fix: isolate temp scope by user within an account

[Hinotoi-agent]

Summary

This PR hardens OpenViking temp-scope isolation so one authenticated user can no longer read, enumerate, or overwrite another same-account user's temporary files.

• temp URIs are now user-scoped instead of account-global
• temp access checks now require the caller to match the temp owner's user space
• content-write temp trees are created with the active request context
• regression tests cover same-account read/write isolation and temp-root listing visibility

Security issues covered

Issue	Impact	Severity
Same-account temp scope was shared across users	Confidentiality + integrity break for temporary data	High
temp root listings exposed other users' temp artifacts	Cross-user enumeration of in-progress work	Medium-High

Before this PR

• viking://temp/* was treated as accessible to any non-root authenticated user
• temp paths resolved under /local/{account_id}/temp/... without a user ownership segment
• content-write temporary trees inherited that shared temp namespace
• one same-account user could read or overwrite another user's temp files if they knew or discovered the URI

After this PR

• temp URIs are created as viking://temp/<user-space>/<temp-id>
• non-root access to temp is limited to the owning user space
• content-write temp trees are created with the request context so they land in the correct user-scoped temp namespace
• regression tests lock in same-account isolation and temp listing behavior

Why this matters

Temporary files can contain uploaded inputs, parser intermediates, or working copies created during write flows. Sharing the temp namespace across all users in the same account breaks user isolation and lets one user interfere with another user's in-progress work.

Attack flow

same-account authenticated user
    -> accesses viking://temp/*
        -> temp ACL treated all temp URIs as globally accessible
            -> reads, enumerates, or overwrites another user's temporary files

Affected code

Area	Files
Temp URI generation	openviking_cli/utils/uri.py
Temp access control	openviking/storage/viking_fs.py
Content write temp staging	openviking/storage/content_write.py
Regression coverage	tests/server/test_temp_scope_acl.py

Root cause

• Temp paths were scoped only by account, not by user ownership.
• _is_accessible() treated the entire temp scope as universally readable/writable for non-root users.

CVSS assessment

Issue	CVSS v3.1	Vector
Same-account cross-user temp access	7.7 High	AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L

Rationale:

• low-privileged authenticated users could cross a user-isolation boundary
• the flaw affected confidentiality and integrity of temporary processing data
• exploitation did not require user interaction once the attacker had same-account access

Safe reproduction steps

1. Create a temp artifact as user A under viking://temp/....
2. As user B in the same account, try to read or write that temp file.
3. As user B, list viking://temp.
4. Observe whether user B can see or modify user A's temp content.

Expected vulnerable behavior

• same-account user B can read user A's temp file
• same-account user B can overwrite user A's temp file
• same-account user B can discover user A's temp directory through temp listing

Changes in this PR

• add user-space ownership to generated temp URIs
• restrict temp-scope access checks to the owning user space
• pass request context into content-write temp URI creation
• add regression tests for same-account temp isolation and temp-root listing visibility

Files changed

Category	Files	What changed
URI generation	openviking_cli/utils/uri.py	Added user-scoped temp URI generation with compatibility fallback
Access control	openviking/storage/viking_fs.py	Temp scope now checks caller user space before allowing access
Write pipeline	openviking/storage/content_write.py	Temp staging now creates user-scoped temp roots from request context
Tests	tests/server/test_temp_scope_acl.py	Added regression coverage for temp isolation

Maintainer impact

• The patch is narrow and limited to temp URI generation and temp-scope authorization.
• Resource, user, agent, and session scopes keep their existing behavior.
• The regression tests are self-contained and do not require external services.

Fix rationale

Temp data should be isolated at least as strictly as other user-scoped working data. User-scoped temp URIs preserve the existing temp workflow while restoring the expected user boundary inside a shared account.

Type of change

• Bug fix (non-breaking change which fixes a vulnerability)
• Security hardening
• Test coverage for regression prevention
• New feature
• Breaking change
• Documentation-only change

Test plan

• Added regression tests for same-account temp read/write isolation
• Added regression tests for temp root listing visibility
• Verified generated temp URIs include the caller user space

Executed:

python -m pytest -o addopts='' tests/server/test_temp_scope_acl.py -q

Disclosure notes

• Claims in this PR are limited to the reviewed temp-scope code paths and reproduced VikingFS behavior.
• This PR does not change unrelated storage scopes.
• The issue appears to affect same-account cross-user isolation rather than cross-account isolation.

[CLAassistant]

All committers have signed the CLA.

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🏅 Score: 95

🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ No major issues detected

[github-actions]

PR Code Suggestions ✨

No code suggestions found for the PR.