Bound native cargo builds and individual WASI tests with cancellable deadlines

cli/Cargo.toml

@@ -36,6 +36,7 @@ chrono = { version = "0.4.42", default-features = false, features = ["clock"] }
 tempfile = "3.27.0"
 
 [dev-dependencies]
+tokio = { version = "1", features = ["test-util"] }
 hyper = { version = "1.12.0", features = ["server", "http1"] }
 hyper-util = { version = "0.1.21", features = ["tokio"] }
 sausage-interface = { path = "../interface" }

cli/src/cargo.rs

@@ -4,11 +4,44 @@ use anyhow::{Context, Result, bail};
 use include_dir::{Dir, include_dir};
 use serde_json::{Value, json};
 use sha2::{Digest, Sha256};
+use std::time::Duration;
 use std::{
     path::{Path, PathBuf},
     sync::Arc,
 };
-use tokio::process::Command;
+use tokio::{io::AsyncReadExt, process::Command, time::Instant};
+
+/// Default wall-clock budget after acquiring the build mutex (not queue time).
+pub const DEFAULT_TIMEOUT_SECS: u64 = 900;
+/// Default wall-clock budget for each WASI test instance.
+pub const DEFAULT_TEST_TIMEOUT_SECS: u64 = 120;
+
+/// Wall-clock budgets for a build and its individual WASI tests.
+#[derive(Clone, Copy, Debug)]
+pub struct BuildOptions {
+    pub timeout_secs: u64,
+    pub test_timeout_secs: u64,
+}
+impl Default for BuildOptions {
+    fn default() -> Self {
+        Self {
+            timeout_secs: DEFAULT_TIMEOUT_SECS,
+            test_timeout_secs: DEFAULT_TEST_TIMEOUT_SECS,
+        }
+    }
+}
+/// Optional RPC seconds are positive integers; null does not disable a deadline.
+fn seconds(params: &Value, name: &str, default: u64) -> Result<u64, Value> {
+    match params.get(name) {
+        None => Ok(default),
+        Some(value) => value
+            .as_u64()
+            .filter(|seconds| *seconds >= 1)
+            .ok_or_else(|| {
+                crate::error(-32602, &format!("{name} must be an integer of at least 1"))
+            }),
+    }
+}
 
 /// The native build plugin.
 pub const ID: &str = "cargo";
@@ -38,6 +71,8 @@ pub struct BuildFailure {
     pub reason: String,
     pub tests: TestResults,
     pub output: String,
+    pub elapsed_secs: Option<f64>,
+    pub step: Option<&'static str>,
 }
 impl std::fmt::Display for BuildFailure {
     fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -51,6 +86,8 @@ impl From<anyhow::Error> for BuildFailure {
             reason: "build preparation failed".into(),
             output: format!("{error:#}"),
             tests: TestResults::default(),
+            elapsed_secs: None,
+            step: None,
         }
     }
 }
@@ -142,19 +179,39 @@ impl Cargo {
         host.register_native(ID,Arc::new(move |_context,method,params| {
             let builder=builder.clone();
             Box::pin(async move {
-                if method=="rpc.discover" { return Ok(json!({"openrpc":"1.2.6","info":{"title":"cargo","version":"native"},"methods":[{"name":"build","paramStructure":"by-name","params":[{"name":"plugin","required":true,"schema":{"type":"string"}}],"result":{"name":"build","schema":{"type":"object","required":["wasm","tests","warnings"],"properties":{"wasm":{"type":"string"},"warnings":{"type":"string"},"tests":{"type":"object","required":["passed","failed","output"],"properties":{"passed":{"type":"integer","minimum":0},"failed":{"type":"integer","minimum":0},"output":{"type":"string"}}}}}},"errors":[{"code":-32004,"message":"Build failed"}]}]})); }
+                if method=="rpc.discover" { return Ok(json!({"openrpc":"1.2.6","info":{"title":"cargo","version":"native"},"methods":[{"name":"build","paramStructure":"by-name","description":"Copies source, runs bounded WASI tests, then builds a release component. Deadlines kill cargo and its descendants; cancellation releases the build mutex.","params":[{"name":"plugin","required":true,"schema":{"type":"string"}},{"name":"timeout_secs","required":false,"description":"Total wall-clock limit in seconds for tests and release build after acquiring the build mutex (queue time excluded). Default 900; minimum 1. Cannot be disabled.","schema":{"type":"integer","minimum":1,"default":DEFAULT_TIMEOUT_SECS}},{"name":"test_timeout_secs","required":false,"description":"Wall-clock limit in seconds for each WASI test instance. Default 120; minimum 1. A timed-out test is named and fails; remaining tests continue.","schema":{"type":"integer","minimum":1,"default":DEFAULT_TEST_TIMEOUT_SECS}}],"result":{"name":"build","schema":{"type":"object","required":["wasm","tests","warnings"],"properties":{"wasm":{"type":"string"},"warnings":{"type":"string"},"tests":{"type":"object","required":["passed","failed","output"],"properties":{"passed":{"type":"integer","minimum":0},"failed":{"type":"integer","minimum":0},"output":{"type":"string"}}}}}},"errors":[{"code":-32004,"message":"Build failed"}]}]})); }
                 if method!="build" { return Err(crate::error(-32601,"cargo method not found")); }
                 let plugin=params["plugin"].as_str().ok_or_else(||crate::error(-32602,"plugin must be a string"))?;
-                match builder.build(&builder.world.plugin_dir(plugin).join("source")).await {
+                let options = BuildOptions {
+                    timeout_secs: seconds(&params, "timeout_secs", DEFAULT_TIMEOUT_SECS)?,
+                    test_timeout_secs: seconds(&params, "test_timeout_secs", DEFAULT_TEST_TIMEOUT_SECS)?,
+                };
+                match builder.build_with_options(&builder.world.plugin_dir(plugin).join("source"), options).await {
                     Ok(output)=>Ok(json!({"wasm":format!("/{}",output.wasm.strip_prefix(&builder.world.root).unwrap().display()),"tests":output.tests,"warnings":output.warnings})),
-                    Err(failure)=>Err(json!({"code":-32004,"message":failure.reason,"data":{"tests":failure.tests,"output":failure.output}})),
+                    Err(failure)=>Err(json!({"code":-32004,"message":failure.reason,"data":{"reason":failure.reason,"tests":failure.tests,"output":failure.output,"elapsed_secs":failure.elapsed_secs,"step":failure.step}})),
                 }
             })
         }));
     }
     /// Copies source once, runs WASI tests, then publishes a release component under state/cargo/builds.
     pub async fn build(&self, source: &Path) -> std::result::Result<BuildOutput, BuildFailure> {
+        self.build_with_options(source, BuildOptions::default())
+            .await
+    }
+    /// Like build, with explicit positive wall-clock budgets. Waiting for the mutex is unbounded.
+    pub async fn build_with_options(
+        &self,
+        source: &Path,
+        options: BuildOptions,
+    ) -> std::result::Result<BuildOutput, BuildFailure> {
+        if options.timeout_secs == 0 || options.test_timeout_secs == 0 {
+            return Err(anyhow::anyhow!("timeouts must be at least 1 second").into());
+        }
         let build_guard = self.builds.clone().lock_owned().await;
+        let started = Instant::now();
+        let deadline = started
+            .checked_add(Duration::from_secs(options.timeout_secs))
+            .ok_or_else(|| anyhow::anyhow!("timeout_secs is too large"))?;
         let work = self.world.state_dir(ID).join("work");
         let target = self.target.clone();
         let temporary = self.world.state_dir(ID).join("tmp");
@@ -208,16 +265,27 @@ impl Cargo {
         .await
         .map_err(anyhow::Error::from)??;
         let mut test = Command::new("cargo");
-        test.args(["test", "--release", "--target", TARGET, "--target-dir"])
-            .arg(&target)
-            .current_dir(&work)
-            .env("TMPDIR", &temporary)
-            .arg("--config")
-            .arg(format!(
-                "target.wasm32-wasip2.runner={}",
-                json!([self.runner, "test-runner"])
-            ));
-        let output = run_command(test).await?;
+        test.args([
+            "test",
+            "--no-fail-fast",
+            "--release",
+            "--target",
+            TARGET,
+            "--target-dir",
+        ])
+        .arg(&target)
+        .current_dir(&work)
+        .env("TMPDIR", &temporary)
+        .env(
+            "SAUSAGE_TEST_TIMEOUT_SECS",
+            options.test_timeout_secs.to_string(),
+        )
+        .arg("--config")
+        .arg(format!(
+            "target.wasm32-wasip2.runner={}",
+            json!([self.runner, "test-runner"])
+        ));
+        let output = run_command(test, started, deadline, "tests", TestResults::default()).await?;
         let stdout = String::from_utf8_lossy(&output.stdout);
         let stderr = String::from_utf8_lossy(&output.stderr);
         let tests = TestResults {
@@ -234,22 +302,24 @@ impl Cargo {
                 reason: "WASI tests failed".into(),
                 output: tests.output.clone(),
                 tests,
+                elapsed_secs: None,
+                step: None,
             });
         }
+        let mut build = Command::new("cargo");
+        build
+            .args([
+                "build",
+                "--release",
+                "--target",
+                TARGET,
+                "--message-format=json-render-diagnostics",
+                "--target-dir",
+            ])
+            .arg(&target)
+            .current_dir(&work);
+        let output = run_command(build, started, deadline, "release build", tests.clone()).await?;
         let result = async {
-            let mut build = Command::new("cargo");
-            build
-                .args([
-                    "build",
-                    "--release",
-                    "--target",
-                    TARGET,
-                    "--message-format=json-render-diagnostics",
-                    "--target-dir",
-                ])
-                .arg(&target)
-                .current_dir(&work);
-            let output = run_command(build).await?;
             let stdout = String::from_utf8_lossy(&output.stdout);
             let stderr = String::from_utf8_lossy(&output.stderr);
             let diagnostics = stderr.to_string();
@@ -292,6 +362,8 @@ impl Cargo {
             reason: "release build failed".into(),
             output: format!("{error:#}"),
             tests,
+            elapsed_secs: None,
+            step: None,
         })
     }
 }
@@ -306,16 +378,81 @@ impl Drop for ProcessGroup {
     }
 }
 /// Starts one process group and retains its guard across all output collection.
-async fn run_command(mut command: Command) -> Result<std::process::Output> {
+async fn run_command(
+    mut command: Command,
+    started: Instant,
+    deadline: Instant,
+    step: &'static str,
+    mut tests: TestResults,
+) -> std::result::Result<std::process::Output, BuildFailure> {
     command
         .process_group(0)
         .kill_on_drop(true)
         .stdin(std::process::Stdio::null())
         .stdout(std::process::Stdio::piped())
         .stderr(std::process::Stdio::piped());
-    let child = command.spawn().context("start cargo")?;
-    let _group = ProcessGroup(child.id().unwrap());
-    Ok(child.wait_with_output().await?)
+    let mut child = command.spawn().context("start cargo")?;
+    let group = ProcessGroup(child.id().unwrap());
+    let mut stdout = child.stdout.take().unwrap();
+    let mut stderr = child.stderr.take().unwrap();
+    let mut out = Vec::new();
+    let mut err = Vec::new();
+    let (status, timed_out) = {
+        let collect = async {
+            let (status, _, _) = tokio::try_join!(
+                child.wait(),
+                stdout.read_to_end(&mut out),
+                stderr.read_to_end(&mut err)
+            )?;
+            Ok::<_, std::io::Error>(status)
+        };
+        tokio::pin!(collect);
+        tokio::select! {
+            biased;
+            _ = tokio::time::sleep_until(deadline) => {
+                // Kill the entire tree before waiting for EOF/reaping cargo. The guard also
+                // covers cancellation while collecting, and runs before the mutex drops.
+                let _ = nix::sys::signal::killpg(nix::unistd::Pid::from_raw(group.0 as i32), nix::sys::signal::Signal::SIGKILL);
+                (collect.await, true)
+            }
+            status = &mut collect => (status, false),
+        }
+    };
+    let status = status.map_err(anyhow::Error::from)?;
+    if timed_out {
+        let output = format!(
+            "{}\n{}",
+            String::from_utf8_lossy(&out),
+            String::from_utf8_lossy(&err)
+        );
+        let output = output
+            .trim_end()
+            .lines()
+            .rev()
+            .take(50)
+            .collect::<Vec<_>>()
+            .into_iter()
+            .rev()
+            .collect::<Vec<_>>()
+            .join("\n");
+        if step == "tests" {
+            tests.passed = test_count(&String::from_utf8_lossy(&out), "passed");
+            tests.failed = test_count(&String::from_utf8_lossy(&out), "failed");
+            tests.output = output.clone();
+        }
+        return Err(BuildFailure {
+            reason: "timeout".into(),
+            tests,
+            output,
+            elapsed_secs: Some(started.elapsed().as_secs_f64()),
+            step: Some(step),
+        });
+    }
+    Ok(std::process::Output {
+        status,
+        stdout: out,
+        stderr: err,
+    })
 }
 /// Copies only source, excluding build outputs and git internals at every level.
 fn copy_source(source: &Path, destination: &Path, root: bool) -> Result<()> {
@@ -457,3 +594,40 @@ fn strip_progress(output: &str) -> String {
         .collect::<Vec<_>>()
         .join("\n")
 }
+
+#[cfg(test)]
+mod timeout_tests {
+    use super::*;
+
+    /// Deadline errors retain the shared start time, phase, test totals, and output tail.
+    #[tokio::test]
+    async fn timeout_diagnostics() {
+        let mut command = Command::new("sh");
+        command.args([
+            "-c",
+            "i=0; while [ $i -lt 100 ]; do echo diagnostic-$i; i=$((i+1)); done; exec sleep 1000",
+        ]);
+        let now = Instant::now();
+        let failure = run_command(
+            command,
+            now - Duration::from_secs(10),
+            now + Duration::from_secs(1),
+            "release build",
+            TestResults {
+                passed: 7,
+                failed: 0,
+                output: "successful tests".into(),
+            },
+        )
+        .await
+        .unwrap_err();
+        assert_eq!(failure.reason, "timeout");
+        assert_eq!(failure.step, Some("release build"));
+        assert!(failure.elapsed_secs.unwrap() >= 11.0);
+        assert_eq!(failure.tests.passed, 7);
+        assert_eq!(failure.tests.output, "successful tests");
+        assert_eq!(failure.output.lines().count(), 50);
+        assert!(failure.output.contains("diagnostic-99"));
+        assert!(!failure.output.contains("diagnostic-0\n"));
+    }
+}

cli/src/test_runner.rs

@@ -64,12 +64,21 @@ async fn instance(
         ("SAUSAGE_PLUGIN".into(), "test".into()),
         ("SAUSAGE_PARENT".into(), "core".into()),
     ]);
+    let timeout_secs = std::env::var("SAUSAGE_TEST_TIMEOUT_SECS")
+        .ok()
+        .and_then(|value| value.parse::<u64>().ok())
+        .filter(|value| *value >= 1)
+        .unwrap_or(sausage::cargo::DEFAULT_TEST_TIMEOUT_SECS);
+    let deadline = tokio::time::Instant::now()
+        .checked_add(std::time::Duration::from_secs(timeout_secs))
+        .ok_or_else(|| anyhow::anyhow!("test_timeout_secs is too large"))?;
+    let (ended, mut ended_rx) = tokio::sync::watch::channel(true);
     let mut guest = runtime
         .start_with_args(
             &component,
             InstanceConfig {
                 filesystem,
-                store_ended: tokio::sync::watch::channel(true).0,
+                store_ended: ended,
                 network: true,
                 env,
             },
@@ -88,6 +97,7 @@ async fn instance(
     let mut stdout_open = true;
     let mut stderr_open = true;
     let mut handlers = tokio::task::JoinSet::new();
+    let result = tokio::time::timeout_at(deadline, async {
     while stdout_open || stderr_open || !pending.is_empty() {
         tokio::select! {
             line=async { if let Some(line) = pending.pop_front() { Some(line) } else { guest.stdout.recv().await } }, if stdout_open || !pending.is_empty()=>match line {
@@ -129,11 +139,18 @@ async fn instance(
             },
         }
     }
+    Ok::<_, anyhow::Error>(guest.wait().await)
+    }).await;
     handlers.abort_all();
-    let exit = guest.wait().await;
+    // Dropping the instance aborts even a CPU-bound WASI loop. Wait for the
+    // store and outstanding filesystem work before removing its test world.
+    drop(guest);
+    let _ = ended_rx.wait_for(|ended| *ended).await;
     let _ = stderr_task.await;
     tracker.idle().await;
     host.stop().await;
+    let exit =
+        result.map_err(|_| anyhow::anyhow!("timed out after {timeout_secs} s\n{output}"))??;
     Ok(Run { exit, output })
 }
 /// Extracts libtest names from its stable list format.

cli/tests/host/cargo.rs

@@ -12,6 +12,23 @@ impl TestWorld {
         World::create(&path).unwrap();
         Self(path)
     }
+    /// Short-deadline tests must not queue on another test's Cargo target lock.
+    async fn timeout_host(&self, name: &str) -> Host {
+        Host::start_with_cache(&self.0, &Path::new(CACHE).join("timeouts").join(name))
+            .await
+            .unwrap()
+    }
+    /// Creates a dependency-free plugin fixture.
+    fn simple(&self, name: &str, text: &str) {
+        let root = self.0.join(format!("plugins/{name}/source"));
+        std::fs::create_dir_all(root.join("src")).unwrap();
+        std::fs::write(
+            root.join("Cargo.toml"),
+            format!("[package]\nname='{name}'\nversion='0.1.0'\nedition='2024'\n"),
+        )
+        .unwrap();
+        std::fs::write(root.join("src/main.rs"), text).unwrap();
+    }
     /// Copies a fixture into its plugin source folder.
     fn source(&self, name: &str, source: &Path) {
         copy(source, &self.0.join(format!("plugins/{name}/source")));
@@ -606,6 +623,257 @@ async fn standalone_builder() {
         1
     );
 }
+/// SAU-126: a named CPU-bound WASI test times out, while other instances still run.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn named_test_timeout_and_mutex_release() {
+    let world = TestWorld::new();
+    world.simple("test-timeout", "fn main() {} #[test] fn a_hung() { loop { std::hint::black_box(1); } } #[test] fn z_remaining() { eprintln!(\"REMAINING_TEST_RAN\"); }");
+    world.simple("next", "fn main() {} #[test] fn passes() {}");
+    let integration = world.0.join("plugins/test-timeout/source/tests");
+    std::fs::create_dir_all(&integration).unwrap();
+    std::fs::write(
+        integration.join("remaining.rs"),
+        "#[test] fn integration_remaining() { eprintln!(\"REMAINING_BINARY_RAN\"); }",
+    )
+    .unwrap();
+    let host = world.timeout_host("named").await;
+    let error = tokio::time::timeout(
+        std::time::Duration::from_secs(60),
+        host.call(
+            "cargo.build",
+            json!({"plugin":"test-timeout", "test_timeout_secs":1, "timeout_secs":45}),
+        ),
+    )
+    .await
+    .unwrap()
+    .unwrap_err();
+    assert_eq!(error["code"], -32004);
+    assert_eq!(error["message"], "WASI tests failed");
+    assert_eq!(error["data"]["tests"]["failed"], 1);
+    assert_eq!(error["data"]["tests"]["passed"], 2);
+    let output = error["data"]["output"].as_str().unwrap();
+    assert!(output.contains("test a_hung ... FAILED"), "{output}");
+    assert!(output.contains("timed out after 1 s"), "{output}");
+    assert!(output.contains("REMAINING_TEST_RAN"), "{output}");
+    assert!(output.contains("REMAINING_BINARY_RAN"), "{output}");
+    let next = tokio::time::timeout(
+        std::time::Duration::from_secs(30),
+        host.call("cargo.build", json!({"plugin":"next"})),
+    )
+    .await
+    .unwrap()
+    .unwrap();
+    assert_eq!(next["tests"]["passed"], 1);
+    host.stop().await;
+}
+
+/// Wait for a build-script child without using timing sleeps.
+async fn script_child(world: &TestWorld) -> u32 {
+    tokio::time::timeout(std::time::Duration::from_secs(60), async {
+        loop {
+            if let Ok(text) = std::fs::read_to_string(world.0.join("state/cargo/work/child.pid"))
+                && let Ok(pid) = text.trim().parse()
+            {
+                break pid;
+            }
+            tokio::task::yield_now().await;
+        }
+    })
+    .await
+    .expect("build script never started")
+}
+/// A killed descendant may briefly remain as a zombie, but cannot keep executing.
+async fn child_ended(child: u32) {
+    tokio::time::timeout(std::time::Duration::from_secs(10), async {
+        loop {
+            match std::fs::read_to_string(format!("/proc/{child}/stat")) {
+                Ok(status) if status.split_whitespace().nth(2) == Some("Z") => break,
+                Err(error) if error.kind() == std::io::ErrorKind::NotFound => break,
+                _ => tokio::task::yield_now().await,
+            }
+        }
+    })
+    .await
+    .expect("cargo descendant survived cancellation/timeout");
+}
+
+/// SAU-126: an explicit small total budget kills build.rs and unblocks a queued build.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn build_timeout_and_queued_build() {
+    let world = TestWorld::new();
+    world.source("hang", &fixture("cargo-hang"));
+    world.simple("next", "fn main() {} #[test] fn passes() {}");
+    let host = world.timeout_host("queued").await;
+    let building = host.clone();
+    let task = tokio::spawn(async move {
+        building
+            .call("cargo.build", json!({"plugin":"hang", "timeout_secs":5}))
+            .await
+    });
+    let child = script_child(&world).await;
+    let queued_host = host.clone();
+    let queued = tokio::spawn(async move {
+        queued_host
+            .call("cargo.build", json!({"plugin":"next", "timeout_secs":3}))
+            .await
+    });
+    let error = task.await.unwrap().unwrap_err();
+    assert_eq!(error["code"], -32004);
+    assert_eq!(error["message"], "timeout");
+    assert_eq!(error["data"]["reason"], "timeout");
+    assert_eq!(error["data"]["step"], "tests");
+    assert!(error["data"]["elapsed_secs"].as_f64().unwrap() >= 5.0);
+    assert!(!error["data"]["output"].as_str().unwrap().is_empty());
+    child_ended(child).await;
+    let next = tokio::time::timeout(std::time::Duration::from_secs(20), queued)
+        .await
+        .unwrap()
+        .unwrap()
+        .unwrap();
+    assert_eq!(next["tests"]["passed"], 1);
+    host.stop().await;
+}
+
+/// SAU-126: the same total deadline covers release compilation and retains test results.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn release_build_timeout_retains_tests() {
+    let world = TestWorld::new();
+    world.simple(
+        "release-timeout",
+        r#"fn main() {}
+#[test] fn prepare_release() {
+    std::fs::write(concat!(env!("CARGO_MANIFEST_DIR"), "/release-marker"), "ready").unwrap();
+}"#,
+    );
+    std::fs::write(
+        world.0.join("plugins/release-timeout/source/build.rs"),
+        r#"
+fn main() {
+    println!("cargo:rerun-if-changed=release-marker");
+    if std::path::Path::new("release-marker").exists() {
+        std::process::Command::new("sh")
+            .args(["-c", "echo $$ > child.pid; exec sleep 1000"])
+            .status().unwrap();
+    }
+}"#,
+    )
+    .unwrap();
+    let host = world.timeout_host("release").await;
+    let building = host.clone();
+    let task = tokio::spawn(async move {
+        building
+            .call(
+                "cargo.build",
+                json!({"plugin":"release-timeout", "timeout_secs":5}),
+            )
+            .await
+    });
+    let child = script_child(&world).await;
+    let error = tokio::time::timeout(std::time::Duration::from_secs(10), task)
+        .await
+        .unwrap()
+        .unwrap()
+        .unwrap_err();
+    assert_eq!(error["code"], -32004);
+    assert_eq!(error["data"]["reason"], "timeout");
+    assert_eq!(error["data"]["step"], "release build");
+    assert_eq!(error["data"]["tests"]["passed"], 1);
+    assert!(error["data"]["elapsed_secs"].as_f64().unwrap() >= 5.0);
+    child_ended(child).await;
+    host.stop().await;
+}
+
+/// SAU-126: omission selects the real 900-second deadline, without a 15-minute test.
+#[tokio::test]
+async fn omitted_build_timeout_uses_default() {
+    let world = TestWorld::new();
+    world.source("hang", &fixture("cargo-hang"));
+    let host = world.timeout_host("default").await;
+    let building = host.clone();
+    let task =
+        tokio::spawn(async move { building.call("cargo.build", json!({"plugin":"hang"})).await });
+    let child = script_child(&world).await;
+    tokio::time::pause();
+    tokio::time::advance(std::time::Duration::from_secs(
+        sausage::cargo::DEFAULT_TIMEOUT_SECS,
+    ))
+    .await;
+    // Let the awakened deadline observe the advanced clock before resuming it.
+    tokio::task::yield_now().await;
+    let error = task.await.unwrap().unwrap_err();
+    tokio::time::resume();
+    assert_eq!(error["data"]["reason"], "timeout");
+    assert!(error["data"]["elapsed_secs"].as_f64().unwrap() >= 900.0);
+    child_ended(child).await;
+    host.stop().await;
+}
+
+/// SAU-126: a caller ending stops its attached native build and releases the mutex.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn ended_caller_releases_build_mutex() {
+    let world = TestWorld::new();
+    world.source("hang", &fixture("cargo-hang"));
+    world.simple("next", "fn main() {} #[test] fn passes() {}");
+    let host = world.timeout_host("caller").await;
+    let (finish, finished) = tokio::sync::watch::channel(false);
+    host.register_native(
+        "caller",
+        std::sync::Arc::new(move |context, _, _| {
+            let mut finished = finished.clone();
+            Box::pin(async move {
+                tokio::spawn(
+                    async move { context.call("cargo.build", json!({"plugin":"hang"})).await },
+                );
+                let _ = finished.wait_for(|done| *done).await;
+                Ok(json!({}))
+            })
+        }),
+    );
+    let calling = host.clone();
+    let caller = tokio::spawn(async move { calling.call("caller.run", json!({})).await });
+    let child = script_child(&world).await;
+    let queued_host = host.clone();
+    let queued = tokio::spawn(async move {
+        queued_host
+            .call("cargo.build", json!({"plugin":"next"}))
+            .await
+    });
+    finish.send_replace(true);
+    caller.await.unwrap().unwrap();
+    let next = tokio::time::timeout(std::time::Duration::from_secs(12), queued)
+        .await
+        .expect("ended caller retained mutex")
+        .unwrap()
+        .unwrap();
+    assert_eq!(next["tests"]["passed"], 1);
+    child_ended(child).await;
+    host.stop().await;
+}
+
+/// SAU-126: discovery exposes non-null defaults; invalid budgets cannot disable limits.
+#[tokio::test]
+async fn timeout_params_discovery_and_validation() {
+    let world = TestWorld::new();
+    let host = Host::start_with_cache(&world.0, Path::new(CACHE))
+        .await
+        .unwrap();
+    let doc = host.call("cargo.rpc.discover", json!({})).await.unwrap();
+    let params = doc["methods"][0]["params"].as_array().unwrap();
+    for (name, default) in [("timeout_secs", 900), ("test_timeout_secs", 120)] {
+        let param = params.iter().find(|param| param["name"] == name).unwrap();
+        assert_eq!(param["schema"]["default"], default);
+        assert_eq!(param["schema"]["minimum"], 1);
+        assert!(!param["description"].as_str().unwrap().is_empty());
+        for value in [json!(0), json!(-1), json!(1.5), json!("1"), json!(null)] {
+            let mut args = json!({"plugin":"missing"});
+            args[name] = value;
+            let error = host.call("cargo.build", args).await.unwrap_err();
+            assert_eq!(error["code"], -32602, "{error}");
+        }
+    }
+    host.stop().await;
+}
+
 /// PROTOCOL 11: killing a native build also kills its build-script descendants.
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn kill_process_group() {
@@ -615,9 +883,7 @@ async fn kill_process_group() {
     );
     let world = TestWorld::new();
     world.source("hang", &fixture("cargo-hang"));
-    let host = Host::start_with_cache(&world.0, Path::new(CACHE))
-        .await
-        .unwrap();
+    let host = world.timeout_host("kill").await;
     let building = host.clone();
     let task =
         tokio::spawn(async move { building.call("cargo.build", json!({"plugin":"hang"})).await });
@@ -685,8 +951,23 @@ async fn kill_process_group() {
             .unwrap()
             .is_empty()
     );
+    // Queue a build on the SAME builder before cancelling the lock holder.
+    world.simple("next", "fn main() {} #[test] fn passes() {}");
+    let queued_host = host.clone();
+    let queued = tokio::spawn(async move {
+        queued_host
+            .call("cargo.build", json!({"plugin":"next"}))
+            .await
+    });
     host.call("core.kill", json!({"pid":pid})).await.unwrap();
     assert!(task.await.unwrap().is_err());
+    child_ended(ancestor).await;
+    let next = tokio::time::timeout(std::time::Duration::from_secs(10), queued)
+        .await
+        .expect("cancelled build retained mutex")
+        .unwrap()
+        .unwrap();
+    assert_eq!(next["tests"]["passed"], 1);
     tokio::time::timeout(std::time::Duration::from_secs(10), async {
         loop {
             let status = std::fs::read_to_string(format!("/proc/{child}/stat"));