implement-from-stub

name	implement-from-stub
description	Write the minimum production code to turn the target's tests green, implementing the .py from its fixed .pyi.

Implement From Stub

1. Load [[software-craft/source-stubs]], [[software-craft/tdd]], [[software-craft/design-patterns]] — stub sync, the cycle, and implementation patterns.
2. Implement — or, for rework, re-implement — the .py from its .pyi. The .pyi signature is the spec; fill or correct the body to satisfy it and pass the tests. Keep the .py consistent with its sibling .pyi.
3. Emit the structural artifacts the module requires, keyed on what it is: IF an ORM model THEN emit an Alembic migration (the migration is the schema spec); IF an external adapter THEN reproduce the recorded request shape exactly (method, path, query parameters, headers from external-contracts.md) — vcr matches the request strictly, so the implementation conforms to the cassette, not the other way around. Config follows 12-factor per [[software-craft/secrets-and-config]]: non-secret config via load_dotenv() from the workspace .env; secrets via dotenv_values() from ~/.secrets/<project>.env — read once into a frozen typed Settings, never into os.environ. IF an auth-dependent test fails on credentials THEN stop and ask the user with suggestions — do not investigate the secret.
4. IF the body cannot satisfy the .pyi without changing it THEN that is a contract gap — do not edit the stub; escalate at review.
5. Run stubtest scoped to the modules built this cycle — the source module(s) and the test module(s) whose pending marks were removed. The whole-suite stubtest waits until every source .py exists, because unbuilt sibling stubs would false-fail per [[software-craft/source-stubs]], [[software-craft/tdd]].
6. Stubtest imports the runtime module, so every transitive runtime dependency must be installed in the project venv. IF an import is used only for types THEN prefer if typing.TYPE_CHECKING: so stubtest does not pull heavy runtime deps for type-only references.