fix(pi): leave page keys out, and pin the strip that makes the wheel work

transcriptPageKeys applied to every pi, and a pi in `tuiMode: regular` binds
PageUp/PageDown to its editor. It emits no mouse enable, so the flag stays
false, and on a fresh pane the buffer is hollow: the wheel sent PageUp, the
caret of a multi-line draft moved, and the next keystroke landed on the wrong
line. Measured on real pi 1.1.0, 1.4.0 and 1.5.0. Regular mode is not exotic,
it only takes one line in pi's settings. Telling the two modes apart would
need a new capability, since the paging gate takes no id, so pi has no
fallback: a fullscreen pi with "Wheel scrolls local history" on stays where
master left it.

altScreen, the half of the fix that does the work, was pinned by nothing:
reverting it left 1328 tests green. The strip decision table reads its
expected value from the same registry entry. pi now has its own block using
the bytes it really emits, which also pins that focus reporting survives.

The fullscreen default dates from pi 1.0.0, not 1.4.0, so the comments say
that, and the sites still calling pi narrow-strip or main-screen by default
are corrected. Where a comment listed CLIs it now names the capability.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/config/cli-registry/stock.ts

@@ -1180,15 +1180,21 @@ const PI: CliEntry = {
     // (hasTrustRequiringProjectResources, pi 1.1.0), which would stall a spawned worker on
     // a dialog. pi reads the user-level `~/.agents/skills` without that prompt, so a pi
     // user installs it there (`npx skills add Ark0N/Codeman --skill codeman -g`).
-    // pi 1.4.0 measured (tmux pane: alternate_on=1, history_size=0, mouse on, SGR): a fullscreen
-    // TUI that enables tracking once at start. Codeman's replay (tab switch, reload) drops that
-    // mode in xterm, so the wheel hit an empty local buffer and went dead until a redraw. Same
-    // shape as copilot: strip the DECSETs (a drag selects locally), publish `cliMouseTracking`,
-    // and forward the wheel by hand from that flag. pi scrolls on SGR wheel (1 line per report)
-    // and on PageUp/PageDown, which is the fallback for a stale flag.
+    // Fullscreen is pi's default `tuiMode` since 1.0.0 (measured 1.0.0, 1.1.0, 1.4.0, 1.5.0 in
+    // tmux: alternate_on=1, history_size=0, mouse on, SGR): a TUI that enables tracking once at
+    // start. Codeman's replay (tab switch, reload) drops that mode in xterm, so the wheel hit an
+    // empty local buffer and went dead until a redraw. Same shape as copilot: strip the DECSETs
+    // (a drag selects locally), publish `cliMouseTracking`, and forward the wheel by hand from
+    // that flag. pi scrolls on SGR wheel reports, one row each at a low rate, faster on a spin.
+    // `tuiMode: regular` (and every pi below 1.0.0) is inline and emits no mouse DECSET, so the
+    // strip finds nothing and the flag stays false.
+    // ⚠️ No `transcriptPageKeys`, though fullscreen pi does page on PageUp/PageDown. pi binds
+    // those keys to its editor in regular mode too, where they page nothing and move the caret
+    // of a multi-line draft, so a wheel over a fresh regular pane sent the next keystroke to the
+    // wrong line (measured). The cost: a fullscreen pi with "Wheel scrolls local history" on
+    // has no paging fallback.
     altScreen: 'strip-mux-and-mouse',
     wheelForward: { mode: 'always' },
-    transcriptPageKeys: true,
     echo: { policy: 'buffer', anchor: { kind: 'cursor' } },
     // Measured on a live pi 1.1.0 pane (capture-pane every 250 ms through a turn,
     // 2026-10-09): pi has no composer glyph. Its composer sits between two `─` rules, and

src/config/cli-registry/types.ts

@@ -546,7 +546,7 @@ export interface CliCapabilities {
    * `strip-full` is `isAltScreenStripMode`; `strip-mux-and-mouse` is `isMuxMouseStripMode`;
    * every other value takes `isMuxAltScreenOnlyStripMode`, so at runtime `preserve` and
    * `strip-mux-only` are the same row — `preserve` only says what such a CLI's pane
-   * holds (terminal-owned scrollback: a shell, pi), not a different strip.
+   * holds (terminal-owned scrollback: a shell), not a different strip.
    *
    * - alt-screen: the tmux CLIENT emits `smcup` as its first bytes at attach, parking
    *   xterm in the scrollback-less alternate buffer; a pane program's own toggles never