fix: resolve generated-output downloads per user

[mvanhorn]

Description

Update SafeOutputStaticFiles in deeptutor/api/main.py to select a PathService for each request instead of delegating lookup to the startup-bound StaticFiles.directory: read the dt_token cookie from the ASGI request, decode it through the existing auth service, convert the payload through the existing multi-user identity mapping, and resolve that scope with get_path_service_for_scope. Resolve and serve the requested file against that service's public-output root only after is_public_output_path accepts it, so validation and physical lookup use the same account root. Preserve the default service only for auth-disabled/local-admin operation; when authentication is enabled, a missing or invalid credential should return the same non-revealing 404 rather than falling back to another account's files.

SafeOutputStaticFiles is constructed at application startup with the default PathService, so its Starlette directory remains rooted at the admin output tree for every request. Generated files for authenticated non-admin users are written beneath data/users/<uid>/user, causing otherwise valid /api/outputs/... links to return 404 even though the artifact exists. The bundle provides a concrete reproduction and diagnosis, and the current code still contains the startup-bound mount; there are no competing or prior cross-referenced PRs. The fix must preserve the existing public-output whitelist, private-suffix rejection, traversal protection, and account isolation.

Closes #790

Related Issues

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Module(s) Affected

• agents
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• api
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• config
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• core
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• knowledge
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• logging
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• services
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• tools
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• utils
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• web (Frontend)
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• docs (Documentation)
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• scripts
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• tests
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Checklist

• I have read and followed the contribution guidelines.
• My code follows the project's coding standards.
• I have run pre-commit run --all-files and fixed any issues.
  Not claimed: the workspace test run did not pass; see the notes above.
• I have added relevant tests for my changes.
• My changes do not introduce any new security vulnerabilities.

Additional Notes

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[mvanhorn]

Looks like this landed upstream independently. 712d413 added deeptutor/api/routers/outputs.py, which serves outputs through a request-scoped path service and fails closed with a 404 when there is no authenticated user, and tests/api/test_output_files.py covers #790 directly.

I compared the two before saying anything: resolve_public_output_path already handles what my tests exercised, traversal outside the outputs root, private suffixes, and non-files. Its docstring also makes a fair point about the shape I used, which validated against one workspace and then rebuilt the path from another root.

Happy to close this out. Let me know if there is anything here worth keeping instead.