test: add deterministic browser characterization suite

[provos]

Summary

• add an explicit offline E2E server that replaces expensive inference boundaries with deterministic depth, segmentation, checkerboard inpainting, and upscaling fakes
• add five high-fidelity Playwright workflows for upload/slicing, segmentation, painted-mask inpainting and undo, state restoration, glTF export, and animation artifacts
• isolate state per test, block external model traffic, record browser diagnostics, and run Chromium in CI on Node 24
• track the npm lockfile and include the E2E support package in built distributions

Verification

• python -m pytest: 110 passed
• npm run test:e2e: 5 passed
• focused Flake8 fatal checks: clean
• wheel build and packaged python -m parallax_maker.e2e_server --help: passed
• independent review: no remaining P1/P2 findings

Characterized existing behavior

Animation export currently writes numbered PNG frames server-side and does not start a browser download. The test records that contract without changing production behavior.

[Copilot]

Pull request overview

Adds a deterministic, fully offline end-to-end (E2E) browser characterization harness for Parallax Maker by introducing a test-only server that installs model-boundary fakes and a Playwright suite that exercises real Dash UI workflows (upload/slicing, segmentation, inpainting/undo, restore, glTF export, and animation artifacts). This strengthens regression detection around UI + persistence + exporters without paying inference/network cost.

Changes:

• Introduces parallax_maker.e2e_server and parallax_maker.e2e_support fakes/fixtures to run deterministic offline workflows and block external traffic.
• Adds Playwright test suite + config + helpers under e2e/, plus npm scripts and lockfile tracking.
• Extends CI workflow to run Chromium Playwright tests and upload diagnostics artifacts on failure; updates Python packaging include pattern to ship E2E support.

Reviewed changes

Copilot reviewed 13 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pyproject.toml	Expands setuptools package discovery to include subpackages (e.g., E2E support).
parallax_maker/test_e2e_support.py	Unit tests covering deterministic fakes + fixture state + mask metadata.
parallax_maker/e2e_support/fixtures.py	Deterministic image/state fixture creation for browser workflows.
parallax_maker/e2e_support/fakes.py	Fake depth/segmentation/inpainting/upscaling plus offline/network blocking + Dash monkeypatch install.
parallax_maker/e2e_support/__init__.py	Exposes E2E support helpers for the test server.
parallax_maker/e2e_server.py	Test-only Dash/Flask server wiring fakes, isolated state, and artifact/state inspection endpoints.
package.json	Adds Playwright E2E scripts and dev dependency.
package-lock.json	Locks Playwright dependency tree for reproducible CI/local runs.
e2e/README.md	Documents how to run and what the characterization suite asserts/contracts.
e2e/playwright.config.ts	Single-worker Playwright configuration with optional embedded server command and diagnostics output.
e2e/parallax-maker.spec.ts	High-fidelity UI characterization scenarios covering main workflows and artifact assertions.
e2e/helpers/app.ts	Centralized selectors and UI interaction helpers for Dash UI automation and assertions.
e2e/fixtures.ts	Playwright fixture that captures and soft-fails on browser console/page/network issues, attaching diagnostics.
.gitignore	Ignores Playwright outputs (test results / report) and stops ignoring package-lock.json.
.github/workflows/python-app.yml	Runs Playwright Chromium E2E in CI (Node 24), installs browsers, uploads diagnostics on failure.

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[Copilot]

Pull request overview

Copilot reviewed 13 out of 15 changed files in this pull request and generated no new comments.

Suppressed comments (2)

parallax_maker/e2e_support/fakes.py:282

• The monkeypatched serve_main_image_with_unique_url wrapper hard-codes the current serve_main_image(self, image) signature. If AppState.serve_main_image gains parameters, this patch will break at runtime. Use *args/**kwargs when forwarding to the original method to keep the monkeypatch resilient.

    def serve_main_image_with_unique_url(state, image):
        url = original_serve_main_image(state, image)
        path = url.split("?", maxsplit=1)[0]
        return f"{path}?e2e-v={next(image_versions)}"

parallax_maker/e2e_support/fakes.py:164

• _load_inpainting_base() is called immediately in the FakeInpaintingModel base class list, so it doesn’t actually defer importing parallax_maker.inpainting (and it adds indirection that makes static analysis/type checking harder). Prefer a direct import + explicit base class, or (if the goal is truly lazy import) switch to composition instead of dynamic inheritance.

def _load_inpainting_base():
    from parallax_maker.inpainting import InpaintingModel

    return InpaintingModel


class FakeInpaintingModel(_load_inpainting_base()):
    """Use the real inpainting composition around a checkerboard generator."""