StarPunk/docs/reports/2025-12-09-media-display-validation.md

Media Display Implementation Validation Report

Date: 2025-12-09 Developer: Agent-Developer Task: Validate existing media display implementation against architect's specification Specification: /docs/design/media-display-fixes.md

Executive Summary

Validated the complete media display implementation against the authoritative specification. All requirements successfully implemented - no gaps found. Added comprehensive security tests for HTML/JavaScript escaping. Fixed unrelated test fixture issues in test_media_upload.py.

Validation Results

1. CSS Implementation (static/css/style.css)

Status: PASS - Complete implementation

Lines 103-193: All CSS requirements from spec implemented:

• ✓ .note-media container with proper margin and width
• ✓ Single image full-width layout with :has() pseudo-class
• ✓ Two-image side-by-side grid layout
• ✓ Three/four-image 2x2 grid layout
• ✓ Media item wrapper with Instagram-style square aspect ratio (1:1)
• ✓ Image constraints with object-fit: cover for grid items
• ✓ Single image natural aspect ratio with 500px max-height constraint
• ✓ Figcaption hidden with display: none (captions for alt text only)
• ✓ Mobile responsive adjustments (vertical stacking, 16:9 aspect)

Note: Implementation uses semantic <figure> elements as specified, not <div> elements.

2. Template Implementation

templates/partials/media.html

Status: PASS - Exact match to spec

• ✓ Reusable display_media() macro defined
• ✓ .note-media container
• ✓ .media-item figure elements (semantic HTML)
• ✓ Image with u-photo class for Microformats2
• ✓ Alt text from caption or "Image" fallback
• ✓ loading="lazy" for performance optimization
• ✓ No visible figcaption (comment documents this decision)
• ✓ Uses url_for('public.media_file', path=item.path) for URLs

templates/note.html

Status: PASS - Correct usage

• ✓ Line 2: Imports display_media from partials/media.html
• ✓ Line 17: Uses macro with {{ display_media(note.media) }}
• ✓ Media displays at TOP before e-content (as per ADR-057)

templates/index.html

Status: PASS - Correct usage

• ✓ Line 2: Imports display_media from partials/media.html
• ✓ Line 29: Uses macro with {{ display_media(note.media) }}
• ✓ Media preview between title and content

3. Route Handler Implementation (starpunk/routes/public.py)

index() function (lines 219-241)

Status: PASS - Exact match to spec

• ✓ Imports get_note_media from starpunk.media
• ✓ Fetches notes with list_notes(published_only=True, limit=20)
• ✓ Loops through notes and fetches media for each
• ✓ Attaches media using object.__setattr__(note, 'media', media) (frozen dataclass)
• ✓ Renders template with media-enhanced notes

note() function (lines 244-277)

Status: PASS - Already implemented

• ✓ Imports and uses get_note_media
• ✓ Fetches and attaches media to note

_get_cached_notes() helper (lines 38-74)

Status: PASS - Feed integration

• ✓ Feed caching also includes media attachment for each note

Security Validation

Security Test Implementation

File: tests/test_media_upload.py (lines 318-418)

Added comprehensive security test class TestMediaSecurityEscaping with three test methods:

1. test_caption_html_escaped_in_alt_attribute

   • Tests malicious caption: <script>alert("XSS")</script><img src=x onerror=alert(1)>
   • Verifies HTML tags are escaped to <script>, <img, etc.
   • Confirms XSS attack vectors are neutralized
   • Result: PASS - Jinja2 auto-escaping works correctly

2. test_caption_quotes_escaped_in_alt_attribute

   • Tests quote injection: Image" onload="alert('XSS')
   • Verifies quotes are escaped to " or "
   • Confirms attribute breakout attempts fail
   • Result: PASS - Quote escaping prevents attribute injection

3. test_caption_displayed_on_homepage

   • Tests malicious caption on homepage: <img src=x onerror=alert(1)>
   • Verifies same escaping on index page
   • Confirms consistent security across templates
   • Result: PASS - Homepage uses same secure macro

Security Findings

No security vulnerabilities found. Jinja2's auto-escaping properly handles:

• HTML tags (<script>, <img>) → Escaped to entities
• Quotes (", ') → Escaped to numeric entities
• Special characters (<, >, &) → Escaped to named entities

The display_media macro in templates/partials/media.html does NOT use |safe filter on caption content, ensuring all user-provided text is escaped.

Additional Work Completed

Test Fixture Cleanup

Issue: All tests in test_media_upload.py referenced a non-existent db fixture parameter.

Fix: Removed unused db parameter from 11 test functions:

• TestMediaSave: 3 tests fixed
• TestMediaAttachment: 4 tests fixed
• TestMediaDeletion: 2 tests fixed
• TestMediaSecurityEscaping: 3 tests fixed (new)
• Fixture sample_note: 1 fixture fixed

This was a pre-existing issue unrelated to the media display implementation, but blocked test execution.

Documentation Updates

Marked superseded design documents with status headers:

1. docs/design/v1.2.0-media-css-design.md

   • Added "Status: Superseded by media-display-fixes.md" header
   • Explained this was an earlier design iteration

2. docs/design/v1.1.2-caption-alttext-update.md

   • Added "Status: Superseded by media-display-fixes.md" header
   • Explained this was an earlier approach to caption handling

Test Results

New Security Tests

tests/test_media_upload.py::TestMediaSecurityEscaping
  test_caption_html_escaped_in_alt_attribute PASSED
  test_caption_quotes_escaped_in_alt_attribute PASSED
  test_caption_displayed_on_homepage PASSED

All Media Tests

tests/test_media_upload.py
  23 passed (including 3 new security tests)

Template and Route Tests

tests/test_templates.py: 37 passed
tests/test_routes_public.py: 20 passed

Total: 80 tests passed, 0 failed

Compliance with Specification

Spec Requirement	Implementation	Status
CSS media display rules	style.css lines 103-193	✓ Complete
Reusable media macro	templates/partials/media.html	✓ Complete
note.html uses macro	Line 2 import, line 17 usage	✓ Complete
index.html uses macro	Line 2 import, line 29 usage	✓ Complete
index route fetches media	public.py lines 236-239	✓ Complete
Security: HTML escaping	Jinja2 auto-escape, tested	✓ Verified
Accessibility: alt text	Template uses item.caption or 'Image'	✓ Complete
Performance: lazy loading	loading="lazy" attribute	✓ Complete
Responsive design	Mobile breakpoint at 767px	✓ Complete

Architecture Compliance

The implementation follows all architectural principles from the spec:

1. Consistency: Same media display logic on all pages via shared macro
2. Responsive: Images adapt to viewport with grid layouts and aspect ratios
3. Accessible: Alt text present, no visible captions (as designed)
4. Performance: Lazy loading, efficient CSS selectors
5. Standards: Proper Microformats2 (u-photo), semantic HTML (figure elements)

Recommendations

For Future Versions (Not V1)

The spec lists these as future enhancements:

• Image optimization/resizing on upload (consider for v1.3)
• WebP format with fallbacks (consider for v1.3)
• Lightbox for full-size viewing (consider for v1.4)
• Video/audio media support (consider for v2.0)
• CDN integration (consider for production deployments)

For Immediate Use

No changes needed. Implementation is complete and ready for deployment.

Conclusion

Validation Result: COMPLETE SUCCESS

All components of the media display system are correctly implemented according to the architect's specification in docs/design/media-display-fixes.md. No gaps found. Security validated. Tests passing.

The three reported issues from the spec are resolved:

1. ✓ Images constrained with responsive CSS
2. ✓ Captions hidden (alt text only)
3. ✓ Media displayed on homepage

This implementation is ready for production use.

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Implementation Report: This validation confirms the existing implementation meets all architectural requirements. No additional development work required.