[contracts] IStrategy interface: TargetPosition struct + computePositions + shouldRebalance

[ozpool]

Context

Strategy API. Purity contract (ADR #12) enforced by: no state-reading params. BellStrategy and future strategies implement this.

Ref: PRISM_PRD_v1.0.html §Day 3.

Scope

In scope:

• packages/contracts/src/interfaces/IStrategy.sol
• struct TargetPosition { int24 tickLower; int24 tickUpper; uint256 weight; }
• computePositions(int24 currentTick, int24 tickSpacing, uint256 amount0, uint256 amount1)
• shouldRebalance(int24 currentTick, int24 lastTick, uint256 lastTs)

Out of scope:

• Strategy storage helpers

Acceptance Criteria

• NatSpec declares pure/view where applicable
• weight type documented as basis points summing to exactly 10_000
• Compiles with forge build (Solidity 0.8.25)
• Custom errors only (Errors.sol); no string reverts
• ReentrancyGuardTransient on PoolManager-facing externals where applicable
• NatSpec on every external/public
• Unit tests: happy + reverts + access control
• forge test -vvv passes; forge fmt --check clean
• Slither + Aderyn: no new findings
• Gas snapshot saved; no regression vs CLAUDE.md §Gas Targets

Dependencies

• Blocks: [contracts] BellStrategy.computePositions: bell-curve weight distribution across N ticks (pure) #32, [contracts] BellStrategy.shouldRebalance: tick-drift + time-threshold triggers + 24h fallback #33, [test] BellStrategy unit + fuzz: weight sum == 10_000 exactly, tick-boundary fuzz #39
• Blocked by: [adr] IStrategy purity contract: no vault-state reads, deterministic computePositions #12, [contracts] Monorepo + Foundry workspace: pnpm + Turborepo + foundry.toml (via_ir, cancun) #15, [contracts] Pin v4-core + v4-periphery commits in .gitmodules (document SHAs in README) #16

References

• PRD §Day 3 IStrategy

Estimate

S

[ozpool]

IStrategy shipped in #143. PRD §Day 3 surface verbatim, ADR-005 purity contract documented in NatSpec. Tests cover selector snapshots and a fuzzed weight-sum invariant on the mock; per-strategy fuzz lives with each implementation (BellStrategy in #32).