fix(ui): restore cursor and autowrap when install/migrate aborts

src/cli/install.zig

@@ -530,6 +530,9 @@ fn executeWithOpts(
         // Set up multi-progress: assign line indices and create coordinator
         const download_index = assignDownloadLineIndices(all_jobs.items);
         var multi = progress_mod.MultiProgress.init(download_index);
+        // Anchor the DECSET pair to scope exit so an early return between
+        // here and the worker join doesn't leave the terminal in DECRESET.
+        defer multi.finish();
 
         // Main-thread bar allocation — draw an initial frame on every line
         // before workers spawn, and keep pointers stable for them.
@@ -576,7 +579,6 @@ fn executeWithOpts(
         }
 
         for (threads.items) |t| t.join();
-        multi.finish();
     }
 
     // Emit from the main thread so ndjson order is deterministic

src/main.zig

@@ -3,13 +3,27 @@
 
 const std = @import("std");
 const color_mod = @import("ui/color.zig");
+const progress_mod = @import("ui/progress.zig");
 const AppCtx = @import("app_ctx.zig").AppCtx;
 
-// Release uses simple_panic so debug.Dwarf stays unreachable (~30 KB smaller).
-pub const panic = if (@import("builtin").mode == .Debug)
-    std.debug.FullPanic(std.debug.defaultPanic)
-else
-    std.debug.simple_panic;
+// Wrap the panic path so the cursor + autowrap state owned by
+// MultiProgress / Spinner is restored before abort. Defers don't run
+// on panic, so this is the only way to leave the terminal usable when
+// install/migrate trips a safety check.
+pub const panic = std.debug.FullPanic(maltPanic);
+
+fn maltPanic(msg: []const u8, first_trace_addr: ?usize) noreturn {
+    progress_mod.restoreTerminal();
+    if (@import("builtin").mode == .Debug) {
+        std.debug.defaultPanic(msg, first_trace_addr);
+    } else {
+        // Release mirror of std.debug.simple_panic.call: emit the
+        // message and trap, keeping debug.Dwarf out of the binary.
+        const stderr_writer = &std.debug.lockStderr(&.{}).file_writer.interface;
+        stderr_writer.writeAll(msg) catch {};
+        @trap();
+    }
+}
 
 // Gate `.debug` on the runtime --debug flag so release builds still
 // surface std.log.debug diagnostics in bug reports.
@@ -343,7 +357,6 @@ pub fn main(init: std.process.Init.Minimal) !void {
     // Seed the ui package state once so output/progress/color stop
     // pulling io/environ/stdio from module-level globals.
     const output_mod = @import("ui/output.zig");
-    const progress_mod = @import("ui/progress.zig");
     output_mod.setRuntime(ctx.io, ctx.environ, ctx.stdout, ctx.stderr);
     progress_mod.setRuntime(ctx.io, ctx.stderr);
     color_mod.setRuntime(ctx.io, ctx.environ);

src/ui/progress.zig

@@ -46,6 +46,14 @@ fn sleepNs(ns: u64) void {
 /// Braille-based spinner frames, shared by ProgressBar and Spinner.
 const spinner_chars = [_][]const u8{ "⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏" };
 
+/// Best-effort restore of terminal state mutated by `MultiProgress.init`
+/// or `Spinner.start`: re-enable autowrap, show the cursor, return to
+/// column 0. Safe to call from a panic / signal handler — the bytes are
+/// idempotent, and writes silently drop when stderr is unconfigured.
+pub fn restoreTerminal() void {
+    writeStderrAll("\x1b[?7h\x1b[?25h\r");
+}
+
 /// Coordinates multiple progress bars on separate terminal lines.
 /// Reserves N lines upfront, then uses ANSI cursor movement so each
 /// bar updates its own line without interfering with others.
@@ -84,8 +92,7 @@ pub const MultiProgress = struct {
     /// Must be called after all download threads have joined.
     pub fn finish(self: *MultiProgress) void {
         if (self.is_tty and !output.isQuiet()) {
-            // Re-enable autowrap, show cursor, return to col 0.
-            writeStderrAll("\x1b[?7h\x1b[?25h\r");
+            restoreTerminal();
         }
     }
 };
@@ -657,3 +664,11 @@ test "ProgressBar render survives label larger than the draw buffer" {
     indet.is_tty = true;
     indet.update(0);
 }
+
+test "restoreTerminal is callable without an active MultiProgress" {
+    // Panic / signal handlers may emit the restore sequence without ever
+    // having paired it to an init: the call must be allocation-free,
+    // re-entrant, and idempotent.
+    restoreTerminal();
+    restoreTerminal();
+}