split-view phase 4: split-aware status, min-width gate, verified nav

Polish for the split view:
* _split_status(): status line now reads "name @ ea [split · pseudocode line N
  ↔ K insn]" / "[split · listing]" from the focused pane, instead of the
  single-view [pseudocode]/[listing] labels clobbering it. Wired into both
  cursor-moved handlers and _apply_decomp.
* min-width gate: action_toggle_split refuses to enter split below
  _SPLIT_MIN_WIDTH (100 cols) so two usable code panes always have room.
* navigation keeps both panes on the same function: verified (not fixed —
  goto/follow in split already routes _open_entry -> _show_active split branch,
  reloading the listing + decomp + region map for the new function).

Review turned two roadmap items into non-issues: split is a persistent mode
orthogonal to nav entries (back/forward just navigate within split), and search
is already per-focused-pane.

Pilot split_view gains: split-aware status, goto-in-split navigates, and both
panes reload on navigation (16/16). Full suite 157/2-flake. Split view is
feature-complete (phases 1-4).

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/test_scenarios.py b/tests/test_scenarios.py
index 0bca4d8..3401645 100644
--- a/tests/test_scenarios.py
+++ b/tests/test_scenarios.py
@@ -350,6 +350,9 @@ async def s_split_view(c: Ctx):
     loaded = await c.wait(lambda: dec.loaded_ea == app._cur.ea, 25)
     c.check("split loads the pseudocode alongside the listing", loaded,
             f"loaded={dec.loaded_ea} cur={app._cur.ea if app._cur else None}")
+    await c.wait(lambda: "[split" in c.status(), 5)
+    c.check("split view shows a split-aware status", "[split" in c.status(),
+            f"status={c.status()!r}")
     # phase 3: the rich per-line instruction map (decomp_map tool, run on the
     # pilot's real worker) — verify it returns, aligns with the markers, and
     # bands a whole region for a multi-instruction C line.
@@ -412,6 +415,19 @@ async def s_split_view(c: Ctx):
     await c.pause(0.1)
     c.check("Tab again focuses the listing pane", app._active == "listing",
             f"active={app._active}")
+    # navigation in split keeps BOTH panes on the (new) function
+    nf = c.find_func(lambda f: f.addr != app._cur.ea and f.size > 80)
+    if nf is not None:
+        await c.press("g")
+        await c.type(hex(nf.addr))
+        await c.press("enter")
+        nav = await c.wait(lambda: app._cur and app._cur.ea == nf.addr, 15)
+        c.check("goto in split navigates", nav,
+                f"cur={app._cur.ea if app._cur else None} want={nf.addr}")
+        both = await c.wait(lambda: dec.loaded_ea == nf.addr and app._split
+                            and lst.display and dec.display, 25)
+        c.check("split reloads both panes on navigation", both,
+                f"dec={dec.loaded_ea} split={app._split}")
     await c.press("s")
     gone = await c.wait(lambda: not app._split and lst.display
                         and not dec.display, 10)