FE-1153: Collapse per-type switches into a type-policy registry

[kube]

🌟 What is the purpose of this PR?

Pure refactor closing out the discrete-types architecture retrospective: adding a token dimension type previously meant editing switch (element.type) statements in seven far-apart places (buffer layout, coercion/defaults, generated kernel code, LSP virtual files, schema migration, scenario compilation, spreadsheet cell parsing) that stayed consistent by convention only. This PR gathers the per-type data into a single TYPE_POLICIES registry in petrinaut-core and adds a conformance test so a sixth type fails loudly until every touchpoint is defined.

🔗 Related links

• FE-1153: Petrinaut: collapse per-type switches into a type-policy registry (internal)
• Top of the discrete-types stack: FE-769: Add String token dimension type (string interning) #8956 → FE-1121: Add UUID token dimension type #8953 → FE-1139: Simulation architecture documentation #8951 → FE-1130: Token frame format v2 — packed struct token layout #8944 → FE-1129: Token encoding playground (Storybook) #8943 → H-6519: Add discrete token attribute types #8764.

🚫 Blocked by

• FE-769: Add String token dimension type (string interning) #8956 (and its base chain — merges first)

🔍 What does this change?

New simulation/engine/type-policies.ts: TYPE_POLICIES: Record<ColorElementType, TypePolicy> where each policy carries:

• physicalKind (f64 | u8 | u64 | u64x2) — packed-struct layout kind
• defaultValue (runtime form) and defaultValueSource (TS expression for generated default kernels, e.g. Uuid.generate())
• tsInputType / tsKernelOutputType / kernelOutputOptional — LSP virtual-file type strings
• coerce(value, context) — runtime coercion (the old switch bodies)
• decodeNumberSlot — f64/u8 slot decode, null for uuid/string (decoded in token-layout.ts)
• encodeAtRest(value) — runtime → JSON-safe document form (uuid bigint → canonical lowercase string)
• parseEditorText(raw) — total spreadsheet cell parse

Plus COLOR_ELEMENT_TYPES, the canonical runtime list of the union (as const satisfies keeps it in lockstep; the Record shape guarantees the reverse direction at compile time).

Consumers converted (existing exported function names kept as thin wrappers, so the public API is unchanged): token-values.ts (defaults/coercion/number-slot decode; new shared coerceToStoredTokenAttributeValue helper), token-layout.ts (physicalTypeFor), default-codes.ts, lsp/lib/generate-virtual-files.ts, schema-migration.ts, compile-scenario.ts, and in the React package migrate-initial-marking.ts and the spreadsheet's parseCellValue. The zod colour element schema's type enum now derives from COLOR_ELEMENT_TYPES.

Deliberately left structural (control flow, not per-type data): uuid sentinel/RNG handling and string interning in encode-kernel-token.ts; uuid-lane/string-pool read-write paths in token-layout.ts; the real+stochasticity Distribution union and ?: never derivative exclusions in the LSP generator; spreadsheet uuid short-form/overlay and boolean-checkbox rendering (presentation); scenario-mapping.ts / initial-state-editor.tsx at-rest decoding (intentionally laxer semantics than core coercion — converting them would change behaviour).

Pre-Merge Checklist 🚀

🚢 Has this modified a publishable library?

This PR:

• modifies an npm-publishable library and I have added a changeset file(s) (fe-1153-type-policy-registry.md — the registry and its types are new public exports)

📜 Does this require a change to the docs?

The changes in this PR:

• do not require any changes to docs (no user-facing behaviour change)

🕸️ Does this require a change to the Turbo Graph?

The changes in this PR:

• do not affect the execution graph

⚠️ Known issues

• The registry intentionally does not absorb mode-dependent LSP logic or UI rendering; those stay exhaustive switches at their sites.

🐾 Next steps

• A future Enum element type should be addable by filling in one TypePolicy record plus the structural sites the conformance test points at.

🛡 What tests cover this?

• New type-policies.test.ts (32 assertions): registry keys ≡ COLOR_ELEMENT_TYPES ≡ the zod enum's options; per type: physicalKind agrees with computeTokenSlotLayout (kind, width, alignment); decodeNumberSlot present iff f64/u8; defaults round-trip coercion unchanged; at-rest encode is JSON-serializable; editor parse is total and coercion-stable.
• All pre-existing tests pass unmodified (665 core + 149 UI), which is the no-behaviour-change evidence.

❓ How to test this?

npx turbo run lint:tsc lint:eslint test:unit --filter '@hashintel/petrinaut-core' --filter '@hashintel/petrinaut' — behaviour is otherwise identical to #8956.

📹 Demo

N/A — no user-facing change.

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Project	Deployment	Actions	Updated (UTC)
hash	Ready	Preview, Comment	Jul 7, 2026 12:48pm
petrinaut	Ready	Preview, Comment	Jul 7, 2026 12:48pm

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
hashdotdesign-tokens	Ignored	Preview	Jul 7, 2026 12:48pm

[cursor]

PR Summary

Medium Risk
Touches coercion, scenario/migration storage, and simulation token codecs across core and UI, but the PR positions it as behavior-preserving with existing unit tests unchanged; risk is mainly regression in edge-case parsing/coercion rather than new features.

Overview
Centralizes per-token-type behavior in a new TYPE_POLICIES registry (type-policies.ts) so each ColorElementType defines layout kind, defaults, coercion, at-rest encoding, LSP type strings, and spreadsheet parseEditorText in one place, instead of duplicated switch (element.type) blocks across the codebase.

Refactors call sites to delegate to the registry: token-values (plus shared coerceToStoredTokenAttributeValue), token-layout, default-codes, LSP virtual-file generation, schema migration, scenario compilation, initial-marking migration, and the spreadsheet cell parser. The Zod colour-element type enum now derives from COLOR_ELEMENT_TYPES.

Exports TYPE_POLICIES, COLOR_ELEMENT_TYPES, TypePolicy, and StoredTokenAttributeValue from @hashintel/petrinaut-core (patch changeset). Adds type-policies.test.ts conformance coverage so a new element type must get a full policy and stay aligned with layout and schema.

Mode-specific LSP widening (e.g. stochastic Distribution on real) and uuid/string buffer paths in token-layout / kernel encoding stay as structural code outside the registry.

^{Reviewed by Cursor Bugbot for commit 30ca842. Bugbot is set up for automated code reviews on this repo. Configure here.}

[Copilot]

Pull request overview

Refactors Petrinaut’s token-dimension “per-type” behavior into a single TYPE_POLICIES registry in @hashintel/petrinaut-core, replacing multiple scattered switch (element.type) blocks while keeping existing exported wrapper APIs stable.

Changes:

• Adds simulation/engine/type-policies.ts (TYPE_POLICIES, COLOR_ELEMENT_TYPES, TypePolicy) to centralize per-type defaults, coercion, layout kind, at-rest encoding, and editor parsing.
• Migrates key consumers (token codec/layout, LSP virtual-file generation, scenario compilation, schema migration, UI spreadsheet parsing) to read behavior from the registry.
• Adds a conformance test (type-policies.test.ts) and derives the Zod enum from COLOR_ELEMENT_TYPES to keep the union/list/schema in lockstep.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
libs/@hashintel/petrinaut/src/ui/components/spreadsheet.tsx	Uses core TYPE_POLICIES for spreadsheet cell parsing instead of a local per-type switch.
libs/@hashintel/petrinaut/src/react/simulation/provider/migrate-initial-marking.ts	Simplifies stored-value coercion via shared coerceToStoredTokenAttributeValue.
libs/@hashintel/petrinaut-core/src/simulation/engine/type-policies.ts	Introduces the centralized type-policy registry and canonical COLOR_ELEMENT_TYPES list.
libs/@hashintel/petrinaut-core/src/simulation/engine/type-policies.test.ts	Adds conformance coverage to ensure registry/schema/layout invariants stay aligned.
libs/@hashintel/petrinaut-core/src/simulation/engine/token-values.ts	Replaces switches with policy-driven defaults/coercion/decoding; adds coerceToStoredTokenAttributeValue.
libs/@hashintel/petrinaut-core/src/simulation/engine/token-layout.ts	Derives physical layout kind via TYPE_POLICIES rather than a switch.
libs/@hashintel/petrinaut-core/src/simulation/authoring/scenario/compile-scenario.ts	Encodes compiled initial state to JSON-safe at-rest form via policies.
libs/@hashintel/petrinaut-core/src/schemas/entity-schemas.ts	Derives the color-element type enum from COLOR_ELEMENT_TYPES.
libs/@hashintel/petrinaut-core/src/schema-migration.ts	Reuses policy-driven stored coercion/defaulting for scenario row migration.
libs/@hashintel/petrinaut-core/src/lsp/lib/generate-virtual-files.ts	Uses policy-driven TS type strings and optionality for generated token types.
libs/@hashintel/petrinaut-core/src/index.ts	Exposes TYPE_POLICIES, COLOR_ELEMENT_TYPES, and related types/utility to consumers.
libs/@hashintel/petrinaut-core/src/default-codes.ts	Uses policy-driven defaultValueSource for generated default code.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

[kube]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• FE-1153: Collapse per-type switches into a type-policy registry #8964 👈 (View in Graphite)
• FE-769: Add String token dimension type (string interning) #8956
• FE-1121: Add UUID token dimension type #8953
• FE-1139: Simulation architecture documentation #8951
• FE-1130: Token frame format v2 — packed struct token layout #8944
• FE-1129: Token encoding playground (Storybook) #8943
• main

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[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.