defi/asset-leasing: rename roles to holder/short_seller; rewrite README

WHY
- Mike's terminology rule: one canonical name per concept, used
  consistently across code, tests, and docs. The old README mixed
  "lessor", "lender", "long holder", "lessee", "borrower", and
  "short seller" for the same two parties; the code used yet another
  pair (lessor/lessee) that the README excused as a legacy artefact.
  That's three names per role for readers to keep straight, which is
  two too many.
- Mike's writing rules (no abbreviations, no ambiguous "it"/"this",
  no "TradFi-vs-onchain" framing for things that exist onchain too,
  no "skip ahead" suggestions, no inline glossary when Solana docs
  already define the terms).
- "Securities lending" framing is wrong: SOL is not legally a
  security, this program isn't restricted to tokenised securities,
  and the mechanics work for any directional token loan.

WHAT
Code + tests:
- Renamed `lessor` -> `holder` and `lessee` -> `short_seller` across
  every Rust source file, the test file, and Cargo.toml.
  Includes struct fields (Lease.holder, Lease.short_seller), account
  context fields (e.g. holder_leased_account,
  short_seller_collateral_account), local variables, function
  parameters, comments, and doc strings.
- Updated PDA seed bytes to match: b"lessor" -> b"holder",
  b"lessee" -> b"short_seller". This breaks address compatibility
  with the previous build, which is fine — the program is not
  deployed.
- Cleaned up a couple of incidental abbreviations Mike's coding
  style forbids (denom -> denominator in liquidate.rs,
  liq_ix -> liquidate_instruction in tests, "8 disc" comment ->
  "8 discriminator").
- All 11 LiteSVM integration tests still pass; `anchor build`
  produces a clean .so.

README:
- Used "holder" and "short seller" exclusively; dropped lessor /
  lessee / lender / borrower / long holder framings entirely.
- Replaced the ambiguous "if it falls" sentence with explicit
  antecedents ("if the asset falls, the short seller profits").
- Reframed the TradFi parenthetical: the entities listed (ETFs,
  pension funds, passive allocators) exist both in TradFi and
  onchain, so dropped the "vs onchain" split.
- Removed the "you can skip straight to" suggestion. Background
  sections are useful for everyone.
- Replaced "onchain securities lending" with "directional token
  lending" in the lede; SOL isn't a security, and the program
  works for any directional loan.
- Inline-linked Solana terminology (Anchor, instruction handler,
  program-derived address, associated token account, cross-program
  invocation) to https://solana.com/docs/terminology on first
  occurrence. No glossary footer note.
- Removed the paragraph that excused the lessor/lessee identifiers
  as legacy — those identifiers no longer exist.
- Misc consistency pass: "instruction handler" not "instruction"
  for the function/code, "onchain" one word everywhere, kept
  "TradFi" only where the analogy is to actual TradFi (securities
  lending).

Author: mikemaccana-edwardbot

defi/asset-leasing/anchor/README.md

@@ -21,7 +21,7 @@ custom-panic = []
 
 [dependencies]
 # `init-if-needed` is required because several instructions lazily create the
-# counterparty's associated token accounts (keeper's collateral associated token account on first liquidation, lessor's
+# counterparty's associated token accounts (keeper's collateral associated token account on first liquidation, holder's
 # leased associated token account on first return, etc.). Anchor forces an opt-in to make us
 # re-affirm that we verify ownership on every touch — which we do via the
 # `associated_token::authority = ...` constraints.

defi/asset-leasing/anchor/programs/asset-leasing/Cargo.toml

@@ -1,25 +1,25 @@
-/// program-derived address seed for the `Lease` account. Combined with the lessor pubkey and a
-/// u64 `lease_id` so one lessor can run many leases in parallel.
+/// program-derived address seed for the `Lease` account. Combined with the holder pubkey and a
+/// u64 `lease_id` so one holder can run many leases in parallel.
 pub const LEASE_SEED: &[u8] = b"lease";
 
 /// program-derived address seed for the token vault that holds the leased tokens while the lease
 /// is `Listed` and that accepts returned tokens on settlement.
 pub const LEASED_VAULT_SEED: &[u8] = b"leased_vault";
 
-/// program-derived address seed for the token vault that escrows the lessee's collateral for the
+/// program-derived address seed for the token vault that escrows the short_seller's collateral for the
 /// life of the lease.
 pub const COLLATERAL_VAULT_SEED: &[u8] = b"collateral_vault";
 
 /// Denominator for basis-point (basis points) ratios used for the maintenance margin
 /// and the liquidation bounty. 10_000 basis points = 100%.
 pub const BASIS_POINTS_DENOMINATOR: u64 = 10_000;
 
-/// Maximum allowed maintenance margin: 50_000 basis points = 500%. Prevents the lessor
+/// Maximum allowed maintenance margin: 50_000 basis points = 500%. Prevents the holder
 /// setting an impossible margin that would let them liquidate on day one.
 pub const MAX_MAINTENANCE_MARGIN_BASIS_POINTS: u16 = 50_000;
 
 /// Maximum liquidation bounty the keeper can claim: 2_000 basis points = 20%. Keeps
-/// most of the collateral flowing to the lessor on default.
+/// most of the collateral flowing to the holder on default.
 pub const MAX_LIQUIDATION_BOUNTY_BASIS_POINTS: u16 = 2_000;
 
 /// A Pyth price update is considered stale if its `publish_time` is older

defi/asset-leasing/anchor/programs/asset-leasing/src/constants.rs

@@ -14,27 +14,27 @@ use crate::{
     state::{Lease, LeaseStatus},
 };
 
-/// Lessor-only recovery path. Two real-world situations collapse here:
+/// Holder-only recovery path. Two real-world situations collapse here:
 ///
-/// - The lease sat in `Listed` and the lessor wants to cancel it, recovering
+/// - The lease sat in `Listed` and the holder wants to cancel it, recovering
 ///   the leased tokens they pre-funded. Allowed any time.
-/// - The lease was `Active` but the lessee ghosted past `end_timestamp`. The lessor
+/// - The lease was `Active` but the short_seller ghosted past `end_timestamp`. The holder
 ///   takes the collateral as compensation and closes the books.
 #[derive(Accounts)]
 pub struct CloseExpired<'info> {
     #[account(mut)]
-    pub lessor: Signer<'info>,
+    pub holder: Signer<'info>,
 
     #[account(
         mut,
-        seeds = [LEASE_SEED, lessor.key().as_ref(), &lease.lease_id.to_le_bytes()],
+        seeds = [LEASE_SEED, holder.key().as_ref(), &lease.lease_id.to_le_bytes()],
         bump = lease.bump,
-        has_one = lessor,
+        has_one = holder,
         has_one = leased_mint,
         has_one = collateral_mint,
         constraint = matches!(lease.status, LeaseStatus::Listed | LeaseStatus::Active)
             @ AssetLeasingError::InvalidLeaseStatus,
-        close = lessor,
+        close = holder,
     )]
     pub lease: Account<'info, Lease>,
 
@@ -63,21 +63,21 @@ pub struct CloseExpired<'info> {
 
     #[account(
         init_if_needed,
-        payer = lessor,
+        payer = holder,
         associated_token::mint = leased_mint,
-        associated_token::authority = lessor,
+        associated_token::authority = holder,
         associated_token::token_program = token_program,
     )]
-    pub lessor_leased_account: Box<InterfaceAccount<'info, TokenAccount>>,
+    pub holder_leased_account: Box<InterfaceAccount<'info, TokenAccount>>,
 
     #[account(
         init_if_needed,
-        payer = lessor,
+        payer = holder,
         associated_token::mint = collateral_mint,
-        associated_token::authority = lessor,
+        associated_token::authority = holder,
         associated_token::token_program = token_program,
     )]
-    pub lessor_collateral_account: Box<InterfaceAccount<'info, TokenAccount>>,
+    pub holder_collateral_account: Box<InterfaceAccount<'info, TokenAccount>>,
 
     pub token_program: Interface<'info, TokenInterface>,
     pub associated_token_program: Program<'info, AssociatedToken>,
@@ -111,14 +111,14 @@ pub fn handle_close_expired(context: Context<CloseExpired>) -> Result<()> {
         core::slice::from_ref(&collateral_vault_bump),
     ];
 
-    // Drain whatever is in the leased vault back to the lessor. For a Listed
+    // Drain whatever is in the leased vault back to the holder. For a Listed
     // lease this is the full leased_amount; for a defaulted Active lease the
-    // vault is empty (the lessee never returned) and this is a no-op.
+    // vault is empty (the short_seller never returned) and this is a no-op.
     let leased_vault_balance = context.accounts.leased_vault.amount;
     if leased_vault_balance > 0 {
         transfer_tokens_from_vault(
             &context.accounts.leased_vault,
-            &context.accounts.lessor_leased_account,
+            &context.accounts.holder_leased_account,
             leased_vault_balance,
             &context.accounts.leased_mint,
             &context.accounts.leased_vault.to_account_info(),
@@ -127,13 +127,13 @@ pub fn handle_close_expired(context: Context<CloseExpired>) -> Result<()> {
         )?;
     }
 
-    // Drain the collateral vault to the lessor. For a Listed lease this is 0.
-    // For a defaulted Active lease this is the lessee's forfeited collateral.
+    // Drain the collateral vault to the holder. For a Listed lease this is 0.
+    // For a defaulted Active lease this is the short_seller's forfeited collateral.
     let collateral_vault_balance = context.accounts.collateral_vault.amount;
     if collateral_vault_balance > 0 {
         transfer_tokens_from_vault(
             &context.accounts.collateral_vault,
-            &context.accounts.lessor_collateral_account,
+            &context.accounts.holder_collateral_account,
             collateral_vault_balance,
             &context.accounts.collateral_mint,
             &context.accounts.collateral_vault.to_account_info(),
@@ -144,26 +144,26 @@ pub fn handle_close_expired(context: Context<CloseExpired>) -> Result<()> {
 
     close_vault(
         &context.accounts.leased_vault,
-        &context.accounts.lessor.to_account_info(),
+        &context.accounts.holder.to_account_info(),
         &context.accounts.token_program,
         &[leased_vault_seeds],
     )?;
     close_vault(
         &context.accounts.collateral_vault,
-        &context.accounts.lessor.to_account_info(),
+        &context.accounts.holder.to_account_info(),
         &context.accounts.token_program,
         &[collateral_vault_seeds],
     )?;
 
     // Settle lease-fee accounting on the default path.
     //
-    // We are not forwarding any accrued lease fees to the lessor here — on default
-    // the lessor takes the whole collateral vault as compensation — but we
+    // We are not forwarding any accrued lease fees to the holder here — on default
+    // the holder takes the whole collateral vault as compensation — but we
     // still bump \`last_paid_timestamp\` so the invariant
     // \`last_paid_timestamp <= now.min(end_timestamp)\` stays intact. That matters for
     // any future version of the program that wants to split the collateral
     // differently (pro-rata lease fees, partial refund on default, haircut to the
-    // lessee for unused time): such a version can read
+    // short_seller for unused time): such a version can read
     // \`last_paid_timestamp\` and trust that everything up to \`now\` is already
     // settled, rather than having to reason about whether this branch ever
     // bumped the timestamp.

defi/asset-leasing/anchor/programs/asset-leasing/src/instructions/close_expired.rs

@@ -15,7 +15,7 @@ use crate::{
 #[instruction(lease_id: u64)]
 pub struct CreateLease<'info> {
     #[account(mut)]
-    pub lessor: Signer<'info>,
+    pub holder: Signer<'info>,
 
     #[account(mint::token_program = token_program)]
     pub leased_mint: InterfaceAccount<'info, Mint>,
@@ -26,16 +26,16 @@ pub struct CreateLease<'info> {
     #[account(
         mut,
         associated_token::mint = leased_mint,
-        associated_token::authority = lessor,
+        associated_token::authority = holder,
         associated_token::token_program = token_program,
     )]
-    pub lessor_leased_account: Box<InterfaceAccount<'info, TokenAccount>>,
+    pub holder_leased_account: Box<InterfaceAccount<'info, TokenAccount>>,
 
     #[account(
         init,
-        payer = lessor,
+        payer = holder,
         space = Lease::DISCRIMINATOR.len() + Lease::INIT_SPACE,
-        seeds = [LEASE_SEED, lessor.key().as_ref(), &lease_id.to_le_bytes()],
+        seeds = [LEASE_SEED, holder.key().as_ref(), &lease_id.to_le_bytes()],
         bump,
     )]
     pub lease: Account<'info, Lease>,
@@ -45,7 +45,7 @@ pub struct CreateLease<'info> {
     /// returns / liquidation; any handler just signs with the vault seeds.
     #[account(
         init,
-        payer = lessor,
+        payer = holder,
         seeds = [LEASED_VAULT_SEED, lease.key().as_ref()],
         bump,
         token::mint = leased_mint,
@@ -56,7 +56,7 @@ pub struct CreateLease<'info> {
 
     #[account(
         init,
-        payer = lessor,
+        payer = holder,
         seeds = [COLLATERAL_VAULT_SEED, lease.key().as_ref()],
         bump,
         token::mint = collateral_mint,
@@ -84,7 +84,7 @@ pub fn handle_create_lease(
     // Reject leased_mint == collateral_mint. Allowing both to be the same
     // mint would collapse the two vaults' seed derivations into one shared
     // token-balance pool, making lease-fee-vs-collateral accounting ambiguous and
-    // enabling griefing paths where the lessee's "collateral" is the same
+    // enabling griefing paths where the short_seller's "collateral" is the same
     // asset they already hold as the lease principal.
     require!(
         context.accounts.leased_mint.key() != context.accounts.collateral_mint.key(),
@@ -108,23 +108,23 @@ pub fn handle_create_lease(
     );
 
     // Lock the leased tokens into the program-owned vault up-front. Doing this
-    // here (not on take_lease) guarantees a lessee can never accept a lease
-    // the lessor no longer has the funds to deliver.
+    // here (not on take_lease) guarantees a short_seller can never accept a lease
+    // the holder no longer has the funds to deliver.
     transfer_tokens_from_user(
-        &context.accounts.lessor_leased_account,
+        &context.accounts.holder_leased_account,
         &context.accounts.leased_vault,
         leased_amount,
         &context.accounts.leased_mint,
-        &context.accounts.lessor,
+        &context.accounts.holder,
         &context.accounts.token_program,
     )?;
 
     let lease = &mut context.accounts.lease;
     lease.set_inner(Lease {
         lease_id,
-        lessor: context.accounts.lessor.key(),
-        // No lessee yet — will be populated by take_lease.
-        lessee: Pubkey::default(),
+        holder: context.accounts.holder.key(),
+        // No short_seller yet — will be populated by take_lease.
+        short_seller: Pubkey::default(),
         leased_mint: context.accounts.leased_mint.key(),
         leased_amount,
         collateral_mint: context.accounts.collateral_mint.key(),

defi/asset-leasing/anchor/programs/asset-leasing/src/instructions/create_lease.rs

@@ -36,17 +36,17 @@ pub struct Liquidate<'info> {
 
     /// CHECK: program-derived address seed + lease-fee / collateral destination.
     #[account(mut)]
-    pub lessor: UncheckedAccount<'info>,
+    pub holder: UncheckedAccount<'info>,
 
     #[account(
         mut,
-        seeds = [LEASE_SEED, lessor.key().as_ref(), &lease.lease_id.to_le_bytes()],
+        seeds = [LEASE_SEED, holder.key().as_ref(), &lease.lease_id.to_le_bytes()],
         bump = lease.bump,
-        has_one = lessor,
+        has_one = holder,
         has_one = leased_mint,
         has_one = collateral_mint,
         constraint = lease.status == LeaseStatus::Active @ AssetLeasingError::InvalidLeaseStatus,
-        close = lessor,
+        close = holder,
     )]
     pub lease: Account<'info, Lease>,
 
@@ -77,10 +77,10 @@ pub struct Liquidate<'info> {
         init_if_needed,
         payer = keeper,
         associated_token::mint = collateral_mint,
-        associated_token::authority = lessor,
+        associated_token::authority = holder,
         associated_token::token_program = token_program,
     )]
-    pub lessor_collateral_account: Box<InterfaceAccount<'info, TokenAccount>>,
+    pub holder_collateral_account: Box<InterfaceAccount<'info, TokenAccount>>,
 
     #[account(
         init_if_needed,
@@ -160,7 +160,7 @@ pub fn handle_liquidate(context: Context<Liquidate>) -> Result<()> {
     drop(price_data);
 
     // Feed pinning: reject any `PriceUpdateV2` whose feed_id does not match
-    // the one the lessor committed to at `create_lease`. Without this guard,
+    // the one the holder committed to at `create_lease`. Without this guard,
     // a keeper could pass in any feed the Pyth Receiver program owns — e.g.
     // a wildly volatile pair that dips enough to flag the position as
     // underwater — and trigger a spurious liquidation.
@@ -174,8 +174,8 @@ pub fn handle_liquidate(context: Context<Liquidate>) -> Result<()> {
         AssetLeasingError::PositionHealthy
     );
 
-    // Settle accrued lease fees first (up to end_timestamp) so the lessor is paid for the
-    // time the lessee actually used. Only then slice off bounty + remainder.
+    // Settle accrued lease fees first (up to end_timestamp) so the holder is paid for the
+    // time the short_seller actually used. Only then slice off bounty + remainder.
     let lease_fee_due = compute_lease_fee_due(&context.accounts.lease, now)?;
     let lease_fee_payable = lease_fee_due.min(context.accounts.lease.collateral_amount);
 
@@ -196,7 +196,7 @@ pub fn handle_liquidate(context: Context<Liquidate>) -> Result<()> {
     if lease_fee_payable > 0 {
         transfer_tokens_from_vault(
             &context.accounts.collateral_vault,
-            &context.accounts.lessor_collateral_account,
+            &context.accounts.holder_collateral_account,
             lease_fee_payable,
             &context.accounts.collateral_mint,
             &context.accounts.collateral_vault.to_account_info(),
@@ -232,33 +232,33 @@ pub fn handle_liquidate(context: Context<Liquidate>) -> Result<()> {
         )?;
     }
 
-    let lessor_share = remaining
+    let holder_share = remaining
         .checked_sub(bounty)
         .ok_or(AssetLeasingError::MathOverflow)?;
-    if lessor_share > 0 {
+    if holder_share > 0 {
         transfer_tokens_from_vault(
             &context.accounts.collateral_vault,
-            &context.accounts.lessor_collateral_account,
-            lessor_share,
+            &context.accounts.holder_collateral_account,
+            holder_share,
             &context.accounts.collateral_mint,
             &context.accounts.collateral_vault.to_account_info(),
             &context.accounts.token_program,
             &[collateral_vault_seeds],
         )?;
     }
 
-    // The leased vault is empty (lessee kept the tokens on default) but was
-    // rent-exempt funded at creation. Close both vaults so the lessor recoups
+    // The leased vault is empty (short_seller kept the tokens on default) but was
+    // rent-exempt funded at creation. Close both vaults so the holder recoups
     // the rent-exempt lamports.
     close_vault(
         &context.accounts.leased_vault,
-        &context.accounts.lessor.to_account_info(),
+        &context.accounts.holder.to_account_info(),
         &context.accounts.token_program,
         &[leased_vault_seeds],
     )?;
     close_vault(
         &context.accounts.collateral_vault,
-        &context.accounts.lessor.to_account_info(),
+        &context.accounts.holder.to_account_info(),
         &context.accounts.token_program,
         &[collateral_vault_seeds],
     )?;
@@ -286,7 +286,7 @@ pub fn is_underwater(lease: &Lease, price: &DecodedPriceUpdate, now: i64) -> Res
     let leased_amount = lease.leased_amount as u128;
     let collateral_amount = lease.collateral_amount as u128;
     let margin_basis_points = lease.maintenance_margin_basis_points as u128;
-    let denom = BASIS_POINTS_DENOMINATOR as u128;
+    let denominator = BASIS_POINTS_DENOMINATOR as u128;
 
     let (collateral_scaled, debt_scaled) = if price.exponent >= 0 {
         let scale = ten_pow(price.exponent as u32)?;
@@ -307,7 +307,7 @@ pub fn is_underwater(lease: &Lease, price: &DecodedPriceUpdate, now: i64) -> Res
     };
 
     let lhs = collateral_scaled
-        .checked_mul(denom)
+        .checked_mul(denominator)
         .ok_or(AssetLeasingError::MathOverflow)?;
     let rhs = debt_scaled
         .checked_mul(margin_basis_points)