[ericklt]

Gloe currently requires separate transformer variants and repeated decorators to express sync, async, multiargument and configured stages. This breaking 0.8 proposal replaces them with one immutable Transformer[P, R] and ordinary typed callables, with a bundled mypy plugin checking the actual composition boundaries.

import gloe

@gloe.transformer
def add(value: int, *, amount: int) -> int:
    return value + amount

def multiply(value: int) -> int:
    return value * 2

def divide(value: int) -> float:
    return value / 2

pipe = gloe.input() >> add(amount=2) >> (multiply, divide) >> sum >> print
pipe.sync(2)  # prints 10.0
# From async code: await pipe(2)

Public behavior

• Infer concrete input types from the first stage; retain input[T]() for generic or ambiguous entries. Accept typed functions, configured callables, partials, bound methods, and callable objects.
• Await pipeline calls consistently, resolving sync and async stages through one execution path. .sync(...) is the blocking entry and rejects a running event loop. Synchronous work stays on the caller's thread.
• Use positional callbacks for gloe.map(fn), gloe.filter(predicate), gloe.parallel(branches), gloe.sequential(branches), and gloe.condition(predicate, then=..., otherwise=...).
• Preserve keyword-only configuration through @gloe.transformer, decorator-based ensure, and explicit tuple spreading through gloe.unpack.
• Keep early values with prefix >> (gloe.input(), work) >> gloe.unpack(finish). Branches retain references; there is no hidden context store or cache. Composing complete pipelines repeats their stages; prefix >> (left, right) shares the prefix explicitly.
• Cancel and await sibling branches on failure or cancellation. Graph projection is side-effect free and optional Graphviz export remains available.

Migration and guardrails

Support Python 3.12–3.14 and pin the tested mypy 2.3.1 release in gloe[types]. Users enable gloe.mypy_plugin explicitly in checker configuration; installation does not modify their files. The composition contract fails closed without the plugin and does not claim equivalent support from other checkers.

Remove the old async/multiargument transformer hierarchy, helper class variants and bridge API. Document the migration, limitations, architecture and agent-oriented guidance. Examples include actual calls and expected results; the runnable cookbook is checked by both runtime tests and mypy. Workflow tests cover reporting, reconciliation, monetary conservation, route preparation, indicators, transactional imports, request handling, and event ingestion with in-memory fixtures. tests/contract-matrix.md accounts for the removed 0.7 test groups, supported forms, rejected forms and adapter boundaries.

Validation

• 84 unittest checks pass on Python 3.12, 3.13 and 3.14, including the typing harness; the optional image test also passes in the isolated Graphviz environment.
• Public typing fixtures cover exact inferred results, generic factories, overloads, partials, callable objects, recursive aliases, async normalization, narrowing and ensurers. Representative programs are both type-checked and executed. There are 94 exact type assertions and 166 rejection cases (including missing plugin setup), with expected messages and error codes. The harness also checks cold/warm caches and invalidation after a dependency changes.
• Strict source mypy, Black, Flake8 and Sphinx warnings-as-errors pass.
• Built wheel and source distribution; verified the installed wheel in a clean Python 3.12 environment and the extracted source distribution. CI runs the supported Python matrix, type contract, graph export, documentation build and packaging checks.

This is a source-breaking change targeting main.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (db8da8c) to head (fa6f3a1).

Additional details and impacted files

@@             Coverage Diff             @@
##              main       #43     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files           37         5     -32     
  Lines         1496       324   -1172     
  Branches         0        37     +37     
===========================================
- Hits          1496       324   -1172     

Flag	Coverage Δ
python-3.12	99.07% <99.07%> (?)
python-3.13	99.07% <99.07%> (?)
python-3.14	99.38% <99.38%> (?)

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