revert(android): roll back to build #6 (35642d1) — pre-oboe known-good state

Spent 10+ builds chasing a __init_tcb+4 / pthread_create SIGSEGV after
adding the oboe audio backend. Every "fix" made things worse. Reverting
all Android-specific files to the state at 35642d1 (build #6), which
was the last commit where the Tauri Android app actually launched,
rendered the home screen, and successfully registered on a relay.

Reverted files (all back to their 35642d1 content):
  - desktop/src-tauri/Cargo.toml        (no build-dep cc, no tracing-android)
  - desktop/src-tauri/build.rs          (git hash only, no Oboe / cc build)
  - desktop/src-tauri/src/lib.rs        (engine cfg-gated on non-android)
  - desktop/src-tauri/src/main.rs       (two-line desktop entry)
  - desktop/src-tauri/src/engine.rs     (desktop-only audio setup)
  - scripts/Dockerfile.android-builder  (no android24→26 clang shim)
  - scripts/build-tauri-android.sh      (no linker env vars / manifest patch)

Deleted (were added between b314138 and e2e023d):
  - desktop/src-tauri/cpp/getauxval_fix.c
  - desktop/src-tauri/cpp/oboe_bridge.{h,cpp}
  - desktop/src-tauri/cpp/oboe_stub.cpp
  - desktop/src-tauri/src/oboe_audio.rs

Next: rebuild image on remote (to drop the baked-in clang shim), build
an APK, install on Pixel 6, verify the UI renders the same way build #6
did. From there we add features back ONE at a time so we can actually
bisect which one triggers the tao::ndk_glue crash. User's rule:
"if you want to change stack, change incrementally, so we can debug".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/src-tauri/build.rs

@@ -1,8 +1,9 @@
-use std::path::PathBuf;
 use std::process::Command;
 
 fn main() {
-    // ─── Embedded git hash ─────────────────────────────────────────────────
+    // Capture short git hash so the running app can prove which build it is.
+    // Falls back to "unknown" if git isn't available (e.g. when building from
+    // a tarball without a .git dir).
     let git_hash = Command::new("git")
         .args(["rev-parse", "--short", "HEAD"])
         .output()
@@ -13,138 +14,10 @@ fn main() {
         .unwrap_or_else(|| "unknown".into());
 
     println!("cargo:rustc-env=WZP_GIT_HASH={git_hash}");
+    // Re-run if the HEAD pointer or its target moves so the embedded hash
+    // tracks reality between builds.
     println!("cargo:rerun-if-changed=../../.git/HEAD");
     println!("cargo:rerun-if-changed=../../.git/refs/heads");
 
-    // ─── Oboe C++ bridge (Android only) ────────────────────────────────────
-    let target = std::env::var("TARGET").unwrap_or_default();
-    if target.contains("android") {
-        build_oboe_android(&target);
-    }
-
     tauri_build::build()
 }
-
-fn build_oboe_android(target: &str) {
-    // Rerun if bridge sources change
-    println!("cargo:rerun-if-changed=cpp/oboe_bridge.cpp");
-    println!("cargo:rerun-if-changed=cpp/oboe_bridge.h");
-    println!("cargo:rerun-if-changed=cpp/oboe_stub.cpp");
-    println!("cargo:rerun-if-changed=cpp/getauxval_fix.c");
-
-    // getauxval_fix: override broken static getauxval from compiler-rt that
-    // SIGSEGVs in shared libraries (runs before any app code).
-    cc::Build::new()
-        .file("cpp/getauxval_fix.c")
-        .compile("getauxval_fix");
-
-    let oboe_dir = fetch_oboe();
-    match oboe_dir {
-        Some(oboe_path) => {
-            println!("cargo:warning=Building with Oboe from {:?}", oboe_path);
-
-            let mut build = cc::Build::new();
-            build
-                .cpp(true)
-                .std("c++17")
-                // Shared libc++ — static pulls broken libc stubs that crash
-                // in shared libraries (getauxval, __init_tcb, pthread_create).
-                .cpp_link_stdlib(Some("c++_shared"))
-                .include("cpp")
-                .include(oboe_path.join("include"))
-                .include(oboe_path.join("src"))
-                .define("WZP_HAS_OBOE", None)
-                .file("cpp/oboe_bridge.cpp");
-
-            add_cpp_files_recursive(&mut build, &oboe_path.join("src"));
-            build.compile("oboe_bridge");
-        }
-        None => {
-            println!("cargo:warning=Oboe not found, building with stub");
-            cc::Build::new()
-                .cpp(true)
-                .std("c++17")
-                .cpp_link_stdlib(Some("c++_shared"))
-                .file("cpp/oboe_stub.cpp")
-                .include("cpp")
-                .compile("oboe_bridge");
-        }
-    }
-
-    // libc++_shared.so must sit next to libwzp_desktop_lib.so in jniLibs —
-    // copy it there from the NDK sysroot. Tauri's gradle project expects the
-    // jniLibs in gen/android/app/src/main/jniLibs/<abi>/.
-    if let Ok(ndk) = std::env::var("ANDROID_NDK_HOME")
-        .or_else(|_| std::env::var("NDK_HOME"))
-    {
-        let (triple, abi) = match target {
-            t if t.contains("aarch64") => ("aarch64-linux-android", "arm64-v8a"),
-            t if t.contains("armv7")   => ("arm-linux-androideabi", "armeabi-v7a"),
-            t if t.contains("x86_64")  => ("x86_64-linux-android", "x86_64"),
-            t if t.contains("i686")    => ("i686-linux-android", "x86"),
-            _                           => ("aarch64-linux-android", "arm64-v8a"),
-        };
-        let lib_dir = format!(
-            "{ndk}/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/{triple}"
-        );
-        println!("cargo:rustc-link-search=native={lib_dir}");
-
-        let shared_so = format!("{lib_dir}/libc++_shared.so");
-        if std::path::Path::new(&shared_so).exists() {
-            let manifest = std::env::var("CARGO_MANIFEST_DIR").unwrap_or_default();
-            // Tauri mobile layout: gen/android/app/src/main/jniLibs/<abi>/
-            let jni_dir = format!("{manifest}/gen/android/app/src/main/jniLibs/{abi}");
-            if std::fs::create_dir_all(&jni_dir).is_ok() {
-                let _ = std::fs::copy(&shared_so, format!("{jni_dir}/libc++_shared.so"));
-                println!("cargo:warning=Copied libc++_shared.so to {jni_dir}");
-            }
-        }
-    }
-
-    // Oboe requires Android log + OpenSLES backends
-    println!("cargo:rustc-link-lib=log");
-    println!("cargo:rustc-link-lib=OpenSLES");
-}
-
-/// Recursively add all .cpp files from a directory to a cc::Build.
-fn add_cpp_files_recursive(build: &mut cc::Build, dir: &std::path::Path) {
-    if !dir.is_dir() {
-        return;
-    }
-    for entry in std::fs::read_dir(dir).unwrap() {
-        let entry = entry.unwrap();
-        let path = entry.path();
-        if path.is_dir() {
-            add_cpp_files_recursive(build, &path);
-        } else if path.extension().map_or(false, |e| e == "cpp") {
-            build.file(&path);
-        }
-    }
-}
-
-/// Try to find or fetch Oboe headers + source (v1.8.1).
-fn fetch_oboe() -> Option<PathBuf> {
-    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
-    let oboe_dir = out_dir.join("oboe");
-
-    if oboe_dir.join("include").join("oboe").join("Oboe.h").exists() {
-        return Some(oboe_dir);
-    }
-
-    let status = Command::new("git")
-        .args([
-            "clone",
-            "--depth=1",
-            "--branch=1.8.1",
-            "https://github.com/google/oboe.git",
-            oboe_dir.to_str().unwrap(),
-        ])
-        .status();
-
-    match status {
-        Ok(s) if s.success() && oboe_dir.join("include").join("oboe").join("Oboe.h").exists() => {
-            Some(oboe_dir)
-        }
-        _ => None,
-    }
-}