[feature] Console: search workspace prompt history with Ctrl+R #325

Problem and result

Up/Down history works, but finding an earlier instruction in a long workspace session requires stepping through entries. Aether already persists bounded workspace prompt history, so search can improve the existing feature without adding a database or model call.

Add an incremental Ctrl+R search over the history already loaded for this workspace.

Acceptance checks

• Search newest-first; typing updates the query, and repeated Ctrl+R moves to older matches. Display the query, selected result, and a clear no-match state.
• Accepting a match inserts it into the editable composer; it does not send it. Escape restores the exact pre-search draft and cursor. Empty-query behavior is documented and deterministic.
• Respect AETHER_NO_HISTORY, the existing entry cap, and workspace scoping. Add no capture or persistence of shell commands, tool output, approval feedback, or other workspaces. Existing prompt history contains submitted prompt text; this feature does not claim automatic secret filtering.
• Bound per-entry examination, total search work, and rendered match size; visibly identify skipped or clipped entries. Accepting a displayed match restores its complete stored prompt, rather than the clipped display text. Include oversized-entry fixtures.
• The composer must own input. Ctrl+R in PTY, password, approval, shell review, or an unsupported busy state retains that owner’s behavior. Non-TTY input stays unchanged.
• Fixtures cover duplicate entries, multiline/Unicode prompts, no matches, disabled history, cancellation, composer undo boundaries, and transitions to/from the slash picker. Search makes zero model or process calls.

Landing boundary

Build on history_store and the shared input ownership contract; do not add global terminal key interception. Integrate PR #309, then establish composer owner/Enter/Escape precedence before history and picker overlays land. Test opening, switching, accepting, and dismissing both. No cross-session full-text index or capture of historical tool output.

Evidence and planning

Package: Input and discovery. Priority: P2. Rough engineering estimate: 1–2 days, including focused fixtures; this is a planning estimate, not a measured benchmark.

Reviewed against v4.20.0 at 4f1717bc120917e1b04d0baa939855417ef866a4: src/core/history_store.ts, src/ui/input_line.ts, src/ui/keys.ts, src/commands/chat.ts.

Comparator: Claude Code interactive mode and Hermes CLI document reverse history search. This improves Aether’s existing workspace history rather than introducing a memory system.

Created from the LOOP-19 review of the README, all 23 open issues, four open PRs, and recent shipped work on 2026-10-09. These are proposed changes; the acceptance checks below have not been executed.