feat(swap): add Oxedium single-sided liquidity protocol

[zelmkhan]

Summary

Adds swap support for the Oxedium single-sided liquidity protocol (oV3SkLhiXSG946FaqDf1yNocFMhE1ZvomGsoWF8Mzap ).

Oxedium is an AMM where LPs deposit a single token into a vault and traders swap between vaults using Pyth oracle prices to determine the exchange rate.

• Add crates/swap/oxedium crate implementing the Swap<'info> trait
• OxediumSwapAccounts — 16 accounts (program sentinel + 15 instruction accounts)
• Instruction data: 8-byte Anchor discriminator (sha256("global:swap")[0..8]) + amount_in + minimum_out = 24 bytes
• No extra swap data required (type Data = ())
• Wire up oxedium-swap feature flag in root Cargo.toml
• Export oxedium module in src/lib.rs
• Add SwapContext::Oxedium variant and protocol-detection routing in src/context.rs

Account layout

#	Account	Writable	Signer
0	oxedium_program (detector)	no	no
1	signer	yes	yes
2	token_mint_in	no	no
3	token_mint_out	no	no
4	pyth_price_in	no	no
5	pyth_price_out	no	no
6	signer_ata_in	yes	no
7	signer_ata_out	yes	no
8	vault_pda_in	yes	no
9	vault_pda_out	yes	no
10	vault_ata_in	yes	no
11	vault_ata_out	yes	no
12	oxe_global_pda	no	no
13	associated_token_program	no	no
14	token_program	no	no
15	system_program	no	no

Test plan

• Verify cargo check --features oxedium-swap compiles without errors
• Verify cargo check (all features) compiles without errors
• Test swap routing via try_from_swap_context with Oxedium program ID as first account

[BretasArthur1]

Hey @zelmkhan overall looks good, but please remove claude as contributor from your history

[L0STE]

The context.rs wiring has two bugs where Oxedium code was inserted into the middle of Omnipair blocks instead of as self-contained blocks:

1. swap_signed match arm is unclosed — the Oxedium arm opens swap_signed( but never passes arguments or closes. Omnipair's arm starts mid-expression:

// broken — missing args, ), and }
(SwapContext::Oxedium(accounts), SwapData::Oxedium(())) => {
    crate::oxedium::Oxedium::swap_signed(
// omnipair starts here

Should be a complete arm:

#[cfg(feature = "oxedium-swap")]
(SwapContext::Oxedium(accounts), SwapData::Oxedium(())) => {
    crate::oxedium::Oxedium::swap_signed(
        accounts,
        in_amount,
        minimum_out_amount,
        &(),
        signer_seeds,
    )
}

2. try_from_swap_context — Oxedium if block never closes, so it nests around the Omnipair block. The split_at, try_from, and return lines for Oxedium ended up inside Omnipair's scope. Needs to be its own standalone block before the Omnipair one:

#[cfg(feature = "oxedium-swap")]
if address_eq(detector_account.address(), &crate::oxedium::OXEDIUM_PROGRAM_ID) {
    let n = crate::oxedium::OxediumSwapAccounts::NUM_ACCOUNTS;
    if accounts.len() < n {
        return Err(ProgramError::NotEnoughAccountKeys);
    }
    let (mine, rest) = accounts.split_at(n);
    let ctx = crate::oxedium::OxediumSwapAccounts::try_from(mine)?;
    return Ok((SwapContext::Oxedium(ctx), rest));
}

Both fixes are just restructuring — copy the Omnipair pattern as a complete block rather than inserting lines into it.

Also missing a test file (tests/swap/oxedium.rs) — can't merge without one. Rebase onto master after fixing.

[zelmkhan]

@L0STE @BretasArthur1 Please check

[L0STE]

LGTM, a few minor style nits:

• src/context.rs: Missing blank line between Oxedium and Omnipair variants in both SwapContext and SwapData enums (every other variant has one)
• src/context.rs: The try_from_swap_data arm for Oxedium is between Gamma and ScaleAmm, but the enum declaration puts it between ScaleVmm and Omnipair — would be easier to scan if they matched
• crates/swap/oxedium/src/lib.rs:285: The "no extra data" doc comment is on the NUM_ACCOUNTS impl block rather than near type Data = ()