Merge pull request #711: fix(mobile): hold the PTY rows while the on-screen keyboard is up

docs/architecture-invariants.md

@@ -1155,7 +1155,9 @@ Tests: `test/mobile-prompt-composer.test.ts` (in the CI gate, deliberately not u
 
 ### PTY and browser terminal geometry
 
-**The PTY and the browser terminal must never disagree about size** (issue #464, `syncTerminalGeometry()` in terminal-ui.js): Claude Code's TUI wraps its frame at the width the PTY reported and erases the previous frame by walking the cursor up the number of rows it BELIEVES that frame occupied. A browser terminal of a different width makes each logical line take more physical rows than Ink counted, so `eraseLines(n)` clears too few and the new frame paints over rows nothing erased — the doubled lines and half-overwritten prose in #464, **measured** against this repo's xterm (a 120-column PTY against a 62-column terminal renders every wrapped line twice; `test/terminal-pty-geometry.test.ts` pins it, and pins the clean render at matching widths so the assertion cannot pass against code that fixes nothing). ⚠️ **`fitAddon.fit()` is NOT the way to resize this terminal.** It resizes xterm to `proposeDimensions()` RAW while every server-facing path reports those floored at 40x10, so whenever the floor bit the two diverged silently — **measured in Chrome at 430px**: font size 44 proposed 13 columns, the server was told 40, and xterm stayed at 13. `syncTerminalGeometry()` fits, floors and applies as one step and is the ONE function that may change the size; `test/terminal-pty-geometry.test.ts` sweeps the seven modules that touch the main terminal (terminal-ui, mobile-handlers, app, ralph-panel, settings-ui, tab-rail-resize, notification-manager) for a bare fit; the split pane and teammate terminals own their own sizing and are out of scope. ⚠️ **Withhold the fit wherever you withhold the SIGWINCH.** `throttledResize` (virtual keyboard up) and `sendResize` (session detached into its own window) used to reflow locally and skip only the server write, which is the one combination that cannot be right. ⚠️ **A font change is a geometry change**: `setFontSize`/`setFontFamily`/`setFontWeight` move the cell size and told the server nothing, so raising the font on a phone left the CLI wrapping at the old column count (`_refitAfterCellSizeChange`). ⚠️ **Resize is no longer write-only.** `Session.resize` DECLINES a small-viewport request while a desktop connection holds an active sizing claim and says nothing, so both transports now answer with `Session.ptyGeometry` (`{"t":"zc"}` on the socket, the body of the resize POST) and `_onPtyGeometryReport` adopts it — a terminal that keeps a WIDTH the PTY refused renders GARBLED, not merely wrong-sized. ⚠️ While that refusal stands (`_paneWidthRefused`), a resize ASKS for the container's width without applying it (`_geometryForResizeRequest`: rows follow the container, columns stay at the PTY's): fitting first re-wrapped the whole buffer to the container and back on every 30s mobile retry, and ran the scrollback clear for a resize that brings no redraw. `selectSession` clears the flag, since it belongs to the previous pane. ⚠️ **`ptyGeometry` is null without a live pane**, never the field values: they are seeded at spawn (`_notePtySpawnGeometry`, so a reattached pane reports its tmux window's real size) and moved by `resize()`, but a dead-pane session still holds the constructor defaults of 120x40 or a gone pane's size — reporting those made a client adopt a size no process was ever told and claim another device owned the pane when none existed. ⚠️ **COLUMNS ONLY.** Adopting the PTY's ROWS was a regression: a phone taking a desktop's 43 rows into a viewport with room for 18 painted an `.xterm-screen` far taller than its container, xterm's own viewport then had nothing to scroll, and the CLI's input line sat below the container with no gesture able to reach it — output visible, typing invisible, for as long as the claim stayed hot. Width is the axis the wrap arithmetic depends on; rows only decide how much is on screen, and keeping the local count keeps the composer at the bottom of a viewport that scrolls. ⚠️ **`.term-overflows-x` keys on what does not FIT, not on a PTY mismatch**, because the 40-column floor widens the terminal past a narrow container with the PTY agreeing throughout (measured at 360px: font 18 paints 433px, font 24 paints 578px — 38% unreachable, and `increaseFontSize` reaches 24 in two taps). `_syncTerminalOverflowAffordance()` MEASURES `.xterm-screen` against the container on the next frame rather than deriving it from cell arithmetic. ⚠️ That rule sets **both** overflow axes — mobile.css loads later with `.terminal-container { overflow: visible }`, and a bare `overflow-x` would leave overflow-y computing to `auto`, handing the browser a vertical scroll container the terminal's touch handler does not know about — and sets **no `touch-action`**: the terminal's own touchmove handler pans it (`canPanHorizontally`), because `touchstart` preventDefault()s every 'content' tap and that cancels a native `pan-x` before it starts (measured: a 140px swipe reached scrollLeft 141 without that preventDefault and 0 with it).Line truncated
+**The PTY and the browser terminal must never disagree about size** (issue #464, `syncTerminalGeometry()` in terminal-ui.js): Claude Code's TUI wraps its frame at the width the PTY reported and erases the previous frame by walking the cursor up the number of rows it BELIEVES that frame occupied. A browser terminal of a different width makes each logical line take more physical rows than Ink counted, so `eraseLines(n)` clears too few and the new frame paints over rows nothing erased — the doubled lines and half-overwritten prose in #464, **measured** against this repo's xterm (a 120-column PTY against a 62-column terminal renders every wrapped line twice; `test/terminal-pty-geometry.test.ts` pins it, and pins the clean render at matching widths so the assertion cannot pass against code that fixes nothing). ⚠️ **`fitAddon.fit()` is NOT the way to resize this terminal.** It resizes xterm to `proposeDimensions()` RAW while every server-facing path reports those floored at 40x10, so whenever the floor bit the two diverged silently — **measured in Chrome at 430px**: font size 44 proposed 13 columns, the server was told 40, and xterm stayed at 13. `syncTerminalGeometry()` fits, floors and applies as one step and is the ONE function that may change the size; `test/terminal-pty-geometry.test.ts` sweeps the seven modules that touch the main terminal (terminal-ui, mobile-handlers, app, ralph-panel, settings-ui, tab-rail-resize, notification-manager) for a bare fit; the split pane and teammate terminals own their own sizing and are out of scope. ⚠️ **Withhold the fit wherever you withhold the SIGWINCH.** `throttledResize` (virtual keyboard up) and `sendResize` (session detached into its own window) used to reflow locally and skip only the server write, which is the one combination that cannot be right. ⚠️ **A font change is a geometry change**: `setFontSize`/`setFontFamily`/`setFontWeight` move the cell size and told the server nothing, so raising the font on a phone left the CLI wrapping at the old column count (`_refitAfterCellSizeChange`). ⚠️ **Resize is no longer write-only.** `Session.resize` DECLINES a small-viewport request while a desktop connection holds an active sizing claim and says nothing, so both transports now answer with `Session.ptyGeometry` (`{"t":"zc"}` on the socket, the body of the resize POST) and `_onPtyGeometryReport` adopts it — a terminal that keeps a WIDTH the PTY refused renders GARBLED, not merely wrong-sized. ⚠️ While that refusal stands (`_paneWidthRefused`), a resize ASKS for the container's width without applying it (`_geometryForResizeRequest`: rows follow the container, columns stay at the PTY's): fitting first re-wrapped the whole buffer to the container and back on every 30s mobile retry, and ran the scrollback clear for a resize that brings no redraw. `selectSession` clears the flag, since it belongs to the previous pane. ⚠️ **`ptyGeometry` is null without a live pane**, never the field values: they are seeded at spawn (`_notePtySpawnGeometry`, so a reattached pane reports its tmux window's real size) and moved by `resize()`, but a dead-pane session still holds the constructor defaults of 120x40 or a gone pane's size — reporting those made a client adopt a size no process was ever told and claim another device owned the pane when none existed. ⚠️ **COLUMNS ONLY** (one documented exception, the keyboard row hold in the next paragraph). Adopting the PTY's ROWS was a regression: a phone taking a desktop's 43 rows into a viewport with room for 18 painted an `.xterm-screen` far taller than its container, xterm's own viewport then had nothing to scroll, and the CLI's input line sat below the container with no gesture able to reach it — output visible, typing invisible, for as long as the claim stayed hot. Width is the axis the wrap arithmetic depends on; rows only decide how much is on screen, and keeping the local count keeps the composer at the bottom of a viewport that scrolls. ⚠️ **`.term-overflows-x` keys on what does not FIT, not on a PTY mismatch**, because the 40-column floor widens the terminal past a narrow container with the PTY agreeing throughout (measured at 360px: font 18 paints 433px, font 24 paints 578px — 38% unreachable, and `increaseFontSize` reaches 24 in two taps). `_syncTerminalOverflowAffordance()` MEASURES `.xterm-screen` against the container on the next frame rather than deriving it from cell arithmetic. ⚠️ That rule sets **both** overflow axes — mobile.css loads later with `.terminal-container { overflow: visible }`, and a bare `overflow-x` would leave overflow-y computing to `auto`, handing the browser a vertical scroll container the terminal's touch handler does not know about — and sets **no `touch-action`**: the terminal's own touchmove handler pans it (`canPanHorizontally`), because `touchstart` preventDefault()s every 'content' tap and that cancels a native `pan-x` before it starts (measured: a 140px Line truncated
+
+**The one exception to COLUMNS ONLY: rows held under the on-screen keyboard** (#672, `keyboardHoldsRows`, per-device, default ON): every PTY height change makes Claude Code's inline renderer clear the screen and reprint only the transcript tail that fits the new height, so the rows above that tail are gone from tmux and older ones stay in history as stale copies, and the phone keyboard opening and closing was such a change each time. **Measured** on Claude Code 2.1.306 with tmux 3.2a, a fresh session already at the phone's size printing 100 numbered lines: five keyboard cycles (PTY 62x38 to 62x15 and back, one SIGWINCH per transition) left 75 of the 100 in `tmux capture-pane` history; with the rows held the PTY stayed 62x38, no SIGWINCH reached the pane and all 100 remained. So `KeyboardHandler` captures `terminal.rows` on the show transition (`app._keyboardHeldRows`) and `getTerminalDimensions()` never reports fewer rows while the keyboard is visible; columns still follow the container, so the #464 width rule is untouched. ⚠️ **Why this is not the regression the COLUMNS ONLY note describes.** There the extra rows came from ANOTHER device's sizing claim, adopted from `ptyGeometry`, and nothing kept the composer in view: an `.xterm-screen` taller than its container with the input line below it and no gesture able to reach it. Here the rows are this device's own keyboard-free rows, held on purpose only while the keyboard is up, and the screen is translated up by `--kb-clip` (`_applyKeyboardClip()`, pure math in `keyboardClipPx()` in constants.js) so the last content row sits at the bottom of the visible box: following live output, the cursor counts only within `KEYBOARD_CLIP_CURSOR_REACH` (2) rows below the last content (a TUI that parks its cursor far below what it drew must not scroll its content away); reading history, the offset follows the scroll position so the top of the scrollback stays reachable. The local-echo overlay is bounded to the visible rows through `setRowLimit()`, which narrows the overlay renderer's existing `totalRows` bound rather than adding a second one, so a long draft grows upward from the last row the user can see. `reconcilePtyGeometry` still adopts columns only: nothing here takes rows from the PTY's report. `test/keyboard-held-rows.test.ts` pins the composer row inside the visible box with the rows held, against a real headless xterm and the shipped `_applyKeyboardClip()`. ⚠️ Holding goes through `getTerminalDimensions()`, never one caller, so the fit, the PTY resize and the capture-geometry comparisons agree; `syncTerminalGeometry()` skips `fitAddon.fit()` while held, so xterm never visits the short size. ⚠️ A shape change (rotation, fold) releases the hold AND arms the viewport settle (`_scheduleViewportSettle()`), which refits and tells the PTY: with the keyboard still up `throttledResize` stands aside and a rotation alone arms nothing, so without it xterm kept the held rows with no clip and the composer sat under the keyboard until it closed. A rotation with no hold arms nothing, as before. ⚠️ ONLY inline renderers qualify (`_keyboardHoldEligible()`): the registry's `capabilities.keyboardHold: 'inline'` (Claude alone; read through `window.__codemanKeyboardHoldModes`, never an id literal), never while `cliMouseTracking` reports Claude's fullscreen mode (it lays out the full height and has not been measured losing lines, so it resizes as before), never remote or docker (their local pane hosts a nested client). A full-height layout (codex: banner at the top, composer pinned to the bottom) cannot fit both ends above the keyboard, which is what the first, unscoped version got wrong. ⚠️ The hold lives on the shared terminal, so `_reconcileKeyboardHold()` releases it whenever the active session stops qualifying (tab switch, a `session:updated`, a reconnect, the setting turned off), and keyboard close releases it too; it never re-holds with the keyboard already up, so a session that becomes eligible mid-keyboard keeps the short rows until the keyboard closes.
 
 ### Terminal resilience: replay clears, renderer liveness, fetch deadlines
 

docs/wiki/Mobile-Guide.md

@@ -153,6 +153,12 @@ already writing in the editor.
 
 - The terminal and toolbar shift up when the keyboard opens, tracked through the browser's
   visual viewport rather than guessed.
+- **Opening the keyboard does not resize a Claude session.** Each resize made Claude reprint
+  its screen at the new height and drop transcript lines from the session's history, so for a
+  local Claude session the terminal keeps its size while the keyboard is up and the view
+  scrolls instead, with the prompt and the line under it just above the keyboard. Codex,
+  Claude's fullscreen mode, remote and Docker sessions still resize. **Keep Size Under
+  Keyboard** in App Settings turns it off on this device.
 - **Two ways to dismiss the keyboard**: tap outside the terminal on inert space, or tap twice
   on inert terminal content. Tapping a control never dismisses it, and tapping the prompt row
   keeps focus so you can place the caret.

docs/wiki/Settings-Reference.md

@@ -21,7 +21,7 @@ desktop.
 
 | Category                | Examples                                                                        |
 | ----------------------- | ------------------------------------------------------------------------------- |
-| **Per-device, local**   | Skin, WebGL renderer, local echo, CJK input, extended keyboard bar, File Viewer and Cron header buttons. Never sent to the server at all. |
+| **Per-device, local**   | Skin, WebGL renderer, local echo, keep size under keyboard, CJK input, extended keyboard bar, File Viewer and Cron header buttons. Never sent to the server at all. |
 | **Per-device policy**   | Most `show*` toggles, plan usage chip, language. Stored server-side, but a device only takes the server value when it has no local one of its own. |
 | **Synced**              | Models, effort, CLI options, notification preferences, voice settings, display name, the agent skill and approvals toggles. |
 
@@ -46,6 +46,7 @@ supervised by systemd or launchd; npm installs report as non-updatable. See
 | Setting                       | Default              | Notes                                                                 |
 | ----------------------------- | -------------------- | --------------------------------------------------------------------- |
 | Local Echo                    | On for touch devices | Paints keystrokes locally and flushes on Enter. See [Input And Voice](Input-And-Voice). |
+| Keep Size Under Keyboard      | On                   | For local Claude sessions, the on-screen keyboard no longer resizes the session: the terminal keeps its rows and the view scrolls so the prompt sits just above the keyboard. Resizing made Claude reprint its screen and drop transcript lines from history. Codex, Claude's fullscreen mode, remote and Docker sessions resize as before. See [Mobile Guide](Mobile-Guide). |
 | CJK Input                     | Off                  | IME composition through a dedicated text field.                        |
 | Extended Keyboard Bar         | Per device           | Which accessory bar phones get. Shell sessions override it while they are active. |
 | Wheel Scrolls Local History   | Off                  | Keeps the wheel on the local buffer instead of forwarding it to the CLI. |