docs(usage): track review follow-ups for #5387

[Sun-GLiang]

Summary

Track the quality findings that Astro-Han approved as follow-up work in the review of #5387 at e4c4abe48. #5387 establishes a complete, revision-consistent Settings Usage screen; the follow-up discussion asks for fixes at the shared validation and paging boundaries.

This Draft PR starts with a scope document on main. It records the problems and acceptance criteria so implementation can be added and reviewed here after #5387 lands. The current commit changes no runtime behavior.

Refs #5387

Verification

• Passed the staged Biome, ASF license-header, protocol-epoch, and git diff --cached --check checks; the commit hook ran successfully.
• Runtime tests, typecheck, and build were not run for this documentation-only commit. Run affected checks as implementation commits are added.

Follow-up scope

• P2: Avoid a full Host screen read on every search keystroke; test rapid edits, Refresh, range/Host changes, and unmount.
• P2: Keep cached pages navigable after a stale/error result while fencing only unloaded pages; cover revision, capacity, and failed-filter cases.
• P3: Unify the search length rule across protocol and Storage, including multibyte boundary tests.
• P3: Align stored timestamps with safe continuation cursors and test a fractional timestamp across two pages.
• P3: Measure session_metadata INSERT/DELETE invalidation churn and narrow it if material without losing correctness coverage.
• P3: Include readUsageScreen in the store drain barrier and test the close race.
• P3: Measure deep-page jump latency, provide progress feedback, and decide whether the paging contract needs further change.
• P3: Carry a typed capacity failure instead of detecting it from an error string.
• P3: Remove the unused displayedRange hook result.
• P3: Validate the usage:activity request kind at its IPC boundary.
• P3: Assert retained totals and rows in the capacity-failure Story.
• P3: Separate the activity bridge operation if it simplifies the overloaded usageStats contract.
• Run the affected tests and repository checks, preserving fix(usage): read revision-consistent screens and activity pages #5387's complete-or-no-install invariant.

If the removed Astryx pagination patch is reintroduced, cover its source-condition build as well as distributed JavaScript and declarations. The later source-condition review applies to that removed patch.

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex drafted the tracking document and this PR description from the linked review findings.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No