diff --git a/Cargo.lock b/Cargo.lock
index 369c0aa..e97e4da 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2264,6 +2264,7 @@ name = "searchi-core"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "libc",
  "lopdf",
  "quick-xml",
  "rusqlite",
@@ -2273,6 +2274,19 @@ dependencies = [
  "sha2 0.10.9",
  "tempfile",
  "walkdir",
+ "windows-sys 0.61.2",
+ "zip",
+]
+
+[[package]]
+name = "searchi-extract-worker"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "libc",
+ "searchi-core",
+ "serde_json",
+ "windows-sys 0.61.2",
  "zip",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 12c9794..8dcb843 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,5 @@
 [workspace]
-members = ["crates/searchi-core", "crates/searchi-cli", "crates/searchi-semantic", "crates/searchi-service", "crates/searchi-assets", "crates/searchi-media", "crates/searchi-ai"]
+members = ["crates/searchi-core", "crates/searchi-cli", "crates/searchi-semantic", "crates/searchi-service", "crates/searchi-assets", "crates/searchi-media", "crates/searchi-ai", "crates/searchi-extract-worker"]
 resolver = "2"
 
 [workspace.package]
diff --git a/crates/searchi-core/Cargo.toml b/crates/searchi-core/Cargo.toml
index c219931..0039319 100644
--- a/crates/searchi-core/Cargo.toml
+++ b/crates/searchi-core/Cargo.toml
@@ -16,6 +16,12 @@ lopdf = { version = "0.45", default-features = false }
 zip = { version = "8", default-features = false, features = ["deflate"] }
 quick-xml = "0.42"
 
+[target.'cfg(windows)'.dependencies]
+windows-sys = { version = "0.61", features = ["Win32_Foundation", "Win32_Security", "Win32_System_JobObjects", "Win32_System_Threading"] }
+
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+
 [dev-dependencies]
 tempfile = "3"
 serde_json.workspace = true
diff --git a/crates/searchi-core/src/extraction_process.rs b/crates/searchi-core/src/extraction_process.rs
new file mode 100644
index 0000000..1fbea63
--- /dev/null
+++ b/crates/searchi-core/src/extraction_process.rs
@@ -0,0 +1,459 @@
+//! One bounded, path-free document request per resource-limited child process.
+//! The configured executable is trusted application code, not a search result.
+use crate::{
+    extraction_protocol::{ExtractionResponse, RequestHeader},
+    extraction_transport,
+};
+use std::{
+    io::{Read, Write},
+    path::PathBuf,
+    process::{Child, Command, Stdio},
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        mpsc,
+    },
+    thread,
+    time::{Duration, Instant},
+};
+
+/// Parser limits are fixed; callers may shorten, but never extend, the deadline.
+#[derive(Debug, Clone)]
+pub struct ProcessConfig {
+    pub executable: PathBuf,
+    pub timeout: Duration,
+}
+
+#[derive(Debug)]
+pub enum ProcessError {
+    Cancelled,
+    TimedOut,
+    Failed(String),
+}
+impl std::fmt::Display for ProcessError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Cancelled => f.write_str("Document extraction cancelled"),
+            Self::TimedOut => f.write_str("Document extraction timed out"),
+            Self::Failed(s) => write!(f, "Document extraction failed: {s}"),
+        }
+    }
+}
+impl std::error::Error for ProcessError {}
+fn failed(error: impl std::fmt::Display) -> ProcessError {
+    ProcessError::Failed(error.to_string())
+}
+enum Event {
+    Written,
+    Response(ExtractionResponse),
+    Stderr,
+}
+
+/// Includes pipe writes, response EOF and process exit in the same deadline.
+/// No parser fallback occurs when limits, transport or worker execution fail.
+pub fn run(
+    config: &ProcessConfig,
+    request: RequestHeader,
+    input: Vec<u8>,
+    cancelled: &AtomicBool,
+) -> Result<ExtractionResponse, ProcessError> {
+    if config.timeout.is_zero() || config.timeout > Duration::from_secs(30) {
+        return Err(failed("Invalid extraction deadline"));
+    }
+    request.validate_payload(&input).map_err(failed)?;
+    if cancelled.load(Ordering::Relaxed) {
+        return Err(ProcessError::Cancelled);
+    }
+    let started = Instant::now();
+    let mut command = Command::new(&config.executable);
+    command
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped());
+    #[cfg(unix)]
+    {
+        use std::os::unix::process::CommandExt;
+        command.process_group(0);
+    }
+    #[cfg(windows)]
+    {
+        use std::os::windows::process::CommandExt;
+        command.creation_flags(0x08000000);
+    }
+    let child = command.spawn().map_err(failed)?;
+    let mut owned = OwnedChild {
+        child,
+        threads: Vec::new(),
+        completed: false,
+        #[cfg(windows)]
+        job: None,
+    };
+    // The writer cannot transmit even the admission prefix until assignment succeeds.
+    #[cfg(windows)]
+    {
+        owned.job = Some(Job::assign(&owned.child).map_err(failed)?);
+    }
+    let mut stdin = owned
+        .child
+        .stdin
+        .take()
+        .ok_or_else(|| failed("Missing stdin"))?;
+    let mut stdout = owned
+        .child
+        .stdout
+        .take()
+        .ok_or_else(|| failed("Missing stdout"))?;
+    let mut stderr = owned
+        .child
+        .stderr
+        .take()
+        .ok_or_else(|| failed("Missing stderr"))?;
+    let (tx, rx) = mpsc::sync_channel(3);
+    let writer_tx = tx.clone();
+    let writer_request = request.clone();
+    owned.spawn("document-input", move || {
+        let result = (|| {
+            extraction_transport::write_request(&mut stdin, &writer_request, &input)
+                .map_err(failed)?;
+            stdin.flush().map_err(failed)?;
+            Ok(Event::Written)
+        })();
+        drop(stdin);
+        let _ = writer_tx.send(result);
+    })?;
+    let reader_tx = tx.clone();
+    owned.spawn("document-output", move || {
+        let result = (|| {
+            let response =
+                extraction_transport::read_response(&mut stdout, &request).map_err(failed)?;
+            let mut extra = [0];
+            if stdout.read(&mut extra).map_err(failed)? != 0 {
+                return Err(failed("Trailing extraction output"));
+            }
+            Ok(Event::Response(response))
+        })();
+        let _ = reader_tx.send(result);
+    })?;
+    owned.spawn("document-errors", move || {
+        // Do not log document-derived stderr. Bound total bytes, not just retention.
+        let result = (|| {
+            let mut total = 0usize;
+            let mut buffer = [0; 1024];
+            loop {
+                let count = stderr.read(&mut buffer).map_err(failed)?;
+                if count == 0 {
+                    break;
+                }
+                total += count;
+                if total > 16 * 1024 {
+                    return Err(failed("Worker stderr exceeds budget"));
+                }
+            }
+            Ok(Event::Stderr)
+        })();
+        let _ = tx.send(result);
+    })?;
+    let mut received = 0;
+    let mut response = None;
+    loop {
+        if cancelled.load(Ordering::Relaxed) {
+            return Err(ProcessError::Cancelled);
+        }
+        if started.elapsed() >= config.timeout {
+            return Err(ProcessError::TimedOut);
+        }
+        match rx.recv_timeout(
+            Duration::from_millis(5).min(config.timeout.saturating_sub(started.elapsed())),
+        ) {
+            Ok(Ok(event)) => {
+                received += 1;
+                if let Event::Response(value) = event {
+                    response = Some(value);
+                }
+            }
+            Ok(Err(error)) => return Err(error),
+            Err(mpsc::RecvTimeoutError::Timeout) => {}
+            Err(mpsc::RecvTimeoutError::Disconnected) if received != 3 => {
+                return Err(failed("Extraction I/O worker stopped"))
+            }
+            Err(mpsc::RecvTimeoutError::Disconnected) => thread::sleep(Duration::from_millis(1)),
+        }
+        // Keep the leader unreaped while pipes may still be inherited by descendants.
+        // Its PID then anchors the owned process-group identity during error cleanup.
+        if received == 3 {
+            if let Some(status) = owned.child.try_wait().map_err(failed)? {
+                owned.completed = true;
+                if !status.success() {
+                    return Err(failed("Extraction worker exited unsuccessfully"));
+                }
+                let response = response.ok_or_else(|| failed("Missing extraction response"))?;
+                return Ok(response);
+            }
+        }
+    }
+}
+
+struct OwnedChild {
+    child: Child,
+    threads: Vec<thread::JoinHandle<()>>,
+    completed: bool,
+    #[cfg(windows)]
+    job: Option<Job>,
+}
+impl OwnedChild {
+    fn spawn(
+        &mut self,
+        name: &str,
+        work: impl FnOnce() + Send + 'static,
+    ) -> Result<(), ProcessError> {
+        self.threads.push(
+            thread::Builder::new()
+                .name(name.into())
+                .spawn(work)
+                .map_err(failed)?,
+        );
+        Ok(())
+    }
+}
+impl Drop for OwnedChild {
+    fn drop(&mut self) {
+        #[cfg(windows)]
+        if let Some(job) = self.job.take() {
+            drop(job);
+        }
+        if !self.completed {
+            #[cfg(unix)]
+            unsafe {
+                libc::kill(-(self.child.id() as i32), libc::SIGKILL);
+            }
+            let _ = self.child.kill();
+            let _ = self.child.wait();
+        }
+        for handle in self.threads.drain(..) {
+            let _ = handle.join();
+        }
+    }
+}
+
+#[cfg(windows)]
+struct Job(windows_sys::Win32::Foundation::HANDLE);
+#[cfg(windows)]
+impl Job {
+    fn assign(child: &Child) -> std::io::Result<Self> {
+        use std::os::windows::io::AsRawHandle;
+        use windows_sys::Win32::System::JobObjects::*;
+        unsafe {
+            let handle = CreateJobObjectW(std::ptr::null(), std::ptr::null());
+            if handle.is_null() {
+                return Err(std::io::Error::last_os_error());
+            }
+            let job = Self(handle);
+            let mut limits: JOBOBJECT_EXTENDED_LIMIT_INFORMATION = std::mem::zeroed();
+            limits.BasicLimitInformation.LimitFlags =
+                JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE | JOB_OBJECT_LIMIT_PROCESS_MEMORY;
+            limits.ProcessMemoryLimit = 512 * 1024 * 1024;
+            if SetInformationJobObject(
+                handle,
+                JobObjectExtendedLimitInformation,
+                (&limits as *const JOBOBJECT_EXTENDED_LIMIT_INFORMATION).cast(),
+                std::mem::size_of_val(&limits) as u32,
+            ) == 0
+                || AssignProcessToJobObject(handle, child.as_raw_handle()) == 0
+            {
+                return Err(std::io::Error::last_os_error());
+            }
+            Ok(job)
+        }
+    }
+}
+#[cfg(windows)]
+impl Drop for Job {
+    fn drop(&mut self) {
+        unsafe {
+            windows_sys::Win32::Foundation::CloseHandle(self.0);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::extraction_protocol::{DocumentFormat, ExtractionOutcome};
+
+    // These tests compile real executables. Avoid concurrent rustc/linker and
+    // executable-admission load contaminating the deliberately short deadlines.
+    static PROCESS_FIXTURE_SLOT: std::sync::Mutex<()> = std::sync::Mutex::new(());
+    fn fixture_slot() -> std::sync::MutexGuard<'static, ()> {
+        PROCESS_FIXTURE_SLOT
+            .lock()
+            .unwrap_or_else(|poisoned| poisoned.into_inner())
+    }
+
+    fn fixtures() -> tempfile::TempDir {
+        let directory = tempfile::tempdir().unwrap();
+        let source = directory.path().join("fake.rs");
+        std::fs::write(&source, r#"
+use std::{io::{Read, Write},time::Duration};
+fn main() {
+ let mode=std::env::current_exe().unwrap().file_stem().unwrap().to_string_lossy().into_owned();
+ if mode=="blocked" { std::thread::sleep(Duration::from_secs(60)); return; }
+ if mode=="crash" { std::process::exit(7); }
+ let mut bytes=Vec::new(); std::io::stdin().read_to_end(&mut bytes).unwrap();
+ if mode=="sleep" { std::thread::sleep(Duration::from_secs(60)); return; }
+ if mode=="oversize" { std::io::stdout().write_all(&u32::MAX.to_le_bytes()).unwrap(); return; }
+ let size=u32::from_le_bytes(bytes[..4].try_into().unwrap()) as usize;
+ let header=std::str::from_utf8(&bytes[4..4+size]).unwrap();
+ let digest=header.split("\"input_sha256\":\"").nth(1).unwrap().split('"').next().unwrap();
+ let json=format!("{{\"version\":1,\"input_sha256\":\"{}\",\"outcome\":{{\"status\":\"rejected\",\"reason\":\"controlled fixture\"}}}}",digest);
+ let mut out=std::io::stdout(); out.write_all(&(json.len() as u32).to_le_bytes()).unwrap();out.write_all(json.as_bytes()).unwrap();
+ if mode=="stderr" { std::io::stderr().write_all(&vec![b'x';17000]).unwrap(); }
+ if mode=="extra" { out.write_all(b"extra").unwrap(); }
+}
+"#).unwrap();
+        let executable = directory
+            .path()
+            .join(format!("valid{}", std::env::consts::EXE_SUFFIX));
+        let output = Command::new("rustc")
+            .arg("--edition=2021")
+            .arg(&source)
+            .arg("-o")
+            .arg(&executable)
+            .output()
+            .unwrap();
+        assert!(
+            output.status.success(),
+            "{}",
+            String::from_utf8_lossy(&output.stderr)
+        );
+        for mode in ["blocked", "crash", "sleep", "oversize", "stderr", "extra"] {
+            std::fs::copy(
+                &executable,
+                directory
+                    .path()
+                    .join(format!("{mode}{}", std::env::consts::EXE_SUFFIX)),
+            )
+            .unwrap();
+        }
+        directory
+    }
+    fn config(directory: &tempfile::TempDir, mode: &str) -> ProcessConfig {
+        ProcessConfig {
+            executable: directory
+                .path()
+                .join(format!("{mode}{}", std::env::consts::EXE_SUFFIX)),
+            timeout: Duration::from_secs(2),
+        }
+    }
+    fn request(bytes: &[u8]) -> RequestHeader {
+        RequestHeader::from_bytes(DocumentFormat::Pdf, bytes).unwrap()
+    }
+
+    #[test]
+    fn valid_response_requires_complete_input_eof_frame_and_exit() {
+        let _slot = fixture_slot();
+        let directory = fixtures();
+        let result = run(
+            &config(&directory, "valid"),
+            request(b"fixture"),
+            b"fixture".to_vec(),
+            &AtomicBool::new(false),
+        )
+        .unwrap();
+        assert!(matches!(result.outcome, ExtractionOutcome::Rejected { .. }));
+    }
+    #[test]
+    fn crashes_oversized_trailing_output_and_stderr_fail_closed() {
+        let _slot = fixture_slot();
+        let directory = fixtures();
+        for mode in ["crash", "oversize", "extra", "stderr"] {
+            let result = run(
+                &config(&directory, mode),
+                request(b"fixture"),
+                b"fixture".to_vec(),
+                &AtomicBool::new(false),
+            );
+            assert!(
+                matches!(result, Err(ProcessError::Failed(_))),
+                "{mode}: {result:?}"
+            );
+        }
+    }
+    #[test]
+    fn deadline_covers_blocked_stdin_and_missing_response() {
+        let _slot = fixture_slot();
+        let directory = fixtures();
+        for mode in ["blocked", "sleep"] {
+            let bytes = vec![0; 1024 * 1024];
+            let started = Instant::now();
+            assert!(matches!(
+                run(
+                    &config(&directory, mode),
+                    request(&bytes),
+                    bytes,
+                    &AtomicBool::new(false)
+                ),
+                Err(ProcessError::TimedOut)
+            ));
+            assert!(started.elapsed() < Duration::from_secs(5));
+        }
+    }
+    #[test]
+    fn cancellation_reaps_a_blocked_writer_and_invalid_limits_do_not_spawn() {
+        let _slot = fixture_slot();
+        let directory = fixtures();
+        let cancelled = AtomicBool::new(false);
+        thread::scope(|scope| {
+            scope.spawn(|| {
+                thread::sleep(Duration::from_millis(50));
+                cancelled.store(true, Ordering::Relaxed);
+            });
+            let bytes = vec![0; 1024 * 1024];
+            assert!(matches!(
+                run(
+                    &config(&directory, "blocked"),
+                    request(&bytes),
+                    bytes,
+                    &cancelled
+                ),
+                Err(ProcessError::Cancelled)
+            ));
+        });
+        let mut invalid = config(&directory, "valid");
+        invalid.timeout = Duration::from_secs(31);
+        assert!(matches!(
+            run(&invalid, request(b""), Vec::new(), &AtomicBool::new(false)),
+            Err(ProcessError::Failed(_))
+        ));
+    }
+
+    #[test]
+    #[ignore = "requires a separately built SEARCHI_EXTRACT_WORKER executable"]
+    fn real_worker_parses_exact_docx_bytes_in_parent_owned_limits() {
+        use std::io::Cursor;
+        let mut archive = zip::ZipWriter::new(Cursor::new(Vec::new()));
+        archive
+            .start_file(
+                "word/document.xml",
+                zip::write::SimpleFileOptions::default(),
+            )
+            .unwrap();
+        archive.write_all(b"<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:r><w:t>Supplier cancellation notice</w:t></w:r></w:p></w:body></w:document>").unwrap();
+        let input = archive.finish().unwrap().into_inner();
+        let header = RequestHeader::from_bytes(DocumentFormat::Docx, &input).unwrap();
+        let config = ProcessConfig {
+            executable: std::env::var_os("SEARCHI_EXTRACT_WORKER")
+                .expect("Set actual worker executable")
+                .into(),
+            timeout: Duration::from_secs(5),
+        };
+        let response = run(&config, header, input, &AtomicBool::new(false)).unwrap();
+        match response.outcome {
+            ExtractionOutcome::Extracted { passages } => {
+                assert_eq!(passages.len(), 1);
+                assert_eq!(passages[0].text, "Supplier cancellation notice");
+                assert_eq!(passages[0].source.kind, "paragraph");
+                assert_eq!(passages[0].source.number, 1);
+            }
+            _ => panic!("Actual DOCX unexpectedly rejected"),
+        }
+    }
+}
diff --git a/crates/searchi-core/src/lib.rs b/crates/searchi-core/src/lib.rs
index 9b37da2..639d6e3 100644
--- a/crates/searchi-core/src/lib.rs
+++ b/crates/searchi-core/src/lib.rs
@@ -5,6 +5,7 @@
 //! Worker isolation remains a production milestone.
 mod code;
 mod extraction;
+pub mod extraction_process;
 pub mod extraction_protocol;
 pub mod extraction_transport;
 pub use code::{code_file_predicate, is_code_path, CODE_EXTENSIONS};
diff --git a/crates/searchi-extract-worker/Cargo.toml b/crates/searchi-extract-worker/Cargo.toml
new file mode 100644
index 0000000..78942dc
--- /dev/null
+++ b/crates/searchi-extract-worker/Cargo.toml
@@ -0,0 +1,20 @@
+[package]
+name = "searchi-extract-worker"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+anyhow.workspace = true
+searchi-core = { path = "../searchi-core" }
+
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+
+[target.'cfg(windows)'.dependencies]
+windows-sys = { version = "0.61", features = ["Win32_Foundation", "Win32_System_JobObjects", "Win32_System_Threading"] }
+
+[dev-dependencies]
+serde_json.workspace = true
+zip = { version = "8", default-features = false, features = ["deflate"] }
+
diff --git a/crates/searchi-extract-worker/src/main.rs b/crates/searchi-extract-worker/src/main.rs
new file mode 100644
index 0000000..c03f81d
--- /dev/null
+++ b/crates/searchi-extract-worker/src/main.rs
@@ -0,0 +1,40 @@
+//! Single-request, path-free document parser helper. Parent owns deadline,
+//! cancellation and Windows Job lifetime; this helper never spawns children.
+mod resources;
+use anyhow::{ensure, Result};
+use searchi_core::{extraction_protocol::extract_document, extraction_transport};
+use std::io::{self, Read, Write};
+
+fn run() -> Result<()> {
+    ensure!(std::env::args_os().len() == 1, "Arguments are unsupported");
+    let mut input = io::stdin().lock();
+    #[cfg(unix)]
+    resources::apply()?;
+    // Prefix arrival synchronizes with Windows parent job assignment. No
+    // attacker-declared allocation or parser runs before the policy check.
+    let mut prefix = [0u8; 4];
+    input.read_exact(&mut prefix)?;
+    #[cfg(not(unix))]
+    resources::apply()?;
+    let mut input = io::Cursor::new(prefix).chain(&mut input);
+    let (request, bytes) = extraction_transport::read_request(&mut input)?;
+    // Parent closes stdin after the single frame. Extra data never reaches a parser.
+    let mut trailing = [0u8; 1];
+    ensure!(
+        input.read(&mut trailing)? == 0,
+        "Trailing input is unsupported"
+    );
+    let response = extract_document(&request, &bytes)?;
+    let mut output = io::stdout().lock();
+    extraction_transport::write_response(&mut output, &response, &request)?;
+    output.flush()?;
+    Ok(())
+}
+
+fn main() {
+    if run().is_err() {
+        // Do not echo document contents, external paths or untrusted protocol values.
+        eprintln!("searchi extraction worker rejected request or resource policy");
+        std::process::exit(1);
+    }
+}
diff --git a/crates/searchi-extract-worker/src/resources.rs b/crates/searchi-extract-worker/src/resources.rs
new file mode 100644
index 0000000..3b89517
--- /dev/null
+++ b/crates/searchi-extract-worker/src/resources.rs
@@ -0,0 +1,61 @@
+use anyhow::{ensure, Result};
+
+const MEMORY_BYTES: usize = 512 * 1024 * 1024;
+
+#[cfg(windows)]
+pub fn apply() -> Result<()> {
+    use windows_sys::Win32::System::JobObjects::{
+        JobObjectExtendedLimitInformation, QueryInformationJobObject,
+        JOBOBJECT_EXTENDED_LIMIT_INFORMATION, JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE,
+        JOB_OBJECT_LIMIT_PROCESS_MEMORY,
+    };
+    let mut information: JOBOBJECT_EXTENDED_LIMIT_INFORMATION = unsafe { std::mem::zeroed() };
+    // NULL addresses the job associated with the current process. The parent
+    // must assign this process before writing its first input bytes.
+    let success = unsafe {
+        QueryInformationJobObject(
+            std::ptr::null_mut(),
+            JobObjectExtendedLimitInformation,
+            &mut information as *mut _ as *mut _,
+            std::mem::size_of_val(&information) as u32,
+            std::ptr::null_mut(),
+        )
+    };
+    ensure!(
+        success != 0,
+        "Extraction worker requires parent resource job"
+    );
+    let required = JOB_OBJECT_LIMIT_PROCESS_MEMORY | JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
+    ensure!(
+        information.BasicLimitInformation.LimitFlags & required == required
+            && information.ProcessMemoryLimit > 0
+            && information.ProcessMemoryLimit <= MEMORY_BYTES,
+        "Extraction worker job resource policy is missing"
+    );
+    Ok(())
+}
+
+#[cfg(unix)]
+pub fn apply() -> Result<()> {
+    for (resource, maximum) in [
+        (libc::RLIMIT_AS, MEMORY_BYTES as libc::rlim_t),
+        (libc::RLIMIT_CPU, 30 as libc::rlim_t),
+    ] {
+        let value = libc::rlimit {
+            rlim_cur: maximum,
+            rlim_max: maximum,
+        };
+        // Applied before allocating input or invoking any parser. Platform
+        // enforcement semantics, especially macOS, require native evidence.
+        ensure!(
+            unsafe { libc::setrlimit(resource, &value) } == 0,
+            "Cannot install extraction resource limit"
+        );
+    }
+    Ok(())
+}
+
+#[cfg(not(any(windows, unix)))]
+pub fn apply() -> Result<()> {
+    anyhow::bail!("Extraction resource policy unsupported on this platform")
+}
diff --git a/crates/searchi-extract-worker/tests/parent_roundtrip.rs b/crates/searchi-extract-worker/tests/parent_roundtrip.rs
new file mode 100644
index 0000000..aa3f090
--- /dev/null
+++ b/crates/searchi-extract-worker/tests/parent_roundtrip.rs
@@ -0,0 +1,63 @@
+//! Exercise the real helper through the shared engine's process owner.
+use searchi_core::{
+    extraction_process::{run, ProcessConfig, ProcessError},
+    extraction_protocol::{DocumentFormat, ExtractionOutcome, RequestHeader},
+};
+use std::{
+    io::{Cursor, Write},
+    path::PathBuf,
+    sync::atomic::AtomicBool,
+    time::Duration,
+};
+
+fn config() -> ProcessConfig {
+    ProcessConfig {
+        executable: PathBuf::from(env!("CARGO_BIN_EXE_searchi-extract-worker")),
+        timeout: Duration::from_secs(10),
+    }
+}
+
+#[test]
+fn actual_parent_and_worker_return_original_docx_passage_and_digest() {
+    let mut document = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    document
+        .start_file(
+            "word/document.xml",
+            zip::write::SimpleFileOptions::default(),
+        )
+        .unwrap();
+    document.write_all(br#"<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p><w:r><w:t>Cancel with sixty days written notice.</w:t></w:r></w:p></w:body></w:document>"#).unwrap();
+    let input = document.finish().unwrap().into_inner();
+    let request = RequestHeader::from_bytes(DocumentFormat::Docx, &input).unwrap();
+    let expected_hash = request.input_sha256.clone();
+    let response = run(&config(), request, input, &AtomicBool::new(false)).unwrap();
+    assert_eq!(response.input_sha256, expected_hash);
+    let ExtractionOutcome::Extracted { passages } = response.outcome else {
+        panic!("Valid document rejected");
+    };
+    assert_eq!(passages.len(), 1);
+    assert_eq!(passages[0].text, "Cancel with sixty days written notice.");
+    assert_eq!(passages[0].source.kind, "paragraph");
+    assert_eq!(passages[0].source.number, 1);
+}
+
+#[test]
+fn parser_rejection_and_cancellation_remain_distinct() {
+    let input = b"invalid PDF".to_vec();
+    let request = RequestHeader::from_bytes(DocumentFormat::Pdf, &input).unwrap();
+    let response = run(
+        &config(),
+        request.clone(),
+        input.clone(),
+        &AtomicBool::new(false),
+    )
+    .unwrap();
+    assert!(matches!(
+        response.outcome,
+        ExtractionOutcome::Rejected { .. }
+    ));
+    assert!(matches!(
+        run(&config(), request, input, &AtomicBool::new(true)),
+        Err(ProcessError::Cancelled)
+    ));
+}
diff --git a/crates/searchi-extract-worker/tests/protocol.rs b/crates/searchi-extract-worker/tests/protocol.rs
new file mode 100644
index 0000000..16afaba
--- /dev/null
+++ b/crates/searchi-extract-worker/tests/protocol.rs
@@ -0,0 +1,153 @@
+use searchi_core::{
+    extraction_protocol::{DocumentFormat, ExtractionOutcome, RequestHeader, MAX_HEADER_BYTES},
+    extraction_transport::{read_response, write_request},
+};
+use std::{
+    io::{Cursor, Write},
+    process::{Command, Stdio},
+    time::{Duration, Instant},
+};
+
+#[cfg(windows)]
+struct Job(windows_sys::Win32::Foundation::HANDLE);
+#[cfg(windows)]
+impl Job {
+    fn attach(child: &std::process::Child) -> Self {
+        use std::os::windows::io::AsRawHandle;
+        use windows_sys::Win32::System::JobObjects::*;
+        let handle = unsafe { CreateJobObjectW(std::ptr::null(), std::ptr::null()) };
+        assert!(!handle.is_null());
+        let guard = Self(handle);
+        let mut info: JOBOBJECT_EXTENDED_LIMIT_INFORMATION = unsafe { std::mem::zeroed() };
+        info.BasicLimitInformation.LimitFlags =
+            JOB_OBJECT_LIMIT_PROCESS_MEMORY | JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
+        info.ProcessMemoryLimit = 512 * 1024 * 1024;
+        assert_ne!(
+            unsafe {
+                SetInformationJobObject(
+                    handle,
+                    JobObjectExtendedLimitInformation,
+                    &info as *const _ as *const _,
+                    std::mem::size_of_val(&info) as u32,
+                )
+            },
+            0
+        );
+        assert_ne!(
+            unsafe { AssignProcessToJobObject(handle, child.as_raw_handle() as _) },
+            0
+        );
+        guard
+    }
+}
+#[cfg(windows)]
+impl Drop for Job {
+    fn drop(&mut self) {
+        unsafe {
+            windows_sys::Win32::Foundation::CloseHandle(self.0);
+        }
+    }
+}
+
+fn exchange(wire: &[u8], arguments: &[&str], attach: bool) -> std::process::Output {
+    let mut child = Command::new(env!("CARGO_BIN_EXE_searchi-extract-worker"))
+        .args(arguments)
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    #[cfg(windows)]
+    let _job = attach.then(|| Job::attach(&child));
+    #[cfg(not(windows))]
+    let _ = attach;
+    let mut input = child.stdin.take().unwrap();
+    // Unknown arguments may terminate before the request write.
+    let _ = input.write_all(wire);
+    drop(input);
+    let deadline = Instant::now() + Duration::from_secs(30);
+    while child.try_wait().unwrap().is_none() {
+        if Instant::now() >= deadline {
+            child.kill().unwrap();
+            child.wait().unwrap();
+            panic!("Worker subprocess exceeded deadline");
+        }
+        std::thread::sleep(Duration::from_millis(10));
+    }
+    child.wait_with_output().unwrap()
+}
+
+fn wire(format: DocumentFormat, input: &[u8]) -> (RequestHeader, Vec<u8>) {
+    let request = RequestHeader::from_bytes(format, input).unwrap();
+    let mut bytes = Vec::new();
+    write_request(&mut bytes, &request, input).unwrap();
+    (request, bytes)
+}
+
+#[test]
+fn valid_docx_and_corrupt_pdf_are_real_worker_responses() {
+    let mut archive = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    archive
+        .start_file(
+            "word/document.xml",
+            zip::write::SimpleFileOptions::default(),
+        )
+        .unwrap();
+    archive.write_all(br#"<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p><w:r><w:t>supplier cancellation</w:t></w:r></w:p></w:body></w:document>"#).unwrap();
+    let input = archive.finish().unwrap().into_inner();
+    let (request, bytes) = wire(DocumentFormat::Docx, &input);
+    let output = exchange(&bytes, &[], true);
+    assert!(
+        output.status.success(),
+        "{}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+    let response = read_response(&mut Cursor::new(output.stdout), &request).unwrap();
+    let ExtractionOutcome::Extracted { passages } = response.outcome else {
+        panic!("Valid DOCX rejected");
+    };
+    assert_eq!(passages[0].text, "supplier cancellation");
+    assert_eq!(passages[0].source.number, 1);
+    let (request, bytes) = wire(DocumentFormat::Pdf, b"not a PDF");
+    let output = exchange(&bytes, &[], true);
+    assert!(output.status.success());
+    let response = read_response(&mut Cursor::new(output.stdout), &request).unwrap();
+    assert!(matches!(
+        response.outcome,
+        ExtractionOutcome::Rejected { .. }
+    ));
+}
+
+#[test]
+fn rejects_unknown_arguments_trailing_input_hash_version_and_header_budget() {
+    let (request, mut bytes) = wire(DocumentFormat::Pdf, b"invalid PDF");
+    bytes.push(0);
+    let output = exchange(&bytes, &[], true);
+    assert!(!output.status.success() && output.stdout.is_empty());
+    for change_version in [false, true] {
+        let mut changed = request.clone();
+        if change_version {
+            changed.version += 1;
+        } else {
+            changed.input_sha256 = "0".repeat(64);
+        }
+        let header = serde_json::to_vec(&changed).unwrap();
+        let mut bytes = (header.len() as u32).to_le_bytes().to_vec();
+        bytes.extend(header);
+        bytes.extend(b"invalid PDF");
+        let output = exchange(&bytes, &[], true);
+        assert!(!output.status.success() && output.stdout.is_empty());
+    }
+    let output = exchange(&((MAX_HEADER_BYTES + 1) as u32).to_le_bytes(), &[], true);
+    assert!(!output.status.success() && output.stdout.is_empty());
+    let output = exchange(&[], &["--arbitrary-path"], true);
+    assert!(!output.status.success() && output.stdout.is_empty());
+}
+
+#[cfg(windows)]
+#[test]
+fn rejects_worker_without_parent_job_before_payload_parsing() {
+    let (_, bytes) = wire(DocumentFormat::Pdf, b"invalid PDF");
+    let output = exchange(&bytes, &[], false);
+    assert!(!output.status.success() && output.stdout.is_empty());
+}
diff --git a/docs/EXTRACTION-ISOLATION.md b/docs/EXTRACTION-ISOLATION.md
index 8a40355..2d9c9ec 100644
--- a/docs/EXTRACTION-ISOLATION.md
+++ b/docs/EXTRACTION-ISOLATION.md
@@ -43,8 +43,10 @@ Source files and SQLite are not one atomic transaction. Preserve semantic and
 agent excerpt provenance checks and clear old passages on parser rejection.
 
 - [x] Buffer API and typed protocol with independent limits and genuine fixtures.
-- [ ] Headless Rust helper with no GUI dependencies or arbitrary path access.
-- [ ] Parent process deadlines, cancellation, resource setup and kill/reap tests.
+- [x] Headless Rust helper with no GUI dependencies or arbitrary path arguments
+  (Windows execution tested; native Unix resource verification remains open).
+- [x] Parent process deadlines, cancellation, resource setup and kill/reap tests
+  on Windows; native Unix execution remains open.
 - [ ] Shared-engine document adapter, explicit failures and post-parser guards.
 - [ ] Normal helper discovery and required release staging on all target systems.
 - [ ] Relocated Windows/WSL packages and actual parser fixtures through the helper.
@@ -100,3 +102,30 @@ parsing or structured parser rejection must produce one bounded, flushed frame;
 the parent independently checks EOF and exit status. None of these limits is a
 filesystem/network sandbox or proof that every malicious parser input is safe.
 The helper does not add arbitrary file reads or writes to its application API.
+
+## Windows worker and process-owner evidence
+
+The new workspace binary and `searchi-core::extraction_process` now work
+together. Three real worker subprocess tests cover DOCX parsing, corrupt PDF
+rejection, malformed/trailing input, wrong version/hash, excessive header,
+unknown arguments and missing Windows Job protection. Two further tests execute
+the actual helper through the shared parent adapter, checking paragraph text,
+source position, exact digest and parser-rejection/cancellation distinction.
+
+Four controlled child-process cases exercise crash, oversized/trailing output,
+excess stderr, blocked input, missing response, timeout and cancellation.
+The stderr case has a valid response, so an unrelated missing-frame failure
+cannot mask the stderr budget. Per-test helper compiler activity is serialized
+to avoid contaminating two-second test deadlines; product deadlines were not
+relaxed. Owned temporary fixtures are cleaned after process/thread cleanup.
+Unix cleanup defers reaping until all I/O events, avoiding use of a reaped
+leader's process-group identifier. Native Unix execution still needs validation.
+
+The final combined Windows CPU run passed 59 tests (54 core and 5 worker);
+the initially ignored actual-worker core test then passed explicitly, giving
+60 executed checks. Strict all-target Clippy passed for both crates. No GPU or
+model inference was used. Windows Job configuration/verification is exercised,
+but adversarial memory-exhaustion behavior and native Unix limits remain open.
+Default indexing still uses the earlier in-process parser; worker discovery,
+post-parser source validation, production adapter activation and required
+release staging are the next steps. No published installer contains this helper.