LaunchFeeLadderHook is built and its tests pass. On a clean tree, forge build --offline, forge test --offline (37 tests) and forge fmt --check all pass. I haven't committed anything; the work is untracked in the working tree.

• What it does: the pool's LP fee is startFee in the initialization block, falls linearly to floorFee over decayBlocks blocks, then stays at the floor. All three are constructor arguments and immutable, and each pool's start block is recorded in afterInitialize.
• Validation and authentication: afterInitialize reverts unless the pool carries DYNAMIC_FEE_FLAG. Every callback is restricted to the PoolManager given at construction, and sender and hookData are ignored. The hook has no owner, admin or upgrade path, and it does not use delegatecall, callcode or selfdestruct.
• Permissions: only afterInitialize and beforeSwap are enabled, so LP exits are never gated and the hook can't touch swap amounts.
• Tests: they run on a real vendored PoolManager with PoolSwapTest and PoolModifyLiquidityTest.
  • Start, midpoint, one block before the floor, floor and long after are covered, in both swap directions and for exact-output.
  • A second pool starting later runs its own ladder.
  • Failure cases covered: a static-fee pool is rejected, afterInitialize can't be replayed, and every callback refuses non-manager callers, including a second real PoolManager.
• Checking the fee actually charged: each swap is rolled back and replayed on a hookless pool with the expected static fee, and the balance deltas must match.
• Mutation check: I broke the hook on purpose in several ways and the suite caught each one.
• Protected checks: I ran your two protected suites against the hook's creation code. The three hook tests pass, and the token suite skips because no token code was supplied.
• Vendored code: lib/ holds unmodified v4-core (46c6834), solmate (89365b8) and forge-std (v1.16.2), with no submodules. The pins are in the README.

Additions beyond the brief:

• I wrote src/HookFlags.sol and test/mocks/MockERC20.sol because the protected hook test imports them.
• v4-periphery no longer ships BaseHook, so I wrote a minimal one in src/base/BaseHook.sol.

What the README covers:

• Constructor parameters and address mining: the address must carry flag bits 0x1080.
• Operational responsibilities: decayBlocks counts blocks on the deployment chain, not seconds, and initialization and first liquidity should happen together.
• Known gaps: pool initialization is permissionless, so someone else can start your intended pool's clock, and slot0.lpFee reads 0 for a dynamic pool.

This is not an audit.

Completed the review and wrote the required output to .imd-findings.json:

{"findings":[]}

I found no substantiated defects with concrete failing inputs. I also ran forge test; all 37 tests passed.