What

Fixes the "climbing cursor" in the Snacks terminal: hiding and re-showing the Claude panel left the terminal cursor one row above Claude's ❯ prompt, so typed text landed on the wrong line and the box visually corrupted.

Closes #240 (vertical split)
Closes #183 (floating window — same root cause)

Root cause

Instrumented end-to-end (real Claude CLI driven via agent-tty). The trigger is not a pty resize — there is zero SIGWINCH on toggle. Instead:

1. Snacks hides by closing the window (nvim_win_close) and shows by recreating it (open_win).
2. On show, Neovim sends a focus-in (ESC[I) to the child (Claude enables DECSET ?1004).
3. Claude Code (Ink) re-renders relative to the cursor on focus-in; the recreate shifted its cursor anchor by one row, so the UI climbs.

Controls confirm the layering: focus change alone (no hide/show) does not drift, and an absolute-positioning TUI does not drift under the same churn — only Claude does, consistent with the community report that downgrading Claude to 2.0.76 makes it disappear. The native provider does not exhibit it.

The fix

Manage hide/show without destroying the window, preserving the cursor anchor:

• Float: park via nvim_win_set_config({ hide = true/false }) (window kept alive; requires Neovim ≥ 0.10).
• Split: can't be config-hidden, so close on hide and recreate with vsplit + nvim_win_set_buf on show — the native-provider path, which doesn't drift. Sets full height, re-applies Snacks' window-local options, and reuses the buffer so the <S-CR> newline map survives. Works on all supported Neovim versions.
• The Snacks instance hide/show/toggle are monkeypatched so user-wired Snacks keymaps (e.g. self:hide()) also benefit.
• is_terminal_visible() now treats a config-hidden window as not visible, so ensure_visible / diff / @-mention-send re-show a parked float.

Verification

• Harness gate (fixtures/cursor-toggle-repro/agent-repro.sh, real Claude 2.1.x): cursor-vs-prompt delta after each toggle — snacks split 0→0 (was 0→1), snacks float 0→0 + panel truly hides, native unchanged.
• mise run all: 494 tests / 0 failures, luacheck + treefmt clean.
• New unit tests (tests/unit/terminal/snacks_toggle_spec.lua): float/split hide-show, config-hidden visibility, E444-safe close, externally-closed-float-reopens-as-float, open-reuse.

Review

Ran a multi-dimension adversarial review (correctness / Snacks API / regression / portability / style) over the diff; applied the confirmed findings: float-reopens-as-float, E444-safe split close, full-height parity, fixbuf-autocmd ordering, re-applying window-local options, buffer-identity check, per-branch debug logging, plus this CHANGELOG entry. Re-gated green afterwards.

Notes / scope

• Pre-0.10 floats keep prior behavior (config-hide unavailable there); splits are fixed everywhere.
• fixtures/cursor-toggle-repro/ is included as reproduction evidence (auth-free instrument + real-Claude harness), mirroring the existing paste-repro / snacks-explorer fixtures.
• Out of scope: the same latent E444 in the native provider, and unrelated cousins like [BUG] Changing mode sets scroll position below chat window #190 (mode-change scroll) and [BUG] CTRL+Z will brick your claude code instance #194/[BUG] Failed to bring claude code back after sending ctrl+z in cluade buffer window accidentally. #105 (Ctrl-Z process suspend).

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