chore: sync Ditto Desktop with upstream t3code

[Peyton-Spencer]

Summary

Sync the Ditto fork with pingdotgg/t3code main at d7819c18813fa03b033cc1c9472c9acc0ffc0618. The fork was 383 upstream commits behind and 24 fork commits ahead. Preserve Ditto sign-in, host bridge, integrations, and branding while reconciling upstream contract, projection, mobile UI, and packaging changes.

Repair merge omissions found by CI: server worktree setup completion, project filtering in the thread action menu, and mobile imports and screen APIs. Remove seven obsolete upstream mobile cloud-list tests for functions no longer present in the client. Set the Ditto fork's existing UI override baseline at 664, retaining the gate against further growth.

Validation

• GitHub CI at 461d042b72e1f3494b80873c2a1e57fc236c3616: Check, Test, all three server shards, Rust, Release Smoke, Discord sidecar, and mobile checks passed.
• Local: full vp run typecheck; focused server bootstrap, mobile, desktop, and web tests; vp run lint:restyle-ceiling; vp run knip:check.
• vp run dist:desktop:dmg:arm64 built the macOS production artifact. Installed Ditto (Alpha).app 0.0.42 on this arm64 Mac; installed app.asar matches the final DMG SHA-256 and the app launches.

The local artifact is ad hoc signed. Its ignored build-time configuration points to the Ditto production API and uses the existing public Firebase client values. Authenticated production behavior was not exercised.

Model: GPT-6 Astra via Codex desktop.

[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	13.6 KiB	13.5 KiB	−87 B (−0.6%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	+4 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.6 KiB	6.5 KiB	−91 B (−1.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.1 KiB	56.3 KiB	−822 B (−1.4%)	66.4 KiB	✅
Codex	Live turn messages	10	10	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.5 KiB	−58 B (−0.4%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+14 B (+0.2%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−72 B (−1.1%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.8 KiB	57.0 KiB	−796 B (−1.3%)	66.4 KiB	✅
Claude	Live turn messages	8	9	+1 (+12.5%)	21	✅

Baseline: f9db2db · PR result: 461d042 · 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: 113.9 KiB
• Claude decoded thread snapshot: 114.6 KiB

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