feat(workflows): compare workflow versions and preview fork sync changes by mzxchandra · Pull Request #8455 · simstudioai/sim

mzxchandra · 2026-09-30T06:58:48Z

Summary

Adds a workflow version diff: a read-only canvas that paints added, modified and removed blocks and connections, next to a change list with field-level diffs.
It is used in two places.

Deploy modal: "View changes" compares any two deployment versions, or a version against the current draft.
Workspace fork sync: each workflow in the sync list gets a "View changes" button that previews what the sync would write over the target's current draft.

How it works:

lib/workflows/comparison gains container (loop/parallel) config changes and buildWorkflowDiffOverlay, which merges both states into one canvas with removed blocks and edges drawn as ghosts, nudged clear of live blocks.
The change list renders every field as a diff: code and prompts as line diffs with word marks and folded context, lists (conditions, routes, tools, input fields) as keyed item diffs, and added or removed blocks as a diff against nothing.
Secrets are masked everywhere: password sub-blocks, secret-looking keys at any depth (including JSON-encoded tool params and header tables), and block tools' own password params. A change hidden by masking still shows as "a masked value changed".
The fork preview re-keys the source's block ids into the target's through the persisted block map (O(1) lookups, falling back to the same deterministic derive the promote uses), so a block present on both sides compares as itself. The diff joins by id with Maps and Sets, so it is linear in block count.
The fork preview loads only the previewed workflow: its deployed state, its identity mapping, its target row and its block pairs. The plan item comes from the same buildForkPromotePlanItems decision the promote makes.

Guards against slow input: line diffs cap at 2000 lines, word marks give up past 64 edits per line pair or 4000 characters, and both diff modals are lazy-loaded.

The settings route's module baseline is re-recorded (+355 modules). The growth is the block registry that the diff canvas needs, reached only through the lazy chunk opened on click. The tool registry stays out.

Follow-ups, not in this PR:

The fork preview shows the source as deployed. The resource remaps, custom block swaps and cleared references that the sync applies at write time are listed by the sync page's own sections, not painted on the canvas. A reference the sync would clear already hard-blocks the sync until it is dropped.
Credential and selector values show as stored ids rather than resolved display names.

Type of Change

Testing

Unit tests for the comparison engine, overlay, change-list helpers (masking, pairing, text diff rows), compare-pair resolution, the fork preview use case and its route: 2,835 tests passing across the affected areas.
bun run check:api-validation:strict, the module-budget check, biome, and type-check for apps/sim and packages/workflow-renderer all pass.
Browser E2E on local dev: compared deployment versions and the draft in the deploy modal, previewed push and pull syncs on a fork, and checked ghosts, container changes, long code bodies and masked fields.
The single-workflow fork preview returns byte-identical responses to the previous whole-workspace implementation on a live fork, in both directions.

Reviewers: the overlay placement (lib/workflows/comparison/overlay.ts) and the single-workflow plan resolution (resolveForkPlanItem) deserve the closest look.

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

Screenshots available on request; the deploy modal and fork sync page both open the same comparison view.

🤖 Generated with Claude Code

…verlay The comparison engine now reports which loop and parallel fields changed and which blocks entered or left a container, and exposes the field lists and a shared hasChanges helper. A new overlay module merges two workflow states into one canvas: removed blocks, containers and edges ride along as ghosts at their old positions (nudged clear of live cards), deleted condition and router branches stay on the surviving card so their ghost edge keeps a handle, and every edge is classified by canonical port key. The renderer edge view gains a quiet ghost style for those removed connections.

The preview canvas accepts per-block and per-edge diff status: added and modified cards get a ring and a shared status label, removed cards and containers fade to a ghost, changed sub-block rows and sentence chips tint, and ghost edges sit under live ones so a rewired port shows the new line on top.

Side-by-side view of two workflow states: the overlaid canvas on the left and a change list on the right, sharing selection. Each touched block is a collapsible card with the app's block tile; modified blocks show field rows as folded line diffs with word marks, item-by-item list diffs for tools, conditions, routes and input fields, old to new pairs for scalars, and only the fact for secrets. Added and removed blocks show every field diffed against nothing, with long one-sided bodies capped behind one expander. Fork comparisons group credentials, picked resources and trigger paths into a muted environment bindings section.

The deploy modal offers "View changes" (live against the draft) when a redeploy is pending and a "Compare" action on every version row, opening a full-width comparison whose two sides are pickable from the header. The draft state hook is shared with change detection and only subscribes while something to compare against exists.

The synced deployed workflows list gets a "View changes" action per row. A new internal route and fork use case return the target as its editor holds it and the source deployment re-keyed into the target's block ids through the fork block map (or the derived id the sync would assign), with condition and route ids and variable ids aligned, so the two sides diff block for block like two versions of one workflow.

Comparison: keep basic/advanced mode changes visible, include a tool's permission, server and implementation fields in list diffs, include input field defaults, read checkbox records as records, show whitespace-only edits, cap word and line diffing so a pathological prompt cannot stall the pane, slot deleted branches back at their old position, never reuse a ghost edge id, and mask secret-looking keys at any depth (including key/value table rows) with a name-based fallback when a block definition is unknown. Change list: memoized cards that only re-render when their own selection changes, nested cards for blocks inside an added or removed container, a shared sign map, muted tokens that exist, hover and focus treatment, scroll edge fades, and a shared skeleton for both hosts. Fork preview: the before side is the target draft the sync overwrites, read in one snapshot and scoped to the target workspace; variables and their assignments are re-keyed by unique name; a create reports no target id; the change rows are a discriminated union; the query key sits under the fork diff keys so a sync invalidates it; a direction switch closes the preview.

…ew gaps - Fork "View changes" now loads only the previewed workflow: its deployed state, its identity mapping, its target row and its block pairs, instead of every deployed state in the source workspace plus the full promote plan. The plan item comes from the same buildForkPromotePlanItems decision the promote uses. The route gets a per-user rate limit. - Word marks give up past 64 edits per line pair, so many long rewritten lines cannot stall the tab. - Agent tool params that their block marks as password fields are masked whatever their name. - A list item whose label changed but whose body did not is no longer flagged as a masked value change. - Hoist double casts under their annotations, make sourceWorkflowId optional on the wire for rollout, lazy-load both diff modals, and re-record the settings module baseline: the block registry the diff canvas needs is reached only through the lazy chunk opened on click.

vercel · 2026-09-30T06:58:58Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
docs	Ready	Preview	Oct 1, 2026 12:52am UTC

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greptile-apps · 2026-09-30T07:05:07Z

Confidence Score: 5/5

[Medium risk] Adds workflow version comparison and fork sync preview features.

The PR appears safe to merge based on the changes since the previous review and the resolved prior findings.

Summary

The PR adds a read-only workflow comparison canvas and field-level change list for deployment versions and fork-sync previews. Fork previews load one workflow and align source block IDs with the target; the latest changes switch five tests to absolute imports.

Previously reported findings are resolved or fixed in the current code.
No new issue was identified in the changes since the previous review.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Deployment versions or fork-sync workflow] --> B[Load comparison states]
  B --> C[Generate workflow diff]
  C --> D[Build canvas overlay]
  C --> E[Render field-level change list]

_{Reviews (8) · Last reviewed commit: "test(workflows): use absolute imports in..."}

- Sync details load each replaced target's draft and diff it against the projected source, using the same projection and "has changes" rule as the per-workflow preview, so a row and its preview never disagree. Rows the sync would not change read "No changes" and offer no comparison. - Preview buttons wait until the list matches the selected direction. - Mask JSON-encoded secrets in text and scalar fields, and say "A masked value changed" when masking hides the only difference. - Show role changes on agent messages, highlight a router's changed Context on the canvas, and keep ghost edges under live ones into containers. - Added or removed loops and parallels list their iteration settings. - Size ghost containers the way the preview draws them. - "Order changed" only when items moved; CRLF and CR read as line breaks; collapsing unchanged lines closes every fold; selecting a nested block opens its container card; the version pickers have distinct names. - Drop redundant mock resets flagged by check:test-patterns.

mzxchandra · 2026-09-30T07:42:21Z

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- The sync list's per-workflow change check measures the target drafts in one query first and skips itself past the fork state limit, then reads drafts a few at a time and drops each after comparing, instead of holding them all. - Mask keys with a secret word anywhere in them (secretAccessKey, aws_secret_access_key) while credential references stay readable. - Inline diffs show whitespace-only changes. - Opened folds reset when the compared bodies change. - Ghost collision boxes use the canvas's own block measurement.

mzxchandra · 2026-09-30T07:55:51Z

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…ection per comparison - Agent message bodies go through the same masking as other text fields. - The sync change check's size guard counts block outputs and data, not only sub-blocks. - Picking another version clears the block selection.

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…comes, not mock calls - Key the comparison view by the picked version pair instead of resetting on state identity, so live draft updates no longer clear the selection. - Agent message changes hidden by masking say so, like other fields. - Fork preview tests assert results, with mocks that answer only the right arguments, instead of asserting mock calls.

mzxchandra · 2026-09-30T08:14:27Z

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…ists on both sides

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mzxchandra · 2026-09-30T08:39:49Z

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mzxchandra added 8 commits September 29, 2026 22:49

test(forks): use a neutral workflow name in preview fixtures

43feafc