fix(workflow): hide idle nested subflow end handles

[BillLeoutsakosvl346]

Summary

• Hide the fixed right end port for nested Loop and Parallel containers when no displayed edge uses the canonical end handle.
• Keep the semantic React Flow end handle mounted and preserve cursor-swell authoring, saved handle IDs, and edge topology.
• Remove the rejected 98px Start-lane constraint so nested blocks and containers again use the existing 24px left gutter and can move left when vertically clear.
• Render every persisted edge entering a Loop or Parallel on the target container layer. React Flow paints the equal-z target afterward, so the target covers the incoming segment while the edge remains above its parent container.
• Apply the same target-aware layering in the editor, execution/application preview, and flattened docs renderer. Selected-edge controls follow the target occlusion layer; in-flight connection lines remain elevated.

Eng Todo: https://sim-ai.slack.com/archives/C093DF8MA21/p1786560718145569

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation
• Other: ___________

Compatibility

• Existing and new layouts keep the pre-existing container positioning behavior; no workflow positions are migrated or rewritten.
• Persisted schemas, extent values, edge IDs, serialization, validation, auto-layout, execution topology, and handle normalization are unchanged.
• Highlight and execution state still change edge styling, but cannot lift an incoming edge over its Loop or Parallel target.
• Covered edge segments intentionally yield pointer interaction to the target; visible segments remain above the parent body and interactive.

Testing

Automated:

• Workflow renderer focused suites: 49 tests passed across canvas layering, edge rendering, and Loop/Parallel handle rendering.
• Sim positioning and node-utility suites: 8 tests passed.
• Docs workflow transformation suite: 2 tests passed.
• bun run --cwd packages/workflow-renderer lint:check
• bun run --cwd packages/workflow-renderer type-check
• bun run --cwd apps/sim type-check
• bun run --cwd apps/docs type-check
• bun run check:api-validation
• git diff --check

Manual local-app verification:

• Moved the nested Parallel down and left to the normal relative X 24 gutter; it no longer snaps to X 98.
• Confirmed the incoming nested edge renders at z=1 above the parent Loop at z=0 and beneath the Parallel at z=1.
• Confirmed the low-left route remains visible over the Loop body and stops visually at the Parallel boundary without crossing its title.
• Returned the Parallel to the overlapping Start-pill case and confirmed the covered line segment disappears beneath the Parallel instead of remaining visible across its title.
• Retained the prior verification that idle nested end ports are absent, canonical handles remain mounted, cursor-swell creation works, and connected canonical end ports remain visible.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

Screenshots/Videos

Not attached; the manual geometry and layer verification results are listed above.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview	Aug 23, 2026 8:07pm

[cursor]

PR Summary

Medium Risk
Touches React Flow z-order and subflow handle painting across editor, preview, and docs. Wrong layering or handle visibility can hide connections or break nested-container UX, but schemas and execution topology are unchanged.

Overview
Fixes nested Loop/Parallel chrome: idle nested containers no longer paint the fixed right end port, while the semantic React Flow handle stays mounted. Top-level containers and nested ones that already have a canonical end-handle edge still show the knob.

Incoming edges that target a Loop/Parallel now share that container’s z-layer via getEdgeZIndexForTarget, so React Flow paints the target over the last segment while the line stays above the parent body. Highlight/execution z no longer lifts those edges over the target. The same rule is applied in the editor, execution preview, and flattened docs renderer; selected-edge delete controls follow labelZIndex when the target is a container.

Docs preview nodes now carry parentId and nesting-based z-index. Adds renderer, docs, and mount tests (including no extra nested-subflow rerenders on unrelated edge changes) and a vitest script in apps/docs.

^{Reviewed by Cursor Bugbot for commit b71ba64. Configure here.}

[BillLeoutsakosvl346]

Screen.Recording.2026-08-22.at.12.32.30.PM.mov

[greptile-apps]

Greptile Summary

The PR hides unused visual end ports on nested Loop and Parallel containers while retaining their semantic handles, and aligns incoming-edge occlusion across editor and preview renderers.

• Adds target-aware edge z-index resolution for container targets.
• Propagates nesting metadata through Sim and docs previews.
• Adds focused tests for handle visibility, layering, and selected-edge controls.

Confidence Score: 5/5

The PR appears safe to merge because no blocking failure remains within the eligible follow-up-review scope.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/workflow-renderer/src/subflow/subflow-node-view.tsx	Conditionally includes the fixed visual end port for nested subflows while leaving the semantic React Flow handle mounted.
packages/workflow-renderer/src/canvas-layers.ts	Adds shared target-aware edge layering so incoming segments are occluded by their container target.
apps/sim/app/workspace/[workspaceId]/w/[workflowId]/workflow.tsx	Applies target-aware layering to editor edges and their selected-edge controls.
apps/sim/app/workspace/[workspaceId]/w/components/preview/components/preview-workflow/preview-workflow.tsx	Applies container-target occlusion consistently in execution and application previews.
apps/docs/components/workflow-preview/workflow-data.ts	Computes semantic nesting depth for flattened docs nodes and applies corresponding node and edge layers.

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^{Reviewed by Cursor Bugbot for commit b71ba64. Configure here.}