[lightapi] feat: Keep NEM transfer message semantics in lightapi by exposing the original message type

[cryptoBeliever]

Summary

• Keep NEM transfer message semantics in lightapi by exposing the original message type in Message objects instead of a derived boolean.
• Rename the transfer message field from is_plain to type in lightapi mapping (1 = plain, 2 = encrypted).
• Update lightapi tests to validate message type mapping for plain and encrypted transfer messages.
• Use MessageType.PLAIN instead of forwarding the raw NEM message type integer (1 / 2).

Motivation

A boolean is_plain loses message-type information and makes downstream handling brittle if new NEM message types appear in the future. Keeping the raw type in lightapi preserves protocol semantics and centralizes interpretation in Explorer/UI logic while maintaining a clear migration path for already persisted data.

Issue: #2352

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.01%. Comparing base (84e4aea) to head (5425b82).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #2382      +/-   ##
==========================================
+ Coverage   95.38%   97.01%   +1.62%     
==========================================
  Files         631      276     -355     
  Lines       49344    21314   -28030     
  Branches     1362      206    -1156     
==========================================
- Hits        47068    20678   -26390     
+ Misses       2226      630    -1596     
+ Partials       50        6      -44     

Flag	Coverage Δ
lightapi-python	98.69% <100.00%> (ø)
wallet-mobile-symbol	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ightapi/python/symbollightapi/model/Transaction.py	99.31% <100.00%> (ø)

... and 355 files with indirect coverage changes

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[AnthonyLaw]

👍🏼

[Wayonb]

The fix looks fine 👍🏾
Is there a reason not to fix this on the Explorer side?
I think api is correct and should just return the information from the node. 🤔

[cryptoBeliever]

The fix looks fine 👍🏾 Is there a reason not to fix this on the Explorer side? I think api is correct and should just return the information from the node. 🤔

@Wayonb, there’s a fix on the Explorer side as well -> #2383

The variable in lightapi is called is_plain, so I changed it here to return a boolean as the name suggests. The alternative would be to rename it to message_type and handle the interpretation accordingly on the Explorer side. I chose to keep the original name. Ultimately, there are only two possible values in NEM anyway.

If you’d prefer lightapi to return a numeric type, I can change it (and rename the property). But if the current approach is fine, I’d leave it as it is.

[Wayonb]

The fix looks fine 👍🏾 Is there a reason not to fix this on the Explorer side? I think api is correct and should just return the information from the node. 🤔

@Wayonb, there’s a fix on the Explorer side as well -> #2383

The variable in lightapi is called is_plain, so I changed it here to return a boolean as the name suggests. The alternative would be to rename it to message_type and handle the interpretation accordingly on the Explorer side. I chose to keep the original name. Ultimately, there are only two possible values in NEM anyway.

If you’d prefer lightapi to return a numeric type, I can change it (and rename the property). But if the current approach is fine, I’d leave it as it is.

Yea, ideally it should return the type but I see your point its already broken. The issue is that if we ever add a new message type, this will not work, and we will need to update all downstream products.
I think the rename to message_type is a better fix. Thanks.

[cryptoBeliever]

@Wayonb updated 👍

[Wayonb]

👍🏾