fix(blocks): stop registry.ts reading BLOCK_REGISTRY at module scope

[waleedlatif1]

Summary

import('@/blocks/registry-maps') throws today:

ReferenceError: Cannot access 'BLOCK_REGISTRY' before initialization.
    at apps/sim/blocks/registry.ts:28:56

blocks/registry-maps and blocks/registry sit in an import cycle — a block config reaches back through providers/utils → tools/params → blocks/index → blocks/registry, which imports registry-maps. Whichever module the cycle is entered through evaluates first, so blocks/registry can run while registry-maps is still initializing.

Two module-scope reads, not one

const HAS_PREVIEW_BLOCKS = Object.values(BLOCK_REGISTRY).some(...)   // line 28
export const registry: Record<string, BlockConfig> = BLOCK_REGISTRY  // line 238

Only line 28 appears in the stack trace, so fixing it alone would have silently moved the failure to line 238. Both are now deferred:

• anyPreviewBlocks() memoizes on first use — still "computed once", as the old comment promised, just not at import time
• the raw map is exposed as getBlockRegistry() instead of an eager const alias

Scope: only the entry point was broken

Worth being precise, because the original report overstated it. @/blocks/registry and @/tools/registry both imported fine before this change; only @/blocks/registry-maps as the entry point threw. After:

entry point	before	after
@/blocks/registry-maps	THROWS	OK
@/blocks/registry	OK	OK
@/tools/registry	OK	OK
@/blocks/index, @/tools/params, @/tools/utils, @/providers/utils	OK	OK

Why fix it if the app works

It works under Turbopack only because that bundler happens to order the modules favourably. That's not a property to build on, and it makes blocks/registry-maps un-importable from scripts and tests under Bun.

More concretely: the tool-registry module-graph audit found the registry is 68–78% of every workspace route's graph and proposed a metadata/implementation split. Any such restructuring perturbs module ordering. This is a prerequisite to that work, not something to discover halfway through it.

tsc caught two consumers grep missed

Three consumers updated. Two of them destructure the binding off a dynamic import rather than naming it in a static one:

const { registry: blockRegistry } = await import('@/blocks/registry')

My rg for the named import found only one callsite; tsc --noEmit found the other two (use-mention-data.ts:195, process-contents.ts:548). Worth noting for anyone doing similar refactors — a grep-only sweep here would have shipped two runtime undefined lookups.

Behaviour preservation

getBlockRegistry()[type] is the same raw lookup the alias provided. Deliberately not getBlock(), which would additionally apply version normalization and custom-block overlay fallback — correct-looking, but a behaviour change smuggled into a cycle fix.

Type of Change

• Bug fix

Testing

• tsc --noEmit exit 0
• All 7 cycle entry points import cleanly (table above)
• 47 test files / 561 tests passing across apps/sim/blocks and apps/sim/lib/copilot/chat
• biome check clean on all changed files

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Jul 30, 2026 1:45am

[cursor]

PR Summary

Low Risk
Initialization-order fix with behavior-preserving registry access; limited to registry wiring and three consumers, with no auth or data-path changes.

Overview
Fixes ReferenceError: Cannot access 'BLOCK_REGISTRY' before initialization when the import cycle between blocks/registry and blocks/registry-maps is entered through registry-maps (common in Bun scripts/tests; Turbopack ordering masked it).

blocks/registry.ts no longer touches BLOCK_REGISTRY at load time: preview detection moves to memoized anyPreviewBlocks() on first use, and the eager registry export becomes getBlockRegistry() so both former module-scope reads are deferred.

Call sites that needed the raw map now call getBlockRegistry() — chat integration chips, copilot mention workflow-block icons, and server block-metadata validation — preserving direct keyed lookup (not getBlock() normalization/overlay).

^{Reviewed by Cursor Bugbot for commit b34b2d1. Configure here.}

[greptile-apps]

Greptile Summary

Defers module-scope BLOCK_REGISTRY reads in blocks/registry.ts so import-cycle entry via registry-maps no longer throws TDZ ReferenceError.

• Replaces eager HAS_PREVIEW_BLOCKS with lazy memoized anyPreviewBlocks()
• Replaces exported registry alias with getBlockRegistry()
• Updates three callers (static + dynamic imports) to the new accessor without switching to getBlock() (preserves raw-map lookup semantics)

Confidence Score: 5/5

Safe to merge; the cycle fix is localized, callers of the removed export are updated, and no behavioral or security regressions are evident.

Both module-scope BLOCK_REGISTRY reads are deferred; remaining production imports use getBlock/getAllBlocks or the new getter; no leftover named registry import was found.

Important Files Changed

Filename	Overview
apps/sim/blocks/registry.ts	Lazily reads BLOCK_REGISTRY for preview detection and raw-map export to avoid TDZ under the registry/registry-maps cycle.
apps/sim/app/workspace/[workspaceId]/home/components/chat-context-kind-registry/chat-context-kind-registry.tsx	Switches static import from registry alias to getBlockRegistry() with the same raw type lookup.
apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/copilot/components/user-input/hooks/use-mention-data.ts	Dynamic import updated to call getBlockRegistry() instead of destructuring removed registry binding.
apps/sim/lib/copilot/chat/process-contents.ts	Dynamic import updated to getBlockRegistry() for blockId existence check; behavior unchanged vs prior alias.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Entry: import registry-maps or registry] --> B{Import cycle}
  B --> C[registry-maps still initializing]
  B --> D[registry evaluating]
  C --> E[Old: module-scope BLOCK_REGISTRY read]
  E --> F[ReferenceError TDZ]
  D --> G[New: anyPreviewBlocks / getBlockRegistry on first use]
  G --> H[BLOCK_REGISTRY fully initialized]
  H --> I[Safe lookup]

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_{Reviews (1): Last reviewed commit: "fix(blocks): stop registry.ts reading BL..." | Re-trigger Greptile}