refactor: extract missing model refresh pipeline (#11751)

## Summary

Extracts the missing-model pipeline orchestration out of `ComfyApp` and
into an app-independent platform module, while tightening the
workflow-flattening type boundary that refresh needs when rescanning the
live LiteGraph graph.

This PR is intentionally refactor-heavy. It is the follow-up to the
earlier missing-model refresh work: instead of keeping refresh-specific
candidate recheck logic beside the UI, this change makes the refresh
path reuse the existing missing-model pipeline and removes the direct
dependency on private `ComfyApp` pipeline methods.

Linear: FE-499

Issues covered by this PR:

- Fixes #11678
- Fixes #11680
- Partially addresses #11679 by removing the missing-model refresh
path's unsafe `graph.serialize() as unknown as ComfyWorkflowJSON` cast
and replacing it with the narrower flattenable workflow contract.
Broader workflow serialization/type-boundary cleanup outside this
missing-model refresh path remains deferred.

## Changes

- **What**:
- Added `src/platform/missingModel/missingModelPipeline.ts` as the
orchestration module for missing-model detection/verification.
- `runMissingModelPipeline(...)` now owns the pipeline previously
embedded in `ComfyApp`:
      - candidate scan and enrichment
      - active ancestor filtering for muted/bypassed subgraph containers
      - pending warning cache updates
      - OSS folder path and file-size follow-up work
      - cloud asset verification follow-up work
- surfaced missing-model errors via the existing execution error store
- `refreshMissingModelPipeline(...)` handles the refresh-specific flow:
      - calls the injected `reloadNodeDefs()` first
      - serializes the current live graph
- preserves model metadata by preferring active workflow `models`, then
falling back to current missing-model candidate metadata
      - delegates back into the same pipeline used during workflow load
- Kept `ComfyApp` as the compatibility caller instead of the owner of
the pipeline.
- `loadGraphData(...)` now calls `runMissingModelPipeline(...)` with
`graph`, `graphData`, `missingNodeTypes`, and `silent` options.
- `refreshMissingModels(...)` is now a thin wrapper around
`refreshMissingModelPipeline(...)` and keeps the existing default
`silent: true` refresh behavior.
- The new pipeline module does not import `@/scripts/app`; app-owned
data/actions are passed in as inputs.
- Moved the workflow node-flattening helpers out of `workflowSchema.ts`
and into `src/platform/workflow/core/utils/workflowFlattening.ts`.
- This includes `flattenWorkflowNodes`, `buildSubgraphExecutionPaths`,
and `isSubgraphDefinition`.
- The move is intentional: these helpers are not zod schema definitions
or workflow validation logic. They are core workflow traversal utilities
used to flatten root workflow nodes plus nested subgraph definition
nodes into the execution-shaped node list needed by missing-model
scanning.
- The refresh path receives data from `LGraph.serialize()`, whose return
type is serialized LiteGraph data rather than validated
`ComfyWorkflowJSON`. Previously this forced unsafe typing like
`graph.serialize() as unknown as ComfyWorkflowJSON`.
- The new `FlattenableWorkflowGraph` / `FlattenableWorkflowNode`
structural contract describes only what flattening actually needs:
`nodes`, `definitions.subgraphs`, node `id`, `type`, `mode`,
`widgets_values`, and `properties`.
- This lets both normal workflow-load data (`ComfyWorkflowJSON`) and
refresh-time live graph serialization (`LGraph.serialize()`) flow into
the same scan/enrichment path without pretending serialized LiteGraph
output is a fully validated workflow schema document.
- Updated `missingModelScan.ts` to consume that minimal flattenable
workflow shape via `MissingModelWorkflowData`.
- `MissingModelWorkflowData` extends the flattenable workflow contract
with optional workflow-level `models` metadata.
- Removed now-unnecessary casts around execution IDs, flattened nodes,
and `widgets_values` object access.
- Updated `getSelectedModelsMetadata(...)` to accept readonly widget
value arrays so flattened workflow data can stay read-only.
- Reduced the exported surface of the new pipeline module after `knip`
flagged unused exported internal option/store interfaces.
- Kept `workflowSchema.ts` focused on validation schemas. The flattening
helpers are not re-exported from the schema module because they are
internal workflow core utilities, not public schema API.

- **Breaking**: None intended.
  - Internal imports were updated to the new core utility path.
- This repo is not exposing these flattening helpers as a public package
API, so the old schema-local helper location is treated as an internal
implementation detail.

- **Dependencies**: None.

## Review Focus

- **Pipeline extraction / dependency direction**:
- Please verify that `missingModelPipeline.ts` stays independent from
`@/scripts/app`.
- `ComfyApp` should remain the caller/adapter, not the owner of
missing-model pipeline orchestration.

- **Workflow flattening type boundary**:
- The main type-cleanup goal is removing the refresh-time
`graph.serialize() as unknown as ComfyWorkflowJSON` lie.
- `LGraph.serialize()` and validated workflow JSON are not the same
contract. The new flattenable workflow contract is deliberately smaller
and structural because the missing-model enrichment path only needs
enough data to flatten nodes and read embedded model metadata.
- This is why the flattening helpers moved from `workflowSchema.ts` to
`workflow/core/utils`: the logic is reusable workflow traversal, not
validation schema.

- **Behavior preservation**:
- The PR is intended to preserve existing user-facing missing-model
behavior while moving ownership out of `app.ts`.
- Existing async follow-up behavior remains intentionally
fire-and-forget:
- cloud asset verification still surfaces after verification completes
- OSS folder paths still update asynchronously before surfacing
confirmed missing models
    - file-size metadata fetching remains asynchronous
- More invasive behavior changes, such as adding non-cloud post-fetch
`isMissingCandidateActive(...)` re-verification or redesigning the
fire-and-forget result contract, are intentionally left for follow-up
work because they are not pure extraction.

- **Downloadable model metadata**:
- `missingModels` returned for download metadata now requires both `url`
and `directory`.
- Candidates without a directory still remain in `confirmedCandidates`,
but they are not exposed as downloadable model metadata. This keeps the
returned downloadable list aligned with what the download flow can
actually use.

- **Test ownership**:
- Complex missing-model pipeline behavior tests moved out of
`src/scripts/app.test.ts` and into
`src/platform/missingModel/missingModelPipeline.test.ts`.
- `app.test.ts` now only covers thin delegation for
`app.refreshMissingModels(...)`.
- Workflow flattening tests moved with the helper from schema tests into
`src/platform/workflow/core/utils/workflowFlattening.test.ts`.

- **Deferred follow-ups**:
  - Broader function decomposition for cognitive complexity.
- Wider dependency-injection/port cleanup for stores and services beyond
the app boundary.
- Cloud-specific pipeline unit tests, which need a separate `isCloud`
mocking strategy.
- Additional E2E coverage expansion beyond the existing OSS refresh
path.
- More general workflow serialization/type-boundary cleanup outside the
missing-model refresh path.

## Validation

- `pnpm format`
- `pnpm lint`
- Passed. Existing lint output included a pre-existing
`no-misused-spread` warning and icon-name logs, but the command exited
successfully.
- `pnpm typecheck`
- `pnpm test:unit`
  - `714 passed`, `9514 passed | 8 skipped`
- Pre-push `pnpm knip`
- Passed after reducing the exported surface of the new pipeline module.

## Screenshots (if applicable)

Not applicable. This PR is a pipeline/type-boundary refactor with no UI
changes.

┆Issue is synchronized with this [Notion
page](https://app.notion.com/p/PR-11751-refactor-extract-missing-model-refresh-pipeline-3516d73d3650816d9245d4b1324b71c9)
by [Unito](https://www.unito.io)

---------

Co-authored-by: DrJKL <DrJKL0424@gmail.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>

src/platform/missingModel/missingModelScan.ts

@@ -1,9 +1,6 @@
-import type {
-  ComfyWorkflowJSON,
-  ModelFile,
-  NodeId
-} from '@/platform/workflow/validation/schemas/workflowSchema'
-import { flattenWorkflowNodes } from '@/platform/workflow/validation/schemas/workflowSchema'
+import type { ModelFile } from '@/platform/workflow/validation/schemas/workflowSchema'
+import type { FlattenableWorkflowGraph } from '@/platform/workflow/core/utils/workflowFlattening'
+import { flattenWorkflowNodes } from '@/platform/workflow/core/utils/workflowFlattening'
 import type {
   MissingModelCandidate,
   MissingModelViewModel,
@@ -28,6 +25,10 @@ import {
 import { LGraphEventMode } from '@/lib/litegraph/src/types/globalEnums'
 import { resolveComboValues } from '@/utils/litegraphUtil'
 
+export type MissingModelWorkflowData = FlattenableWorkflowGraph & {
+  models?: ModelFile[]
+}
+
 function isComboWidget(widget: IBaseWidget): widget is IComboWidget {
   return widget.type === 'combo'
 }
@@ -180,7 +181,7 @@ function scanAssetWidget(
   if (!isModelFileName(value)) return null
 
   return {
-    nodeId: executionId as NodeId,
+    nodeId: executionId,
     nodeType: node.type,
     widgetName: widget.name,
     isAssetSupported: true,
@@ -206,7 +207,7 @@ function scanComboWidget(
   const inOptions = options.includes(value)
 
   return {
-    nodeId: executionId as NodeId,
+    nodeId: executionId,
     nodeType: node.type,
     widgetName: widget.name,
     isAssetSupported: nodeIsAssetSupported,
@@ -218,7 +219,7 @@ function scanComboWidget(
 
 export async function enrichWithEmbeddedMetadata(
   candidates: readonly MissingModelCandidate[],
-  graphData: ComfyWorkflowJSON,
+  graphData: MissingModelWorkflowData,
   checkModelInstalled: (name: string, directory: string) => Promise<boolean>,
   isAssetSupported?: (nodeType: string, widgetName: string) => boolean
 ): Promise<MissingModelCandidate[]> {
@@ -388,7 +389,7 @@ function isAncestorPathActiveInFlattened(
 
 function collectEmbeddedModelsWithSource(
   allNodes: ReturnType<typeof flattenWorkflowNodes>,
-  graphData: ComfyWorkflowJSON
+  graphData: MissingModelWorkflowData
 ): EmbeddedModelWithSource[] {
   const result: EmbeddedModelWithSource[] = []
 
@@ -399,9 +400,7 @@ function collectEmbeddedModelsWithSource(
     )
       continue
 
-    const selected = getSelectedModelsMetadata(
-      node as Parameters<typeof getSelectedModelsMetadata>[0]
-    )
+    const selected = getSelectedModelsMetadata(node)
     if (!selected?.length) continue
 
     for (const model of selected) {
@@ -435,8 +434,7 @@ function findWidgetNameForModel(
   modelName: string
 ): string {
   if (Array.isArray(node.widgets_values) || !node.widgets_values) return ''
-  const wv = node.widgets_values as Record<string, unknown>
-  for (const [key, val] of Object.entries(wv)) {
+  for (const [key, val] of Object.entries(node.widgets_values)) {
     if (val === modelName) return key
   }
   return ''