[DeFi][FIN-05][M2] Reproduce a second AMM pool through public SDK and package interfaces #55

Implementation ownership — protocol-first, no finance-specific compiler feature

Primary implementation layer: developer experience, SDK and external integration; no consensus-language work. This measures whether independent application developers can actually consume existing public package interfaces, not whether a new Pool primitive can be invented.

Implementation shape: use a fresh checkout, normal CellScript package dependency, compiler, generated builder, documented CKB adapter and exact token deployments to instantiate a second pool with different admitted tokens/parameters. Reproduce a real swap/LP transaction and record every manual workaround, diagnostic and byte identity.

Acceptance interpretation: a developer must not need to hand-modify compiled verifier bytes, patch a custom finance-only compiler, or bypass generated ABI encoding. General tooling DX bugs can be fixed at the existing SDK/compiler boundary, but new grammar is outside this issue.

Compiler-change gate (all FIN work): This issue does not authorise finance-specific grammar, IR, opcodes, codegen branches or hidden protocol semantics. First try existing general CellScript constructs. Any genuinely missing general capability needs a minimal failing application, a non-financial use case, its own narrow issue and independent checker/ABI/resource/gate acceptance as required by #43 §2.2. Application correctness and builder convenience are distinct from language support.

Parent: #43 FIN-05/M2. Owner role: developer experience / external integrator; outside developer: not yet assigned; reviewer unassigned.
Status: proposed; independent reproduction must not be claimed until actually performed.

Dependency / start condition

• Starts once FIN-04 has a runnable generated-builder + pool package, without waiting for FIN-04 final release acceptance.
• Consume FIN-02/03's frozen custody and numerical contracts through FIN-04; do not create a bespoke test-only verifier or bypass failing compiler/SDK contracts.
• Work can continue alongside FIN-04 hardening. Unblocks FIN-10 final independent reproduction, but FIN-05 alone is not full programme acceptance.

Scope

1. From documented package/API entry points, have a developer other than the implementation author initialise a second pool using a distinct admitted token pair and parameters, with exact code/deployment/asset identities.
2. Execute real pool creation, at least one swap and a permitted LP operation through generated SDK/CKB-adapter interfaces; test rebuilding from a clean checkout and a clean package lock.
3. Inventory manual steps (contract hashes, witness bytes, decoding, token deployment, fee/capacity, signing), API incompatibilities and errors. Treat any manual replacement of compiled verifier bytes as a failure.
4. Correct material general DX shortcomings at their owning layer, with narrow linked issues where relevant; preserve the existing package and signing models. Record reproducible setup and accepted boundaries.

Acceptance

• Name the external developer, independent checkout and pinned versions; publish reproducible commands, documentation and fully identified testnet/local-node environment.
• A second pool with different assets/parameters is constructed and verified through the existing generated interfaces, with authentic token/pool/LP Scripts and no hand-encoded ABI shortcut.
• Capture reproducible positives and malicious/invalid inputs, all-group execution, signing/preflight, actual transaction bytes, capacities and failure classifications.
• Document manual operations and developer-visible friction; close material correctness/usability defects or link explicit accepted blockers with owners. Re-test after fixes.
• Keep usability evidence distinct from an independent security audit, network deployment or universal Rust equivalence; apply relevant gates.

Boundaries: The repeat integration must not fork the AMM protocol or silently admit new assets with unexamined issuer powers. FIN-10 later proves the combined pool/order/settlement workflow. Ref: #43 §11, M2, M6.

Dependency cross-links (confirmed GitHub issues)

Start condition: #54 FIN-04's first genuinely executable pool plus generated SDK path, not its final closure. Required by: #60 FIN-10 independent final acceptance. This early outside-developer integration does not substitute for FIN-10's composite settlement reproduction.

Umbrella dependency graph and authoritative financial acceptance: #43.