fix(files): fix large file editor performance and selection toolbar placement

[waleedlatif1]

Summary

• Avoid rereading the complete Monaco model and reapplying static editor options after local edits.
• Bound XLSX conversion to the existing 1,000-row preview window and a 200-column safety window, with explicit row/column truncation messaging.
• Anchor whole-document Markdown selections to the leading position so the formatting toolbar flips below the header instead of clipping.
• Add focused regression coverage for editor synchronization, worksheet bounds, and whole-document selection geometry.

Testing

• bun run lint
• bun run lint:check
• bun run type-check
• bun run check:api-validation
• bun run check:audits
• bun run apps/sim/scripts/check-block-registry.ts origin/staging
• bunx vitest run (51 focused file-editor tests)

Compatibility

No migrations, API changes, or environment changes. Text and Markdown editor limits are unchanged. XLSX files remain fully downloadable; only the in-app preview uses the existing 1,000-row boundary plus a 200-column safety boundary to prevent rendering more than 200,000 cells at once.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Aug 27, 2026 6:58pm

[greptile-apps]

Greptile Summary

This follow-up improves large-file editor performance and selection-toolbar placement while bounding XLSX conversion to the displayed preview window.

• Avoids rereading Monaco content after ordinary local edits and memoizes static editor options.
• Limits XLSX conversion to 1,000 rows and 200 columns with corresponding truncation messaging.
• Anchors whole-document Markdown selections at the document’s leading position.
• Adds focused synchronization, worksheet-boundary, and selection-geometry tests.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/text-editor.tsx	Adds cached Monaco value tracking and stable editor options to reduce work during local edits while retaining external-content reconciliation.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/xlsx-preview-data.ts	Extracts bounded XLSX preview conversion with explicit row and column truncation metadata.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/xlsx-preview.tsx	Uses bounded worksheet data and reports whether rows, columns, or both were truncated.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/menus/use-bubble-menu-floating.ts	Collapses whole-document selection geometry to a leading-position anchor while preserving ordinary selection ranges.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/text-editor-sync.test.tsx	Covers local-edit fast-path behavior and external-update reconciliation.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/xlsx-preview-data.test.ts	Covers row limits, exact-boundary behavior, and extremely wide worksheet ranges.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/menus/use-bubble-menu-floating.test.ts	Covers whole-document anchor collapse and preservation of ordinary text-selection geometry.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[File viewer] --> B{File type}
  B -->|Text| C[Monaco editor]
  C --> D[Cached editor value]
  D --> E[External-content reconciliation]
  B -->|XLSX| F[Decode worksheet range]
  F --> G[Bound to 1000 rows and 200 columns]
  G --> H[Data table preview]
  B -->|Markdown| I[ProseMirror selection]
  I --> J{Whole-document selection?}
  J -->|Yes| K[Collapse anchor to leading position]
  J -->|No| L[Preserve selection range]
  K --> M[Floating formatting toolbar]
  L --> M

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_{Reviews (2): Last reviewed commit: "fix(files): bound wide spreadsheet previ..." | Re-trigger Greptile}

[cubic-dev-ai]

All reported issues were addressed across 7 files

<sub>Reply with feedback, questions, or to request a fix.

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[waleedlatif1]

@greptile