tui: composer editing depth — up-arrow prompt history, kill-ring, undo

[KvFxKaido]

What

Three editor capabilities the composer lost (or never regained) in the silvery migration:

1. Prompt history recall — Up/Down arrow at the composer cycles through previously submitted prompts. This existed pre-migration (createInputHistory in cli/tui-input.ts) but is now test-only: nothing wires it into the silvery TextArea. For a "repo you run by chatting" product, recalling and editing your last prompt is table stakes.
2. Kill-ring — Ctrl+K/Ctrl+U/Ctrl+W kills accumulate into a ring, Ctrl+Y yanks, Alt+Y cycles. Silvery's TextArea owns the readline chords today (per the comment in resolveComposerShortcut, cli/silvery/surface.tsx), but kill-without-yank is half a feature.
3. Undo/redo — coalesced undo in the composer (typing bursts group into one undo step; kills/pastes are their own steps).

Design reference

pi-tui (earendil-works/pi, packages/tui) ships all three as small framework-independent modules: kill-ring.ts, undo-stack.ts, word-navigation.ts. Worth cribbing the semantics (kill accumulation rules — consecutive kills append, any other edit breaks the chain; undo coalescing boundaries) regardless of which layer implements them.

Layering question (decide first)

Each item lands either in silvery (upstream PR/request — it owns TextArea key handling) or in our layer (a controlled-component wrapper that intercepts keys before TextArea). History recall is probably ours regardless (the history store is session state — persisted prompts live in the session store, and seeding across restarts should Just Work via the same path cli/tui-history.ts uses for transcript seeding). Kill-ring and undo want to live wherever the text-mutation primitives live, which today is silvery.

Constraint: whatever the split, don't reintroduce a parallel hand-rolled key parser — cli/tui-input.ts's 500-line input engine is orphaned precisely because silvery owns parsing now. Intercept at the useInput/props layer, not raw stdin (exception precedent: bridgeSilveryCompletionKey for Tab, which is already flagged for deletion when focus scopes land — don't grow that pattern).

Acceptance

• Up-arrow with an empty composer recalls the previous prompt; Down returns toward the draft; a non-empty draft is preserved when cycling starts. History persists across CLI restarts for the same repo session.
• Ctrl+K/U/W kills feed a ring; Ctrl+Y yanks the head; consecutive kills accumulate.
• Undo restores coherent steps, not per-keystroke churn.
• Covered in the FakeStdin/FakeStdout harness (cli/tests/silvery-tui-p0.test.mjs pattern) — assert on emitted composer content, not helpers.

Related: #1530 (adoption track), #1562 (IME — both touch composer input routing; sequence so they don't conflict).

[KvFxKaido]

Item 1 (up-arrow prompt history) shipped in #1565 (merged as ee44279). Recall is derived from the persisted transcript source at navigation time — works across restarts/resumes, both inline and daemon-attached. Known scope cut: slash commands are handled locally and never persisted, so they aren't recallable yet. Items 2–3 (kill-ring, coalesced undo) remain open.

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Generated by Claude Code

[KvFxKaido]

Scope correction for item 2 after inspecting silvery 0.21.1: the kill-ring already exists upstream — Ctrl+K/U/W/Alt+D feed a shared 10-entry ring, Ctrl+Y yanks, Alt+Y cycles — so most of item 2 was already working. The one genuine gap is consecutive-kill accumulation (bash appends consecutive kills into a single ring entry so one yank restores them all; silvery pushes each kill as its own entry). That ring is a module-global fed inside TextArea's input handler, so accumulation can only be fixed upstream — filed as the remaining piece of this item.

Item 3 (undo/redo) is implemented on claude/pi-tui-design-review-gyarrl (87b6f4f): snapshot kernel over the controlled composer value with ±1-char run coalescing (20-edit cap), discrete steps for kills/yanks/recall/completion, reset on submit/session switch. Ctrl+Z / Ctrl+_ undo, kitty Ctrl+Shift+Z redo. Integration tests pin the existing kill/yank chords flowing through onChange.

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Generated by Claude Code

[KvFxKaido]

Item 3 (undo/redo) shipped in #1566 (merged as 0ef2525), including the review-round hardening that makes the kernel authoritative for the current value. With item 1 shipped in #1565 and item 2 mostly pre-existing in silvery, the only remaining scope on this issue is consecutive-kill accumulation, which requires an upstream silvery change (TextArea feeds a module-global kill ring internally). Also still open from the pi-tui comparison: slash-command recall (not persisted, noted on item 1).

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Generated by Claude Code