Greptile Summary

This PR adds end-to-end tracking of the outbound network interface for sent messages, surfaced as a "Sent Via" card in the Message Details screen. It plumbs a new getNextHopInterfaceName() call through the full AIDL IPC stack (Python rns_api.py → PythonWrapperManager → RoutingManager → ReticulumServiceBinder → IReticulumService.aidl → ServiceReticulumProtocol), adds a Room migration (42→43) for the sentInterface column, and renames ReceivingInterfaceInfo → InterfaceInfo for bidirectional use.

• The concerns raised in previous reviews have been addressed: enrichment is now gated strictly to update.status == "delivered" (excluding failed and retrying_propagated), the propagation guard (deliveryMethod == "propagated") is in place, rns_api.py now logs errors via log_debug instead of silently swallowing them, and the unreachable get_active_propagation_node_hash stub has been removed from rns_api.py.
• The send-time capture correctly uses receipt.destinationHash (which resolves to the propagation node hash for propagated sends), while the delivery-time enrichment uses message.conversationHash only for non-propagated, non-enriched messages.
• The updateSentInterface DAO method signature accepts a nullable sentInterface parameter — see inline comment for a minor tightening suggestion.
• The MockReticulumProtocol stub and all test renames are complete and consistent.

Confidence Score: 4/5

• Safe to merge — no regressions to existing receive-side interface display, migration is backward-compatible, and all previous critical concerns have been addressed.
• The logic is sound and previously flagged issues are resolved. The only remaining observation is the nullable DAO parameter, which is a style concern rather than a correctness issue. The best-effort, null-fallback design of the entire feature means any edge-case failure surfaces as a missing "Sent Via" card rather than a crash or data corruption.
• No files require special attention. MessagingViewModel.kt carries the most complexity but the enrichment guard logic is now well-scoped.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant UI as MessageDetailScreen
    participant VM as MessagingViewModel
    participant RP as ReticulumProtocol (AIDL)
    participant PW as PythonWrapperManager
    participant PY as rns_api.py
    participant DB as Room DB (messages)

    Note over VM: Send path
    VM->>RP: getNextHopInterfaceName(receipt.destinationHash)
    RP->>PW: getNextHopInterfaceName(destHash)
    PW->>PY: rnsApi.get_next_hop_interface_name(dest_hash)
    PY->>PY: RNS.Transport.has_path(dest_hash)
    PY->>PY: RNS.Transport.next_hop_interface(dest_hash)
    PY->>PY: format_interface_name(iface)
    PY-->>PW: "TCPInterface[Server/1.2.3.4:4242]" or None
    PW-->>RP: String? 
    RP-->>VM: sentInterface?
    VM->>DB: insertMessage(... sentInterface=sentInterface)

    Note over VM: Delivery enrichment path (status == "delivered" && sentInterface == null)
    VM->>VM: enrichSentInterfaceOnDelivery(message, messageHash)
    VM->>RP: getNextHopInterfaceName(conversationHash bytes)
    RP-->>VM: sentInterface?
    VM->>DB: updateSentInterface(messageHash, sentInterface)

    Note over UI: Display
    DB-->>VM: MessageEntity (sentInterface field)
    VM->>UI: MessageUi.sentInterface
    UI->>UI: Show "Sent Via" card (if non-null)

This is a comment left during a code review.
Path: data/src/main/java/com/lxmf/messenger/data/db/dao/MessageDao.kt
Line: 739-743

Comment:
**Nullable `sentInterface` parameter can silently clear the field**

`sentInterface: String?` means any future caller can pass `null` and erase a previously captured interface name. There is currently no use-case for nulling this field out — all existing callers always pass a non-null value (guarded by `if (sentInterface != null)` in the call site). Using a non-null type here makes the intent explicit and prevents accidental data loss.

```suggestion
    suspend fun updateSentInterface(
        messageId: String,
        identityHash: String,
        sentInterface: String,
    )
```

The corresponding repository method `updateMessageSentInterface(messageId, sentInterface: String?)` signature can be tightened to `String` as well, since the only caller already null-checks before invoking it.

How can I resolve this? If you propose a fix, please make it concise.

_{Last reviewed commit: 514d8ba}

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