✉️ L-CHAT-4: Sealed Sender envelope over trios-mesh ETX

[gHashTag]

Lane L-CHAT-4

Parent EPIC: #28 (Trinity Secure Chat)
Anchor: φ² + φ⁻² = 3
ETA: 4 days

See parent EPIC #28 for full mission scope, threat model (TM-1..TM-10), R-CHAT laws (R-CHAT-1..R-CHAT-12), acceptance gates G-C1..G-C10, and 21 cited sources.

Detailed design: docs/chat/trinity-chat-design.md (added in PR feat/trios-chat-epic).

Coordination Protocol

• 🛡 claim · 💓 heartbeat (60min) · ✅ done · 🚫 block · 🔓 release after 4h silence

φ² + φ⁻² = 3 · TRINITY · CHAT · NEVER STOP

[gHashTag]

🔥 IGNITE — Trinity Secure Chat scaffold landing

Anchor: φ² + φ⁻² = 3 · TRINITY · CHAT · ZERO-METADATA

PR: gHashTag/trios#631
Local trios tracker: gHashTag/trios#632

Verification snapshot [VERIFIED]

• cargo test -p trios-chat --lib — 35/35 pass
• cargo run --bin e2e_chat_25 — 25/25 pass
• cargo run --bin falsifier_runner — direct 100 % / indirect 90 % / multi-turn 100 %
• cargo test --tests r_chat_guard — 3/3 pass
• 6 Coq theorems Defined + 1 Admitted (R5 budget honored)
• 200-attack falsifier corpus committed
• 10 ADR-CHAT-001..010 + 29 KB design doc with 21 sources

Honesty (R5)

Lanes 3 (MLS) and 5 (Persistence) are explicitly [ASPIRATIONAL] in this
scaffold — ADR-CHAT-001 / ADR-CHAT-008 capture the design; full impl lands
in follow-up PRs. Coq INV-CHAT-4 (sender unlinkability) is Admitted
within the documented R5 budget.

L1 ✅ no .sh · L2 ✅ Closes #632 in PR body.