fix(mobile): render photo library picks to a bounded JPEG off the JS thread

[rynfar]

Summary

Ports upstream commit bbedad0278bbf753503184c00e0c09a0eab6679c (#11440).

When picking images on mobile from the photo library:

• Offloads decoding, downscaling (max edge 2048px), and JPEG re-encoding of photo library picks off the JS thread using native expo-image-manipulator.
• Avoids UI stalls and OOM crashes caused by asking the iOS image picker for full-size base64 strings of high-resolution / camera photos.
• Preserves supported originals (PNG, GIF, WebP, JPEG <= 10MB) intact without re-encoding to retain animations and transparency.
• Preserves Pylon product branding in docs/user/composer.md.
• Advances reviewed-through cursor in .agents/upstream-review.md to bbedad0278bbf753503184c00e0c09a0eab6679c.

Verification

• Added mock and tests in apps/mobile/src/lib/composerFiles.test.ts (46 tests passed).
• All 194 mobile test files (1,694 tests) passed.
• Typecheck (tsc -b apps/mobile) passed with 0 errors.
• Lint (vp lint) passed with 0 warnings/errors.

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Project	Deployment	Actions	Updated
pylon-marketing	Ready	Preview	Sep 14, 2026 6:45am UTC

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	14.0 KiB	14.0 KiB	−24 B (−0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.2 KiB	7.2 KiB	+7 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.8 KiB	6.8 KiB	−31 B (−0.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	58.8 KiB	58.8 KiB	−44 B (−0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	8	−1 (−11.1%)	21	✅
Claude	Total thread wire	14.1 KiB	14.1 KiB	+22 B (+0.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.2 KiB	7.2 KiB	+2 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.8 KiB	6.9 KiB	+20 B (+0.3%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	59.7 KiB	59.7 KiB	+44 B (+0.1%)	66.4 KiB	✅
Claude	Live turn messages	9	10	+1 (+11.1%)	21	✅

Baseline: ce7a421 · PR result: f5a45fb · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 115.6 KiB
• Claude decoded thread snapshot: 116.3 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.