[cxymds]

Pull Request

Description

Opening an extensionless text object such as fred with missing or generic MIME metadata currently shows a blank iframe. Preview now checks objects up to 2 MiB for complete, valid UTF-8 text and displays accepted content as literal text.

Binary, empty, or oversized content shows a clear fallback with download when permitted; request failures show an error. Preview downloads retain the selected object key. Ordinary downloads use an unversioned GET and require s3:GetObject; explicitly selected versions are kept separately from HEAD metadata and require object-scoped s3:GetObjectVersion, including when HEAD does not expose the version header. Existing image, audio, video, PDF, Parquet, and TIFF renderer priorities are preserved.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Performance improvement
• Test improvements
• Security fix

Testing

• Unit tests added/updated
• Manual testing completed

Passed all repository checks, including 924 tests:

nvm use v22
pnpm install --frozen-lockfile
pnpm type-check
pnpm lint
pnpm format:check
pnpm test:run
pnpm build

Regression coverage includes split UTF-8 sequences, non-ASCII content, binary controls, invalid UTF-8, empty/BOM-only content, exact and exceeded size limits, inaccurate size metadata, HTTP/network errors, cancellation, stale responses, selected key/version preservation, current-object versus version-read permissions, object scope, and explicit version-read denials.

Browser checks used real Console preview components, BrowserContent, and the signed-URL download hook with local HTTP fixtures: generic/missing MIME text, loading, binary, empty, oversized, error, literal HTML, download permission, selected-version download, and mobile layouts at 390 × 844. Independent Reviewer, Tester, and UX/Simplifier checks passed.

Checklist

• Code follows the project's style guidelines
• Self-review completed
• TypeScript types are properly defined
• All commit messages are in English (Conventional Commits)
• All existing tests pass
• No new dependencies added, or they are justified

Related Issues

Fixes rustfs/rustfs#9230

Screenshots (if applicable)

The before/after pair uses the main and updated Console components with the same object, HTTP fixture, and 1280 × 720 viewport.

Before	After

Loading, fallback, error, and permission states

State	Screenshot
Loading
Binary
Empty
Oversized
HTTP error
Download permission denied
Missing MIME
Literal HTML

Mobile preview and fallback

Text	Binary fallback

Preview download permission regression

With the same selected version and a policy allowing only s3:GetObject, the previous implementation showed an unusable download action. The updated implementation checks s3:GetObjectVersion for selected versions and hides that action when denied. Ordinary downloads remain available using an unversioned GET.

Before	After

Ordinary download with GetObject	Selected version with GetObjectVersion

Actual browser downloads were checked against local HTTP fixture response bodies: the ordinary path returned current content without versionId, while the selected-version path returned the chosen version.

Additional Notes

Detection only applies to missing MIME, application/octet-stream, and binary/octet-stream. It bounds actual streamed bytes and rejects binary control characters. Object metadata is unchanged and detected HTML is displayed literally.

Browser evidence uses local HTTP fixtures; no live RustFS deployment was exercised. Screenshots are stored on a separate evidence branch and do not add assets to this implementation diff.

[Copilot]

🟡 Changes recommended

Ordinary preview downloads in versioned buckets incorrectly use the HEAD-returned version, requiring unchecked s3:GetObjectVersion permission and potentially causing AccessDenied for users with s3:GetObject access.

1 open issue

• Keep ordinary preview downloads unversioned · New

What changed in this PR

This PR fixes blank previews for extensionless objects with missing or generic MIME metadata by detecting bounded UTF-8 content and displaying it as literal text.

Changes:

• Adds text detection up to 2 MiB while preserving existing renderer priorities.
• Adds loading, error, and download fallback states, with selected key/version handling.
• Adds regression coverage for decoding, size limits, cancellation, and stale responses.

File	Description
tests/​lib/​object-preview.test.ts	Tests text detection, limits, and preview metadata.
tests/​lib/​object-preview-source.test.js	Updates dispatch and request-handling assertions.
tests/​hooks/​use-object-preview-text.test.ts	Tests loading, errors, cancellation, and stale responses.
lib/​object-preview.ts	Adds bounded UTF-8 detection and metadata helpers.
hooks/​use-object.ts	Supports version-specific signed download URLs.
hooks/​use-object-preview-text.ts	Manages text fetching and preview state.
components/​object/​preview-modal.tsx	Integrates detection and download/error fallbacks.
components/​object/​info.tsx	Preserves selected key and version in preview metadata.
app/​(dashboard)/​browser/​content.tsx	Connects preview downloads to permissions and object metadata.

_{Review effort: Balanced}