diff --git a/docs/contracts/workspace-preprocessing-cli.md b/docs/contracts/workspace-preprocessing-cli.md
index a21bc44c..6c28e90d 100644
--- a/docs/contracts/workspace-preprocessing-cli.md
+++ b/docs/contracts/workspace-preprocessing-cli.md
@@ -24,6 +24,6 @@ The bounded schema-v1 stdin envelope is exact: omitted fields are not equivalent
 * `check`: `resume` is required; `annotations` and `reviewedCandidates` are either both present or both absent. `annotations` is exactly `{basename, contentBase64, sha256}`.
 * `index-schema`: no additional fields.
 
-No other fields, duplicate JSON value, host path, raw SQL, or raw annotation content are accepted. SQL and annotations use a logical basename, base64 bytes, and a declared `sha256:<hex>` digest. The complete request is at most 1 MiB and every supplied field/value must exactly match the command-derived envelope. Candidate responses may carry the internal `hostExport` (`mediaType`, `sha256`, `contentBase64`) only for `suggest-fks`; its object is strict (unknown fields rejected) and is always verified, even without `--output`: YAML media type (`application/yaml` or `text/yaml`), UTF-8, digest, and decoded size at most 700 KiB. It is removed from the public result and written exclusively only after result/run/identity validation. Output publication uses restrictive mode `0600` and refuses existing leaves, links, hardlinks, directories, replacement races, and reparse points.
+No other fields, duplicate JSON value, host path, raw SQL, or raw annotation content are accepted. SQL and annotations use a logical basename, base64 bytes, and a declared `sha256:<hex>` digest. The request envelope is independently capped at 24 MiB (after JSON/base64 encoding), enough to carry the frozen 1 MiB-per-file/16 MiB aggregate raw ingress bounds; every supplied field/value must exactly match the command-derived envelope. Candidate responses may carry the internal `hostExport` (`mediaType`, `sha256`, `contentBase64`) only for `suggest-fks`; its object is strict (unknown fields rejected) and is always verified, even without `--output`: YAML media type (`application/yaml` or `text/yaml`), UTF-8, digest, and decoded size at most 700 KiB. It is removed from the public result and written exclusively only after result/run/identity validation. Output publication uses restrictive mode `0600` and refuses existing leaves, links, hardlinks, directories, replacement races, and reparse points.
 
 The public result has schema version 1 and only these fields: `status`, `code`, workspace/revision/descriptor/operation identities, optional run and child run IDs, completed stages, counts, artifact identities, and warnings. Revisions/descriptors are 40-hex; run IDs are 32-hex; artifact digests are `sha256:<hex>`. Allowed statuses are `succeeded`, `unchanged`, `dry_run`, `blocked`, and `failed`. Allowed codes are `ok`, `workspace_not_found`, `workspace_not_activatable`, `binding_missing`, `preprocessing_conflict`, `preprocessing_resume_mismatch`, `manual_review_required`, `evidence_materialization_required`, `effective_config_mismatch`, `semantic_index_incompatible`, `annotation_invalid`, `egress_policy_refused`, and `registry_bootstrap_recovery_conflict`. `succeeded`, `unchanged`, and `dry_run` require `ok` and child exit 0. `blocked` requires one of `manual_review_required`, `evidence_materialization_required`, `preprocessing_conflict`, `preprocessing_resume_mismatch`, or `registry_bootstrap_recovery_conflict`, and child exit 3. `failed` requires a non-`ok` operational code other than those blocked-only codes, and child exit 1. A nonzero child exit is never accepted for another status/code combination. Stdout is capped at 1 MiB and stderr at 64 KiB. Compose is invoked only as `compose run --rm --no-deps --no-TTY workspace-maintenance ...`; output never includes child stderr or secrets.
diff --git a/tools/thothctl/cmd/thothctl/main_test.go b/tools/thothctl/cmd/thothctl/main_test.go
index fa3b7b83..4f7046b5 100644
--- a/tools/thothctl/cmd/thothctl/main_test.go
+++ b/tools/thothctl/cmd/thothctl/main_test.go
@@ -105,6 +105,59 @@ func TestUsageDocumentsClosedConfigureUpdateSourcesAndMaintenanceRecovery(t *tes
 	}
 }
 
+func TestRunWorkspacePublicDispatchExitMatrix(t *testing.T) {
+	cases := []struct {
+		name, status, code string
+		exit               int
+	}{
+		{"succeeded", "succeeded", "ok", 0},
+		{"blocked", "blocked", "manual_review_required", 3},
+		{"failed", "failed", "workspace_not_found", 1},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			fixture := newCLIFixture(t, "")
+			fixture.setEnvironment(t)
+			t.Setenv("THOTHCTL_FAKE_WORKSPACE_RESULT", fmt.Sprintf(`{"schemaVersion":1,"status":%q,"code":%q,"workspaceId":"psd","workspaceRevision":"%s","descriptorBlob":"%s","operation":"inspect","completedStages":[]}`, tc.status, tc.code, strings.Repeat("0", 40), strings.Repeat("a", 40)))
+			t.Setenv("THOTHCTL_FAKE_WORKSPACE_EXIT", strconv.Itoa(tc.exit))
+			var stdout, stderr bytes.Buffer
+			got := run(context.Background(), []string{"--installation", fixture.installationPath, "workspace", "inspect", "--workspace", "psd", "--json"}, &stdout, &stderr)
+			if got != tc.exit || stderr.Len() != 0 {
+				t.Fatalf("exit=%d stderr=%q; want exit %d", got, stderr.String(), tc.exit)
+			}
+			if len(fixture.invocations(t)) != 1 {
+				t.Fatalf("workspace dispatch invocations = %#v, want one", fixture.invocations(t))
+			}
+		})
+	}
+}
+
+func TestRunWorkspaceOperationalFailureExitsOne(t *testing.T) {
+	fixture := newCLIFixture(t, "")
+	fixture.setEnvironment(t)
+	t.Setenv("THOTHCTL_FAKE_WORKSPACE_RESULT", "not-json")
+	var stdout, stderr bytes.Buffer
+	got := run(context.Background(), []string{"--installation", fixture.installationPath, "workspace", "inspect", "--workspace", "psd"}, &stdout, &stderr)
+	if got != 1 || !strings.Contains(stderr.String(), "invalid workspace result") {
+		t.Fatalf("exit=%d stderr=%q; want operational exit 1", got, stderr.String())
+	}
+}
+
+func TestRunWorkspaceUnsafeOutputDoesNotInvokeCompose(t *testing.T) {
+	fixture := newCLIFixture(t, "")
+	fixture.setEnvironment(t)
+	output := filepath.Join(fixture.root, "existing.yaml")
+	if err := os.WriteFile(output, []byte("existing"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	var stdout, stderr bytes.Buffer
+	got := run(context.Background(), []string{"--installation", fixture.installationPath, "workspace", "schema", "suggest-fks", "--workspace", "psd", "--output", output}, &stdout, &stderr)
+	if got != 2 || !strings.Contains(stderr.String(), "unsafe output file") {
+		t.Fatalf("exit=%d stderr=%q; want unsafe host failure", got, stderr.String())
+	}
+	assertDockerNotInvoked(t, fixture)
+}
+
 func TestRunWorkspaceRejectsInvalidCommandBeforeDocker(t *testing.T) {
 	fixture := newCLIFixture(t, "")
 	fixture.setEnvironment(t)
@@ -750,6 +803,9 @@ case " $* " in
     else
       printf '%s\n' '{"volumes":{"settings":{}},"services":{"core":{"image":"thothii-core:local","environment":{"THT_LLM_URL":"https://llm.example.invalid"}}}}'
     fi ;;
+  *" run --rm --no-deps --no-TTY workspace-maintenance "*)
+    printf '%s\n' "${THOTHCTL_FAKE_WORKSPACE_RESULT:-}"
+    exit "${THOTHCTL_FAKE_WORKSPACE_EXIT:-0}" ;;
   *" run --rm --no-deps --no-TTY session-migrate "*)
     if [ "${THOTHCTL_FAKE_MIGRATION_EXIT:-0}" -ne 0 ]; then
       printf '%s\n' "$THOTHCTL_FAKE_MIGRATION_FAILURE" >&2
@@ -805,6 +861,8 @@ func (f cliFixture) setEnvContents(t *testing.T, env string) {
 	t.Setenv("THOTHCTL_FAKE_CONFIG", "")
 	t.Setenv("THOTHCTL_FAKE_MIGRATION_FAILURE", "")
 	t.Setenv("THOTHCTL_FAKE_MIGRATION_EXIT", "0")
+	t.Setenv("THOTHCTL_FAKE_WORKSPACE_RESULT", "")
+	t.Setenv("THOTHCTL_FAKE_WORKSPACE_EXIT", "0")
 }
 
 func (f cliFixture) setProfile(t *testing.T, profile string) {
diff --git a/tools/thothctl/internal/compose/process_alive_unix_test.go b/tools/thothctl/internal/compose/process_alive_unix_test.go
new file mode 100644
index 00000000..bcf36283
--- /dev/null
+++ b/tools/thothctl/internal/compose/process_alive_unix_test.go
@@ -0,0 +1,7 @@
+//go:build !windows
+
+package compose
+
+import "syscall"
+
+func processExists(pid int) bool { return syscall.Kill(pid, 0) == nil }
diff --git a/tools/thothctl/internal/compose/process_alive_windows_test.go b/tools/thothctl/internal/compose/process_alive_windows_test.go
new file mode 100644
index 00000000..c85b04ec
--- /dev/null
+++ b/tools/thothctl/internal/compose/process_alive_windows_test.go
@@ -0,0 +1,5 @@
+//go:build windows
+
+package compose
+
+func processExists(int) bool { return true }
diff --git a/tools/thothctl/internal/compose/process_unix.go b/tools/thothctl/internal/compose/process_unix.go
index f69852d9..96370ad6 100644
--- a/tools/thothctl/internal/compose/process_unix.go
+++ b/tools/thothctl/internal/compose/process_unix.go
@@ -3,6 +3,8 @@
 package compose
 
 import (
+	"context"
+	"io"
 	"os/exec"
 	"syscall"
 )
@@ -16,3 +18,7 @@ func terminateOwnedProcess(c *exec.Cmd) {
 		_ = c.Process.Kill()
 	}
 }
+
+func runBoundedPlatform(context.Context, Runner, []string, io.Reader, CaptureLimits) (Result, bool, error) {
+	return Result{}, false, nil
+}
diff --git a/tools/thothctl/internal/compose/process_windows.go b/tools/thothctl/internal/compose/process_windows.go
index 66e208df..061b6bdc 100644
--- a/tools/thothctl/internal/compose/process_windows.go
+++ b/tools/thothctl/internal/compose/process_windows.go
@@ -3,32 +3,57 @@
 package compose
 
 import (
+	"context"
 	"errors"
+	"fmt"
+	"io"
+	"os"
 	"os/exec"
 	"sync"
+	"syscall"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
 )
 
-var ownedJobs = struct {
-	sync.Mutex
-	m map[*exec.Cmd]windows.Handle
-}{m: make(map[*exec.Cmd]windows.Handle)}
+// PROC_THREAD_ATTRIBUTE_JOB_LIST is intentionally kept here because x/sys does
+// not expose this newer SDK constant yet. Supplying it to CreateProcess makes
+// job ownership atomic with process creation; CREATE_SUSPENDED plus a later
+// AssignProcessToJobObject is not sufficient (the parent can die in between).
+const procThreadAttributeJobList = 0x0002000d
 
-// CREATE_SUSPENDED closes the registration race: no child code can create a
-// descendant until the real process HANDLE has been assigned to the job.
-func configureOwnedProcess(c *exec.Cmd) {
-	c.SysProcAttr = &windows.SysProcAttr{CreationFlags: windows.CREATE_NEW_PROCESS_GROUP | windows.CREATE_SUSPENDED}
+// The generic exec.Cmd path is not used on Windows: runBoundedPlatform launches
+// with CreateProcess and a creation-time job-list attribute. These hooks remain
+// for the platform-neutral runner's compile-time shape only.
+func configureOwnedProcess(*exec.Cmd) {}
+func registerOwnedProcess(*exec.Cmd) error {
+	return errors.New("Windows owned processes require creation-time job ownership")
+}
+func releaseOwnedProcess(*exec.Cmd) {}
+func terminateOwnedProcess(c *exec.Cmd) {
+	if c.Process != nil {
+		_ = c.Process.Kill()
+	}
 }
 
-func registerOwnedProcess(c *exec.Cmd) error {
-	if c.Process == nil {
-		return errors.New("owned process has no process handle")
+func runBoundedPlatform(ctx context.Context, runner Runner, args []string, stdin io.Reader, limits CaptureLimits) (Result, bool, error) {
+	if limits.StdoutBytes < 0 || limits.StderrBytes < 0 {
+		return Result{}, true, ErrOutputLimit
 	}
+	result, err := runBoundedWindows(ctx, runner.binary, args, stdin, limits)
+	return result, true, err
+}
+
+type windowsCollector struct {
+	buf      []byte
+	n        int64
+	overflow bool
+}
+
+func runBoundedWindows(ctx context.Context, binary string, args []string, stdin io.Reader, limits CaptureLimits) (Result, error) {
 	job, err := windows.CreateJobObject(nil, nil)
 	if err != nil {
-		return err
+		return Result{}, err
 	}
 	closeJob := true
 	defer func() {
@@ -36,72 +61,178 @@ func registerOwnedProcess(c *exec.Cmd) error {
 			windows.CloseHandle(job)
 		}
 	}()
-	limits := windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION{}
-	limits.BasicLimitInformation.LimitFlags = windows.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE
-	if _, err = windows.SetInformationJobObject(job, windows.JobObjectExtendedLimitInformation, uintptr(unsafe.Pointer(&limits)), uint32(unsafe.Sizeof(limits))); err != nil {
-		return err
+	limitsInfo := windows.JOBOBJECT_EXTENDED_LIMIT_INFORMATION{}
+	limitsInfo.BasicLimitInformation.LimitFlags = windows.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE
+	if _, err = windows.SetInformationJobObject(job, windows.JobObjectExtendedLimitInformation, uintptr(unsafe.Pointer(&limitsInfo)), uint32(unsafe.Sizeof(limitsInfo))); err != nil {
+		return Result{}, err
 	}
-	// c.Process.Pid is used only to obtain a genuine process HANDLE; a PID is
-	// never passed to AssignProcessToJobObject.
-	process, err := windows.OpenProcess(windows.PROCESS_SET_QUOTA|windows.PROCESS_TERMINATE|windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(c.Process.Pid))
-	if err != nil {
-		return err
-	}
-	defer windows.CloseHandle(process)
-	if err = windows.AssignProcessToJobObject(job, process); err != nil {
-		return err
-	}
-	thread, err := suspendedPrimaryThread(uint32(c.Process.Pid))
-	if err != nil {
-		_ = windows.TerminateJobObject(job, 1)
-		return err
-	}
-	_, resumeErr := windows.ResumeThread(thread)
-	windows.CloseHandle(thread)
-	if resumeErr != nil {
-		_ = windows.TerminateJobObject(job, 1)
-		return resumeErr
-	}
-	ownedJobs.Lock()
-	ownedJobs.m[c] = job
-	ownedJobs.Unlock()
-	closeJob = false
-	return nil
-}
 
-func suspendedPrimaryThread(pid uint32) (windows.Handle, error) {
-	snapshot, err := windows.CreateToolhelp32Snapshot(windows.TH32CS_SNAPTHREAD, 0)
+	stdinRead, stdinWrite, err := os.Pipe()
 	if err != nil {
-		return 0, err
+		return Result{}, err
 	}
-	defer windows.CloseHandle(snapshot)
-	entry := windows.ThreadEntry32{Size: uint32(unsafe.Sizeof(windows.ThreadEntry32{}))}
-	err = windows.Thread32First(snapshot, &entry)
-	for err == nil {
-		if entry.OwnerProcessID == pid {
-			return windows.OpenThread(windows.THREAD_SUSPEND_RESUME, false, entry.ThreadID)
+	stdoutRead, stdoutWrite, err := os.Pipe()
+	if err != nil {
+		_ = stdinRead.Close()
+		_ = stdinWrite.Close()
+		return Result{}, err
+	}
+	stderrRead, stderrWrite, err := os.Pipe()
+	if err != nil {
+		_ = stdinRead.Close()
+		_ = stdinWrite.Close()
+		_ = stdoutRead.Close()
+		_ = stdoutWrite.Close()
+		return Result{}, err
+	}
+	closeAll := func() {
+		_ = stdinRead.Close()
+		_ = stdinWrite.Close()
+		_ = stdoutRead.Close()
+		_ = stdoutWrite.Close()
+		_ = stderrRead.Close()
+		_ = stderrWrite.Close()
+	}
+	defer closeAll()
+	childHandles := []windows.Handle{windows.Handle(stdinRead.Fd()), windows.Handle(stdoutWrite.Fd()), windows.Handle(stderrWrite.Fd())}
+	for _, h := range childHandles {
+		if err := windows.SetHandleInformation(h, windows.HANDLE_FLAG_INHERIT, windows.HANDLE_FLAG_INHERIT); err != nil {
+			return Result{}, err
 		}
-		err = windows.Thread32Next(snapshot, &entry)
 	}
-	return 0, err
-}
+	// The attribute list limits inheritance to exactly these standard handles.
+	attributes, err := windows.NewProcThreadAttributeList(2)
+	if err != nil {
+		return Result{}, err
+	}
+	defer attributes.Delete()
+	jobList := []windows.Handle{job}
+	if err := attributes.Update(procThreadAttributeJobList, unsafe.Pointer(&jobList[0]), unsafe.Sizeof(jobList[0])); err != nil {
+		return Result{}, err
+	}
+	if err := attributes.Update(windows.PROC_THREAD_ATTRIBUTE_HANDLE_LIST, unsafe.Pointer(&childHandles[0]), uintptr(len(childHandles))*unsafe.Sizeof(childHandles[0])); err != nil {
+		return Result{}, err
+	}
 
-func releaseOwnedProcess(c *exec.Cmd) {
-	ownedJobs.Lock()
-	h := ownedJobs.m[c]
-	delete(ownedJobs.m, c)
-	ownedJobs.Unlock()
-	if h != 0 {
-		windows.CloseHandle(h)
+	command := syscall.EscapeArg(binary)
+	for _, arg := range args {
+		command += " " + syscall.EscapeArg(arg)
 	}
-}
-func terminateOwnedProcess(c *exec.Cmd) {
-	ownedJobs.Lock()
-	h := ownedJobs.m[c]
-	ownedJobs.Unlock()
-	if h != 0 {
-		_ = windows.TerminateJobObject(h, 1)
-	} else if c.Process != nil {
-		_ = c.Process.Kill()
+	commandLine, err := windows.UTF16FromString(command)
+	if err != nil {
+		return Result{}, err
 	}
+	startup := windows.StartupInfoEx{
+		StartupInfo: windows.StartupInfo{
+			Cb:        uint32(unsafe.Sizeof(windows.StartupInfoEx{})),
+			Flags:     windows.STARTF_USESTDHANDLES,
+			StdInput:  childHandles[0],
+			StdOutput: childHandles[1],
+			StdErr:    childHandles[2],
+		},
+		ProcThreadAttributeList: attributes.List(),
+	}
+	var process windows.ProcessInformation
+	creationFlags := uint32(windows.CREATE_UNICODE_ENVIRONMENT | windows.CREATE_NEW_PROCESS_GROUP | windows.EXTENDED_STARTUPINFO_PRESENT)
+	if err := windows.CreateProcess(nil, &commandLine[0], nil, nil, true, creationFlags, nil, nil, (*windows.StartupInfo)(unsafe.Pointer(&startup)), &process); err != nil {
+		return Result{ExitCode: 127}, err
+	}
+	// The child owns duplicate pipe handles; parent copies use the opposite ends.
+	_ = stdinRead.Close()
+	_ = stdoutWrite.Close()
+	_ = stderrWrite.Close()
+	_ = windows.CloseHandle(process.Thread)
+
+	var inputDone sync.WaitGroup
+	inputDone.Add(1)
+	go func() {
+		defer inputDone.Done()
+		defer stdinWrite.Close()
+		if stdin != nil {
+			_, _ = io.Copy(stdinWrite, stdin)
+		}
+	}()
+	out := windowsCollector{buf: make([]byte, limits.StdoutBytes)}
+	er := windowsCollector{buf: make([]byte, limits.StderrBytes)}
+	overflow := make(chan struct{}, 1)
+	var readers sync.WaitGroup
+	readers.Add(2)
+	read := func(file *os.File, maximum int64, collector *windowsCollector) {
+		defer readers.Done()
+		chunk := make([]byte, 32*1024)
+		for {
+			n, readErr := file.Read(chunk)
+			if n > 0 {
+				remain := maximum - collector.n
+				if remain > 0 {
+					take := int64(n)
+					if take > remain {
+						take = remain
+					}
+					copy(collector.buf[collector.n:collector.n+take], chunk[:take])
+					collector.n += take
+				}
+				if int64(n) > remain {
+					collector.overflow = true
+					select {
+					case overflow <- struct{}{}:
+					default:
+					}
+					return
+				}
+			}
+			if readErr != nil {
+				return
+			}
+		}
+	}
+	go read(stdoutRead, limits.StdoutBytes, &out)
+	go read(stderrRead, limits.StderrBytes, &er)
+	waited := make(chan uint32, 1)
+	go func() {
+		_, waitErr := windows.WaitForSingleObject(process.Process, windows.INFINITE)
+		if waitErr != nil {
+			waited <- uint32(0x103)
+		} else {
+			var code uint32
+			if windows.GetExitCodeProcess(process.Process, &code) != nil {
+				code = 1
+			}
+			waited <- code
+		}
+	}()
+	var exitCode uint32
+	var cancelled error
+	select {
+	case exitCode = <-waited:
+		// Closing the job handle kills any descendants before waiting on pipe readers.
+		_ = windows.CloseHandle(job)
+		closeJob = false
+	case <-overflow:
+		_ = windows.TerminateJobObject(job, 1)
+		exitCode = <-waited
+		_ = windows.CloseHandle(job)
+		closeJob = false
+	case <-ctx.Done():
+		cancelled = ctx.Err()
+		_ = windows.TerminateJobObject(job, 1)
+		exitCode = <-waited
+		_ = windows.CloseHandle(job)
+		closeJob = false
+	}
+	_ = windows.CloseHandle(process.Process)
+	_ = stdinWrite.Close()
+	readers.Wait()
+	inputDone.Wait()
+	result := Result{Stdout: string(out.buf[:out.n]), Stderr: string(er.buf[:er.n]), ExitCode: int(exitCode)}
+	if out.overflow || er.overflow {
+		return result, ErrOutputLimit
+	}
+	if cancelled != nil {
+		return result, cancelled
+	}
+	if exitCode == 0 {
+		return result, nil
+	}
+	return result, fmt.Errorf("child exited with code %d", exitCode)
 }
diff --git a/tools/thothctl/internal/compose/process_windows_test.go b/tools/thothctl/internal/compose/process_windows_test.go
index bdf050cd..c3b081e0 100644
--- a/tools/thothctl/internal/compose/process_windows_test.go
+++ b/tools/thothctl/internal/compose/process_windows_test.go
@@ -8,11 +8,14 @@ import (
 	"testing"
 )
 
-func TestOwnedProcessConfigurationStartsSuspended(t *testing.T) {
+func TestOwnedProcessUsesCreationTimeJobAttribute(t *testing.T) {
+	if procThreadAttributeJobList == 0 {
+		t.Fatal("owned Windows process must carry a creation-time job-list attribute")
+	}
 	cmd := exec.Command("cmd.exe")
 	configureOwnedProcess(cmd)
-	if cmd.SysProcAttr == nil || cmd.SysProcAttr.CreationFlags&windows.CREATE_SUSPENDED == 0 {
-		t.Fatal("owned Windows process must start suspended until job assignment")
+	if cmd.SysProcAttr != nil && cmd.SysProcAttr.CreationFlags&windows.CREATE_SUSPENDED != 0 {
+		t.Fatal("owned Windows process must not rely on a post-start assignment race")
 	}
 }
 
diff --git a/tools/thothctl/internal/compose/runner.go b/tools/thothctl/internal/compose/runner.go
index f915a4a1..aef12700 100644
--- a/tools/thothctl/internal/compose/runner.go
+++ b/tools/thothctl/internal/compose/runner.go
@@ -57,6 +57,9 @@ func (r Runner) Run(ctx context.Context, args []string, stdin io.Reader) (Result
 // RunBounded streams each pipe into a preallocated fixed-capacity collector. It owns the
 // process group and tears it down on the first overflow or cancellation.
 func (r Runner) RunBounded(ctx context.Context, args []string, stdin io.Reader, limits CaptureLimits) (Result, error) {
+	if result, handled, err := runBoundedPlatform(ctx, r, args, stdin, limits); handled {
+		return result, err
+	}
 	if limits.StdoutBytes < 0 || limits.StderrBytes < 0 {
 		return Result{}, ErrOutputLimit
 	}
diff --git a/tools/thothctl/internal/compose/runner_test.go b/tools/thothctl/internal/compose/runner_test.go
index fd630064..beb885d7 100644
--- a/tools/thothctl/internal/compose/runner_test.go
+++ b/tools/thothctl/internal/compose/runner_test.go
@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -123,6 +124,35 @@ func TestRunnerBoundedCancellationWinsOverChildKill(t *testing.T) {
 	}
 }
 
+func TestRunnerBoundedKillsGrandchildProcess(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("shell process-group fixture is Unix-specific")
+	}
+	pidFile := filepath.Join(t.TempDir(), "grandchild.pid")
+	script := "#!/bin/sh\n(sleep 30) &\nprintf '%s' $! > '" + pidFile + "'\nwhile :; do printf x; done\n"
+	runner := NewRunner(writeExecutable(t, script))
+	_, err := runner.RunBounded(context.Background(), nil, nil, CaptureLimits{StdoutBytes: 64, StderrBytes: 64})
+	if !errors.Is(err, ErrOutputLimit) {
+		t.Fatalf("err = %v", err)
+	}
+	pidBytes, readErr := os.ReadFile(pidFile)
+	if readErr != nil {
+		t.Fatal(readErr)
+	}
+	pid, err := strconv.Atoi(strings.TrimSpace(string(pidBytes)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		if !processExists(pid) {
+			return
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	t.Fatalf("grandchild pid %d remained alive after owned-process termination", pid)
+}
+
 func TestRunnerBoundedTerminatesGrandchildHoldingPipe(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.Skip("shell process-group fixture is Unix-specific")
diff --git a/tools/thothctl/internal/safeio/files_test.go b/tools/thothctl/internal/safeio/files_test.go
index 2b34c253..53f5e6b6 100644
--- a/tools/thothctl/internal/safeio/files_test.go
+++ b/tools/thothctl/internal/safeio/files_test.go
@@ -75,3 +75,51 @@ func TestWriteCanonicalExclusiveRejectsExistingAndCreatesPrivateFile(t *testing.
 		t.Fatalf("replacement = %v", err)
 	}
 }
+
+func TestReadCanonicalRegularRejectsHardlinkAndDirectory(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	original := filepath.Join(root, "original.sql")
+	if err := os.WriteFile(original, []byte("select 1"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	hardlink := filepath.Join(root, "hardlink.sql")
+	if err := os.Link(original, hardlink); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := ReadCanonicalRegular(hardlink, 1024); !errors.Is(err, ErrUnsafeFile) {
+		t.Fatalf("hardlink error = %v, want ErrUnsafeFile", err)
+	}
+	directory := filepath.Join(root, "directory.sql")
+	if err := os.Mkdir(directory, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := ReadCanonicalRegular(directory, 1024); !errors.Is(err, ErrUnsafeFile) {
+		t.Fatalf("directory error = %v, want ErrUnsafeFile", err)
+	}
+}
+
+func TestValidateCanonicalOutputPathRejectsExistingDirectoryAndSymlink(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	directory := filepath.Join(root, "existing.yaml")
+	if err := os.Mkdir(directory, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := ValidateCanonicalOutputPath(directory); !errors.Is(err, ErrUnsafeFile) {
+		t.Fatalf("existing directory error = %v, want ErrUnsafeFile", err)
+	}
+	target := filepath.Join(root, "target.yaml")
+	if err := os.WriteFile(target, []byte("target"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	link := filepath.Join(root, "link.yaml")
+	testsupport.SymlinkOrSkip(t, target, link)
+	if err := ValidateCanonicalOutputPath(link); !errors.Is(err, ErrUnsafeFile) {
+		t.Fatalf("output symlink error = %v, want ErrUnsafeFile", err)
+	}
+}
diff --git a/tools/thothctl/internal/safeio/files_unix.go b/tools/thothctl/internal/safeio/files_unix.go
index cb2d5470..1a257a30 100644
--- a/tools/thothctl/internal/safeio/files_unix.go
+++ b/tools/thothctl/internal/safeio/files_unix.go
@@ -79,7 +79,7 @@ func closeUnixDescriptors(descriptors []int) {
 }
 
 func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) error {
-	if err := ValidateCanonicalPath(path); err != nil || len(contents) > 16<<20 || mode.Perm() == 0 || mode.Perm()&0o077 != 0 {
+	if err := ValidateCanonicalPath(path); err != nil || len(contents) > 16<<20 || mode.Perm() != 0o600 {
 		return ErrUnsafeFile
 	}
 	components := strings.Split(strings.TrimPrefix(path, string(os.PathSeparator)), string(os.PathSeparator))
diff --git a/tools/thothctl/internal/safeio/files_windows.go b/tools/thothctl/internal/safeio/files_windows.go
index d6322902..d7094ae8 100644
--- a/tools/thothctl/internal/safeio/files_windows.go
+++ b/tools/thothctl/internal/safeio/files_windows.go
@@ -6,8 +6,11 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 
+	"unsafe"
+
 	"golang.org/x/sys/windows"
 )
 
@@ -119,7 +122,7 @@ func closeWindowsHandles(handles []windows.Handle) {
 }
 
 func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) error {
-	if err := ValidateCanonicalPath(path); err != nil || len(contents) > 16<<20 || mode.Perm() == 0 || mode.Perm()&0o077 != 0 {
+	if err := ValidateCanonicalPath(path); err != nil || len(contents) > 16<<20 || mode.Perm() != 0o600 {
 		return ErrUnsafeFile
 	}
 	parent, retainedParents, err := openWindowsParents(path)
@@ -129,7 +132,11 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
 	defer closeWindowsHandles(retainedParents)
 	// Parent handles stay open with delete sharing denied until publication and
 	// identity recheck complete; this is the Windows equivalent of retained dirfds.
-	h, err := windows.CreateFile(windows.StringToUTF16Ptr(filepath.Join(parent, filepath.Base(path))), windows.GENERIC_WRITE, 0, nil, windows.CREATE_NEW, windows.FILE_ATTRIBUTE_NORMAL|windows.FILE_FLAG_OPEN_REPARSE_POINT, 0)
+	securityDescriptor, securityAttributes, err := ownerOnlySecurityAttributes()
+	if err != nil {
+		return ErrUnsafeFile
+	}
+	h, err := windows.CreateFile(windows.StringToUTF16Ptr(filepath.Join(parent, filepath.Base(path))), windows.GENERIC_WRITE, 0, securityAttributes, windows.CREATE_NEW, windows.FILE_ATTRIBUTE_NORMAL|windows.FILE_FLAG_OPEN_REPARSE_POINT, 0)
 	if err != nil {
 		return ErrUnsafeFile
 	}
@@ -139,7 +146,11 @@ func writeCanonicalExclusive(path string, contents []byte, mode fs.FileMode) err
 		return ErrUnsafeFile
 	}
 	defer f.Close()
-	if err := f.Chmod(mode); err != nil {
+	// Go's Windows Chmod only toggles the read-only attribute; it cannot enforce
+	// owner-only permissions. The restrictive DACL is installed at creation time
+	// through SECURITY_ATTRIBUTES above.
+	_ = securityDescriptor
+	if mode.Perm() != 0o600 {
 		return ErrUnsafeFile
 	}
 	if _, err := f.Write(contents); err != nil {
@@ -202,3 +213,47 @@ func validateCanonicalOutputPath(path string) error {
 func sameWindowsFile(a, b windows.ByHandleFileInformation) bool {
 	return a.VolumeSerialNumber == b.VolumeSerialNumber && a.FileIndexHigh == b.FileIndexHigh && a.FileIndexLow == b.FileIndexLow
 }
+
+// ownerOnlySecurityAttributes builds a non-inheriting DACL granting the current
+// token's user read/write access and no access to inherited or other trustees.
+// The descriptor is retained by the returned Go value for the duration of CreateFile.
+func ownerOnlySecurityAttributes() (*windows.SECURITY_DESCRIPTOR, *windows.SecurityAttributes, error) {
+	user, err := windows.GetCurrentProcessToken().GetTokenUser()
+	if err != nil || user == nil || user.User.Sid == nil {
+		return nil, nil, ErrUnsafeFile
+	}
+	var pinner runtime.Pinner
+	pinner.Pin(user.User.Sid)
+	defer pinner.Unpin()
+	trustee := windows.TRUSTEE{
+		TrusteeForm:  windows.TRUSTEE_IS_SID,
+		TrusteeType:  windows.TRUSTEE_IS_USER,
+		TrusteeValue: windows.TrusteeValueFromSID(user.User.Sid),
+	}
+	entries := []windows.EXPLICIT_ACCESS{{
+		AccessPermissions: windows.FILE_GENERIC_READ | windows.FILE_GENERIC_WRITE,
+		AccessMode:        windows.SET_ACCESS,
+		Inheritance:       windows.NO_INHERITANCE,
+		Trustee:           trustee,
+	}}
+	descriptor, err := windows.BuildSecurityDescriptor(nil, nil, entries, nil, nil)
+	if err != nil || descriptor == nil {
+		return nil, nil, ErrUnsafeFile
+	}
+	acl, _, err := descriptor.DACL()
+	if err != nil || acl == nil {
+		return nil, nil, ErrUnsafeFile
+	}
+	if err := descriptor.SetControl(windows.SE_DACL_PROTECTED, windows.SE_DACL_PROTECTED); err != nil {
+		return nil, nil, ErrUnsafeFile
+	}
+	// BuildSecurityDescriptor returns a self-relative descriptor. Re-using its
+	// DACL as the creation descriptor is valid, and the explicit DACL has no
+	// inheritable ACEs; the protected flag is applied by the kernel on creation.
+	_ = acl
+	attrs := &windows.SecurityAttributes{
+		Length:             uint32(unsafe.Sizeof(windows.SecurityAttributes{})),
+		SecurityDescriptor: descriptor,
+	}
+	return descriptor, attrs, nil
+}
diff --git a/tools/thothctl/internal/safeio/files_windows_test.go b/tools/thothctl/internal/safeio/files_windows_test.go
index 5a1da6f4..154fb25f 100644
--- a/tools/thothctl/internal/safeio/files_windows_test.go
+++ b/tools/thothctl/internal/safeio/files_windows_test.go
@@ -72,3 +72,29 @@ func TestWriteCanonicalExclusiveRequiresRestrictiveMode(t *testing.T) {
 		t.Fatal("accepted non-restrictive output mode")
 	}
 }
+
+func TestWriteCanonicalExclusiveCreatesProtectedOwnerOnlyDACL(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(root, "candidate.yaml")
+	if err := writeCanonicalExclusive(path, []byte("x"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	sd, err := windows.GetNamedSecurityInfo(path, windows.SE_FILE_OBJECT, windows.DACL_SECURITY_INFORMATION)
+	if err != nil {
+		t.Fatal(err)
+	}
+	control, _, err := sd.Control()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if control&windows.SE_DACL_PROTECTED == 0 {
+		t.Fatalf("output DACL control = %#x, want protected", control)
+	}
+	acl, _, err := sd.DACL()
+	if err != nil || acl == nil || acl.AceCount != 1 {
+		t.Fatalf("output DACL = %#v, err=%v; want one owner ACE", acl, err)
+	}
+}
diff --git a/tools/thothctl/internal/workspaceops/operations.go b/tools/thothctl/internal/workspaceops/operations.go
index 572c19a7..81d2fa23 100644
--- a/tools/thothctl/internal/workspaceops/operations.go
+++ b/tools/thothctl/internal/workspaceops/operations.go
@@ -29,8 +29,11 @@ const (
 	maxAssumptions     = 256
 	maxAssumptionBytes = 256
 	maxResult          = 1 << 20
-	maxCandidate       = 700 << 10
-	maxAnnotations     = 16 << 20
+	// Requests carry up to 16 MiB of raw SQL or annotation bytes encoded as base64.
+	// This is deliberately independent from maxResult, which bounds child stdout.
+	maxRequest     = 24 << 20
+	maxCandidate   = 700 << 10
+	maxAnnotations = 16 << 20
 )
 
 var workspaceIDPattern = regexp.MustCompile(`^[a-z][a-z0-9-]{2,62}$`)
@@ -392,7 +395,7 @@ func makeInput(c Command) (inputEnvelope, string, error) {
 	if e != nil {
 		return env, "", e
 	}
-	if len(payload) > maxResult {
+	if len(payload) > maxRequest {
 		return env, "", errors.New("request exceeds limit")
 	}
 	return env, string(payload), nil
@@ -461,8 +464,8 @@ func Run(ctx context.Context, installation config.Installation, runner compose.R
 	}
 	payload := []byte(generated)
 	if stdin != nil {
-		payload, e = io.ReadAll(io.LimitReader(stdin, maxResult+1))
-		if e != nil || len(payload) > maxResult {
+		payload, e = io.ReadAll(io.LimitReader(stdin, maxRequest+1))
+		if e != nil || len(payload) > maxRequest {
 			return Result{}, errors.New("request exceeds limit")
 		}
 		if e = validateIngress(payload, env); e != nil {
diff --git a/tools/thothctl/internal/workspaceops/operations_test.go b/tools/thothctl/internal/workspaceops/operations_test.go
index 2f8149f0..dcdc5643 100644
--- a/tools/thothctl/internal/workspaceops/operations_test.go
+++ b/tools/thothctl/internal/workspaceops/operations_test.go
@@ -83,9 +83,10 @@ func TestRunUsesBase64BasenameIngressAndNoTTY(t *testing.T) {
 	if err := os.WriteFile(sqlPath, []byte("select 1"), 0o600); err != nil {
 		t.Fatal(err)
 	}
-	out := filepath.Join(root, "candidate.yaml")
+	stdinCapture := filepath.Join(root, "stdin.json")
+	argsCapture := filepath.Join(root, "args.txt")
 	resultJSON := `{"schemaVersion":1,"status":"succeeded","code":"ok","workspaceId":"psd","workspaceRevision":"0123456789012345678901234567890123456789","descriptorBlob":"abcdefabcdefabcdefabcdefabcdefabcdefabcd","operation":"suggest-fks","runId":"0123456789abcdef0123456789abcdef","completedStages":[]}`
-	script := "#!/bin/sh\ncat >/dev/null\nprintf '%s' '" + resultJSON + "'\n"
+	script := "#!/bin/sh\nprintf '%s\n' \"$@\" > '" + argsCapture + "'\ncat > '" + stdinCapture + "'\nprintf '%s' '" + resultJSON + "'\n"
 	fake := filepath.Join(root, "docker")
 	if err := os.WriteFile(fake, []byte(script), 0o700); err != nil {
 		t.Fatal(err)
@@ -101,7 +102,20 @@ func TestRunUsesBase64BasenameIngressAndNoTTY(t *testing.T) {
 	if got.Code != "ok" {
 		t.Fatalf("result = %#v", got)
 	}
-	_ = out
+	stdinBytes, err := os.ReadFile(stdinCapture)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(string(stdinBytes), sqlPath) || !strings.Contains(string(stdinBytes), "contentBase64") || !strings.Contains(string(stdinBytes), "schema.sql") {
+		t.Fatalf("stdin envelope = %q; want basename/base64 without host path", stdinBytes)
+	}
+	argsBytes, err := os.ReadFile(argsCapture)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(string(argsBytes), sqlPath) || !strings.Contains(string(argsBytes), "--operation\nsuggest-fks") || !strings.Contains(string(argsBytes), "--workspace\npsd") {
+		t.Fatalf("child args = %q; want closed operation/workspace args", argsBytes)
+	}
 }
 
 func TestRunPublishesOnlyVerifiedCandidateExport(t *testing.T) {
@@ -295,3 +309,43 @@ func TestParseWorkspaceAcceptsAssumptionAndEnforcesLimits(t *testing.T) {
 		t.Fatal("accepted 33 SQL files")
 	}
 }
+
+func TestMakeInputAcceptsMaximumSingleSQLFile(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(root, "schema.sql")
+	if err := os.WriteFile(path, bytes.Repeat([]byte("x"), maxSQLFile), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	command := SuggestFksRequest{WorkspaceID: "psd", FromSQL: []string{path}}
+	if _, payload, err := makeInput(command); err != nil {
+		t.Fatalf("makeInput() error = %v", err)
+	} else if len(payload) <= maxResult {
+		t.Fatalf("payload length = %d, want larger than result cap %d", len(payload), maxResult)
+	}
+}
+
+func TestMakeInputAcceptsMaximumAnnotationWithReviewDigestPair(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(root, "annotations.md")
+	contents := bytes.Repeat([]byte("a"), maxAnnotations)
+	if err := os.WriteFile(path, contents, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	command := CheckSchemaRequest{WorkspaceID: "psd", Resume: strings.Repeat("0", 32), Annotations: path, ReviewedCandidates: DigestBytes([]byte("reviewed"))}
+	env, payload, err := makeInput(command)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if env.Annotations == nil || env.ReviewedCandidates == "" || len(payload) <= maxResult {
+		t.Fatalf("annotation envelope = %#v payload=%d; want pair and request larger than result cap", env, len(payload))
+	}
+	if err := validateIngress([]byte(payload), env); err != nil {
+		t.Fatalf("validateIngress() = %v", err)
+	}
+}