Restore hidden Background Review summary rendering

[shiny-code-bot]

Finish Line

When a Background Review response has no current matching run but has a stale or detached latest run, the TUI renders the hidden-summary explanation instead of presenting old findings as current, and the code contains no expect_used violations.

Current Status

Implementation is committed at 59d179a94a on code/issue-687-background-review-hidden-summary; PR #691 is open, labeled code-reviewed, and being monitored through merge.

• Matching terminal current summaries and hidden latest-only summaries now use explicit separate render paths.
• Latest-only Current/Stale/Detached results explain why prior output is hidden instead of presenting it as current findings.
• Status counts retain manual/background source identity.
• Both prior expect_used paths are replaced with explicit non-panicking control flow.
• Focused snapshot coverage is green and no snapshots are pending.
• Full codex-tui run: 3,550 passed; two existing long-running tests timed out after both attempts.
• Bazel TUI Clippy reports only the 24 unrelated diagnostics assigned to Reconnect named-session lookup to resume flows #688, Remove unreachable TUI helpers and duplicate state #689, and Restore login account management TUI wiring #690.
• Final Opus review reported no actionable findings. Gemini completed without output. JetBrains was inconclusive due an execution-proof tool bug, with no findings and no worktree mutation.

Next action: monitor PR #691 through merge, then continue #688 from merged main.

Acceptance Criteria

• Bind current, latest, and fallback values through explicit non-panicking control flow.
• Route stale/detached latest-only results to new_hidden_auto_review_run_summary_cell.
• Preserve current-run and fallback behavior.
• Add snapshot coverage proving hidden latest results say there are no current findings and explain why the prior run is hidden.
• just test -p codex-tui passes for the focused tests and intended snapshots are reviewed.
• Exact Bazel Clippy advances past these three diagnostics.

Relationships

• First implementation stage of Restore TUI reachability for exact Bazel Clippy #685.
• Corrects a gap following the in-flight status work completed in Show in-flight Background Review state in the TUI #530.

Open Questions

• None.