Static analysis report: ALEX AMM Pool v2 (AIBTC bounty mpwj1ido1a0890ed463c)

alex-amm-pool-v2-static-audit.md

Static Analysis Report: ALEX AMM Pool v2

Target bounty: mpwj1ido1a0890ed463c

Contract: SP102V8P0F7JX67ARQ77WEA3D3CFB5XW39REDT0AM.amm-pool-v2-01

Source reviewed: https://api.hiro.so/v2/contracts/source/SP102V8P0F7JX67ARQ77WEA3D3CFB5XW39REDT0AM/amm-pool-v2-01

Review type: static source review only. I did not execute mainnet swaps.

Responsible disclosure note: I found no high or critical severity issue in this pass. No private disclosure was required before this public report.

1. State Model

Local router/pool state:

Store	Type	Initial	Mutated by	Notes
paused	bool data-var	true	pause	Gates add/reduce/swap flows, but not read-only quote helpers

Registry-backed pool state is read and updated through .amm-registry-v2-01. The reviewed contract treats the registry as canonical for:

• pool existence and pool-id
• balance-x, balance-y
• total-supply
• start-block, end-block
• max-in-ratio, max-out-ratio
• oracle-enabled, oracle-average, oracle-resilient
• threshold-x, threshold-y
• fee-rebate, fee-rate-x, fee-rate-y
• pool-owner

Asset state is held outside this contract:

• SIP-010 token balances are moved through user-supplied token traits.
• Pool reserves are held in .amm-vault-v2-01.
• LP token balances are tracked by .token-amm-pool-v2-01.

Important constants:

Name	Value / role
ONE_8	u100000000, fixed-point scale
MAX_POW_RELATIVE_ERROR	u4, exponentiation rounding guard
ERR-* u1000..u2012	pool/control/swap errors
ERR-* u5009..u5013	fixed-point math bounds errors
MAX_NATURAL_EXPONENT, MIN_NATURAL_EXPONENT, MILD_EXPONENT_BOUND	exponent/log bounds

2. Function Inventory

Read-only functions:

Group	Functions	Notes
Authority/status	is-dao-or-extension, is-blocklisted-or-default, is-paused, check-pool-status	is-dao-or-extension authorizes DAO or extension callers
Pool metadata	get-pool-details*, get-pool-exists, get-balances, get-start-block, get-end-block, ratio/fee/oracle/threshold getters	Registry passthroughs
Quote/oracle	get-oracle-resilient, get-oracle-instant, get-price, get-y-given-x, get-x-given-y, exact-out helpers, price-target helpers	Uses registry balances and fixed-point math
LP math	get-token-given-position, get-position-given-mint, get-position-given-burn	Converts between deposits/burns and LP supply
Multi-hop helpers	get-helper, get-helper-a, get-helper-b, get-helper-c, fee-helper*	Quote-only path helpers
Math	get-invariant plus private fixed-point log/exp/pow helpers	No storage mutation

Public functions:

Function	Authority	Preconditions / asserts	State mutations / external calls
pause	DAO or registered DAO extension	is-dao-or-extension	var-set paused
set-start-block, set-end-block, set-max-in-ratio, set-max-out-ratio, set-oracle-enabled, set-oracle-average, set-threshold-x, set-threshold-y, set-fee-rate-x, set-fee-rate-y	pool owner or DAO/extension	pool exists; caller authorized	as-contract registry updates
create-pool	any non-blocklisted caller	blocklist check	registry pool creation, then initial add-to-position
add-to-position	open	not paused; positive liquidity; dy <= max-dy	transfers both tokens to vault, registry update, LP mint
reduce-position	open	not blocklisted; not paused; percent <= ONE_8	vault transfers both tokens, registry update, LP burn
swap-x-for-y	open	not blocklisted; not paused; pool active; dx > 0; output >= optional min	transfers X to vault, transfers Y out, reserve/registry update
swap-y-for-x	open	not blocklisted; not paused; pool active; dy > 0; output >= optional min	transfers Y to vault, transfers X out, reserve/registry update
swap-helper, swap-helper-a/b/c	open	delegated to swap functions	chained swaps; only final helper call receives the optional min

3. Post-condition Coverage Matrix

Public function	Token movement surface	Suggested postconditions
create-pool	User deposits initial X and Y; LP minted to caller	At-most X spend dx; at-most Y spend dy; at-least/expected LP mint if supported by the LP token contract
add-to-position	User deposits X plus computed Y; LP minted	At-most X spend dx; at-most Y spend supplied max-dy; at-least LP mint based on quote
reduce-position	LP burned; X and Y returned	At-most/exact LP burn; at-least X and Y receives from vault
swap-x-for-y	X in, Y out	At-most X spend dx; at-least Y receive min-dy; bind token principals
swap-y-for-x	Y in, X out	At-most Y spend dy; at-least X receive min-dx; bind token principals
swap-helper-a/b/c	Multiple swaps in sequence	Final output minimum is not enough for user intent in all cases; attach postconditions for total initial input and final output, and prefer explicit single-hop minimums where available
Setter functions	No user token movement	No token postconditions needed; governance monitoring should track registry writes

4. Authority / Access-control Matrix

Surface	Authority model	Notes
Pause switch	DAO or DAO extension	Starts paused; swaps/liquidity require unpaused
Pool scheduling/ratios/oracle/fees/thresholds	Pool owner or DAO/extension	Per-pool owner is powerful and can alter fee, oracle, threshold, and max ratio behavior
Pool creation	Any non-blocklisted caller	Registry determines uniqueness/validity
Add liquidity	Any caller while unpaused	See finding ALEX-M01: blocklist is not checked here
Reduce liquidity	Any non-blocklisted caller while unpaused	Uses caller LP balance
Swaps	Any non-blocklisted caller while unpaused and pool active	Optional min values default to zero
Vault / registry / LP token calls	as-contract	Intended principal escalation to mutate protocol-owned registry/vault/LP state

5. Clarity Best-practice Review

• tx-sender: used for user identity, blocklist checks, pool-owner checks, and transfer sender. This is expected for direct user calls, but integrators should consider proxy/contract-caller behavior.
• contract-caller: used in DAO extension authorization.
• as-contract: used for registry, vault, and LP token operations. This is intentional but should remain tightly scoped.
• unwrap-panic: present in reduce-position for LP balance and in pow-down/pow-up for fixed-point math. The LP balance case is user-facing and could be converted to a normal error.
• Arithmetic: extensive fixed-point math uses guarded helpers, but some public swap paths compute price-ratio divisions before proving the output amount is non-zero.
• Trait conformance: token traits are SIP-010 typed via .trait-sip-010.sip-010-trait.

6. Findings Table

ID	Severity	Function	Line	Finding	Recommended fix
ALEX-M01	Medium	add-to-position	257-278	Add-liquidity does not check is-blocklisted-or-default, while create-pool, reduce-position, and both direct swap functions do. A blocklisted address cannot create, reduce, or swap, but can still add liquidity to an existing pool when the protocol is unpaused.	Add the same blocklist assert used in reduce-position and swaps before accepting liquidity.
ALEX-M02	Medium	set-oracle-average, get-oracle-resilient	227-231, 53-60	set-oracle-average does not enforce new-oracle-average <= ONE_8, even though ERR-ORACLE-AVERAGE-BIGGER-THAN-ONE exists. If a pool owner/DAO sets a larger value, get-oracle-resilient can underflow at (- ONE_8 oracle-average), disabling resilient oracle reads for that pool.	Add asserts! (<= new-oracle-average ONE_8) ERR-ORACLE-AVERAGE-BIGGER-THAN-ONE in the setter.
ALEX-L01	Low	swap-y-for-x	341, 352	If a very small positive dy-net-fees rounds to dx = 0, the price-ratio guard computes (div-down dy-net-fees dx). With dy-net-fees > 0 and dx = 0, this can panic/abort before returning a domain-specific liquidity error.	Assert dx > u0 before the division and return ERR-INVALID-LIQUIDITY or ERR-EXCEEDS-MAX-SLIPPAGE.
ALEX-L02	Low	swap-x-for-y	312, 323-326	The X->Y path can accept a positive dx with dy = 0 when the caller omits min-dy or passes zero. The function will transfer X, skip the zero Y transfer, update reserves, and return {dy: u0}. This is caller-protectable with min-dy, but the default behavior is sharp.	Consider asserting dy > u0, or document that callers must always pass a non-zero minimum output.
ALEX-L03	Low	swap-helper-a/b/c	364-375	Multi-hop public helpers pass none as the intermediate minimum and only apply the optional min to the final hop. A final min can still protect final output, but callers have no per-hop slippage controls through these helpers.	Add helper variants that accept per-hop minimums, or document these helpers as convenience functions requiring strong transaction postconditions.
ALEX-I01	Informational	reduce-position, pow-down, pow-up	286, 496, 502	unwrap-panic is used in user-reachable paths. The LP balance unwrap in reduce-position is the most visible case; if the LP token read unexpectedly errors, callers receive a panic rather than a protocol error.	Replace user-facing unwrap-panic with unwrap! and a dedicated error code.

Overall assessment: the contract has clear registry/vault separation and many explicit ratio/slippage checks, but the admin parameter setters should consistently enforce fixed-point bounds, and swap paths should guard zero-output/zero-denominator edge cases before price-ratio divisions.