Introduce a singleton AMM configuration account, a PDA derived from the
constant "CONFIG" seed, created once via a new `Initialize` instruction.
The config stores the Token Program ID the AMM issues every chained call
to, replacing the previous behavior of trusting the program owner of a
caller-supplied holding.
The config account's existence is the Program's initialization gate: the
chained-call instructions (new_definition, add_liquidity, remove_liquidity,
swap_exact_input, swap_exact_output) now take the config as their first
account, validate it against `compute_config_pda(self_program_id)`, and
read the Token Program ID from it on demand — rejecting calls until the
Program is initialized. Vaults and user holdings are asserted to match the
configured Token Program. sync_reserves is left ungated, as it cannot act
on a pool that could not have existed before initialization.
- amm_core: AmmConfig type, compute_config_pda/_seed, Initialize variant
- amm: initialize.rs + config threading through chained-call instructions
- guest: initialize instruction; config + self_program_id on gated calls
- tests: config fixtures, init-gate unit tests, end-to-end Initialize VM test
Adds the CreatePriceObservations instruction to the TWAP oracle program.
The instruction initialises a PriceObservations PDA for a given price
source account and time window, writing the initial tick and timestamp
as the first entry.
Key design decisions:
- Per-window accounts: each (price_source, window_duration) pair maps to
a distinct PriceObservations PDA. The window duration is baked into the
PDA seed so a single price source can support multiple TWAP windows
(24h, 7d, 30d) at independent sampling rates without sharing a buffer.
- window_duration not stored on struct: it is implicit in the PDA address.
Any reader that located the account already knows the window duration
used to derive it. Storing it would be redundant.
- Authorization is implicit: the PriceObservations PDA is derived from
the price source account ID, so is_authorized = true on the price source
proves the caller controls it without a redundant authority field.
- Impersonation is prevented by the PDA check: passing a controlled price
source with a victim's observations account ID fails immediately because
the computed PDA (from the attacker's source) does not match.
Closes#126
