state-and-cqrs

name

state-and-cqrs

description

Zustand stores (src/core/store/) and the CQRS v2 pipeline (src/core/cqrs/) — adding a command/event end-to-end with defineCommand and its hand-maintained registries, undo capture and batch(), event versioning/migrations, persistence (localStorage/IndexedDB/useAutoSave), the init-time-literal store rule (#1466), useShallow. Symptoms: "No handler registered for command type", undo toast shows generic "Undid: Action", Ctrl+Z not reverting, "Maximum update depth exceeded", "Missing migration".

State & CQRS

When to use

• Adding or changing a domain command/event, undo behavior, or middleware in src/core/cqrs/.
• Adding a Zustand store or store selector in src/core/store/.
• Persistence bugs (state lost on reload) or event versioning/migration work.
• Any of the symptoms in the traps table below.

Mental model

• Flow: component calls useMutations() (src/shared/contexts/MutationsContext.tsx) → createCqrsMutations (src/core/cqrs/integration/mutationsAdapter.ts) → commandBus.dispatch → middleware pipeline, fixed order in src/core/cqrs/middleware/index.ts getDefaultPipeline(): validation → undoCapture → analytics → logging → handler. The bus publishes the returned events only after the handler returns ok — handlers never publish directly.
• Zustand stores are the source of truth. The IndexedDB event log (gridfinity-events-db, src/core/cqrs/store/eventStore.ts) is best-effort observability: retry queue drops after 3 attempts, 10,000-events-per-aggregate eviction. Command success must never depend on it.
• Every local layout mutation must stamp lastEditSource = 'local': v2 commands get it from applyToDraft (src/core/cqrs/v2/runtime.ts); direct layout-store actions must go through the setLocal wrapper (src/core/store/layout/index.ts), never raw set. Collab push (src/core/sync/triggers/useDebouncedPush.ts), cloud-share dirty tracking (useOwnedShareSync), and ML telemetry fire only on 'local'. importLayout takes an explicit source (remote applies pass 'remote' so they don't echo back); restoreLayout stamps 'local' deliberately.
• v2 core invariant (src/core/cqrs/v2/runtime.ts): handle(payload, ctx) reads a frozen aggregate snapshot and may not mutate; apply(event, draft) is a deterministic Immer-draft write, and the event payload alone must reproduce the state change. Generate IDs and computed placement inside handle() and put them IN the event payload — src/core/cqrs/v2/domain/bin/addBin.ts is the canonical example.
• Undo is snapshot-based, not event replay: undoCapture.ts structuredClones the layout plus a selection snapshot BEFORE the handler, pushes only on ok (max 100, src/core/cqrs/undo/historyStore.ts). Undo/redo re-enter the bus as layout.restore with the restore profile (validation=false, undo=false), handled by v1 src/core/cqrs/handlers/restoreHandlers.ts.
• The v2 defineCommand fields payload, middleware, descriptionKey, schemaVersion are NOT consumed by the runtime. Real behavior comes from four separate registries (table below). Editing only the v2 def silently changes nothing.
• Undo capture is NOT behind a Labs flag: undoCaptureMiddleware is always in the pipeline and runs for every domain-profile command, gated only by getMiddlewareFlags(command.type).undo (src/core/cqrs/middleware/undoCapture.ts). Domain handlers live under v2/domain/ — the v1 <domain>Handlers.ts files were deleted (see git show 2b0c11b). designer.save and layout.restore stay v1 by design; the designer aggregate is not wired and throws in v2/runtime.ts.

Recipe: add a domain command + event (v2)

1. Create src/core/cqrs/v2/domain/<aggregate>/<name>.ts copying addBin.ts: brand IDs/units at the boundary (layerId(), gridUnits() from @/core/types), validate against ctx.aggregate, return ok({ value, event: { payload } }); keep apply() a dumb draft write. Aggregate is 'layout' or 'library' only.
2. Add the command type + union member in src/core/cqrs/commands/<domain>Commands.ts, the event in src/core/cqrs/events/<domain>Events.ts, and re-export through commands/index.ts, events/index.ts, and src/core/cqrs/index.ts.
3. Work through every row of this table. Only two rows are compile-enforced; the rest fail silently.

Registration	File	If missed
v2HandlerOverrides AND v2Commands	src/core/cqrs/v2/registry.ts	runtime throw "No handler registered for command type" at first dispatch
COMMAND_PROFILES entry ('domain' = validated + undoable, 'library' = validated, no undo)	src/core/cqrs/middleware/middlewareConfig.ts	compile error (exhaustive Record)
CURRENT_EVENT_VERSIONS entry	src/core/cqrs/versioning/eventVersions.ts	compile error (exhaustive Record)
Zod schema in COMMAND_SCHEMAS + type in ALL_COMMAND_TYPES	src/core/cqrs/validation/schemas.ts, validation/schemas.test.ts	silent — COMMAND_SCHEMAS is Partial, unvalidated payloads reach the handler
DESCRIPTIONS entry + i18n key	src/core/cqrs/commandDescriptions.ts, src/i18n/locales/en.ts then every locale JSON	silent — undo toast falls back to "↩ Undid: Action" (key undo.unknownAction)
applyEvent case	src/core/cqrs/projection/replay.ts	silent — debug replay drops the event
Mutations method	src/shared/contexts/MutationsContext.tsx + src/core/cqrs/integration/mutationsAdapter.ts	command unreachable from components

4. Write colocated tests for the v2 file (pre-commit blocks files without a sibling test — see the testing skill).

Recipe: multi-command single undo step

1. Import batch from @/core/cqrs. Wrap dispatches: batch(() => { mutations.deleteBin(a); mutations.deleteBin(b); }).
2. The callback MUST be synchronous — async escapes the isBatching scope and later dispatches get their own undo entries. Nesting is safe; the outer batch owns the snapshot. Undo description uses the first command type dispatched inside; the snapshot is pushed even if the callback throws.
3. Test that useHistoryStore.getState().past grows by exactly 1; reset with _resetUndoCaptureState from @/core/cqrs between tests.

Recipe: change a persisted event's payload shape

1. Change the event type in src/core/cqrs/events/<domain>Events.ts and the emitting command's handle/apply.
2. Bump the version in versioning/eventVersions.ts; registerMigration('<event>', 1, 2, fn) in versioning/migrations.ts. Migrations must be pure, must default new fields, must never remove fields. Chains walk v1→v2→v3 automatically, but a gap makes migrateEvent log and return the ORIGINAL unmigrated event — register every v→v+1 step and test the chain.
3. Update projection/replay.ts; keep tolerance for schemaVersion !== current (events without schemaVersion are treated as v1).

Recipe: add a Zustand store

1. Create src/core/store/<name>.ts. Initial state MUST be a pure literal with zero imported function calls — Zustand creators run at module init and chunk-level static-import cycles leave imported bindings undefined (#1466; enforced partially by eslint local/no-init-time-imported-call). Cast branded literals directly; hydrate real data from src/main.tsx like initLibrary/importLayout. Model: PLACEHOLDER_LAYOUT in src/core/store/layout/index.ts.
2. Export use<Name>Store plus an INITIAL_<NAME>_STATE constant for test resets (see src/core/store/selection.ts); re-export from src/core/store/index.ts. There is no zustand/persist anywhere — persist manually (localStorage like settings.ts, or IndexedDB via storage facade).
3. Wrap object-returning selectors in useShallow; put shared derived hooks in src/core/store/selectors.ts only when used 3+ times (guidelines in its header).

Verification

pnpm run test:run src/core/cqrs/     # after any CQRS change
pnpm run test:run src/core/store/    # after store changes (scenario tests cover displacement/half-grid/multi-bin)
pnpm run typecheck                      # exhaustive Records surface missing registrations
pnpm run check:i18n                     # after adding undo-description keys
pnpm run quality                        # before commit

A missing exhaustive-Record entry fails typecheck with "Property '' is missing" pointing at middlewareConfig.ts / eventVersions.ts. The silent registrations surface only at runtime or via validation/schemas.test.ts.

Traps

Symptom	Cause	Fix
Throw "No handler registered for command type: X"	v2 file not in v2HandlerOverrides/v2Commands, or type string mismatch with the command union	register in src/core/cqrs/v2/registry.ts; strings must match exactly
Invalid payload reaches handler, no validation error	schema only in the inert v2 def; validation middleware passes unknown types through	add to COMMAND_SCHEMAS + ALL_COMMAND_TYPES
Ctrl+Z doesn't revert (or reverts too much)	profile isn't domain; or dispatched with source replay/cascade/collab; or inside someone else's batch()	fix COMMAND_PROFILES; dispatch user actions with default source
Boot crash "undefined is not a function", often production-only	imported function called at store module init (#1466 chunk cycle)	pure-literal placeholder state; defer imported calls
"Maximum update depth exceeded" / frozen UI	selector returns fresh object/array without useShallow — Zustand 5 + React 19 makes this an infinite loop, and it's convention-only, not lint-enforced	useShallow from zustand/react/shallow, or select primitives
Undo restores layout but selection/active layer jumps	stale IDs pruned; fallback active layer is layers[layers.length - 1] (top in UI — layers[0] is bottom)	expected behavior lives in restoreHandlers.ts; preserve it
"[migrations] Missing migration X v1→v2"	version bumped without registering every chain step	registerMigration per step; readers tolerate old versions
cloudShare metadata lost after reload	useAutoSave (1s debounce, keyed to layout changes, skips SHARED_PREVIEW_ID) never fires for library-only mutations	emit an event src/core/cqrs/subscribers/libraryPersistence.ts handles, or add a subscription there
Events missing from

Also: never add per-frame/per-pointer-move dispatches — structuredClone of the full layout runs per domain command; interactions batch final state into one command (see the grid-editor skill). New middleware must check getMiddlewareFlags first or it will also see layout.restore with a full Layout payload. event.meta.version is a per-session in-memory counter (handlers/shared.ts) — order persisted events by timestamp, never by version. selectionPruning.ts (live deletes) and restoreHandlers.ts (undo) are two separate selection-consistency mechanisms; keep both. In eventStore.ts append, keep all IDB reads in one up-front Promise.all — interleaved awaits let WebKit auto-commit the transaction mid-loop. Undo toasts use getStaticTranslation (English-only, noted in historyStore.ts).

For test setup and the real-deps rule, see the testing skill. For methodology (reproduce-first, fix-all-layers), see the debugging-playbook skill.