[ Interactive Graph | Vector Graph ] PR2: State Management

[SonicScrewdriver]

Summary

This PR was created with the help of AI, albeit with heavy oversight and review.

This is part of a series of PRs implementing the vector graph type for the Interactive Graph widget:

PR1 – type definitions and schema
▶️ PR2 – state management (this PR)
PR3 – rendering & accessibility
PR4 – scoring
PR5 – editor support

Issue: LEMS-3971

• Added state management logic for the vector graph type
• The graph is now stateful and interactive but not yet visible — rendering still throws "Not implemented" from PR 1's stub. This is a pure additive change — no runtime behavior is altered and all existing tests continue to pass.

Changes:

• interactive-graph-action.ts — Adds vector: { moveTip, moveVector } to the actions object. moveTip dispatches movePoint(1, destination) for the tip (the only draggable point). moveVector dispatches moveLine(0, delta) for body translation.
• initialize-graph-state.ts — Replaces the PR 1 stub with a real case "vector". Adds and exports getVectorCoords() with the standard three-path fallback: explicit coords → startCoords → normalized defaults. Default is a horizontal vector from [-5, 0] to [5, 0].
• interactive-graph-reducer.ts — Adds vector case in doMovePoint (snap to grid, enforce bounds, reject if tip would overlap with tail). Adds "vector" to the existing doMoveLine case alongside "linear" / "ray" for body translation.
• interactive-graph-state.ts — Adds getGradableGraph() branch for vector (coords passthrough, same shape as ray).
• interactive-graph-question-builder.ts — Adds withVector() builder method and VectorGraphConfig class (matches RayGraphConfig pattern).
• interactive-graph-widget-generator.ts — Adds generateIGVectorGraph() generator function (new pattern, replacing builder long-term).
• perseus-core/src/index.ts — Re-exports generateIGVectorGraph.
• perseus/src/index.ts — Re-exports getVectorCoords.
• interactive-graph.testdata.ts — Adds vectorQuestion and vectorQuestionWithDefaultCorrect test fixtures.

Test plan:

• pnpm tsc — no new type errors
• pnpm test packages/perseus/src/widgets/interactive-graphs/reducer/ — 143 tests pass, including 9 new vector tests:
  • 3 initialization tests (explicit coords, startCoords fallback, defaults)
  • 3 moveTip tests (basic move, hasBeenInteractedWith, overlap rejection)
  • 3 moveVector tests (body translation, hasBeenInteractedWith, bounds enforcement)
• No existing interactive graph tests regress

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[github-actions]

🗄️ Schema Change: No Changes ✅

[github-actions]

npm Snapshot: Published

Good news!! We've packaged up the latest commit from this PR (046eb1c) and published it to npm. You
can install it using the tag PR3434.

Example:

pnpm add @khanacademy/perseus@PR3434

If you are working in Khan Academy's frontend, you can run the below command.

./dev/tools/bump_perseus_version.ts -t PR3434

If you are working in Khan Academy's webapp, you can run the below command.

./dev/tools/bump_perseus_version.js -t PR3434

[github-actions]

🛠️ Item Splitting: No Changes ✅

[github-actions]

Size Change: +88 B (+0.02%)

Total Size: 499 kB

📦 View Changed

Filename	Size	Change
packages/perseus-core/dist/es/index.js	25.2 kB	+12 B (+0.05%)
packages/perseus/dist/es/index.js	196 kB	+76 B (+0.04%)

ℹ️ View Unchanged

Filename	Size
packages/kas/dist/es/index.js	20.6 kB
packages/keypad-context/dist/es/index.js	1 kB
packages/kmath/dist/es/index.js	6.36 kB
packages/math-input/dist/es/index.js	98.5 kB
packages/math-input/dist/es/strings.js	1.61 kB
packages/perseus-core/dist/es/index.item-splitting.js	12 kB
packages/perseus-editor/dist/es/index.js	102 kB
packages/perseus-linter/dist/es/index.js	9.42 kB
packages/perseus-score/dist/es/index.js	9.7 kB
packages/perseus-utils/dist/es/index.js	403 B
packages/perseus/dist/es/strings.js	8.28 kB
packages/pure-markdown/dist/es/index.js	1.39 kB
packages/simple-markdown/dist/es/index.js	6.71 kB

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[ivyolamit]

🎉 LGTM 👍🏼

[ivyolamit]

Wow this file is really getting longer 😢 I almost got confused on the diff 🙈
No action required here for now. I'm just thinking if we want to move the functions to a reducer-utils/doMoveLine.ts and reducer-utiles/* 🤔

[SonicScrewdriver]

That'd be a great ticket imo! Maybe we can do a holistic review after we've made all the graphs, and do a little refactoring / re-organization. :)