feat: add generation cancel job functionality and improve job handling

- Introduced `generationCancelJob` command ID in `commands/ids.ts`.
- Added `GenerationCancelJobPayload` type in `commands/payloads.ts`.
- Enhanced job status to include "cancelled" in `editor/state.ts`.
- Updated `runGenerationJob` to accept an `AbortSignal` and handle cancellation.
- Implemented cancellation logic in `runGenerate` and related functions.
- Added tests for job cancellation in `operations/generation/workflow.test.ts`.
- Improved layer rendering logic to prevent stack overflow in `editor/document-indexes.ts`.
- Added raster size assertions in `platform/browser/rasterLimits.ts` for image processing limits.
- Enhanced image file handling to check for size limits in `platform/browser/imageFiles.ts`.
- Updated UI components to reflect job cancellation state in `view/GenerationJobStatus.tsx` and `view/bottom-controls/GenerateActionControls.tsx`.

commands/generation.test.ts

@@ -12,6 +12,7 @@ import {
   generationFailJobCommand,
   generationStartJobCommand,
   generationSucceedJobCommand,
+  generationCancelJobCommand,
 } from "./generation";
 
 describe("generation commands", () => {
@@ -40,6 +41,16 @@ describe("generation commands", () => {
     expect(next.editor.generation.compareMode).toBe("split");
   });
 
+  test("bounds retained candidate source memory as well as candidate count", () => {
+    const largeSource = "x".repeat(34 * 1024 * 1024);
+    const first = { ...generationCandidate("candidate-1"), source: largeSource };
+    const second = { ...generationCandidate("candidate-2"), source: largeSource };
+    const withFirst = generationAddCandidateCommand.execute({ state: createInitialAppState("Test") }, { candidate: first });
+    const withSecond = generationAddCandidateCommand.execute({ state: withFirst }, { candidate: second });
+
+    expect(withSecond.editor.generation.candidates.map((candidate) => candidate.id)).toEqual(["candidate-2"]);
+  });
+
   test("clears the candidate session and resets comparison", () => {
     const withCandidate = generationAddCandidateCommand.execute(
       { state: createInitialAppState("Test") },
@@ -159,6 +170,13 @@ describe("generation commands", () => {
 
     expect(failed.editor.generation.jobs[0]).toMatchObject({ id: "job-1", status: "failed", error: "Backend unavailable", finishedAt: 125 });
   });
+
+  test("records explicit cancellation separately from failure", () => {
+    const running = generationStartJobCommand.execute({ state: createInitialAppState("Test") }, { jobId: "job-1", kind: "generate", label: "Generating", startedAt: 100 });
+    const cancelled = generationCancelJobCommand.execute({ state: running }, { jobId: "job-1", finishedAt: 110 });
+
+    expect(cancelled.editor.generation.jobs[0]).toMatchObject({ id: "job-1", status: "cancelled", finishedAt: 110 });
+  });
 });
 
 function documentWithSourceLayer() {