fix(daemon): isolate empty application state storage

[hyperb1iss]

What this changes

Empty application-state constructors now use unique temporary storage in every build mode. Explicit directory builders and live daemon composition retain their selected storage.

Why

Dependent crates compile the daemon library without cfg(test). The previous constructor consequently sent downstream tests to the developer's real data and state directories. The temporary directory now belongs to the state and is removed after its stores are dropped.

Verification

• Added or updated tests
• Added or updated docs (README, AGENTS.md, relevant spec, or guide)
• just verify passes locally (Rust fmt + lint + test)
• just deny passes (required for dependency or license changes)
• just ui-test and just ui-build pass (required for crates/hypercolor-ui/)
• just sdk-lint, just sdk-check, and just sdk-build pass (required for sdk/)
• just python-verify passes (required for python/)
• just compat-check passes (required for data/drivers/vendors/*.toml)
• just docs-build passes (required for docs or README changes)
• cd docs && zola check passes (required for docs link/content changes)
• Packaging scripts were syntax-checked (required for scripts/ or packaging/)
• just e2e-build passes with the normal Servo stack (required for daemon/UI/effect integration changes)
• just e2e-build-cpu passes when validating the CPU smoke fallback
• just e2e passes against the Servo stack (required for end-to-end behavior changes; starts daemon/browser)
• Tested on real hardware, simulator, or e2e harness (describe below)

The external integration regression, strict Clippy for that target, and rustfmt pass. The regression substitutes disposable ambient directories before constructing any state, so even a future failure cannot touch developer data. It checks independent fixtures, cleanup, and explicit-directory persistence. An independent source review passed.

The full daemon suite passes all 1,847 tests with the CI feature set (builtin-drivers,persistence-test-hooks). Persistence fixtures now pass their directories explicitly so seeded files and API stores share the intended path. The fixture changes also passed independent review.

Notes for reviewers

The host transport and CSP foundation (#299) is merged. This PR targets main and contains the constructor change, its regression test, and persistence fixture updates.

Summary by CodeRabbit

• Bug Fixes

  • Improved temporary application-state handling to keep separate instances isolated from one another.
  • Temporary state directories are now cleaned up automatically when their associated state is released.
  • Explicitly configured data directories continue to be honored and remain available after temporary state cleanup.

• Tests

  • Added coverage for state isolation, directory placement, cleanup behavior, and attachment persistence.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 228a4962-431f-43c9-ab25-c8a44eddc7b0

📥 Commits

Reviewing files that changed from the base of the PR and between a0c4779 and ac99755.

📒 Files selected for processing (4)

• crates/hypercolor-daemon/src/app_state.rs
• crates/hypercolor-daemon/tests/app_state_isolation_tests.rs
• crates/hypercolor-daemon/tests/attachment_api_tests.rs
• crates/hypercolor-daemon/tests/effect_registry_invalidation_tests.rs

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

AppState now creates isolated temporary storage for default construction and retains it through state-owned stores. New and updated tests verify directory isolation, cleanup, explicit directory behavior, and test-specific persistence paths.

Changes

AppState isolation

Layer / File(s)	Summary
Temporary storage lifecycle crates/hypercolor-daemon/src/app_state.rs	Default AppState construction creates a TempDir. The builder transfers ownership to AppState, while daemon-backed state stores no temporary directory.
Isolation validation and test setup crates/hypercolor-daemon/tests/app_state_isolation_tests.rs, crates/hypercolor-daemon/tests/attachment_api_tests.rs, crates/hypercolor-daemon/tests/effect_registry_invalidation_tests.rs	Tests verify unique temporary directories, cleanup, explicit directory behavior, and persistence within test-specific data directories. Shared ambient storage overrides are removed from effect-registry test setup.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 12 functions across 4 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: isolating empty daemon application-state storage. It is concise and specific.

✨ Finishing Touches

📝 Generate docstrings

• Commit to this branch
• Create a new PR

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