fix(generate): read WORKSPACE_DIR dynamically so relocated output isn't lost

[kevin9327]

What

After the workspace is relocated at runtime (POST /settings/paths), 3D generations kept writing their output into the previous workspace directory, while /workspace/{path} served files from the new one — so the finished mesh 404s and never appears in the app.

Why it triggers

api/routers/generation.py bound the workspace path with from services.generator_registry import WORKSPACE_DIR, capturing the Path at import time. POST /settings/paths → generator_registry.update_paths() rebinds the WORKSPACE_DIR module global (and repoints every loaded generator's outputs_dir):

# services/generator_registry.py
_self_module.WORKSPACE_DIR = workspace_dir
for gen in self._generators.values():
    gen.outputs_dir = workspace_dir

Because _run_generation used the stale imported name, it recomputed coll_dir = WORKSPACE_DIR / collection against the old directory and set gen.outputs_dir back to it — overriding the value update_paths had just written — then built output_url relative to the same stale path. /workspace/... reads the current WORKSPACE_DIR dynamically, so it can't find the file.

This affects both /generate/from-image and /workflow-runs/from-image (both funnel through _run_generation).

Fix

Reference the module attribute registry.WORKSPACE_DIR at call time instead of a name captured at import — the same way optimize.ply_to_splat (comment: "workspace dir may change at runtime") and the settings router already read it.

Verification

• Added api/tests/test_generation_router.py: drives _run_generation with a fake generator after relocating the workspace, and asserts the output is filed under the current workspace (and that output_url matches). Fails before, passes after.
• python -m unittest discover -s tests in api/ (venv with fastapi + python-multipart + httpx): all pass, 0 failures.

[lightningpixel]

Code review

Found 1 issue:

1. Merging as-is will break /generate/from-image with a NameError on every request. The PR's branch was cut before sanitize_collection() was added to dev; that function still references the bare name WORKSPACE_DIR, which this PR removes from the module's import (from services.generator_registry import generator_registry, WORKSPACE_DIR → import services.generator_registry as registry / from services.generator_registry import generator_registry). sanitize_collection is called unconditionally at the top of generate_from_image, so the endpoint would raise NameError: name 'WORKSPACE_DIR' is not defined on line 73 for every call. The PR's own new test only exercises _run_generation directly and doesn't go through sanitize_collection, so it doesn't catch this.

modly/api/routers/generation.py

Lines 72 to 74 in d4d5fc3

	try:
	(WORKSPACE_DIR / collection).resolve().relative_to(WORKSPACE_DIR.resolve())
	except (OSError, ValueError):

(current dev, showing the bare WORKSPACE_DIR usage inside sanitize_collection that this PR's import change would orphan)

modly/api/routers/generation.py

Lines 96 to 98 in d4d5fc3

	collection = sanitize_collection(collection)

(current dev, showing sanitize_collection is called unconditionally on every request)

Fix: rebase onto current dev and update sanitize_collection's two WORKSPACE_DIR references (and its docstring) to registry.WORKSPACE_DIR, consistent with this PR's own stated rule in the import comment.

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[kevin9327]

Rebased onto current dev and addressed the review: sanitize_collection() now reads registry.WORKSPACE_DIR as well (its containment check runs at the top of generate_from_image), so no bare WORKSPACE_DIR remains in the module. Added GenerateFromImageWorkspaceTests, which drives generate_from_image itself after relocating the workspace -- on the rebased branch without the fix it fails with NameError: name 'WORKSPACE_DIR' is not defined, and passes with it.

Verification (venv with fastapi/python-multipart/httpx, run from api/): python -c "import routers.generation, routers.workflow_runs" OK; python -m unittest discover -s tests -> Ran 69 tests, OK (skipped=2).