feat(v1): harden typed runtime boundaries

Elect one canonical EffectBatch codec, remove the parallel postcard API, and strengthen fail-closed host, form, sync, WASM, macro, generated-contract, and test-harness proofs with mutation-driven coverage.

req: wire/008

req: wire/009

req: wire/010

req: push/008

req: client_local/015

req: client_local/016

req: client_local/017

req: client_local/018

req: client_local/019

req: sync/024

req: sync/025

req: sync/026

req: sync/027

req: sync/028

req: sync/029

req: test/020

req: test/021

hemx-derive/tests/compile_fail.rs

@@ -1031,6 +1031,45 @@ pub const MISSING: hemx::CssClass = ui::classes::missing;
     );
 }
 
+#[test]
+fn effect_batch_has_no_parallel_postcard_wire_api() {
+    // req: wire/010 test
+    let fixture = Fixture::new("hemx-effect-batch-postcard-api-fail");
+    fixture.write(
+        "Cargo.toml",
+        &format!(
+            r#"[package]
+name = "hemx-effect-batch-postcard-api-fail"
+version = "0.0.0"
+edition = "2021"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+hemx = {{ path = {:?} }}
+"#,
+            repo_path("hemx")
+        ),
+    );
+    fixture.write(
+        "src/lib.rs",
+        r#"pub fn encode(batch: &hemx::advanced::EffectBatch) {
+    let _ = batch.to_postcard();
+}
+"#,
+    );
+
+    let output = check_fixture(&fixture);
+
+    assert!(!output.status.success(), "fixture unexpectedly compiled");
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("no method named `to_postcard`"),
+        "missing sole-wire-API diagnostic in stderr:\n{stderr}"
+    );
+}
+
 fn check_fixture(fixture: &Fixture) -> std::process::Output {
     Command::new("cargo")
         .arg("check")