refactor: enforce DDD layering with import-linter

[TeKrop]

Summary

Enforces the hexagonal layering (main → graphql | adapters → logging_config → settings → domain) with import-linter, mirroring TeKrop/overfast-api#459. The current code already satisfies every contract: no app code changes.

• import-linter contracts in [tool.importlinter] (pyproject.toml):
  • layers (exhaustive): graphql and adapters are independent siblings, so only main imports the concrete adapter; domain sits at the bottom and imports nothing else from app.
  • domain-pure: app.domain can't import strawberry, starlette, httpx2, cachetools or pydantic_settings.
  • acyclic: no import cycles between sibling modules.
• Not ported from overfast-api: composition-root (covered by layers), adapters-independent (single adapter), services-independent (no services), domain-layers (3-file domain).
• import-linter==2.15.* dev dependency; lint-imports runs in just lint and CI.
• Docs (CLAUDE.md, README.md) updated to match.

Test plan

• uv run lint-imports: 3 kept, 0 broken
• Each contract fails when broken on purpose (graphql → adapters, domain → httpx2, domain → settings, unlisted top-level module)
• ruff check, ty check
• just test: 54 passed

🤖 Generated with Claude Code

Summary by Sourcery

Enforce the application’s hexagonal dependency boundaries with import-linter and include the checks in local linting and CI.

Enhancements:

• Enforce the application’s inward-only hexagonal architecture with exhaustive layering, domain purity, and acyclic dependency contracts.

Build:

• Add import-linter as a development dependency and configure the architecture contracts in pyproject.toml.

CI:

• Run import-linter as part of the CI checks.

Documentation:

• Document the enforced application layers and import-linter checks in the contributor and user documentation.

[sourcery-ai]

Reviewer's Guide

This PR introduces import-linter contracts that enforce the app’s hexagonal layering, framework-independent domain, and acyclic dependencies, then wires the checks into local linting and CI; application behavior is unchanged.

Flow diagram for import-linter enforcement in development and CI

flowchart LR
    code[App imports]
    lint[lint-imports]
    contracts[Import-linter contracts]
    result[Pass or fail]

    code --> lint
    lint --> contracts
    contracts --> result

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File-Level Changes

Change	Details	Files
Adds import-linter architecture contracts to enforce inward-only hexagonal dependencies and domain purity.	Defines exhaustive layer ordering with independent GraphQL and adapter siblings. Forbids framework and I/O dependencies from the domain package. Adds an acyclic-siblings contract for the app package.	pyproject.toml
Integrates import-linter into local and CI validation.	Adds the pinned development dependency and lockfile entries. Runs import-linter from the lint recipe and CI workflow.	justfile .github/workflows/build.yml uv.lock
Updates project documentation to describe the enforced architecture and lint command.	Documents the dependency flow and contract implications for new app modules. Updates lint command descriptions to include import-linter.	CLAUDE.md README.md

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[sourcery-ai]

Hey - I've found 1 issue

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="justfile" line_range="34-35" />
<code_context>
 lint:
     @echo "Running linter..."
     uv run ruff check --fix --exit-non-zero-on-fix
+    uv run lint-imports

 # run formatter
</code_context>
<issue_to_address>
**nitpick (bug_risk):** `just lint` does not run `lint-imports` whenever Ruff applies an autofix, because the preceding `ruff check --fix --exit-non-zero-on-fix` command exits nonzero and stops the recipe before reaching this line.

**Triggers:** When the tree contains any Ruff issue that is automatically fixable.

**Suggested fix:** Run the import-linter command independently of Ruff's fix status, for example by separating the commands with a shell construct that preserves execution while still returning Ruff's failure status.

```suggestion
    uv run ruff check --fix --exit-non-zero-on-fix || (ruff_status=$?; uv run lint-imports; exit $ruff_status)
    uv run lint-imports
```
</issue_to_address>

Sourcery assessment

Approved.

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[sourcery-ai]

nitpick (bug_risk): just lint does not run lint-imports whenever Ruff applies an autofix, because the preceding ruff check --fix --exit-non-zero-on-fix command exits nonzero and stops the recipe before reaching this line.

Triggers: When the tree contains any Ruff issue that is automatically fixable.

Suggested fix: Run the import-linter command independently of Ruff's fix status, for example by separating the commands with a shell construct that preserves execution while still returning Ruff's failure status.

Suggested change

	uv run ruff check --fix --exit-non-zero-on-fix
	uv run lint-imports
	uv run ruff check --fix --exit-non-zero-on-fix || (ruff_status=$?; uv run lint-imports; exit $ruff_status)
	uv run lint-imports