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`
 
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