docs: update status with mesh infrastructure progress

Completed in this session:
- KeyPackage distribution over mesh (announce-based)
- Transport capability negotiation
- MLS-Lite to full MLS upgrade path

Updated mesh-protocol-gaps.md to reflect completed items.

docs/plans/mesh-protocol-gaps.md

@@ -13,9 +13,10 @@ QuicProChat has strong cryptography (MLS, PQ-KEM) but **real gaps** in the mesh
 
 | Gap | Severity | Status |
 |-----|----------|--------|
-| MLS overhead too large for LoRa | **Critical** | **MEASURED** — see actual sizes below |
+| MLS overhead too large for LoRa | **Critical** | **MEASURED** — classical MLS viable! |
 | No lightweight messaging mode | **High** | **DONE** — MLS-Lite implemented |
-| KeyPackage distribution over mesh | **High** | Not solved |
+| KeyPackage distribution over mesh | **High** | **DONE** — announce-based with cache |
+| Transport capability negotiation | **High** | **DONE** — auto-selects crypto mode |
 | Announce/routing not battle-tested | **Medium** | S3-S4 done, needs real-world test |
 | No DTN bundle protocol integration | **Medium** | Priority field added |
 | Battery/duty-cycle optimization | **Medium** | Basic tracker exists |
@@ -167,10 +168,12 @@ KeyPackage propagation:
 
 ### Action Items
 
-- [ ] **Extend MeshAnnounce** with optional `keypackage_hash` field
-- [ ] **Add KeyPackage request/response** to mesh protocol
-- [ ] **Implement KeyPackage cache** in MeshStore (separate from message queue)
+- [x] **Extend MeshAnnounce** with optional `keypackage_hash` field — 8-byte truncated hash
+- [x] **Add KeyPackage request/response** to mesh protocol — `mesh_protocol.rs`
+- [x] **Implement KeyPackage cache** — `keypackage_cache.rs` (separate from MeshStore)
 - [ ] **Design KeyPackage refresh protocol** for mesh-only scenarios
+- [x] **Add transport capability negotiation** — `transport.rs` TransportCapability enum
+- [x] **Add MLS-Lite upgrade path** — `crypto_negotiation.rs`
 
 ---
 

docs/status.md

@@ -47,9 +47,23 @@ New `fapp_router.rs` module:
 
 ---
 
-## 2026-03-30 — Implementation Sprint (S4-S5 + MLS-Lite)
+## 2026-03-30 — Mesh Protocol Infrastructure Sprint
 
-### Completed
+### Completed (Latest)
+- **KeyPackage distribution** — `keypackage_cache.rs` + `mesh_protocol.rs`
+  - MeshAnnounce extended with `keypackage_hash` field
+  - KeyPackageRequest/Response/Unavailable messages
+  - KeyPackageCache with TTL, per-address limits, LRU eviction
+- **Transport capability negotiation** — `transport.rs` TransportCapability
+  - Auto-classification: Unconstrained/Medium/Constrained/SeverelyConstrained
+  - CryptoMode recommendation per capability level
+  - TransportManager.recommended_crypto(), select_for_size()
+- **MLS-Lite upgrade path** — `crypto_negotiation.rs`
+  - GroupCryptoState tracks current mode
+  - MlsLiteBootstrap derives MLS-Lite keys from MLS epoch secret
+  - Enables same group to use full MLS on WiFi, MLS-Lite on LoRa
+
+### Previously Completed
 - **S4: Multi-hop routing** — `MeshRouter` with `send()`, `handle_incoming()`, `forward()`, `drain_store_for()`
 - **S4: REPL commands** — `/mesh trace <address>` and `/mesh stats`
 - **S5: Truncated addresses** — `MeshEnvelopeV2` with 16-byte addresses (~18% smaller)