refactor!: delete the model store and its React Query bridge

[brian-smith-tcril]

Summary

With #2153 the last useModel reader left the app, so the normalized models cache had no readers, no meta-driven mirrors and no explicit writers. This layer deletes it: the model-store module, the React Query → model-store bridge, the QueryCache onSuccess wiring that fed it, and the models reducer, which leaves store.ts registering only the external specialExams reducer, #1978's stated endpoint. No component read changes; no behaviour or request change. The test setup loses its store-seeding half with it: initializeTestStore is replaced by mockCourseRequests(options), which installs the same course endpoint mocks and returns the built payloads, and the shared render passes a Redux store only to the trees that reach the exams library. Breaking for plugins that import @src/generic/model-store; see Plugins — breaking. Part of the Redux → React Query migration (#1946, Stage 1), layer F of the model-store dissolution; stacked above #2153. Closes #1977. Closes #1978.

What changed

• Deleted: src/generic/model-store/ (slice.js, hooks.js, index.js, hooks.test.tsx), src/data/modelStoreBridge.ts and modelStoreBridge.test.ts (decision 1).
• src/queryClient.ts: the onSuccess bridge call, the ModelStoreMeta type and the store parameters go; createAppQueryCache() and createQueryClient() take nothing, Register.queryMeta is { logStatusAs?: Record<number, LogLevel> }. src/index.jsx calls createQueryClient(). src/store.ts drops modelsReducer and the importer-less RootState.
• src/setupTest.js (decisions 3, 6): initializeTestStore, seedCoursewareModels, seedSequenceModels, getTestStoreIds and globalStore go. mockCourseRequests(options) is the synchronous helper left: initializeMockApp(), the factory build, every axios reply the old setup installed (including preventSequenceLoad / preventOutlineSidebarLoad), returning the payloads plus courseId, sequenceId, unitId. render passes AppProvider no store unless given one through a store option. createTestQueryClient() builds TanStack's default QueryCache.
• Tests (decisions 2–5, 7–9): 41 call sites move to mockCourseRequests and lose their await; the 24 getTestStoreIds reads and the 24 getState().models reads take ids and values from the returned payloads; the 18 excludeFetch* options, the 29 second-store builds and the 44 { store } render options go; six exam-reaching suites opt in with { store: initializeStore() } and twelve suites with their own AppProvider pass no store; CourseExit.test.jsx loses its hand seeding; queryClient.test.ts loses the bridge case; two stale react-redux jest mocks go.
• Untouched: package.json's redux packages and docs/decisions/0004-model-store.md (decisions 10–11).

Plugins — breaking

@src/generic/model-store no longer exists, so a plugin that imports useModel, useModels, the models reducer or its actions from it fails to resolve the module at build time. Earlier layers left those imports working and returning {} as each model stopped being written (#2110, #2128, #2134, #2140, #2144, #2153 each named the hook to move to); this layer removes the module itself. It affects sidebar widgets registered through SIDEBAR_WIDGETS and PluginSlot plugins that import this repo's internals; nothing in-repo imports the module and no README documents it.

The replacement is the query hook that owns the data, as a non-fetching reader:

import { useCourseHomeMeta } from '@src/course-home/data/apiHooks';
import { useSequenceMetadata } from '@src/courseware/data/apiHooks';

const MyWidgetPanel = ({ courseId, sequenceId }) => {
  const { org, verifiedMode } = useCourseHomeMeta(courseId, { enabled: false }).data ?? {};
  const { units } = useSequenceMetadata(sequenceId, { enabled: false }).data ?? {};
  // ...
};

Former model	Owning hook
courseHomeMeta	useCourseHomeMeta(courseId) (course-home/data/apiHooks)
outline, dates, progress	useOutlineTabData(courseId), useDatesTabData(courseId), useProgressTabData(courseId, targetUserId)
coursewareMeta	useCoursewareMetadata(courseId) for the metadata fields, useMinimalCourseOutline(courseId) for the outline's courses map
sections, the outline's sequences	useMinimalCourseOutline(courseId)
sequences (the active one), units	useSequenceMetadata(sequenceId), useUnit(sequenceId, unitId)
discussionTopics	useDiscussionTopic(courseId, unitId)

Under any course page the page's own observer has fetched the data, so the disabled reader reads the cached result and adds no request, re-rendering when the fetch lands, as the useModel read did when the bridge wrote the store. Rendered anywhere else, .data stays undefined until something on that page fetches; the query cache is shared, so the simplest shape is the widget mounting the fetch itself, the same hook without the option, beside its read. Unaffected: the sidebar widget config functions, isAvailable and prefetch, still receive the merged course object. The Accessing Course Data section of src/courseware/course/sidebar/README.md documents the hooks.

Testing

npm run types and npm run lint clean; full suite 120 suites, 1186 passed, 0 skipped. git grep -E "model-store|modelStore|useModel|state\.models|initializeTestStore|getTestStoreIds" src is empty; git grep react-redux src returns only the removed line of a migration diff example in generic/plugin-overrides/README.md; git grep "from 'redux'" src is empty; store.ts registers only specialExams. Which suites still need a Redux store was established by running the whole suite with render passing none: six failed, each on react-redux's "could not find react-redux context value", each predicted by its tree reaching SequenceExamWrapper, OuterExamTimer or useExamAccess (decision 3); those six opt in. No request-count assertion observed the deleted seeding requests (decision 5). Manual smoke on tutor local: the five course-home tabs and courseware unit and sequence navigation render and navigate as before.

Decisions

Full decision log

Decisions — dissolve the model-store normalized cache (#1977, layer F)

The teardown layer of the model-store dissolution, above #2153 (#1999, layer
E) on the running stack #2141. Closes #1977 and #1978. Planned and settled
with the user 2026-10-02; the plan is embedded in the #1977 issue body.

1. Deletion only; nothing in the app changes what it reads. After layer E,
   non-test source had zero useModel / useModels readers, zero
   state.models selectors, zero query meta entries the bridge consumed and
   zero explicit model-store dispatches; the only react-redux import left
   was the model-store hooks file itself. So this layer deletes
   src/generic/model-store/ (slice, hooks, index, the hooks test),
   src/data/modelStoreBridge.ts and its test, the QueryCache onSuccess
   wiring, the ModelStoreMeta type and the store parameters in
   src/queryClient.ts (Register.queryMeta is now
   { logStatusAs?: Record<number, LogLevel> }), and the models reducer and
   the importer-less RootState type in src/store.ts. src/index.jsx calls
   createQueryClient().

2. No rendering fallout; the seeds were inert. The issue body expected to
   "fix the fallout across the suites that relied on pre-seeded models". With
   no readers, the models initializeTestStore seeded reached no component:
   suites already loaded through the real queries (MountCourseQueryHooks,
   CourseQueryGate, seedQueryData, queryClient.fetchQuery). What
   depended on the seeds was test-side: 24 getState().models reads in 11
   files (first unit id ×8; four block titles for the Helmet title; a
   sequence's gatedContent; courseHomeMeta.verifiedMode ×2; the whole
   normalized courseHomeMeta to seed a query ×2) and the ids
   getTestStoreIds derived from the model keys. Each has a direct source in
   the API-shaped payloads the setup already built (entry 3).

3. initializeTestStore is deleted, not reshaped. It did three jobs:
   build a store, mock the course endpoints, seed the store from them. The
   third is gone and the first is initializeStore() from src/store.ts to
   the letter, so what is left is the second:

   • No store unless the tree needs one. render in setupTest.js passes
     AppProvider no store by default (AppProvider renders a react-redux
     Provider only when given one; OptionalReduxProvider returns bare
     children for null), and takes a store option for the suites whose
     tree reaches one of the three library entry points, which select
     state.specialExams and throw "could not find react-redux context
     value" under no Provider. Which suites that is was established by
     running the whole suite with no default store: six failed, each on that
     error, and each predicted by its tree — Course.test.jsx,
     SequenceContent.test.jsx and Unit/index.test.jsx (Unit →
     useExamAccess), Sequence.test.jsx (SequenceExamWrapper),
     CourseExit.test.jsx and ProductTours.test.jsx's outline-tab describe
     (TabWithTimer → OuterExamTimer); courseware/course/test-utils.jsx
     renders Course too. Those pass { store: initializeStore() }, the app's
     own store, the way CoursewareContainer.test.jsx and the five tab suites
     already give their own AppProvider one. Nothing else in any test touched
     a store (git grep -E "specialExams|store\.dispatch|store\.subscribe" -- '*.test.*' matched only the seeds and CourseExit.test.jsx's two
     addModel dispatches), so globalStore, the overrideStore parameter,
     the 29 second-store builds (initializeTestStore(…, false)) and the 44
     { store } render options that carried seeded models all went. Twelve
     suites with their own AppProvider whose tree has no exam component
     now pass no store at all: the six that passed a test store
     (CourseBreadcrumbs, CourseOutlineTray, CourseOutlineTrigger,
     SidebarSection, SidebarSequence, SidebarUnit) and six that built
     an app store they did not need (CoursewareResultsFilter,
     CoursewareSearch, GoalUnsubscribe, CourseTabsNavigation,
     CourseBreadcrumbsSlot, preferences-unsubscribe). Rejected: a store
     on every render (the first draft) — the same unconditional store the
     twelve suites had just lost, handed to trees with nothing to select from
     it, and it changed AlertList.test.jsx's empty-container assertion for
     a wrapper div the component did not render.
   • mockCourseRequests(options) is the synchronous helper that is left:
     initializeMockApp(), buildSimpleCourseAndSequenceMetadata(options),
     every axios reply initializeTestStore installed (including
     preventSequenceLoad / preventOutlineSidebarLoad), and a return of the
     built payloads (courseBlocks, sectionBlocks, sequenceBlocks,
     unitBlocks, courseMetadata, sequenceMetadata, courseHomeMetadata)
     plus courseId, sequenceId, unitId picked off them. Seeding was the
     only await, so all 41 call sites lost theirs. Named beside
     logUnhandledRequests for what it does; setUpMockRequests (the
     container suite's local helper, less specific) and buildMockCourse
     (names the return, not the side effect callers depend on) were
     rejected. The excludeFetchCourse / excludeFetchSequence options,
     which only skipped seeding, went with their 18 call sites;
     preventSequenceLoad's comment lost its "pair with excludeFetchSequence"
     clause.
   • Rejected: keeping initializeTestStore and returning the fixtures
     beside the store (a bespoke test store whose only content is the app's
     own reducer, and 29 second-store builds with nothing to distinguish
     them); a WeakMap<store, fixtures> behind a kept getTestStoreIds(store)
     (a store-keyed side table for data the store no longer holds).

4. The test-side reads take their values from the payloads. First unit id
   → unitId (the eight hand-rolled Object.keys/values(models.units)[0]
   reads). Course.test.jsx's Helmet title → unitBlocks[0].display_name,
   sequenceBlocks[0].display_name, sectionBlocks[0].display_name,
   courseMetadata.name (the course block's display_name is
   courseMetadata.name: buildSimpleCourseBlocks(courseId, courseMetadata.name)).
   SequenceContent.test.jsx's gatedContent.prereqSectionName →
   sequenceMetadata[0].gated_content.prereq_section_name.
   LockPaywall.test.jsx's verifiedMode fields → the default
   courseHomeMetadata.verified_mode. HonorCode.test.jsx and
   StreakCelebrationModal.test.jsx seed the metadata query with
   await getCourseHomeCourseMetadata(courseId) fetched through the setup's
   adapter before each suite installs its own, which is the reason they seed
   (their comments say so, now also saying where the value comes from).
   courseware/course/test-utils.jsx lost its first initializeTestStore
   call, which existed only to read ids the second build then overwrote, and
   returns { courseId, sequenceId, unitId } to Course.test.jsx.

5. No request-count assertion observed the seeding requests. Twelve
   suites assert on axiosMock.history; each installs its own
   new MockAdapter(getAuthenticatedHttpClient()) after the setup call (which
   replaces the setup's adapter, so its history starts empty) or resets before
   asserting. The six requests the seeds made were never counted; no
   assertion changed.

6. createTestQueryClient() builds TanStack's default QueryCache. The
   store argument was the only thing selecting the app's cache, so with it
   gone one cache serves all 65 call sites. Tested against three questions:
   does the app cache behave differently (no: QueryCacheConfig is three
   optional callbacks, onError / onSuccess / onSettled, fired after a
   query settles; no query state, data, retry or timing differs, and the
   status-specific hook tests already ran under the default cache); should
   its logging be tested (it is, directly, in queryClient.test.ts against
   createAppQueryCache; no hook's own logStatusAs meta was asserted
   through the helper); is the logging useful for diagnosing tests
   (marginally, and noise wherever the failure is deliberate). The two
   helper-dependent logging assertions in courseware/data/apiHooks.test.tsx
   (the sidebar-toggles network error, the discussion-topics config failure)
   asserted the cache's generic behaviour, not the hooks', and were dropped
   with the initializeStore() arguments and the comment that waited on this
   layer; the cases keep their hook-specific assertions and are renamed for
   what they still check. Rejected: always the app cache (production parity
   bought with console noise, for behaviour no component can observe); a
   flag replacing the store argument (would preserve an accidental split).

7. CourseExit.test.jsx's pre-fetch was seeding by hand. fetchAndRender
   awaited getCourseMetadata + getCourseHomeCourseMetadata, dispatched
   both with addModel, then axiosMock.resetHistory(); the results had no
   other use and the per-URL request counts are taken after the reset. The
   fetch, the dispatches, the store and their imports went;
   MountCourseQueryHooks was already there for the component to read
   through.

8. Two stale react-redux jest mocks removed (CoursewareSearchResults.test.jsx's
   bare jest.mock('react-redux'); CourseTabsNavigation.test.jsx's
   useDispatch mock with a mockDispatch no assertion read), both left from
   the plugins slice (Convert the plugin-store override registry off Redux to React context #2017). The issue's verify line ("git grep react-redux src returns only special-exams-adjacent files") was false while they
   stood; it now returns only the removed line of a migration diff example in
   generic/plugin-overrides/README.md.

9. Two incidental second-store patterns in touched files. OutlineTab.test.jsx's
   fetchAndRender took a renderStore option so one case could render on a
   fresh initializeStore(); with nothing in a store to differ on, the option
   and that case's store went. ProductTours.test.jsx passed
   { store: initializeStore() } to a render of ProductTours alone, which
   reaches no exam component; it went.

10. docs/decisions/0004-model-store.md is left as it is. The ADR log is
    history: no layer of Convert Learning from redux to Context + react-query #1946 has amended an ADR (0006 still describes
    thunks, 0007 still mentions "redux tests"). The superseding ADR that
    records React Query as this app's server-state layer (OEP-67 ADR-0010 is
    the org-level decision) is the epic's closing work alongside Reduce the Redux store to the external specialExams reducer #1978's
    dependency removal, and is named as a task on Reduce the Redux store to the external specialExams reducer #1978.

11. package.json keeps redux, react-redux and @reduxjs/toolkit.
    store.ts still uses configureStore, and AppProvider store= still
    needs a react-redux store for OuterExamTimer / SequenceExamWrapper /
    useExamAccess. Dropping them is Reduce the Redux store to the external specialExams reducer #1978's library-gated step (Adopt @edx/frontend-lib-special-exams v5 (React Query, host-agnostic): mount SpecialExamsProvider, own the submitted-timed-exam slot, delete the Redux store and dependencies #2018).

12. refactor!:. @src/generic/model-store has been importable by
    plugins; nothing in-repo documents it today, but an external plugin could
    still import useModel, as @edx/unit-translation-selector-plugin
    imported @src/generic/plugin-store until Convert the plugin-store override registry off Redux to React context #2017. The footer says the
    module is gone and names the query hooks to read instead.

Manual testing

Manual testing — dissolve the model-store normalized cache (#1977)

In-browser smoke test against a live backend (tutor local), agreed 2026-10-02
as minimal for this layer. Run by the user 2026-10-02.

What changed: the models reducer, the model-store module and the React
Query bridge are deleted; the app QueryCache loses its onSuccess. No
component read changed (no useModel reader existed), so no behaviour or
request change is intended anywhere. The one production code path that
changes shape is the QueryCache, which every query runs through.

Not exercised here: a timed-exam attempt. The exams library's OuterExamTimer,
SequenceExamWrapper and useExamAccess render for real in the unit suites
against the specialExams-only store (and threw, as expected, in a run with
no store), so the store wiring is covered there.

Checks

#	Page / action	Expect	Observed
1	Course home: outline, dates, progress, discussion, live tabs	each renders as before	passed — "everything seems fine from clicking around"
2	Courseware: open a unit, move between units and sequences	renders and navigates as before	passed — same pass
3	Browser console while clicking around	no new errors	not reported

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.75%. Comparing base (6a4c076) to head (5d95871).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2154      +/-   ##
==========================================
+ Coverage   95.59%   95.75%   +0.16%     
==========================================
  Files         374      371       -3     
  Lines        6087     6012      -75     
  Branches     1496     1436      -60     
==========================================
- Hits         5819     5757      -62     
+ Misses        258      246      -12     
+ Partials       10        9       -1     

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[arbrandes]

Nice! 🎆