Feature/pay invoice return fees paid

[Okazakee]

No description provided.

[portal-wheatley]

Review

The implementation looks correct overall. A few notes:

✅ What looks good

• Trait signature change is clean: Result<(String, u64)> where u64 is fees in sats is a sensible contract
• ws.rs correctly converts sats → msat (fees_paid_sats * 1000) for the wire format
• TS client properly updated in both types.ts and client.ts
• NWC: response.fees_paid.unwrap_or(0) / 1000 correctly normalizes NIP-47 millisats to sats

🟡 Minor points

breez.rs — non-Lightning payment methods always return 0 fees

fee_sats is initialized to 0 and only updated inside the PaymentMethod::Lightning { ... } branch. If a payment goes through a different method variant, fees will silently be reported as 0. Probably fine for now, but worth a comment noting the assumption:

let mut fee_sats = 0u64; // only set for Lightning; other payment methods report 0

nwc.rs — integer truncation on msat → sat conversion

fees_paid.unwrap_or(0) / 1000 truncates. E.g. a 999 msat fee becomes 0 sats. Acceptable given the scale of typical Lightning fees, but worth knowing.

lib.rs — doc comment not updated

The pay_invoice doc comment still says nothing about the return value. Minor, but since the signature is now a tuple it'd be helpful to add: /// Returns (preimage, fees_paid_sats) on success.

Empty PR description

Would be good to have a short description referencing issue #148.

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None of the above are blockers — the core logic is sound. Good to merge after adding the PR description.

[denmeh]

In the portal wallet trait definition, I would return to msat, because by default, we use msat in the protocol, not sat.

A future task I might assign myself could be to create a type like Amount in the protocol to avoid disambiguation.

[denmeh]

LGTM