSBuild RootNamespace) |
| Override | MSBuild property TimeWarpSliceRoot (must be CompilerVisibleProperty) |
Slice id = path under SliceRoot after stripping structural suffixes Pages, Components,
Application. Nested ids are the full path:
| Namespace | Slice id / tier |
|---|
…Features | Substrate (bare root) |
…Features.Applications | Platform id Applications |
…Features.Counters | Product id Counters |
…Features.Counters.Pages | Product id Counters (suffix stripped) |
…Features.Admin.Roles | Product id Admin.Roles |
…Components, layouts, app root types | Outside SliceRoot |
Folders usually mirror slices (features/counter/ ↔ …Features.Counters) but moving a file
does not change legal dependencies — only the namespace does.
Tiers (dependency rules)
| Tier | Example | May reference |
|---|
| Outside | …Components, shell, layouts | Anything (composition free) |
| Substrate | bare …Features (BaseComponent, shared base types) | Outside, substrate, platform — not product without opt-out |
| Platform | …Features.Applications | Outside, substrate, platform — not product without opt-out |
| Product | …Features.Counters, …Features.Admin.Roles | Outside, substrate, platform, own product id, contracts (other assembly). Not another product id without opt-out |
Forbidden without opt-out (TWA0009):
- product A → product B (A ≠ B)
- platform → product
- substrate → product
Free by design:
- product → platform (
Applications) — e.g. CounterPage → ApplicationState
- any code → other assemblies (contracts are sharing-by-design)
- Outside → product (nav shell, shared components)
Placement matrix
| Artifact | Where |
|---|
| Page, state, actions, slice-local UI | Inside the product slice namespace |
App chrome / shell / empty MainLayout | Outside SliceRoot (e.g. …Components) — see blazor-layout |
| Shared UI used by multiple slices | components/ → namespace outside SliceRoot |
| Shared API shapes | Contracts project (other assembly; free under TWA0009) |
| Host-wide modal / menu / branding state | Platform Applications |
Living anchors (timewarp-architecture template):
| Role | Path | Namespace |
|---|
| Product | web-spa/features/counter/ | …Features.Counters |
| Nested product | web-spa/features/admin/roles/ | …Features.Admin.Roles |
| Platform | web-spa/features/application/ | …Features.Applications |
| Substrate | web-spa/features/base/base-component.cs | …Features |
| Outside shell | web-spa/components/TimeWarpPage.razor | …Components |
Greenfield scaffold workflow
- Name the slice — plural, domain-oriented (
Clients, Admin.Roles).
- Folder — kebab path under the project’s
features/ tree (match sibling casing).
- Namespace —
{RootNamespace}.Features.{SliceId} (plural segments; nested with .).
- Colocate page, state, actions, and slice-private components in that namespace (pages are
not shared infrastructure — no grab-bag
…Pages for product UI).
- Contracts — same plural feature path under the contracts project (
web-api-contracts
skill). Other assembly → free across SPA slices.
- Wire nav / DI from Outside or platform — not from another product slice.
- Prefer share (Components / contracts) over
[CrossSliceReference].
- Build — fix TWA0009 by relocating code first; mute only for deliberate demo/integration edges.
Share vs opt-out
Prefer share
- Promote shared controls to
…Components.
- Share API shapes via contracts assembly.
- Depend product → platform without attributes when the dependency is real host state.
Opt-out — deliberate edges only
using TimeWarp.Foundation.Features;
[CrossSliceReference(typeof(CounterState), "Living style guide exercises the counter throw-exception pipeline.")]
partial class StyleGuidePage;
Rules:
- Attribute on the referencing type (
AllowMultiple = true for multiple foreign slices).
typeof(T) maps to the target product slice; only edges into that slice are suppressed.- Reason must be non-empty (human paperwork).
- Partial-safe (semantic attributes).
- Type:
TimeWarp.Foundation.Features.CrossSliceReferenceAttribute (package
TimeWarp.Foundation.Contracts / monorepo foundation-contracts).
Living examples:
- Style guide → Counters:
web-spa/features/style-guide/pages/StyleGuidePage.razor.cs
- Auth pipeline deliberate edges: authentication code-behinds with multiple
[CrossSliceReference(...)] when needed
Limits agents must know
| Limit | Implication |
|---|
| Same assembly only | Contracts / NuGet metadata types never trip TWA0009 |
| Hand-written C# | GeneratedCodeAnalysisFlags.None — pure .razor without .razor.cs is not scanned; put deliberate edges on code-behind |
| Folders can lie | Namespace still owns the type |
| Structural suffixes | …Counters.Pages is still product id Counters |
Good / bad examples
| Bad | Why | Fix |
|---|
…Features.Counters type uses WeatherForecastsState | product → product | Share via Components/contracts, or reasoned [CrossSliceReference] |
Product page in grab-bag …Pages outside any slice | not removable with the capability | Namespace under …Features.<Id> |
Platform type reaches into Counters | platform ↛ product | Invert dependency (product → platform) or rare opt-out on platform type |
| Mute TWA0009 globally / without reason | hides real coupling | Relocate or scoped opt-out |
| Good | Why |
|---|
CounterPage uses ApplicationState | product → platform free |
TimeWarpPage in …Components | Outside composition free |
Admin.Roles only uses own types + contracts + platform | nested product isolation |
Agent checklist
Related skills and pointers
web-api-contracts — contract placement; contracts assemblies are free under TWA0009; still use plural …Features.* aligned with SPA product slicesblazor-layout — empty layout + shell; chrome outside SliceRootblazor-css-strategy — shell/component styling onlyagent-context-regions — Purpose/Design on new files (TWA0004)- AGENTS.md — TWA diagnostic table (row TWA0009)
- HowToRemoveDemoFeatures — delete Counter/EventStream demo slices
- Analyzer (source of truth):
source/analyzers/timewarp-architecture-convention-analyzers/slice-isolation-analyzer.cs
- Opt-out attribute:
source/foundation/foundation-contracts/base/cross-slice-reference-attribute.cs
