asset-leasing: merge accounts section into lifecycle

WHAT: Deleted the standalone Accounts and program-derived addresses
section and integrated its content into the Lifecycle handler
walkthroughs. Each account is now introduced at the moment it is
first created or first used:

- Lease, leased_vault, collateral_vault: introduced in create_lease
  with seeds and roles in a new program-derived addresses bullet
  list, plus the Lease struct definition in a new What's on the
  lease account subsection.
- holder, short_seller, payer, keeper user wallets: a one-line
  description added on first appearance in their respective
  handler's Signers bullet.
- Associated token accounts (holder_leased_account,
  holder_collateral_account, short_seller_*, keeper_collateral_account):
  one-line associated-token-account description added on first
  appearance in each handler's Accounts bullet.
- price_update: introduced in liquidate, where the Pyth oracle
  account is first passed in.
- The Closed/Liquidated states paragraph moved to the end of
  return_lease (the first close handler), since it covers all three
  closing paths.

Table of contents and any cross-references to the deleted section
updated.

WHY: A reader walking the lifecycle no longer has to flip back to a
static account dump to know what each account is - the prose
introduces every account the moment it appears in the narrative.

Author: Edward (OpenClaw)

defi/asset-leasing/anchor/README.md

@@ -24,12 +24,11 @@ need to sell short. The program is written in
 ## Table of contents
 
 1. [What does this program do?](#what-does-this-program-do)
-2. [Accounts and program-derived addresses](#accounts-and-program-derived-addresses)
-3. [Lifecycle](#lifecycle)
-4. [Safety and edge cases](#safety-and-edge-cases)
-5. [Running the tests](#running-the-tests)
-6. [Quasar port](#quasar-port)
-7. [Extending the program](#extending-the-program)
+2. [Lifecycle](#lifecycle)
+3. [Safety and edge cases](#safety-and-edge-cases)
+4. [Running the tests](#running-the-tests)
+5. [Quasar port](#quasar-port)
+6. [Extending the program](#extending-the-program)
 
 ---
 
@@ -205,80 +204,6 @@ above is the same machinery applied to a real asset pair.
 
 ---
 
-## Accounts and program-derived addresses
-
-Every call to the program touches some subset of these accounts. The
-three [program-derived addresses](https://solana.com/docs/terminology)
-are created on `create_lease` and destroyed on `return_lease` /
-`liquidate` / `close_expired`.
-
-### State / data accounts
-
-- **`Lease`** - program-derived address with seeds `["lease", holder, lease_id]`. Data account owned by the program, holding all the lease parameters and current lifecycle state (see below).
-
-### Token vaults
-
-- **`leased_vault`** - program-derived address with seeds `["leased_vault", lease]`. Token account whose authority is itself (program-derived-address-signed). Holds `leased_amount` while `Listed`; `0` while `Active` (the short seller has the tokens); full amount again briefly inside `return_lease`.
-- **`collateral_vault`** - program-derived address with seeds `["collateral_vault", lease]`. Token account whose authority is itself (program-derived-address-signed). Holds `0` while `Listed`; `collateral_amount` while `Active`, decreasing as lease fee streams out and increasing on `top_up_collateral`.
-
-### User accounts passed in
-
-- **`holder` wallet** (user-owned) - `create_lease` signer, receives the lease fee and final recovery.
-- **`short_seller` wallet** (user-owned) - `take_lease` / `top_up_collateral` / `return_lease` signer.
-- **`keeper` wallet** (user-owned) - `liquidate` signer, receives the bounty.
-- **`payer` wallet** (user-owned) - `pay_lease_fee` signer (can be anyone, not just the short seller).
-- **`holder_leased_account`** - holder's [associated token account](https://solana.com/docs/terminology) for the leased mint; source on `create_lease`, destination on `return_lease` / `close_expired`.
-- **`holder_collateral_account`** - holder's associated token account for the collateral mint; destination for the lease fee and liquidation proceeds.
-- **`short_seller_leased_account`** - short seller's associated token account for the leased mint; destination on `take_lease`, source on `return_lease`.
-- **`short_seller_collateral_account`** - short seller's associated token account for the collateral mint; source on `take_lease` / `top_up_collateral`, destination for collateral refund on `return_lease`.
-- **`keeper_collateral_account`** - keeper's associated token account for the collateral mint; receives the liquidation bounty.
-- **`price_update`** - `PriceUpdateV2` account owned by the Pyth Receiver program, for the feed the lease is pinned to.
-
-### Fields on `Lease`
-
-From [`state/lease.rs`](programs/asset-leasing/src/state/lease.rs):
-
-```rust
-pub struct Lease {
-    pub lease_id: u64,             // caller-supplied id so one holder can run many leases
-    pub holder: Pubkey,            // who listed it, gets paid the lease fee
-    pub short_seller: Pubkey,      // who took the lease; Pubkey::default() while Listed
-
-    pub leased_mint: Pubkey,
-    pub leased_amount: u64,        // locked at creation, unchanging
-
-    pub collateral_mint: Pubkey,
-    pub collateral_amount: u64,    // increases on top_up, decreases as lease fees pay out
-    pub required_collateral_amount: u64, // what the short seller must post on take_lease
-
-    pub lease_fee_per_second: u64,      // denominated in collateral units
-    pub duration_seconds: i64,
-    pub start_timestamp: i64,             // 0 while Listed
-    pub end_timestamp: i64,               // 0 while Listed; start_timestamp + duration once Active
-    pub last_paid_timestamp: i64,    // Lease fee accrues from here to min(now, end_timestamp)
-
-    pub maintenance_margin_basis_points: u16,   // e.g. 12_000 = 120%
-    pub liquidation_bounty_basis_points: u16,   // e.g. 500 = 5%
-
-    pub feed_id: [u8; 32],         // Pyth feed_id this lease is pinned to
-
-    pub status: LeaseStatus,       // Listed | Active | Liquidated | Closed
-
-    pub bump: u8,
-    pub leased_vault_bump: u8,
-    pub collateral_vault_bump: u8,
-}
-```
-
-The `Closed` and `Liquidated` states are not directly observable
-onchain: all three of `return_lease`, `liquidate` and `close_expired`
-close the `Lease` account in the same transaction (`close = holder`),
-returning the rent-exempt lamports to the holder. The in-memory
-`status` field is set *before* the close so the transaction logs
-record the terminal state, but the account disappears at the end.
-
----
-
 ## Lifecycle
 
 ### What the short seller really gets
@@ -308,16 +233,34 @@ The holder calls `create_lease`, naming the leased mint, the
 collateral mint, the amount of leased tokens to offer, the
 collateral the short seller will have to post, the per-second lease
 fee, the duration, the maintenance-margin and liquidation-bounty
-ratios, and the Pyth `feed_id` the lease will be priced against. The
-program creates the `Lease` account, creates two empty token vault
-[program-derived addresses](https://solana.com/docs/terminology) (one for each
-mint), and moves the leased tokens out of the holder's wallet into
-the leased vault. Locking the leased tokens up front means a short
-seller calling `take_lease` later cannot fail because the holder
-spent the inventory in the meantime - the atomicity guarantee
+ratios, and the Pyth `feed_id` the lease will be priced against.
+This is where every account the rest of the lifecycle uses gets
+created. The handler initialises three
+[program-derived addresses](https://solana.com/docs/terminology):
+
+- **`Lease`** - the state account, owned by the program, holding all
+  the lease parameters and the current lifecycle status. Seeds:
+  `[b"lease", holder, lease_id.to_le_bytes()]` - keying on
+  `lease_id` lets one holder run many leases in parallel.
+- **`leased_vault`** - a token account for the leased mint whose
+  authority is itself (the program signs as the vault using the
+  vault's own seeds). Seeds: `[b"leased_vault", lease]`. Holds
+  `leased_amount` while `Listed`; `0` while `Active` (the short
+  seller has the tokens); the full amount again briefly inside
+  `return_lease`.
+- **`collateral_vault`** - a token account for the collateral mint,
+  also self-authoritative. Seeds: `[b"collateral_vault", lease]`.
+  Created empty here; filled by `take_lease`, drained over time as
+  lease fees stream out, and topped up by `top_up_collateral`.
+
+The handler then moves the leased tokens out of the holder's wallet
+into the leased vault. Locking the leased tokens up front means a
+short seller calling `take_lease` later cannot fail because the
+holder spent the inventory in the meantime - the atomicity guarantee
 transfers to the program the moment the lease is listed.
 
-- **Signers:** `holder`.
+- **Signers:** `holder` (the user wallet listing the tokens; receives
+  the lease fee and the final recovery).
 - **Accounts:**
   - `holder` (signer, mut - pays account rent)
   - `leased_mint`, `collateral_mint` (read-only)
@@ -343,25 +286,65 @@ transfers to the program the moment the lease is listed.
   - `InvalidMaintenanceMargin` if `maintenance_margin_basis_points` is `0` or `> 50_000`
   - `InvalidLiquidationBounty` if `liquidation_bounty_basis_points > 2_000`
 
+#### What's on the lease account
+
+The `Lease` account written above carries the full set of fields
+referenced by the rest of the lifecycle. From [`state/lease.rs`](programs/asset-leasing/src/state/lease.rs):
+
+```rust
+pub struct Lease {
+    pub lease_id: u64,             // caller-supplied id so one holder can run many leases
+    pub holder: Pubkey,            // who listed it, gets paid the lease fee
+    pub short_seller: Pubkey,      // who took the lease; Pubkey::default() while Listed
+
+    pub leased_mint: Pubkey,
+    pub leased_amount: u64,        // locked at creation, unchanging
+
+    pub collateral_mint: Pubkey,
+    pub collateral_amount: u64,    // increases on top_up, decreases as lease fees pay out
+    pub required_collateral_amount: u64, // what the short seller must post on take_lease
+
+    pub lease_fee_per_second: u64,      // denominated in collateral units
+    pub duration_seconds: i64,
+    pub start_timestamp: i64,             // 0 while Listed
+    pub end_timestamp: i64,               // 0 while Listed; start_timestamp + duration once Active
+    pub last_paid_timestamp: i64,    // Lease fee accrues from here to min(now, end_timestamp)
+
+    pub maintenance_margin_basis_points: u16,   // e.g. 12_000 = 120%
+    pub liquidation_bounty_basis_points: u16,   // e.g. 500 = 5%
+
+    pub feed_id: [u8; 32],         // Pyth feed_id this lease is pinned to
+
+    pub status: LeaseStatus,       // Listed | Active | Liquidated | Closed
+
+    pub bump: u8,
+    pub leased_vault_bump: u8,
+    pub collateral_vault_bump: u8,
+}
+```
+
 ### The short seller takes the offer - `take_lease`
 
 A short seller who has spotted the `Lease` account onchain (via an
 indexer or a direct lookup) calls `take_lease` to take delivery. The
-program deposits the short seller's collateral first, then hands over
-the leased tokens - depositing collateral first means that if the
-leased-token payout fails for any reason the whole transaction
-reverts and the short seller gets their collateral back. The lease
-moves from `Listed` to `Active`.
-
-- **Signers:** `short_seller`.
+program deposits the short seller's collateral into `collateral_vault`
+first - the vault was created empty by `create_lease` and this is
+the call that fills it - then hands over the leased tokens.
+Depositing collateral first means that if the leased-token payout
+fails for any reason the whole transaction reverts and the short
+seller gets their collateral back. The lease moves from `Listed` to
+`Active`.
+
+- **Signers:** `short_seller` (the user wallet borrowing the tokens
+  and posting collateral).
 - **Accounts:**
   - `short_seller` (signer, mut)
   - `holder` (UncheckedAccount - read for program-derived address seed derivation only, no signature required)
   - `lease` (mut, `has_one = holder`, `has_one = leased_mint`, `has_one = collateral_mint`, must be `Listed`)
   - `leased_mint`, `collateral_mint`
   - `leased_vault`, `collateral_vault` (both mut, both program-derived addresses)
-  - `short_seller_collateral_account` (mut, short seller's associated token account - source)
-  - `short_seller_leased_account` (mut, **init_if_needed** - destination)
+  - `short_seller_collateral_account` (mut, short seller's associated token account for the collateral mint - source)
+  - `short_seller_leased_account` (mut, **init_if_needed** - short seller's associated token account for the leased mint, destination)
   - `token_program`, `associated_token_program`, `system_program`
 - **What happens:**
   - Two token movements, in order:
@@ -395,13 +378,14 @@ the vault. Fees do not accrue past `end_timestamp` - once the
 deadline hits, the short seller is either returning the tokens,
 being liquidated, or defaulting; no further lease fees are owed.
 
-- **Signers:** `payer` (anyone).
+- **Signers:** `payer` (any user wallet - the short seller, a
+  keeper bot, or anyone else willing to pay the transaction fee).
 - **Accounts:**
   - `payer` (signer, mut - pays for `init_if_needed` of the holder associated token account)
   - `holder` (UncheckedAccount, read-only - used for `has_one` check)
   - `lease` (mut, must be `Active`)
   - `collateral_mint`, `collateral_vault`
-  - `holder_collateral_account` (mut, **init_if_needed**)
+  - `holder_collateral_account` (mut, **init_if_needed** - holder's [associated token account](https://solana.com/docs/terminology) for the collateral mint, destination for the lease fee)
   - `token_program`, `associated_token_program`, `system_program`
 - **What happens:**
   - Compute `lease_fee_due = (min(now, end_timestamp) - last_paid_timestamp) * lease_fee_per_second`.
@@ -501,6 +485,15 @@ time at `end_timestamp`.
   - `Unauthorised` if `lease.short_seller != short_seller.key()`
   - `MathOverflow` if the lease-fee or collateral subtraction overflows
 
+`return_lease` is the first place an account-close happens; the same
+mechanism runs in `liquidate` and `close_expired`. The `Closed` and
+`Liquidated` states are not directly observable onchain: all three
+of `return_lease`, `liquidate` and `close_expired` close the `Lease`
+account in the same transaction (`close = holder`), returning the
+rent-exempt lamports to the holder. The in-memory `status` field is
+set *before* the close so the transaction logs record the terminal
+state, but the account disappears at the end.
+
 ### Branch: position underwater - `liquidate`
 
 If the leased asset rallies far enough that the locked collateral is
@@ -523,16 +516,18 @@ where `debt_value = leased_amount * price * 10^exponent`, with the
 Pyth exponent folded into whichever side of the inequality keeps the
 math non-negative (see [`is_underwater`](programs/asset-leasing/src/instructions/liquidate.rs)).
 
-- **Signers:** `keeper`.
+- **Signers:** `keeper` (any user wallet - typically a bot watching
+  for underwater positions; receives the bounty as payment for
+  cleaning up).
 - **Accounts:**
   - `keeper` (signer, mut - pays `init_if_needed` cost for both associated token accounts)
   - `holder` (UncheckedAccount, mut - receives lease fee, holder share, and the rent-exempt lamports from the three closed accounts)
   - `lease` (mut, `close = holder`, must be `Active`)
   - `leased_mint`, `collateral_mint`
   - `leased_vault`, `collateral_vault` (both mut)
   - `holder_collateral_account` (mut, **init_if_needed**)
-  - `keeper_collateral_account` (mut, **init_if_needed**)
-  - `price_update` (UncheckedAccount, constrained to `owner = PYTH_RECEIVER_PROGRAM_ID`)
+  - `keeper_collateral_account` (mut, **init_if_needed** - keeper's [associated token account](https://solana.com/docs/terminology) for the collateral mint, destination for the bounty)
+  - `price_update` (UncheckedAccount, constrained to `owner = PYTH_RECEIVER_PROGRAM_ID`) - a `PriceUpdateV2` account owned by the Pyth Receiver program for the feed the lease was pinned to at creation. This is the first handler that requires the oracle account itself; `create_lease` only stores the `feed_id` it expects to see here.
   - `token_program`, `associated_token_program`, `system_program`
 - **What happens:**
   - Decode `price_update`: discriminator must match