ADR-032: #[pyclass] Python naming convention — clean names; Py prefix is Rust-internal

Status: accepted.

Follows the ADR-026 precedent for converging divergent naming: policy + mechanical enforcement + direct renames for the existing population (no backward-compat alias shims), each rename in its own task.

Context

The PyO3 layer (the degenbot_rs cdylib, Python module degenbot._ffi) has two coexisting conventions for registered #[pyclass] types:

• Clean Python-facing names: ArbitrageEngine, AlloyProvider, Contract, AsyncContract, AnvilFork, CancelHandle, BlockStream, PathIterator, LogFilter, AlloySubscription, Erc20TokenRow, the *Row / *RowInput types, and the typed exceptions.

• Py-prefixed visible names: the grandfather list in the Decision below (27 names at census time).

At adoption time the consumer layer split policy: degenbot/dispatch/__init__.py stripped the prefix via alias re-exports (stable companion names for driver code), while degenbot/bot/__init__.py recommended the prefixed names (from degenbot.bot import Bot, PyBot, PyBotIo). New types had been picking a convention by drift, not by policy. (The post-adoption VD5MD5 rename below removed the prefixed companion names; the dispatch aliases now map clean FFI names.)

Decision

1. New #[pyclass] types MUST use clean Python-facing names: leading capital, no Py prefix. (Py-prefixed Rust type names remain an acceptable Rust-internal convention; only the Python-facing name= registration is constrained here. The *_py pyfunction suffix stays where it marks the FFI seam — the companion packages strip it for driver code.)

2. A Py-prefixed Python-visible name is a Rust-internal seam type and may exist only on the grandfather list. The prefix is never extended.

3. Grandfather list (runtime census 2026-08-17, 27 names): PyAavePriceOracle, PyBalanceVectorView, PyBot, PyBotIo, PyChainlinkPriceFeed, PyCollateralPositionData, PyConcentratedLiquidityView, PyDatabasePositionQuery, PyDatabaseSnapshot, PyDebtPositionData, PyDexIdentity, PyDispatchCandidate, PyDispatchOutcome, PyDispatcher, PyDivergentPool, PyErc20Token, PyLiquidityPool, PyPayloadComposer, PyPool, PyReservePairView, PySimulateContext, PySolveResult, PySubscription, PySubmitCandidate, PyTxParams, PyTxSigner, PyUserPositionSummary.

4. Retirement: task VD5MD5 (epic C7D2CH) renames the grandfather population to clean names per the ADR-026 precedent (direct rename, all import sites updated in-repo, no backward-compat aliases). Each rename removes the name from this list and from the gate test’s grandfather set in the same commit.

5. Enforcement: tests/ffi/test_ffi_registration_surface.py walks the runtime degenbot._ffi module tree and asserts, in both directions, that the set of registered Py-prefixed class names equals the grandfather list. A new Py-prefixed registration — or a dead list entry — fails the test.

Consequences

• The VD5MD5 rename is mechanical and auditable: the list IS the scope.

• Companion packages (degenbot.dispatch, degenbot.bot) keep working without alias churn until the rename lands; after it, prefix-stripping aliases become the vestige to remove.

• The gate is a runtime test over the built extension: it runs in the same tests/ffi suite as the registration↔stub drift gate (task DSWX6Z), so a renamed class that skips its stub update fails both gates.

Post-adoption: VD5MD5 rename complete (2026-08-17)

The grandfather list is empty: all 27 census names were renamed (task VD5MD5, direct rename, no backward-compat aliases, per the ADR-026 precedent). Mapping:

Python name before	Python name after	Note
PyBot	RustBot	the Python session class degenbot.bot.Bot keeps the clean name; the Rust engine handle is origin-descriptive
PyBotIo	RustBotIo	same collision reasoning
PyErc20Token	RustErc20Token	the Python model class degenbot.erc20.Erc20Token keeps the clean name
PySubscription	PoolStateSubscription	distinct from the Python provider.Subscription wrapper; role-specific name (pool-state-change subscription handle)
PyDatabaseSnapshot	RustDatabaseSnapshot	the Python uniswap.{v3,v4}_snapshot.DatabaseSnapshot sources keep the clean name
PyDatabasePositionQuery	RustDatabasePositionQuery	the Python aave.analysis.orchestrator.DatabasePositionQuery shell keeps the clean name
PyLiquidityPool	LiquidityPool	mechanical
PyPool	Pool	mechanical (structural handle mirroring degenbot_pools::Pool)
PyDexIdentity	DexIdentity	mechanical; degenbot.types already exported this alias — now a direct import
PyDispatcher, PyTxSigner, PyDivergentPool, PySubmitCandidate, PyTxParams	Dispatcher, TxSigner, DivergentPool, SubmitCandidate, TxParams	mechanical; companion aliases in degenbot.dispatch became direct imports
PySimulateContext, PyDispatchCandidate, PyDispatchOutcome, PySolveResult, PyPayloadComposer	SimulateContext, DispatchCandidate, DispatchOutcome, SolveResult, PayloadComposer	mechanical
PyChainlinkPriceFeed, PyAavePriceOracle	ChainlinkPriceFeed, AavePriceOracle	mechanical; degenbot.chainlink / degenbot.aave alias imports became direct
PyUserPositionSummary, PyCollateralPositionData, PyDebtPositionData	UserPositionSummary, CollateralPositionData, DebtPositionData	mechanical (db analysis trio)
PyReservePairView, PyConcentratedLiquidityView, PyBalanceVectorView	ReservePairView, ConcentratedLiquidityView, BalanceVectorView	mechanical (state views)

Mechanically: the 15 pyclasses with explicit name = "PyX" attributes took the new value; the 12 struct-default pyclasses gained an explicit name = "X" (Rust struct names keep the Py qualifier — Rust-internal, per D1). All Python import sites, companion alias imports (collapsed to direct imports), .pyi stubs, tests, and examples were updated in the same change; Python-visible repr/error-message strings in Rust were aligned.

Considered alternatives: keeping Py on the colliding names

Polars names its raw PyO3 layer PySeries / PyDataFrame, and that pattern was the original precedent for this repo’s PyBot. It fits Polars because those names are internal: polars.polars is not part of the documented API, no example imports it, and the public surface is the clean Python class (polars.Series). There, Py works as a keep-out marker for internals, and “wrapping mechanism” is a fair label for things nobody is meant to touch directly.

degenbot inverts that premise: degenbot._ffi is a documented, first-class seam — .pyi-stubbed, drift-gated against its registrations (task DSWX6Z), exercised by the README code-block (sybil) gate, and imported directly by companion modules and shipped examples. The seam’s names are public surface, so:

• Py is zero-information there: every name in the module is PyO3-managed, so the prefix disambiguates nothing and merely repeats the module path’s fact.

• the colliding names (PyBot vs. degenbot.bot.Bot, PyErc20Token vs. degenbot.erc20.Erc20Token, …) collide on layer, not mechanism — Python driver class vs. Rust engine handle — so the informative qualifier is the layer origin: RustBot reads as “the Rust engine handle” at exactly the point where the reader crosses the boundary.

• Rust is the sole core implementation by architectural commitment (Rust is the engine; Python is a driver shell), so Rust encodes a design promise rather than an implementation detail.

Rejected: keep PyBot etc. (Polars precedent). The precedent depends on the raw layer staying hidden; degenbot’s seam is a public, gated, documented surface, and the prefix there would be noise.

Rejected: uniform Rust* prefix on every handle. Over-prefixing — clean names remain the default (D1); the prefix is reserved for names where the clean form is already occupied by a Python type. The Mapping table above lists each such case and why.

Post-adoption, round 2 (2026-08-17): the Rust prefix is retired

The five collision names kept their origin prefix under the D3 escape hatch. The fork decision retires the prefix entirely: the disambiguator is the module path, not the prefix.

Python name before	after	collision resolved by
RustBot	Bot (on degenbot._ffi)	module path vs. degenbot.bot.Bot
RustBotIo	BotIo (on degenbot._ffi)	no driver-side homonym
RustErc20Token	Erc20Token (on degenbot._ffi)	module path vs. degenbot.erc20.Erc20Token
RustDatabaseSnapshot	DatabaseSnapshot (on degenbot._ffi.db)	module path vs. the uniswap.{v3,v4}_snapshot shells
RustDatabasePositionQuery	DatabasePositionQuery (on degenbot._ffi.db)	module path vs. aave.analysis.orchestrator

D3’s collision escape (origin prefix on collision) is superseded. First-party code imports the handles directly from _ffi (the ADR-013 amendment); files that also bind a same-named Python class alias the import locally (e.g. _TokenHandle, _EngineSnapshot). The naming gate now asserts both the Py* and the Rust* registered-name sets are empty: no origin prefix of any kind, full stop.