aadc1228

main: document drawTextCoverageCompareFrame as non-recoverable smoke path

a73x   2026-04-18 15:38

Final review flagged that this function is missing the
submit_done/errdefer fence-state recovery pattern used in drawClear,
drawCells, and renderToOffscreen. Intentional — this is a single-shot
smoke mode where any non-OutOfDateKHR error tears the process down
before the leaked fence becomes a hang. Add a comment so the next
contributor doesn't reuse this shape inside a retry loop without
copying the recovery pattern over.

Part of issue ab6c92f0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---

diff --git a/src/main.zig b/src/main.zig
index ec3e25f..ab6bbfd 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1375,6 +1375,17 @@ fn buildTextCoverageCompareScene(
    };
}

// Smoke-mode draw — non-recoverable on Vulkan errors. Any error returned by
// this function propagates up to the caller in runTextCoverageCompareMode,
// which only handles OutOfDateKHR and exits the mode on anything else.
// Unlike drawClear / drawCells / renderToOffscreen in renderer.zig, this
// function does NOT install a resignalFence errdefer for the post-reset /
// pre-submit failure window — the smoke mode is single-shot and any pre-
// submit error tears the process down before the leaked fence matters.
// If this function is ever reused inside a retry loop, copy the
// `submit_done` / `errdefer if (!submit_done) ctx.resignalFence(...)`
// pattern from drawClear (renderer.zig). resignalFence would need to be
// made `pub fn` on Context for that.
fn drawTextCoverageCompareFrame(
    ctx: *renderer.Context,
    scene: *const TextCoverageCompareScene,