chore(alpha): sync upstream main

[t3-code-alpha-automation]

Merges official upstream/main into Alpha with merge ancestry preserved.

• Alpha base: f533665f63fbfa03eec79f00140647f983c7aabd
• Upstream main: 0ff87f251dafb32703d5f531e7b248ad0a581ee2

Alpha upstream sync classification

Result: no semantic overlap detected.

Incoming upstream paths neither overlap the current Alpha delta nor match a protected surface.

This report is advisory. A conflict-free Git merge and required CI are the automatic merge gates.

Automatic merge gates:

• Git produced a conflict-free merge candidate.
• Required CI must pass on this exact candidate.
• The finalizer must append the reconciliation journal entry.
• Required CI must pass again on the journaled head.
• GitHub must still report the pull request as mergeable.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ The exact PR base did not have a successful artifact. Baseline uses the latest successful main measurement shown below.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+28 B (+0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	+3 B (+0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+25 B (+0.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.2 KiB	56.2 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	8	9	+1 (+12.5%)	21	✅
Claude	Total thread wire	13.6 KiB	13.5 KiB	−57 B (−0.4%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+13 B (+0.2%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−70 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: f373774 · PR result: 1011bd6 · 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.