Fix example crashes: allocator misuse and integer underflow#93
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The fixes from PR #92 landed in feature/examples-batch-7 after #91 had already merged into main, so they never reached main. Re-apply against main directly. Two bug classes: 1. Allocator misuse (5 examples). Component state was initialized with ctx.allocator — the per-frame arena that resets every render — instead of ctx.persistent_allocator. After the first render the internal array_lists pointed at freed memory, causing segfaults / bus errors on the second frame: - braille_canvas.zig — BrailleCanvas cells - data_table.zig — DataTable columns/rows - rich_log.zig — RichLog entries + search_term buffer - screen_stack.zig — ScreenStack stack array - action_system.zig — ActionRegistry actions, CommandPalette commands, palette shortcut strings Switched all per-component init to ctx.persistent_allocator, matching the pattern used by examples/file_browser.zig. 2. Integer underflow in async_tasks. Pressing 's' to relaunch while previous tasks were still in-flight reset tasks_launched to 3 but the OLD generation's completion events kept arriving and decremented past zero. Two-part fix: guard against re-launch while tasks are running, and use saturating subtraction (-|=) so any stray duplicate event can't underflow. Verified with stress tests (rapid keystrokes, multi-launch sequences).
3 tasks
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Summary
Re-apply the fixes from PR #92, which never reached main. (#92 was based on `feature/examples-batch-7`; that branch was merged into main before #92 was merged into the feature branch, so the fixes ended up orphaned.)
Bug 1 — Allocator misuse (5 examples)
Component state was initialized with `ctx.allocator` — the per-frame arena that resets every render — instead of `ctx.persistent_allocator`. The internal `array_list` storage pointed at freed memory after the first `render()`, segfaulting on the second frame.
Switched all per-component init to `ctx.persistent_allocator`, matching the pattern in `examples/file_browser.zig`. Also moved the palette `shortcut` string allocations to persistent in `action_system` since `CommandPalette` stores command structs by reference.
Bug 2 — `async_tasks` integer underflow
Pressing `s` to relaunch while previous tasks were still in-flight reset `tasks_launched` to 3, but the old generation's completion events kept arriving and decremented `tasks_launched` past zero — `u8` underflow panic on the fourth completion.
Two-part fix:
Test plan