v5.0.0: protocol v5 and the browser frontend

Protocol v5 replaces newline lines with bounded [u32 len][text] frames and REQ/RES/EVT envelopes. Requests carry correlation ids and the server replays the last 256 replies per connection, so a gateway retry cannot double-debit and a late reply cannot clobber a newer request. HELLO/PONG carry server time; crash rounds announce started_at and push coalesced 10 Hz ticks. Crash now commits sha256(seed) before a round and reveals the seed when it ends, so clients recompute the crash point.

Adds the webd/ gateway: one blocking thread, one ClientCore and one pinned upstream TLS connection per session, an HttpOnly session cookie, takeover, and a 60-second grace window. The browser sends Command JSON and renders View JSON; it never speaks the game protocol or stores credentials.

Adds the vanilla TypeScript browser app at /play/ (login, lobby, all four games, history, notices, crash verification), the nginx /play and /ws routes, and the headless DOM smoke test. webd and the app stay out of the TUI/GUI/server build graph.

The client/server version moves to 5.0.0 in lockstep; v4 peers are refused at HELLO.

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/crash.rs b/tests/crash.rs
index 797874b..513f9c8 100644
--- a/tests/crash.rs
+++ b/tests/crash.rs
@@ -102,3 +102,42 @@ fn crash_points_are_clamped_to_the_liability_cap() {
     assert_eq!(crash_point_from_uniform(0.999_999), MAX_MULTIPLIER);
     assert_eq!(crash_point_from_uniform(1.0), MAX_MULTIPLIER);
 }
+
+#[test]
+fn a_seed_commits_to_its_crash_point_and_can_be_verified() {
+    use zagan_bet::crash::{
+        SEED_LEN, commit_seed, crash_point_from_seed, seed_from_hex, seed_to_uniform, verify_seed,
+    };
+
+    let mut seed = [0u8; SEED_LEN];
+    let value = (0.67_f64 * 18_446_744_073_709_551_616.0) as u64;
+    seed[..8].copy_from_slice(&value.to_be_bytes());
+    let commit = commit_seed(&seed);
+    let hex = format!(
+        "{}",
+        seed.iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>()
+    );
+
+    assert_eq!(seed_from_hex(&hex).as_deref(), Some(seed.as_slice()));
+    assert!(verify_seed(&hex, &commit));
+    assert!(!verify_seed(&hex, &"00".repeat(32)), "a wrong commit fails");
+    assert!(!verify_seed("nope", &commit), "bad hex fails");
+
+    // The point the client recomputes is the point the server committed to.
+    close(crash_point_from_seed(&seed), 3.0, 1e-9);
+    close(crash_point_from_seed(&seed), 3.0, 1e-9);
+
+    // The first eight bytes are the uniform; the rest are still hashed.
+    close(seed_to_uniform(&seed), 0.67, 1e-9);
+    let mut altered = seed;
+    altered[SEED_LEN - 1] = 1;
+    assert!(!verify_seed(
+        &altered
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>(),
+        &commit
+    ));
+}