verify(P0b): 4-layer verification PASS — REQ-064,067

---ci---
project: orca
phase: P0b
milestone: v0.9
status: verify
---/ci---

.ciagent/CA_MIGRATION_SPEC_v0.9.md

@@ -0,0 +1,109 @@
+# CA Migration Spec — v0.8 Internal CA → v0.9 step-ca (grill C-07)
+
+**Status**: spec (must be implemented in v0.10-P14a, REQ-066)
+**Gate**: C-07 — blocks v0.10-P14a until this spec is reviewed and a dry-run passes on a test cluster
+
+## Problem
+
+The v0.8 internal Go CA (`internal/security/ca.go`) issues RSA-3072 CA
+certs (10-year validity) and ECDSA P-256 server certs (90-day). The CA
+material lives at `~/.orca/ca.crt` and `~/.orca/ca.key` (flat layout, D-011).
+The v0.9 re-architecture reverses AD-010 and replaces the internal CA with
+step-ca (D-101, REQ-076). Existing v0.8 deployments have an internal CA
+root + issued server certs that must be migrated without invalidating
+trust across the cluster.
+
+## Migration options (decision required before v0.10-P14a implementation)
+
+### Option A — Preserve trust root (RECOMMENDED)
+
+Import the existing `ca.key` into step-ca as the root CA key. The cluster's
+trust fingerprint stays unchanged; existing server certs continue to
+validate until their natural expiry; new SVIDs are minted by step-ca using
+the same root.
+
+```bash
+orca upgrade --to-v1.0 --import-ca
+# reads ~/.orca/ca.key → step ca init --deployment-type standalone \
+#   --remote-management --key $(cat ~/.orca/ca.key)
+# issues new SVIDs from step-ca for all existing workloads
+```
+
+**Pros**: zero trust breakage; existing server certs keep working; minimal
+operator disruption.
+**Cons**: requires step-ca to accept an imported RSA-3072 key (step-ca
+supports imported keys via `--key` flag; verify in the spike).
+**Post-migration**: old `internal/security/ca.go` and `csr.go` are deleted
+(v0.10-P14); the `cert_repo` SQLite table (0004) is dropped (step-ca
+manages cert state).
+
+### Option B — Forced re-bootstrap
+
+Document that v0.8 certs are invalidated; every cluster re-bootstraps under
+step-ca with a new root. Existing workloads are re-enrolled.
+
+**Pros**: clean slate; no legacy RSA root.
+**Cons**: trust breakage — every peer's `known_hosts` + CA cert must be
+rotated; running workloads lose mTLS until re-enrolled; higher operator
+disruption.
+**Use case**: only if Option A is technically infeasible (step-ca rejects
+the v0.8 key format).
+
+## Pre-flight checks (must pass before migration)
+
+1. `orca doctor` reports zero FAILs on the v0.8 cluster
+2. All peers reachable via SSH
+3. No in-flight transactions (the migration is stop-the-world for the CA)
+4. Snapshot taken (`orca backup --include-master-key`)
+5. step-ca installed on the lead via `apt-get install step-ca`
+6. `step ca init` dry-run succeeds with the imported key
+
+## Migration steps (Option A)
+
+1. SSH to the lead; install step-ca via apt
+2. Run `step ca init --deployment-type standalone --remote-management \
+     --key <v0.8-ca-key-path> --provisioner orca-admin`
+3. Move the root cert: `cp ~/.orca/ca.crt $ORCA_HOME/cluster/ca.crt`
+4. Issue new SVIDs for every registered workload (via `step ca token` +
+   `step ca certificate` — the CLI mints the provisioner token using
+   `cluster/master.key`-derived material)
+5. Deploy the new SVIDs to peers via SSH-push (the v0.9 SSH-push transport)
+6. Verify: `orca doctor` reports zero FAILs; CA fingerprint unchanged;
+   all workload SVIDs valid
+7. Archive the old `internal/security/ca.go`/`csr.go` and `cert_repo` table
+
+## Rollback
+
+If any post-migration invariant fails:
+1. Restore the v0.8 snapshot via `orca upgrade --rollback <tarball>`
+2. Restart the v0.8 orca daemon on the lead
+3. Verify `orca doctor` passes on the v0.8 cluster
+
+The v0.8 internal CA remains functional during the dual-write window
+(REQ-090); step-ca is additive until the migration completes.
+
+## Post-migration invariants (must all pass)
+
+- CA fingerprint unchanged (Option A)
+- Node count unchanged
+- Workload count unchanged
+- All SVIDs valid (mTLS handshake succeeds lead↔every peer)
+- `orca doctor` zero FAILs
+- No `internal/security/ca.go` or `cert_repo` references remain in code
+
+## Decision required
+
+This spec is gated by C-07. The decision (Option A vs B) must be made
+before v0.10-P14a implementation. Default: Option A (preserve trust root)
+unless the step-ca imported-key spike fails.
+
+## Spike (must run before v0.10-P14a)
+
+Run on a test cluster:
+1. Install step-ca on a clean Linux host
+2. Generate a v0.8-style RSA-3072 CA key via the v0.8 `internal/security` package
+3. Run `step ca init --key <v8-key>` and verify step-ca accepts it
+4. Mint a test SVID via `step ca token` + `step ca certificate`
+5. Verify the SVID validates against the imported root
+
+If the spike fails, fall back to Option B (forced re-bootstrap) and document.

.ciagent/CHECKPOINT.json

@@ -1,20 +1 @@
-{
-  "phase": "P00",
-  "stage": "verify",
-  "milestone": "v0.9",
-  "milestone_slug": "rearchitecture",
-  "phase_role": "execution",
-  "attempts": 0,
-  "updated_at": "2026-08-05T02:45:00Z",
-  "milestone_complete": false,
-  "gates_cleared": ["C-03", "C-05", "C-06", "C-15", "C-16", "C-17", "C-18"],
-  "verify": {
-    "build": "pass",
-    "go_test": "16/16 packages pass",
-    "bats": "20/20 tests pass",
-    "gofmt": "clean",
-    "go_vet": "clean",
-    "verify_reqs": "90 requirements consistent",
-    "shellcheck": "info-level only (no errors)"
-  }
-}
+{ "phase": "P0b", "stage": "verify", "milestone": "v0.9", "phase_role": "execution", "updated_at": "2026-08-05T03:25:00Z", "milestone_complete": false, "verify": { "build": "pass", "go_test": "18/18", "bats": "20/20", "gofmt": "clean", "verify_reqs": "90 consistent" } }

internal/certpaths/certpaths.go

@@ -1,64 +1,73 @@
-// Package certpaths centralizes the on-disk locations of the CA and
-// server cert/key files. The CLI layer, the security layer, and the
-// doctor layer all need to agree on these paths, so they're factored
-// into their own package to avoid import cycles (cli <-> doctor).
+// Package certpaths is the v0.8 path shim. It returns v0.8 flat-layout
+// paths for backward compatibility during the v0.9 dual-write window
+// (REQ-090). The v0.9 paths package (internal/paths) returns the new
+// multi-namespace layout (R-002).
+//
+// certpaths will be deleted after the v0.10-P14 migration. New code
+// should use internal/paths, NOT certpaths.
+//
+// Migration notes (per v0.10-P14):
+//   - CA cert/key, server cert/key, SSH key/pub, known_hosts currently
+//     live at the flat Root() location. The v0.9 internal/paths package
+//     returns the new ClusterDir()/... locations; certpaths keeps the
+//     v0.8 flat locations until the CA migration moves them.
+//   - DBPath keeps returning Root()/orca.db (v0.8 location). The new
+//     paths.NSDb("_defaults") returns Root()/_defaults/db/orca.db; the DB
+//     moves in v0.10-P14.
 package certpaths
 
 import (
 	"os"
 	"path/filepath"
+
+	"git.cloudinit.dev/coreci/orca/internal/paths"
 )
 
-const (
-	defaultCADir   = ".orca"
-	caCertFilename = "ca.crt"
-	caKeyFilename  = "ca.key"
-)
+// Dir returns the v0.8 flat root directory. Delegates to paths.Root()
+// (which honors $ORCA_HOME, else ~/.orca). v0.8 callers expect the CA
+// and DB to live directly under this directory; that does not change
+// until the v0.10-P14 migration.
+func Dir() string { return paths.Root() }
 
-// Dir returns the directory the local CA lives in. Honors $ORCA_HOME
-// for testability; otherwise defaults to ~/.orca.
-func Dir() string {
-	if p := os.Getenv("ORCA_HOME"); p != "" {
-		return p
-	}
-	home, _ := os.UserHomeDir()
-	return filepath.Join(home, defaultCADir)
-}
+// CACertPath returns the v0.8 CA cert path: Dir()/ca.crt.
+// The v0.9 location is paths.CACertPath() = ClusterDir()/ca.crt; certpaths
+// keeps the v0.8 flat location until the CA migration in v0.10-P14.
+func CACertPath() string { return filepath.Join(paths.Root(), "ca.crt") }
 
-// CACertPath returns the path to ca.crt.
-func CACertPath() string { return filepath.Join(Dir(), caCertFilename) }
+// CAKeyPath returns the v0.8 CA key path: Dir()/ca.key.
+// See CACertPath for migration notes.
+func CAKeyPath() string { return filepath.Join(paths.Root(), "ca.key") }
 
-// CAKeyPath returns the path to ca.key.
-func CAKeyPath() string { return filepath.Join(Dir(), caKeyFilename) }
+// ServerCertPath returns the v0.8 server cert path: Dir()/server.crt.
+// See CACertPath for migration notes.
+func ServerCertPath() string { return filepath.Join(paths.Root(), "server.crt") }
 
-// ServerCertPath returns the path to server.crt.
-func ServerCertPath() string { return filepath.Join(Dir(), "server.crt") }
-
-// ServerKeyPath returns the path to server.key.
-func ServerKeyPath() string { return filepath.Join(Dir(), "server.key") }
+// ServerKeyPath returns the v0.8 server key path: Dir()/server.key.
+// See CACertPath for migration notes.
+func ServerKeyPath() string { return filepath.Join(paths.Root(), "server.key") }
 
 // DBPath returns the path to the orca SQLite database. Honors $ORCA_DB
-// for testability and explicit override; otherwise defaults to
-// ~/.orca/orca.db under the same Dir() as the cert files.
+// for testability and explicit override; otherwise defaults to the v0.8
+// flat location Dir()/orca.db. The v0.9 location is
+// paths.NSDb(paths.DefaultNamespace()) = Root()/_defaults/db/orca.db;
+// certpaths keeps the v0.8 flat location until the DB move in v0.10-P14.
 func DBPath() string {
 	if p := os.Getenv("ORCA_DB"); p != "" {
 		return p
 	}
-	return filepath.Join(Dir(), "orca.db")
+	return filepath.Join(paths.Root(), "orca.db")
 }
 
-// SSHKeyPath returns the path to the orca SSH private key (Ed25519,
-// D-037). Used by `orca node join --type proxmox` to authenticate
-// to remote Proxmox hosts after the initial password-based bootstrap.
-// File mode 0600 (enforced by security.WriteKey).
-func SSHKeyPath() string { return filepath.Join(Dir(), "orca_ssh_key") }
+// SSHKeyPath returns the v0.8 SSH private key path: Dir()/orca_ssh_key.
+// The v0.9 location is paths.SSHKeyPath() = ClusterDir()/orca_ssh_key;
+// certpaths keeps the v0.8 flat location until the migration.
+func SSHKeyPath() string { return filepath.Join(paths.Root(), "orca_ssh_key") }
 
-// SSHPubPath returns the path to the orca SSH public key (authorized_keys
-// format). Deployed to remote Proxmox hosts during `orca node join`.
-// File mode 0644 (enforced by security.WriteCert).
-func SSHPubPath() string { return filepath.Join(Dir(), "orca_ssh_key.pub") }
+// SSHPubPath returns the v0.8 SSH public key path: Dir()/orca_ssh_key.pub.
+// See SSHKeyPath for migration notes.
+func SSHPubPath() string { return filepath.Join(paths.Root(), "orca_ssh_key.pub") }
 
-// KnownHostsPath returns the path to the SSH known_hosts file used for
-// TOFU host-key pinning (D-035). Captured on first connect, verified
-// on all subsequent connects via golang.org/x/crypto/ssh/knownhosts.
-func KnownHostsPath() string { return filepath.Join(Dir(), "known_hosts") }
+// KnownHostsPath returns the v0.8 known_hosts path: Dir()/known_hosts.
+// The v0.9 location is paths.KnownHostsPath() = ClusterDir()/known_hosts;
+// certpaths keeps the v0.8 flat location until the migration.
+func KnownHostsPath() string { return filepath.Join(paths.Root(), "known_hosts") }

internal/certpaths/certpaths_test.go

@@ -3,15 +3,17 @@ package certpaths
 import (
 	"os"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"testing"
+
+	"git.cloudinit.dev/coreci/orca/internal/paths"
 )
 
+const defaultHomeSubdir = ".orca"
+
 func TestPaths_HonorORCAHOME(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("ORCA_HOME", dir)
-	// Ensure ORCA_DB doesn't leak from the environment / prior tests.
 	t.Setenv("ORCA_DB", "")
 
 	cases := []struct {
@@ -36,17 +38,26 @@ func TestPaths_HonorORCAHOME(t *testing.T) {
 		})
 	}
 
-	// DBPath defaults to $ORCA_HOME/orca.db.
 	if got, want := DBPath(), filepath.Join(dir, "orca.db"); got != want {
 		t.Errorf("DBPath = %q, want %q", got, want)
 	}
 
-	// Dir() returns ORCA_HOME verbatim.
 	if got, want := Dir(), dir; got != want {
 		t.Errorf("Dir = %q, want %q", got, want)
 	}
 }
 
+func TestShim_DelegatesDirToPaths(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	if got, want := Dir(), paths.Root(); got != want {
+		t.Errorf("Dir() = %q, paths.Root() = %q (shim must delegate)", got, want)
+	}
+	if got, want := Dir(), dir; got != want {
+		t.Errorf("Dir() = %q, want %q", got, want)
+	}
+}
+
 func TestDBPath_OrcaDBOverride(t *testing.T) {
 	home := t.TempDir()
 	t.Setenv("ORCA_HOME", home)
@@ -70,19 +81,14 @@ func TestDBPath_OrcaDBEmptyStringFallsBackToHome(t *testing.T) {
 }
 
 func TestDir_DefaultHomeFallback(t *testing.T) {
-	// Unset ORCA_HOME so Dir() falls back to ~/.orca.
-	// We can't reliably mutate the real HOME in a portable way, so just
-	// assert that the returned path ends with the default subdir on the
-	// current OS and is absolute.
 	os.Unsetenv("ORCA_HOME")
-	// Also clear ORCA_DB so DBPath's fallback to Dir() is exercised.
 	os.Unsetenv("ORCA_DB")
 
 	home, err := os.UserHomeDir()
 	if err != nil {
 		t.Skipf("os.UserHomeDir: %v (cannot verify default fallback)", err)
 	}
-	want := filepath.Join(home, defaultCADir)
+	want := filepath.Join(home, defaultHomeSubdir)
 	if got := Dir(); got != want {
 		t.Errorf("Dir() default = %q, want %q", got, want)
 	}
@@ -92,25 +98,22 @@ func TestDir_DefaultHomeFallback(t *testing.T) {
 }
 
 func TestDir_ORCAHOMEEmptyFallsBack(t *testing.T) {
-	// Empty string ORCA_HOME is treated as unset → ~/.orca fallback.
 	t.Setenv("ORCA_HOME", "")
 	home, err := os.UserHomeDir()
 	if err != nil {
 		t.Skipf("os.UserHomeDir: %v", err)
 	}
-	want := filepath.Join(home, defaultCADir)
+	want := filepath.Join(home, defaultHomeSubdir)
 	if got := Dir(); got != want {
 		t.Errorf("Dir() with empty ORCA_HOME = %q, want %q", got, want)
 	}
 }
 
 func TestDir_ORCAHOMERelativePath(t *testing.T) {
-	// A relative ORCA_HOME is honored verbatim (no cleaning/absolutizing).
 	t.Setenv("ORCA_HOME", "relative/orca/home")
 	if got, want := Dir(), "relative/orca/home"; got != want {
 		t.Errorf("Dir() relative = %q, want %q", got, want)
 	}
-	// CACertPath joins the relative dir with ca.crt using filepath.Join.
 	if got, want := CACertPath(), filepath.Join("relative/orca/home", "ca.crt"); got != want {
 		t.Errorf("CACertPath relative = %q, want %q", got, want)
 	}
@@ -121,7 +124,6 @@ func TestAllPaths_AreConsistentWithDir(t *testing.T) {
 	t.Setenv("ORCA_HOME", dir)
 	t.Setenv("ORCA_DB", "")
 
-	// Every *Path() must live under Dir() except DBPath which also does.
 	base := Dir()
 	for _, p := range []string{
 		CACertPath(), CAKeyPath(),
@@ -135,6 +137,38 @@ func TestAllPaths_AreConsistentWithDir(t *testing.T) {
 	}
 }
 
+func TestShim_ReturnsV08FlatPaths(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	t.Setenv("ORCA_DB", "")
+
+	root := paths.Root()
+	if got, want := CACertPath(), filepath.Join(root, "ca.crt"); got != want {
+		t.Errorf("CACertPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := CAKeyPath(), filepath.Join(root, "ca.key"); got != want {
+		t.Errorf("CAKeyPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := ServerCertPath(), filepath.Join(root, "server.crt"); got != want {
+		t.Errorf("ServerCertPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := ServerKeyPath(), filepath.Join(root, "server.key"); got != want {
+		t.Errorf("ServerKeyPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := SSHKeyPath(), filepath.Join(root, "orca_ssh_key"); got != want {
+		t.Errorf("SSHKeyPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := SSHPubPath(), filepath.Join(root, "orca_ssh_key.pub"); got != want {
+		t.Errorf("SSHPubPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := KnownHostsPath(), filepath.Join(root, "known_hosts"); got != want {
+		t.Errorf("KnownHostsPath = %q, want v0.8 flat %q", got, want)
+	}
+	if got, want := DBPath(), filepath.Join(root, "orca.db"); got != want {
+		t.Errorf("DBPath = %q, want v0.8 flat %q", got, want)
+	}
+}
+
 func TestSSHPaths_Filenames(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("ORCA_HOME", dir)
@@ -148,10 +182,3 @@ func TestSSHPaths_Filenames(t *testing.T) {
 		t.Errorf("KnownHostsPath base = %q, want %q", got, want)
 	}
 }
-
-func init() {
-	// On Windows the default home subdir is still ".orca"; the test for
-	// default fallback uses os.UserHomeDir which is platform-aware. This
-	// guard keeps the suite from running a meaningless check on plan9.
-	_ = runtime.GOOS
-}

internal/cli/job.go

@@ -74,7 +74,7 @@ var jobRunCmd = &cobra.Command{
 			peers := engine.NewPeerRegistry()
 			dispatcher := engine.NewDispatcher(newLogger(), store.NewCapacityRepo(db), peers, exec)
 			specBytes, _ := json.Marshal(map[string]any{
-				"name":    spec.Job.Name,
+				"name":    spec.Name,
 				"command": "/bin/true", // placeholder; full HCL dispatch lands in a later phase
 			})
 			jobID, nodeID, err := dispatcher.Submit(ctx, runTarget, specBytes, runIDKey)
@@ -93,11 +93,11 @@ var jobRunCmd = &cobra.Command{
 
 		job := &model.Job{
 			ID:     uuid.NewString(),
-			Name:   spec.Job.Name,
+			Name:   spec.Name,
 			Spec:   args[0],
 			Status: model.JobStatusPending,
 		}
-		if err := exec.Run(ctx, job, toTaskSpecs(spec.Tasks)); err != nil {
+		if err := exec.Run(ctx, job, workloadToTaskSpecs(spec)); err != nil {
 			if jsonOutput {
 				_ = printJSON(map[string]any{"id": job.ID, "status": "failed", "error": err.Error()})
 				return err
@@ -330,3 +330,22 @@ func toTaskSpecs(in []jobspec.TaskSpec) []engine.TaskSpec {
 	}
 	return out
 }
+
+// workloadToTaskSpecs converts a *WorkloadSpec into the engine.TaskSpec
+// slice consumed by the executor. For the HCL adapter path the runtime
+// block carries the legacy task[0].Command; for the Markdown path the
+// runtime block is the canonical runtime abstraction (P07 will expand
+// this). When Runtime is nil we emit a single no-op task to preserve
+// the legacy "at least one task" invariant.
+func workloadToTaskSpecs(spec *jobspec.WorkloadSpec) []engine.TaskSpec {
+	if spec == nil {
+		return nil
+	}
+	if spec.Runtime == nil {
+		return []engine.TaskSpec{{Name: spec.Name, Command: "/bin/true"}}
+	}
+	return []engine.TaskSpec{{
+		Name:    spec.Name,
+		Command: spec.Runtime.Command,
+	}}
+}

internal/cli/namespace_test.go

@@ -34,6 +34,7 @@ func resetCommandFlags() {
 	stopID, runTarget, runIDKey, jobWatch = "", "", "", false
 	capSetCPU, capSetMem, capSetDisk, capNodeID = 0, 0, 0, ""
 	auditLimit = 50
+	resetNSFlags()
 }
 
 func TestNamespaceDefaultsToUserHome(t *testing.T) {

internal/cli/ns.go

@@ -0,0 +1,338 @@
+// Package cli: ns.go implements the `orca ns` subcommand family
+// (REQ-082, D-176). Subcommands:
+//
+//	orca ns list               — list all namespaces under ORCA_HOME
+//	orca ns create <name>      — create a namespace dir + ns.md
+//	orca ns delete <name>       — remove an empty namespace dir
+//	orca ns inspect <name>      — print effective chain + merged env
+//	orca ns validate <name>     — cycle + missing-parent + schema checks
+//
+// All subcommands honor $ORCA_HOME via internal/paths. The inheritance
+// resolver (internal/ns) is a pure function shared by inspect + validate.
+package cli
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"git.cloudinit.dev/coreci/orca/internal/ns"
+	"git.cloudinit.dev/coreci/orca/internal/paths"
+)
+
+var nsCmd = &cobra.Command{
+	Use:   "ns",
+	Short: "Manage orca namespaces",
+	Long: `Manage orca namespaces under ORCA_HOME (R-002).
+
+Each namespace is a directory with ns.md, .env, .env.secrets, db/,
+jobs/, alloc/. The implicit root namespace _defaults always exists
+(D-159); every namespace inherits from _defaults (D-185) and cannot
+opt out (D-187).`,
+}
+
+var (
+	nsCreateParent         string
+	nsCreateInheritsEnv    bool
+	nsCreateInheritsSecret bool
+)
+
+var nsListCmd = &cobra.Command{
+	Use:   "list",
+	Short: "List all namespaces under ORCA_HOME",
+	Long:  `List all namespaces under ORCA_HOME (directories containing ns.md, plus the implicit _defaults).`,
+	Args:  cobra.NoArgs,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		root := paths.Root()
+		entries, err := os.ReadDir(root)
+		if err != nil {
+			return fmt.Errorf("read ORCA_HOME %s: %w", root, err)
+		}
+		type nsRow struct {
+			Name    string `json:"name"`
+			Path    string `json:"path"`
+			Default bool   `json:"default"`
+		}
+		var rows []nsRow
+		for _, ent := range entries {
+			if !ent.IsDir() {
+				continue
+			}
+			if ent.Name() == "cluster" {
+				continue
+			}
+			nsMd := filepath.Join(root, ent.Name(), "ns.md")
+			if _, err := os.Stat(nsMd); err != nil {
+				continue
+			}
+			rows = append(rows, nsRow{
+				Name:    ent.Name(),
+				Path:    filepath.Join(root, ent.Name()),
+				Default: ent.Name() == paths.DefaultNamespace(),
+			})
+		}
+		sort.Slice(rows, func(i, j int) bool {
+			if rows[i].Name == paths.DefaultNamespace() {
+				return true
+			}
+			if rows[j].Name == paths.DefaultNamespace() {
+				return false
+			}
+			return rows[i].Name < rows[j].Name
+		})
+		if jsonOutput {
+			return printJSON(rows)
+		}
+		if len(rows) == 0 {
+			fmt.Fprintln(cmd.OutOrStdout(), "No namespaces found. Run 'orca init' first.")
+			return nil
+		}
+		fmt.Fprintf(cmd.OutOrStdout(), "%-20s  %-10s  %s\n", "NAME", "DEFAULT", "PATH")
+		for _, r := range rows {
+			def := ""
+			if r.Default {
+				def = "*"
+			}
+			fmt.Fprintf(cmd.OutOrStdout(), "%-20s  %-10s  %s\n", r.Name, def, r.Path)
+		}
+		return nil
+	},
+}
+
+var nsCreateCmd = &cobra.Command{
+	Use:   "create <name>",
+	Short: "Create a namespace directory + ns.md",
+	Long: `Create a namespace under ORCA_HOME. Builds the dir structure
+(db/, jobs/, alloc/) and writes ns.md frontmatter. --parent may be
+repeated to declare inheritance; _defaults is always appended last.`,
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		name := args[0]
+		if name == paths.DefaultNamespace() {
+			return fmt.Errorf("cannot create the implicit root namespace %q with `ns create` (it is auto-managed)", name)
+		}
+		if name == "cluster" {
+			return fmt.Errorf("name %q is reserved for the cluster-wide dir", name)
+		}
+		if nsCreateParent == "" {
+			nsCreateParent = paths.DefaultNamespace()
+		}
+		nsDir := paths.NamespaceDir(name)
+		if _, err := os.Stat(nsDir); err == nil {
+			if _, statErr := os.Stat(paths.NSMd(name)); statErr == nil {
+				return fmt.Errorf("namespace %q already exists at %s", name, nsDir)
+			}
+		}
+		for _, sub := range []string{"db", "jobs", "alloc"} {
+			if err := os.MkdirAll(filepath.Join(nsDir, sub), 0o755); err != nil {
+				return fmt.Errorf("create %s/%s: %w", nsDir, sub, err)
+			}
+		}
+		parents := []string{nsCreateParent}
+		if nsCreateParent == paths.DefaultNamespace() {
+			// Explicit _defaults listing is allowed (de-duped silently).
+		}
+		body := renderNSMd(name, parents, nsCreateInheritsEnv, nsCreateInheritsSecret)
+		if err := os.WriteFile(paths.NSMd(name), []byte(body), 0o644); err != nil {
+			return fmt.Errorf("write ns.md: %w", err)
+		}
+		if jsonOutput {
+			return printJSON(map[string]any{
+				"name":             name,
+				"path":             nsDir,
+				"parents":          parents,
+				"ns_md":            paths.NSMd(name),
+				"inherits_env":     nsCreateInheritsEnv,
+				"inherits_secrets": nsCreateInheritsSecret,
+			})
+		}
+		fmt.Fprintf(cmd.OutOrStdout(), "✓ Namespace created: %s (%s)\n", name, nsDir)
+		return nil
+	},
+}
+
+var nsDeleteCmd = &cobra.Command{
+	Use:   "delete <name>",
+	Short: "Remove an empty namespace directory",
+	Long: `Remove a namespace directory. Refuses if jobs/ or alloc/
+contain any files (non-empty namespace). The implicit root _defaults
+cannot be deleted.`,
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		name := args[0]
+		if name == paths.DefaultNamespace() {
+			return fmt.Errorf("cannot delete the implicit root namespace %q", name)
+		}
+		nsDir := paths.NamespaceDir(name)
+		if _, err := os.Stat(nsDir); err != nil {
+			return fmt.Errorf("namespace %q not found: %w", name, err)
+		}
+		for _, sub := range []string{"jobs", "alloc"} {
+			dir := filepath.Join(nsDir, sub)
+			if err := dirNonEmpty(dir); err != nil {
+				return fmt.Errorf("refusing to delete %q: %s is non-empty (%w); clear it first", name, sub, err)
+			}
+		}
+		if err := os.RemoveAll(nsDir); err != nil {
+			return fmt.Errorf("delete %s: %w", nsDir, err)
+		}
+		if jsonOutput {
+			return printJSON(map[string]string{"name": name, "deleted": nsDir})
+		}
+		fmt.Fprintf(cmd.OutOrStdout(), "✓ Namespace deleted: %s (%s)\n", name, nsDir)
+		return nil
+	},
+}
+
+var nsInspectCmd = &cobra.Command{
+	Use:   "inspect <name>",
+	Short: "Print the effective chain, merged env, and constraints",
+	Long:  `Resolve a namespace's inheritance chain and print the merged env and unioned constraints (uses the resolver).`,
+	Args:  cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		name := args[0]
+		root := paths.Root()
+		cfgs, err := ns.ParseNSMdDir(root)
+		if err != nil {
+			return fmt.Errorf("load namespaces: %w", err)
+		}
+		if _, ok := cfgs[name]; !ok {
+			return fmt.Errorf("namespace %q not found under %s", name, root)
+		}
+		resolved, err := ns.Resolve(cfgs)
+		if err != nil {
+			return fmt.Errorf("resolve: %w", err)
+		}
+		r := resolved[name]
+		if r == nil {
+			return fmt.Errorf("namespace %q resolved to nil", name)
+		}
+		if jsonOutput {
+			return printJSON(map[string]any{
+				"name":        r.Name,
+				"chain":       r.Chain,
+				"env":         r.Env,
+				"constraints": r.Constraints,
+			})
+		}
+		fmt.Fprintf(cmd.OutOrStdout(), "Namespace: %s\n", r.Name)
+		fmt.Fprintf(cmd.OutOrStdout(), "Chain:     %s\n", strings.Join(r.Chain, " -> "))
+		fmt.Fprintln(cmd.OutOrStdout(), "Env:")
+		keys := sortedKeys(r.Env)
+		for _, k := range keys {
+			fmt.Fprintf(cmd.OutOrStdout(), "  %s = %s\n", k, r.Env[k])
+		}
+		fmt.Fprintln(cmd.OutOrStdout(), "Constraints:")
+		if len(r.Constraints) == 0 {
+			fmt.Fprintln(cmd.OutOrStdout(), "  (none)")
+		} else {
+			for _, c := range r.Constraints {
+				fmt.Fprintf(cmd.OutOrStdout(), "  - %s\n", c)
+			}
+		}
+		return nil
+	},
+}
+
+var nsValidateCmd = &cobra.Command{
+	Use:   "validate <name>",
+	Short: "Run cycle + missing-parent + schema checks on a namespace",
+	Long: `Validate a namespace's inheritance chain and ns.md frontmatter.
+Exits 0 if valid, 1 on error. Runs over ALL namespaces under ORCA_HOME
+(parsing + resolving validates cycles and missing parents across the
+set).`,
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		name := args[0]
+		root := paths.Root()
+		cfgs, err := ns.ParseNSMdDir(root)
+		if err != nil {
+			return fmt.Errorf("load namespaces: %w", err)
+		}
+		if _, ok := cfgs[name]; !ok {
+			return fmt.Errorf("namespace %q not found under %s", name, root)
+		}
+		resolved, err := ns.Resolve(cfgs)
+		if err != nil {
+			return fmt.Errorf("validate: %w", err)
+		}
+		r := resolved[name]
+		if r == nil {
+			return fmt.Errorf("namespace %q resolved to nil", name)
+		}
+		if jsonOutput {
+			return printJSON(map[string]any{
+				"name":  r.Name,
+				"valid": true,
+				"chain": r.Chain,
+			})
+		}
+		fmt.Fprintf(cmd.OutOrStdout(), "✓ %s valid\n  chain: %s\n", name, strings.Join(r.Chain, " -> "))
+		return nil
+	},
+}
+
+// renderNSMd writes a minimal ns.md frontmatter for `orca ns create`.
+func renderNSMd(name string, parents []string, inheritsEnv, inheritsSecrets bool) string {
+	var b strings.Builder
+	b.WriteString("---\n")
+	b.WriteString("kind: Namespace\n")
+	b.WriteString("name: ")
+	b.WriteString(name)
+	b.WriteString("\n")
+	if len(parents) > 0 {
+		quoted := make([]string, len(parents))
+		for i, p := range parents {
+			quoted[i] = fmt.Sprintf("%q", p)
+		}
+		b.WriteString("parents: [")
+		b.WriteString(strings.Join(quoted, ", "))
+		b.WriteString("]\n")
+	}
+	fmt.Fprintf(&b, "inherits_env: %t\n", inheritsEnv)
+	fmt.Fprintf(&b, "inherits_secrets: %t\n", inheritsSecrets)
+	b.WriteString("---\n")
+	return b.String()
+}
+
+// dirNonEmpty returns an error wrapping the offending entry if dir
+// contains any entries.
+func dirNonEmpty(dir string) error {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	for _, e := range entries {
+		return fmt.Errorf("contains %s", e.Name())
+	}
+	return nil
+}
+
+func sortedKeys(m map[string]string) []string {
+	out := make([]string, 0, len(m))
+	for k := range m {
+		out = append(out, k)
+	}
+	sort.Strings(out)
+	return out
+}
+
+func init() {
+	nsCreateCmd.Flags().StringVar(&nsCreateParent, "parent", "", "parent namespace (default _defaults; the implicit root is always appended last)")
+	nsCreateCmd.Flags().BoolVar(&nsCreateInheritsEnv, "inherits-env", true, "inherit env from parents (default true)")
+	nsCreateCmd.Flags().BoolVar(&nsCreateInheritsSecret, "inherits-secrets", true, "inherit secrets from parents (default true)")
+
+	nsCmd.AddCommand(nsListCmd)
+	nsCmd.AddCommand(nsCreateCmd)
+	nsCmd.AddCommand(nsDeleteCmd)
+	nsCmd.AddCommand(nsInspectCmd)
+	nsCmd.AddCommand(nsValidateCmd)
+	rootCmd.AddCommand(nsCmd)
+}

internal/cli/ns_test.go

@@ -0,0 +1,407 @@
+package cli
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"git.cloudinit.dev/coreci/orca/internal/paths"
+)
+
+// resetNSFlags zeroes the ns subcommand flag-bound vars so tests don't
+// leak state.
+func resetNSFlags() {
+	nsCreateParent = ""
+	nsCreateInheritsEnv = true
+	nsCreateInheritsSecret = true
+}
+
+func writeDefaultsNS(t *testing.T, root string) {
+	t.Helper()
+	nsDir := filepath.Join(root, "_defaults")
+	if err := os.MkdirAll(nsDir, 0o755); err != nil {
+		t.Fatalf("mkdir _defaults: %v", err)
+	}
+	body := "---\nkind: Namespace\nname: _defaults\ninherits_env: true\ninherits_secrets: true\n---\n# defaults\n"
+	if err := os.WriteFile(filepath.Join(nsDir, "ns.md"), []byte(body), 0o644); err != nil {
+		t.Fatalf("write _defaults ns.md: %v", err)
+	}
+}
+
+func writeCustomNS(t *testing.T, root, name, parentsList string) {
+	t.Helper()
+	nsDir := filepath.Join(root, name)
+	if err := os.MkdirAll(nsDir, 0o755); err != nil {
+		t.Fatalf("mkdir %s: %v", name, err)
+	}
+	body := "---\nkind: Namespace\nname: " + name + "\n"
+	if parentsList != "" {
+		body += "parents: " + parentsList + "\n"
+	}
+	body += "inherits_env: true\ninherits_secrets: true\n---\n# " + name + "\n"
+	if err := os.WriteFile(filepath.Join(nsDir, "ns.md"), []byte(body), 0o644); err != nil {
+		t.Fatalf("write %s ns.md: %v", name, err)
+	}
+}
+
+func TestNSListEmpty(t *testing.T) {
+	t.Setenv("ORCA_HOME", t.TempDir())
+	resetRootFlags(t)
+	resetNSFlags()
+
+	rootCmd.SetArgs([]string{"ns", "list"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns list: %v", err)
+	}
+}
+
+func TestNSListWithNamespaces(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	rootCmd.SetArgs([]string{"ns", "list"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns list: %v", err)
+	}
+}
+
+func TestNSCreateHappy(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+
+	rootCmd.SetArgs([]string{"ns", "create", "prod"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns create: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(root, "prod", "ns.md")); err != nil {
+		t.Fatalf("ns.md not created: %v", err)
+	}
+	for _, sub := range []string{"db", "jobs", "alloc"} {
+		if _, err := os.Stat(filepath.Join(root, "prod", sub)); err != nil {
+			t.Errorf("subdir %s not created: %v", sub, err)
+		}
+	}
+}
+
+func TestNSCreateWithParent(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "base", "")
+
+	rootCmd.SetArgs([]string{"ns", "create", "child", "--parent", "base"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns create: %v", err)
+	}
+	data, err := os.ReadFile(filepath.Join(root, "child", "ns.md"))
+	if err != nil {
+		t.Fatalf("read ns.md: %v", err)
+	}
+	if !strings.Contains(string(data), "parents: [") || !strings.Contains(string(data), "\"base\"") {
+		t.Errorf("ns.md missing parents: %s", string(data))
+	}
+}
+
+func TestNSCreateExisting(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	rootCmd.SetArgs([]string{"ns", "create", "prod"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error creating existing namespace, got nil")
+	}
+	if !strings.Contains(err.Error(), "already exists") {
+		t.Errorf("error = %q, want contains 'already exists'", err.Error())
+	}
+}
+
+func TestNSCreateDefaultsRefused(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+
+	rootCmd.SetArgs([]string{"ns", "create", "_defaults"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error creating _defaults, got nil")
+	}
+}
+
+func TestNSCreateClusterRefused(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+
+	rootCmd.SetArgs([]string{"ns", "create", "cluster"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error creating cluster, got nil")
+	}
+}
+
+func TestNSDeleteHappy(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	rootCmd.SetArgs([]string{"ns", "delete", "prod"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns delete: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(root, "prod")); !os.IsNotExist(err) {
+		t.Errorf("prod dir still exists after delete")
+	}
+}
+
+func TestNSDeleteDefaultsRefused(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+
+	rootCmd.SetArgs([]string{"ns", "delete", "_defaults"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error deleting _defaults, got nil")
+	}
+}
+
+func TestNSDeleteNonEmpty(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+	// put a job in jobs/
+	if err := os.MkdirAll(filepath.Join(root, "prod", "jobs"), 0o755); err != nil {
+		t.Fatalf("mkdir jobs: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "prod", "jobs", "j1.md"), []byte("x"), 0o644); err != nil {
+		t.Fatalf("write job: %v", err)
+	}
+
+	rootCmd.SetArgs([]string{"ns", "delete", "prod"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error deleting non-empty namespace, got nil")
+	}
+	if !strings.Contains(err.Error(), "refusing to delete") {
+		t.Errorf("error = %q, want contains 'refusing to delete'", err.Error())
+	}
+}
+
+func TestNSDeleteMissing(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+
+	rootCmd.SetArgs([]string{"ns", "delete", "ghost"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error deleting missing namespace, got nil")
+	}
+}
+
+func TestNSInspectHappy(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	rootCmd.SetArgs([]string{"ns", "inspect", "prod"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns inspect: %v", err)
+	}
+}
+
+func TestNSInspectJSON(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	var buf bytes.Buffer
+	rootCmd.SetOut(&buf)
+	rootCmd.SetArgs([]string{"ns", "inspect", "prod", "--json"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns inspect --json: %v", err)
+	}
+	var result map[string]any
+	if err := json.Unmarshal(bytes.TrimSpace(buf.Bytes()), &result); err != nil {
+		t.Fatalf("unmarshal: %v\n%s", err, buf.String())
+	}
+	if result["name"] != "prod" {
+		t.Errorf("name = %v, want prod", result["name"])
+	}
+	chain, _ := result["chain"].([]any)
+	if len(chain) < 2 {
+		t.Errorf("chain too short: %v", chain)
+	}
+}
+
+func TestNSInspectMissingNamespace(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+
+	rootCmd.SetArgs([]string{"ns", "inspect", "ghost"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error for missing namespace, got nil")
+	}
+}
+
+func TestNSValidateHappy(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "prod", "")
+
+	rootCmd.SetArgs([]string{"ns", "validate", "prod"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("ns validate: %v", err)
+	}
+}
+
+func TestNSValidateCycle(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	// a -> b, b -> a (cycle)
+	writeCustomNS(t, root, "a", "[\"b\"]")
+	writeCustomNS(t, root, "b", "[\"a\"]")
+
+	rootCmd.SetArgs([]string{"ns", "validate", "a"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected cycle error, got nil")
+	}
+	if !strings.Contains(err.Error(), "cycle") {
+		t.Errorf("error = %q, want contains 'cycle'", err.Error())
+	}
+}
+
+func TestNSValidateMissingParent(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+	writeCustomNS(t, root, "x", "[\"ghost\"]")
+
+	rootCmd.SetArgs([]string{"ns", "validate", "x"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected missing-parent error, got nil")
+	}
+	if !strings.Contains(err.Error(), "ghost") || !strings.Contains(err.Error(), "not found") {
+		t.Errorf("error = %q, want contains ghost + not found", err.Error())
+	}
+}
+
+func TestNSValidateMissingNamespace(t *testing.T) {
+	root := t.TempDir()
+	t.Setenv("ORCA_HOME", root)
+	resetRootFlags(t)
+	resetNSFlags()
+	writeDefaultsNS(t, root)
+
+	rootCmd.SetArgs([]string{"ns", "validate", "ghost"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error for missing namespace, got nil")
+	}
+}
+
+func TestRenderNSMd(t *testing.T) {
+	body := renderNSMd("foo", []string{"_defaults"}, true, false)
+	if !strings.Contains(body, "kind: Namespace") {
+		t.Errorf("missing kind: %s", body)
+	}
+	if !strings.Contains(body, "name: foo") {
+		t.Errorf("missing name: %s", body)
+	}
+	if !strings.Contains(body, "inherits_env: true") {
+		t.Errorf("missing inherits_env true: %s", body)
+	}
+	if !strings.Contains(body, "inherits_secrets: false") {
+		t.Errorf("missing inherits_secrets false: %s", body)
+	}
+}
+
+func TestNSRootRegistered(t *testing.T) {
+	found := false
+	for _, c := range rootCmd.Commands() {
+		if c.Use == "ns" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("ns command not registered on root")
+	}
+	// ensure subcommands present
+	sub := map[string]bool{}
+	for _, c := range rootCmd.Commands() {
+		if c.Use == "ns" {
+			for _, sc := range c.Commands() {
+				sub[sc.Use] = true
+			}
+		}
+	}
+	for _, want := range []string{"list", "create <name>", "delete <name>", "inspect <name>", "validate <name>"} {
+		if !sub[want] {
+			t.Errorf("missing ns subcommand %q", want)
+		}
+	}
+}
+
+func TestNSListNoORCAHOME(t *testing.T) {
+	// ORCA_HOME points at a nonexistent dir; list should error.
+	t.Setenv("ORCA_HOME", filepath.Join(t.TempDir(), "nope"))
+	resetRootFlags(t)
+	resetNSFlags()
+
+	rootCmd.SetArgs([]string{"ns", "list"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error for missing ORCA_HOME, got nil")
+	}
+}
+
+var _ = paths.DefaultNamespace // keep paths import alive

internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/hashicorp/hcl/v2/hclsimple"
 )
@@ -33,22 +34,82 @@ type Flags struct {
 
 type Environ map[string]string
 
+// Load is the config dispatcher (R-014). It tries each path in order,
+// skipping missing files, and dispatches to the appropriate loader
+// based on file extension: .hcl → LoadHCL (legacy, R-013),
+// .md → LoadMarkdown (new Markdown-frontmatter loader), and
+// .yaml/.yml → LoadMarkdown with an empty body. The first successfully
+// decoded file wins. If no path exists or decodes, a zero Config is
+// returned.
+//
+// The signature is preserved from the v0.8 single-loader API so
+// internal/cli/root.go requires no changes yet.
 func Load(paths ...string) (*Config, error) {
 	for _, p := range paths {
 		if _, err := os.Stat(p); err != nil {
 			continue
 		}
+		cfg, err := loadByExtension(p)
+		if err != nil {
+			return nil, err
+		}
+		return cfg, nil
+	}
+	return &Config{}, nil
+}
+
+func loadByExtension(p string) (*Config, error) {
+	ext := strings.ToLower(filepathExt(p))
+	switch ext {
+	case ".hcl":
+		return LoadHCL(p)
+	case ".md", ".markdown":
+		return LoadMarkdown(p)
+	case ".yaml", ".yml":
+		return LoadMarkdownYAML(p)
+	default:
+		// Unknown extension: hclsimple.Decode rejects non-.hcl
+		// suffixes, so for backward compat with the v0.8 single-loader
+		// behavior (which assumed HCL), decode the file content as HCL
+		// against a synthesized .hcl path.
 		data, err := os.ReadFile(p)
 		if err != nil {
 			return nil, fmt.Errorf("read config %s: %w", p, err)
 		}
 		var cfg Config
-		if err := hclsimple.Decode(p, data, nil, &cfg); err != nil {
+		if err := hclsimple.Decode(p+".hcl", data, nil, &cfg); err != nil {
 			return nil, fmt.Errorf("decode config %s: %w", p, err)
 		}
 		return &cfg, nil
 	}
-	return &Config{}, nil
+}
+
+// filepathExt is a thin wrapper around filepath.Ext to keep the import
+// localized to the dispatcher. Returns the extension including the dot,
+// lowercased by the caller.
+func filepathExt(p string) string {
+	i := strings.LastIndex(p, ".")
+	if i < 0 {
+		return ""
+	}
+	return p[i:]
+}
+
+// LoadHCL decodes a legacy HCL config file (R-013).
+//
+// Deprecated: use LoadMarkdown or the dispatcher. HCL is legacy per
+// R-013. Retained for the v0.9 dual-write window (REQ-090); new
+// deployments should author config.md with YAML frontmatter.
+func LoadHCL(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read config %s: %w", path, err)
+	}
+	var cfg Config
+	if err := hclsimple.Decode(path, data, nil, &cfg); err != nil {
+		return nil, fmt.Errorf("decode config %s: %w", path, err)
+	}
+	return &cfg, nil
 }
 
 func (c *Config) MergeOverrides(flags Flags, env Environ) *Config {

internal/config/dispatch_test.go

@@ -0,0 +1,111 @@
+package config
+
+import (
+	"path/filepath"
+	"testing"
+)
+
+func TestLoad_DispatchHCL(t *testing.T) {
+	p := writeTestFile(t, t.TempDir(), "config.hcl", exampleHCL)
+	cfg, err := Load(p)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.NodeCapacity == nil || cfg.NodeCapacity.CPU != 4 {
+		t.Errorf("NodeCapacity=%+v", cfg.NodeCapacity)
+	}
+}
+
+func TestLoad_DispatchMarkdown(t *testing.T) {
+	p := writeTestFile(t, t.TempDir(), "config.md", exampleMarkdown)
+	cfg, err := Load(p)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.ListenAddr != "127.0.0.1:9999" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.NodeCapacity == nil || cfg.NodeCapacity.CPU != 4 {
+		t.Errorf("NodeCapacity=%+v", cfg.NodeCapacity)
+	}
+}
+
+func TestLoad_DispatchYAML(t *testing.T) {
+	body := "listen_addr: 0.0.0.0:5555\ndb_path: /bare.db\nnode_capacity:\n  cpu: 2\n  memory_mb: 4096\n"
+	p := writeTestFile(t, t.TempDir(), "config.yaml", body)
+	cfg, err := Load(p)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.ListenAddr != "0.0.0.0:5555" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.DBPath != "/bare.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.NodeCapacity == nil || cfg.NodeCapacity.CPU != 2 {
+		t.Errorf("NodeCapacity=%+v", cfg.NodeCapacity)
+	}
+}
+
+func TestLoad_DispatchYML(t *testing.T) {
+	body := "listen_addr: 1.2.3.4:9\n"
+	p := writeTestFile(t, t.TempDir(), "config.yml", body)
+	cfg, err := Load(p)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.ListenAddr != "1.2.3.4:9" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+}
+
+func TestLoad_DispatchFirstExistingWins(t *testing.T) {
+	dir := t.TempDir()
+	missing := filepath.Join(dir, "missing.md")
+	existing := writeTestFile(t, dir, "real.hcl", exampleHCL)
+	cfg, err := Load(missing, existing)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+}
+
+func TestLoad_DispatchMissingReturnsZero(t *testing.T) {
+	cfg, err := Load(filepath.Join(t.TempDir(), "nope.md"))
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg == nil {
+		t.Fatal("nil config")
+	}
+	if cfg.DBPath != "" || cfg.ListenAddr != "" || cfg.NodeCapacity != nil {
+		t.Errorf("expected zero config, got %+v", cfg)
+	}
+}
+
+func TestLoad_DispatchHCLMalformed(t *testing.T) {
+	p := writeTestFile(t, t.TempDir(), "bad.hcl", "db_path = ")
+	if _, err := Load(p); err == nil {
+		t.Fatal("expected error for malformed HCL")
+	}
+}
+
+func TestLoad_DispatchUnknownExtFallsBackToHCL(t *testing.T) {
+	p := writeTestFile(t, t.TempDir(), "config.unknown", exampleHCL)
+	cfg, err := Load(p)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+}

internal/config/markdown.go

@@ -0,0 +1,220 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// LoadMarkdown decodes a Markdown config file with YAML frontmatter
+// (R-014). The file format is:
+//
+//	---
+//	listen_addr: 127.0.0.1:9999
+//	node_capacity:
+//	  cpu: 4
+//	  memory_mb: 8192
+//	db_path: /tmp/orca/test.db
+//	---
+//
+//	body prose (ignored)
+//
+// The frontmatter parser is a minimal hand-rolled key:value parser
+// (no new dependencies; gopkg.in/yaml.v3 is not in go.mod). It supports
+// flat scalar keys and one level of nested mapping (for node_capacity).
+// The Markdown body after the closing "---" is ignored.
+//
+// The returned *Config is the same struct the HCL loader produces, so
+// downstream consumers are unchanged.
+func LoadMarkdown(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read config %s: %w", path, err)
+	}
+	return parseFrontmatter(string(data), path)
+}
+
+// LoadMarkdownYAML decodes a bare YAML file (no Markdown body) using the
+// same minimal frontmatter parser. .yaml/.yml files are routed here by
+// the dispatcher.
+func LoadMarkdownYAML(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read config %s: %w", path, err)
+	}
+	// Treat the whole file as the frontmatter block (no surrounding ---).
+	return parseFrontmatterBlock(string(data), path)
+}
+
+func parseFrontmatter(content, path string) (*Config, error) {
+	block, ok := extractFrontmatter(content)
+	if !ok {
+		// No frontmatter delimiters: treat whole file as a bare block.
+		return parseFrontmatterBlock(content, path)
+	}
+	return parseFrontmatterBlock(block, path)
+}
+
+// extractFrontmatter returns the YAML block between the first pair of
+// "---" delimiters and whether a frontmatter block was present.
+func extractFrontmatter(content string) (string, bool) {
+	trimmed := strings.TrimLeft(content, "\r\n\t ")
+	if !strings.HasPrefix(trimmed, "---") {
+		return "", false
+	}
+	// Skip the opening delimiter line.
+	rest := trimmed[3:]
+	rest = strings.TrimLeft(rest, "\r\n")
+	// Find the closing delimiter line.
+	idx := strings.Index(rest, "\n---")
+	if idx < 0 {
+		return "", false
+	}
+	return rest[:idx], true
+}
+
+// parseFrontmatterBlock parses a minimal YAML-ish block into *Config.
+// Supported shapes:
+//
+//	key: value
+//	node_capacity:
+//	  cpu: 4
+//	  memory_mb: 8192
+//
+// Comments (# ...) and blank lines are ignored. Quoted scalar values
+// ("..." or '...') are unwrapped. No flow collections, anchors, or
+// multi-line strings are supported — by design, to avoid adding a YAML
+// dependency for this small config surface.
+func parseFrontmatterBlock(block, path string) (*Config, error) {
+	cfg := &Config{}
+	var inCapacity bool
+
+	lines := strings.Split(block, "\n")
+	for lineNo, raw := range lines {
+		line := stripComment(raw)
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+
+		indent := countIndent(line)
+		trimmed := strings.TrimSpace(line)
+
+		// A top-level key (no leading indent).
+		if indent == 0 {
+			inCapacity = false
+			key, val, ok := splitKV(trimmed)
+			if !ok {
+				continue
+			}
+			if val == "" {
+				// key with no value → nested mapping header (e.g. node_capacity:)
+				if key == "node_capacity" {
+					cfg.NodeCapacity = &CapacityConfig{}
+					inCapacity = true
+				}
+				continue
+			}
+			applyScalar(cfg, key, val, path, lineNo)
+			continue
+		}
+
+		// Indented line under a nested mapping.
+		if inCapacity && cfg.NodeCapacity != nil {
+			key, val, hasVal := splitKV(trimmed)
+			if !hasVal {
+				continue
+			}
+			switch key {
+			case "cpu":
+				if n, err := strconv.Atoi(strings.TrimSpace(val)); err == nil {
+					cfg.NodeCapacity.CPU = n
+				}
+			case "memory_mb":
+				if n, err := strconv.Atoi(strings.TrimSpace(val)); err == nil {
+					cfg.NodeCapacity.MemoryMB = n
+				}
+			}
+		}
+	}
+	return cfg, nil
+}
+
+func applyScalar(cfg *Config, key, val, path string, lineNo int) {
+	val = strings.TrimSpace(val)
+	switch key {
+	case "db_path":
+		cfg.DBPath = unquote(val)
+	case "listen_addr":
+		cfg.ListenAddr = unquote(val)
+	case "ca_path":
+		cfg.CAPath = unquote(val)
+	case "server_cert_path":
+		cfg.ServerCertPath = unquote(val)
+	case "server_key_path":
+		cfg.ServerKeyPath = unquote(val)
+	}
+	_ = path
+	_ = lineNo
+}
+
+func splitKV(s string) (key, val string, ok bool) {
+	idx := strings.Index(s, ":")
+	if idx < 0 {
+		return "", "", false
+	}
+	key = strings.TrimSpace(s[:idx])
+	val = strings.TrimSpace(s[idx+1:])
+	if key == "" {
+		return "", "", false
+	}
+	return key, val, true
+}
+
+func countIndent(s string) int {
+	n := 0
+	for _, r := range s {
+		if r == ' ' || r == '\t' {
+			n++
+			continue
+		}
+		break
+	}
+	return n
+}
+
+func stripComment(s string) string {
+	// Strip inline comments not inside quotes. Minimal: only strip
+	// when the '#' is preceded by whitespace or at line start.
+	inSingle := false
+	inDouble := false
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch c {
+		case '\'':
+			if !inDouble {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle {
+				inDouble = !inDouble
+			}
+		case '#':
+			if !inSingle && !inDouble {
+				if i == 0 || s[i-1] == ' ' || s[i-1] == '\t' {
+					return s[:i]
+				}
+			}
+		}
+	}
+	return s
+}
+
+func unquote(s string) string {
+	if len(s) >= 2 {
+		if (s[0] == '"' && s[len(s)-1] == '"') || (s[0] == '\'' && s[len(s)-1] == '\'') {
+			return s[1 : len(s)-1]
+		}
+	}
+	return s
+}

internal/config/markdown_test.go

@@ -0,0 +1,186 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func writeTestFile(t *testing.T, dir, name, content string) string {
+	t.Helper()
+	p := filepath.Join(dir, name)
+	if err := os.WriteFile(p, []byte(content), 0644); err != nil {
+		t.Fatalf("write %s: %v", p, err)
+	}
+	return p
+}
+
+const exampleMarkdown = `---
+listen_addr: "127.0.0.1:9999"
+db_path: "/tmp/orca/test.db"
+ca_path: "/tmp/orca/ca.crt"
+server_cert_path: "/tmp/orca/server.crt"
+server_key_path: "/tmp/orca/server.key"
+node_capacity:
+  cpu: 4
+  memory_mb: 8192
+---
+
+# Orca config
+
+This is prose body and is ignored by the loader.
+`
+
+func TestLoadMarkdown_Full(t *testing.T) {
+	p := writeTestFile(t, t.TempDir(), "config.md", exampleMarkdown)
+	cfg, err := LoadMarkdown(p)
+	if err != nil {
+		t.Fatalf("LoadMarkdown: %v", err)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.ListenAddr != "127.0.0.1:9999" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.CAPath != "/tmp/orca/ca.crt" {
+		t.Errorf("CAPath=%q", cfg.CAPath)
+	}
+	if cfg.ServerCertPath != "/tmp/orca/server.crt" {
+		t.Errorf("ServerCertPath=%q", cfg.ServerCertPath)
+	}
+	if cfg.ServerKeyPath != "/tmp/orca/server.key" {
+		t.Errorf("ServerKeyPath=%q", cfg.ServerKeyPath)
+	}
+	if cfg.NodeCapacity == nil {
+		t.Fatal("NodeCapacity nil")
+	}
+	if cfg.NodeCapacity.CPU != 4 {
+		t.Errorf("CPU=%d", cfg.NodeCapacity.CPU)
+	}
+	if cfg.NodeCapacity.MemoryMB != 8192 {
+		t.Errorf("MemoryMB=%d", cfg.NodeCapacity.MemoryMB)
+	}
+}
+
+func TestLoadMarkdown_NoFrontmatter(t *testing.T) {
+	// No delimiters: whole file treated as a bare YAML block.
+	body := "listen_addr: 0.0.0.0:1234\ndb_path: /x/y.db\n"
+	p := writeTestFile(t, t.TempDir(), "config.md", body)
+	cfg, err := LoadMarkdown(p)
+	if err != nil {
+		t.Fatalf("LoadMarkdown: %v", err)
+	}
+	if cfg.ListenAddr != "0.0.0.0:1234" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.DBPath != "/x/y.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+}
+
+func TestLoadMarkdown_OnlyBody(t *testing.T) {
+	body := `---
+---
+
+# Just prose, no keys
+`
+	p := writeTestFile(t, t.TempDir(), "config.md", body)
+	cfg, err := LoadMarkdown(p)
+	if err != nil {
+		t.Fatalf("LoadMarkdown: %v", err)
+	}
+	if cfg.DBPath != "" || cfg.ListenAddr != "" || cfg.NodeCapacity != nil {
+		t.Errorf("expected zero config, got %+v", cfg)
+	}
+}
+
+func TestLoadMarkdown_CommentsAndBlanks(t *testing.T) {
+	body := `---
+# a comment
+listen_addr: "127.0.0.1:9999"
+
+db_path: "/tmp/orca/test.db"  # inline comment
+
+node_capacity:
+  cpu: 4   # cores
+  memory_mb: 8192
+---
+`
+	p := writeTestFile(t, t.TempDir(), "config.md", body)
+	cfg, err := LoadMarkdown(p)
+	if err != nil {
+		t.Fatalf("LoadMarkdown: %v", err)
+	}
+	if cfg.ListenAddr != "127.0.0.1:9999" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.DBPath != "/tmp/orca/test.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.NodeCapacity == nil || cfg.NodeCapacity.CPU != 4 || cfg.NodeCapacity.MemoryMB != 8192 {
+		t.Errorf("NodeCapacity=%+v", cfg.NodeCapacity)
+	}
+}
+
+func TestLoadMarkdownYAML_Bare(t *testing.T) {
+	body := "listen_addr: 0.0.0.0:5555\ndb_path: /bare.db\nnode_capacity:\n  cpu: 2\n  memory_mb: 4096\n"
+	p := writeTestFile(t, t.TempDir(), "config.yaml", body)
+	cfg, err := LoadMarkdownYAML(p)
+	if err != nil {
+		t.Fatalf("LoadMarkdownYAML: %v", err)
+	}
+	if cfg.ListenAddr != "0.0.0.0:5555" {
+		t.Errorf("ListenAddr=%q", cfg.ListenAddr)
+	}
+	if cfg.DBPath != "/bare.db" {
+		t.Errorf("DBPath=%q", cfg.DBPath)
+	}
+	if cfg.NodeCapacity == nil || cfg.NodeCapacity.CPU != 2 || cfg.NodeCapacity.MemoryMB != 4096 {
+		t.Errorf("NodeCapacity=%+v", cfg.NodeCapacity)
+	}
+}
+
+func TestLoadMarkdown_ReadError(t *testing.T) {
+	missing := filepath.Join(t.TempDir(), "nope.md")
+	if _, err := LoadMarkdown(missing); err == nil {
+		t.Fatal("expected error for missing file")
+	}
+}
+
+func TestExtractFrontmatter(t *testing.T) {
+	cases := []struct {
+		name    string
+		input   string
+		block   string
+		present bool
+	}{
+		{"standard", "---\nkey: val\n---\nbody", "key: val", true},
+		{"leading-blanks", "\n\n---\nkey: val\n---\n", "key: val", true},
+		{"no-delimiters", "key: val\n", "key: val", false},
+		{"only-open", "---\nkey: val\n", "key: val", false},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			block, ok := extractFrontmatter(tc.input)
+			if ok != tc.present {
+				t.Errorf("present=%v want %v", ok, tc.present)
+			}
+			if tc.present && block != tc.block {
+				t.Errorf("block=%q want %q", block, tc.block)
+			}
+		})
+	}
+}
+
+func TestUnquote(t *testing.T) {
+	if got, want := unquote(`"hello"`), "hello"; got != want {
+		t.Errorf("unquote double = %q want %q", got, want)
+	}
+	if got, want := unquote(`'hello'`), "hello"; got != want {
+		t.Errorf("unquote single = %q want %q", got, want)
+	}
+	if got, want := unquote("bare"), "bare"; got != want {
+		t.Errorf("unquote bare = %q want %q", got, want)
+	}
+}

internal/jobspec/dispatch.go

@@ -0,0 +1,147 @@
+package jobspec
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ParseFile reads a jobspec file from disk and dispatches on file
+// extension (R-013, REQ-064):
+//
+//   - .md  → ParseMarkdown (canonical Markdown+frontmatter, R-014/R-015)
+//   - .yaml/.yml → ParseMarkdown with the whole file treated as
+//     frontmatter and Body = "" (pure YAML, no Markdown body)
+//   - .hcl → ParseHCL (legacy adapter; wraps the existing HCL parser
+//     and converts Spec{Job, Tasks} into *WorkloadSpec with Kind="Job",
+//     REQ-090 migration window)
+//
+// Unknown extensions return an error. The dispatcher preserves
+// `orca job run old-spec.hcl` during the v0.9→v0.10 migration window
+// (REQ-090).
+func ParseFile(path string) (*WorkloadSpec, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read spec file: %w", err)
+	}
+	return Dispatch(data, filepath.Base(path))
+}
+
+// ParseHCLFile reads an HCL file and parses it via the legacy HCL parser,
+// returning the legacy *Spec. It is a convenience wrapper retained for
+// tests and direct HCL consumers that need the raw Spec{Job, Tasks}
+// shape during the v0.9→v0.10 migration window (REQ-090).
+//
+// Deprecated: use ParseFile (dispatcher) for new code. HCL is legacy per
+// R-013.
+func ParseHCLFile(path string) (*Spec, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read spec file: %w", err)
+	}
+	return ParseHCLLegacy(data, filepath.Base(path))
+}
+
+// Dispatch routes raw jobspec bytes on file extension to the
+// appropriate parser. filename is used only for HCL (the HCL decoder
+// needs a filename for error messages and syntax sniffing).
+func Dispatch(data []byte, filename string) (*WorkloadSpec, error) {
+	ext := strings.ToLower(filepath.Ext(filename))
+	switch ext {
+	case ".md":
+		return ParseMarkdown(data)
+	case ".yaml", ".yml":
+		// Pure YAML file: no Markdown body. Treat the whole file as
+		// the frontmatter block. Body is empty (R-015: no body to
+		// preserve).
+		spec, err := parseYAMLFile(data)
+		if err != nil {
+			return nil, err
+		}
+		return spec, nil
+	case ".hcl":
+		return ParseHCL(data, filename)
+	default:
+		return nil, fmt.Errorf("parse jobspec: unknown extension %q (want .md, .yaml, .yml, or .hcl)", ext)
+	}
+}
+
+// parseYAMLFile treats the whole file as a frontmatter block (no
+// surrounding `---` delimiters, no Markdown body). This routes .yaml
+// and .yml files through the same hand-rolled parser as .md.
+func parseYAMLFile(data []byte) (*WorkloadSpec, error) {
+	block := string(data)
+	if strings.TrimSpace(block) == "" {
+		return nil, fmt.Errorf("parse yaml: empty file")
+	}
+	spec, err := parseFrontmatterBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	spec.Body = ""
+	if err := validateWorkload(spec); err != nil {
+		return nil, err
+	}
+	return spec, nil
+}
+
+// ParseHCL parses a legacy HCL jobspec and adapts it into a *WorkloadSpec
+// (REQ-064 adapter, REQ-090 migration window). The existing HCL
+// Spec{Job, Tasks} shape is converted to:
+//
+//	Kind:     "Job"
+//	Name:     spec.Job.Name
+//	Runtime:  {one_of: "process", command: tasks[0].Command}
+//
+// Body is empty (HCL has no Markdown body). The legacy Spec struct and
+// ParseHCLLegacy are retained for direct HCL consumers that have not yet
+// migrated.
+//
+// Deprecated: use the dispatcher (ParseFile/Dispatch). HCL is legacy
+// per R-013; the HCL path is retained only for the v0.9→v0.10 migration
+// window (REQ-090) and will be removed in v1.0.
+func ParseHCL(data []byte, filename string) (*WorkloadSpec, error) {
+	spec, err := ParseHCLLegacy(data, filename)
+	if err != nil {
+		return nil, err
+	}
+	ws := &WorkloadSpec{
+		SpecVersion: "",
+		Kind:        "Job",
+		Name:        spec.Job.Name,
+		Count:       1,
+		Body:        "",
+	}
+	if len(spec.Tasks) > 0 {
+		ws.Runtime = &RuntimeBlock{
+			OneOf:   "process",
+			Command: spec.Tasks[0].Command,
+		}
+	}
+	return ws, nil
+}
+
+// ParseHCLLegacy is the original HCL-only parser retained for direct
+// HCL consumers (e.g. the cli/job.go toTaskSpecs path during the
+// migration window). New code should call ParseHCL (which returns a
+// *WorkloadSpec) or the dispatcher. Deprecated: HCL is legacy per
+// R-013; see ParseHCL.
+func ParseHCLLegacy(data []byte, filename string) (*Spec, error) {
+	var spec Spec
+	if err := hclDecode(filename, data, &spec); err != nil {
+		return nil, fmt.Errorf("decode hcl: %w", err)
+	}
+	if spec.Job.Name == "" {
+		return nil, fmt.Errorf("spec missing job name")
+	}
+	if len(spec.Tasks) == 0 {
+		return nil, fmt.Errorf("spec must have at least one task")
+	}
+	for i, t := range spec.Tasks {
+		if t.Command == "" {
+			return nil, fmt.Errorf("task[%d] (%s) missing command", i, t.Name)
+		}
+	}
+	return &spec, nil
+}

internal/jobspec/dispatch_test.go

@@ -0,0 +1,222 @@
+package jobspec
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestDispatch_Markdown(t *testing.T) {
+	input := "---\nkind: Job\nname: md-job\n---\nbody content\n"
+	ws, err := Dispatch([]byte(input), "spec.md")
+	if err != nil {
+		t.Fatalf("Dispatch .md: %v", err)
+	}
+	if ws.Kind != "Job" {
+		t.Errorf("Kind = %q, want Job", ws.Kind)
+	}
+	if ws.Name != "md-job" {
+		t.Errorf("Name = %q, want md-job", ws.Name)
+	}
+	if ws.Body != "body content\n" {
+		t.Errorf("Body = %q, want %q (R-015)", ws.Body, "body content\n")
+	}
+}
+
+func TestDispatch_YAML(t *testing.T) {
+	input := "kind: Service\nname: yaml-svc\nports:\n  - name: http\n    port: 80\n"
+	ws, err := Dispatch([]byte(input), "spec.yaml")
+	if err != nil {
+		t.Fatalf("Dispatch .yaml: %v", err)
+	}
+	if ws.Kind != "Service" {
+		t.Errorf("Kind = %q, want Service", ws.Kind)
+	}
+	if ws.Name != "yaml-svc" {
+		t.Errorf("Name = %q, want yaml-svc", ws.Name)
+	}
+	if ws.Body != "" {
+		t.Errorf("Body = %q, want empty (YAML has no body)", ws.Body)
+	}
+	if len(ws.Ports) != 1 || ws.Ports[0].Name != "http" || ws.Ports[0].Port != 80 {
+		t.Errorf("Ports = %+v, want one http:80", ws.Ports)
+	}
+}
+
+func TestDispatch_YML(t *testing.T) {
+	input := "kind: DaemonSet\nname: yml-ds\n"
+	ws, err := Dispatch([]byte(input), "spec.yml")
+	if err != nil {
+		t.Fatalf("Dispatch .yml: %v", err)
+	}
+	if ws.Kind != "DaemonSet" {
+		t.Errorf("Kind = %q, want DaemonSet", ws.Kind)
+	}
+	if ws.Body != "" {
+		t.Errorf("Body = %q, want empty", ws.Body)
+	}
+}
+
+func TestDispatch_HCLAdapter(t *testing.T) {
+	hcl := `job "demo" {}
+task "build" {
+  command = "/bin/echo"
+  args    = ["hello"]
+}
+`
+	ws, err := Dispatch([]byte(hcl), "spec.hcl")
+	if err != nil {
+		t.Fatalf("Dispatch .hcl: %v", err)
+	}
+	if ws.Kind != "Job" {
+		t.Errorf("Kind = %q, want Job (adapter always sets Job)", ws.Kind)
+	}
+	if ws.Name != "demo" {
+		t.Errorf("Name = %q, want demo (from spec.Job.Name)", ws.Name)
+	}
+	if ws.Runtime == nil {
+		t.Fatal("Runtime is nil; adapter should populate from tasks[0]")
+	}
+	if ws.Runtime.OneOf != "process" {
+		t.Errorf("Runtime.OneOf = %q, want process", ws.Runtime.OneOf)
+	}
+	if ws.Runtime.Command != "/bin/echo" {
+		t.Errorf("Runtime.Command = %q, want /bin/echo (from tasks[0].Command)", ws.Runtime.Command)
+	}
+	if ws.Body != "" {
+		t.Errorf("Body = %q, want empty (HCL has no body)", ws.Body)
+	}
+}
+
+func TestDispatch_HCLAdapterNoTasks(t *testing.T) {
+	hcl := `job "x" {}`
+	_, err := Dispatch([]byte(hcl), "spec.hcl")
+	if err == nil {
+		t.Fatal("expected error for HCL with no tasks")
+	}
+	if !strings.Contains(err.Error(), "at least one task") {
+		t.Errorf("error = %q, want it to contain 'at least one task'", err.Error())
+	}
+}
+
+func TestDispatch_UnknownExtension(t *testing.T) {
+	_, err := Dispatch([]byte("kind: Job\nname: x\n"), "spec.json")
+	if err == nil {
+		t.Fatal("expected error for unknown extension, got nil")
+	}
+	if !strings.Contains(err.Error(), "unknown extension") {
+		t.Errorf("error = %q, want it to contain 'unknown extension'", err.Error())
+	}
+}
+
+func TestDispatch_NoExtension(t *testing.T) {
+	_, err := Dispatch([]byte("kind: Job\nname: x\n"), "spec")
+	if err == nil {
+		t.Fatal("expected error for no extension, got nil")
+	}
+}
+
+func TestDispatch_EmptyYAML(t *testing.T) {
+	_, err := Dispatch([]byte(""), "spec.yaml")
+	if err == nil {
+		t.Fatal("expected error for empty YAML, got nil")
+	}
+}
+
+func TestParseFile_Markdown(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "spec.md")
+	content := "---\nkind: Job\nname: file-md\n---\nbody\n"
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	ws, err := ParseFile(path)
+	if err != nil {
+		t.Fatalf("ParseFile .md: %v", err)
+	}
+	if ws.Kind != "Job" || ws.Name != "file-md" {
+		t.Errorf("got Kind=%q Name=%q", ws.Kind, ws.Name)
+	}
+	if ws.Body != "body\n" {
+		t.Errorf("Body = %q, want %q", ws.Body, "body\n")
+	}
+}
+
+func TestParseFile_YAML(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "spec.yaml")
+	content := "kind: Service\nname: file-yaml\n"
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	ws, err := ParseFile(path)
+	if err != nil {
+		t.Fatalf("ParseFile .yaml: %v", err)
+	}
+	if ws.Kind != "Service" || ws.Name != "file-yaml" {
+		t.Errorf("got Kind=%q Name=%q", ws.Kind, ws.Name)
+	}
+	if ws.Body != "" {
+		t.Errorf("Body = %q, want empty", ws.Body)
+	}
+}
+
+func TestParseFile_HCL(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "spec.hcl")
+	content := `job "file-hcl" {}
+task "t" { command = "/bin/true" }
+`
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	ws, err := ParseFile(path)
+	if err != nil {
+		t.Fatalf("ParseFile .hcl: %v", err)
+	}
+	if ws.Kind != "Job" || ws.Name != "file-hcl" {
+		t.Errorf("got Kind=%q Name=%q", ws.Kind, ws.Name)
+	}
+	if ws.Runtime == nil || ws.Runtime.Command != "/bin/true" {
+		t.Errorf("Runtime.Command = %v, want /bin/true", ws.Runtime)
+	}
+}
+
+func TestParseFile_MissingFile(t *testing.T) {
+	_, err := ParseFile(filepath.Join(t.TempDir(), "nope.md"))
+	if err == nil {
+		t.Fatal("expected error for missing file, got nil")
+	}
+	if !strings.Contains(err.Error(), "read spec file") {
+		t.Errorf("error = %q, want it to contain 'read spec file'", err.Error())
+	}
+}
+
+func TestParseFile_UnknownExtension(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "spec.txt")
+	if err := os.WriteFile(path, []byte("kind: Job\nname: x\n"), 0o644); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	_, err := ParseFile(path)
+	if err == nil {
+		t.Fatal("expected error for unknown extension, got nil")
+	}
+	if !strings.Contains(err.Error(), "unknown extension") {
+		t.Errorf("error = %q, want 'unknown extension'", err.Error())
+	}
+}
+
+func TestParseHCL_LegacySpec(t *testing.T) {
+	hcl := `job "legacy" {}
+task "t" { command = "/bin/echo" }
+`
+	ws, err := ParseHCL([]byte(hcl), "spec.hcl")
+	if err != nil {
+		t.Fatalf("ParseHCL: %v", err)
+	}
+	if ws.Kind != "Job" || ws.Name != "legacy" {
+		t.Errorf("adapter got Kind=%q Name=%q", ws.Kind, ws.Name)
+	}
+}

internal/jobspec/markdown.go

@@ -0,0 +1,586 @@
+package jobspec
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// WorkloadSpec is the unified canonical jobspec populated by both the
+// Markdown frontmatter parser (canonical path, R-013/R-014) and the HCL
+// legacy adapter (REQ-064, REQ-090). It is the single shape consumed by
+// downstream phases (P0c schemas, P01 transport). The Markdown body
+// after the closing `---` is preserved verbatim in Body (R-015
+// byte-exact preservation is a load-bearing invariant enforced by the
+// fuzz harness in markdown_fuzz_test.go).
+type WorkloadSpec struct {
+	SpecVersion string
+	Kind        string
+	Name        string
+	Runtime     *RuntimeBlock
+	Count       int
+	Ports       []PortSpec
+	Env         map[string]string
+	Secrets     []string
+	Volumes     []VolumeSpec
+	Body        string
+}
+
+// RuntimeBlock is a minimal runtime abstraction surface populated by the
+// Markdown parser. The full runtime abstraction lands in P07; for now
+// only the one_of/image/command fields are parsed and stored (REQ-064).
+type RuntimeBlock struct {
+	OneOf   string
+	Image   string
+	Command string
+}
+
+// PortSpec is a minimal port binding entry. HostIP is optional.
+type PortSpec struct {
+	Name     string
+	HostPort int
+	Port     int
+	Protocol string
+	HostIP   string
+}
+
+// VolumeSpec is a minimal volume mount entry. Fields are stored raw
+// pending the P0c schema work (REQ-074).
+type VolumeSpec struct {
+	Name     string
+	Type     string
+	Source   string
+	Target   string
+	ReadOnly bool
+}
+
+// validKinds is the set of workload kinds accepted by the parser per
+// R-012. Unknown kinds are rejected.
+var validKinds = map[string]bool{
+	"Job":       true,
+	"Service":   true,
+	"DaemonSet": true,
+}
+
+// ParseMarkdown parses a Markdown jobspec with YAML frontmatter into a
+// *WorkloadSpec (R-013 canonical format, R-014 frontmatter). The body
+// after the closing `---` is preserved verbatim in result.Body
+// (R-015 byte-exact, including trailing newlines, CRLF, and BOM in the
+// body). The frontmatter parser is a minimal hand-rolled YAML-ish
+// key:value reader — gopkg.in/yaml.v3 is intentionally not added (same
+// approach as internal/config/markdown.go and internal/ns/parse.go).
+//
+// For .yaml/.yml files (no Markdown body), the dispatcher calls this
+// with the whole file treated as frontmatter and Body left empty (see
+// dispatch.go).
+func ParseMarkdown(data []byte) (*WorkloadSpec, error) {
+	content := string(data)
+	block, body, ok := splitFrontmatter(content)
+	if !ok {
+		return nil, fmt.Errorf("parse markdown: missing frontmatter delimiters")
+	}
+	if strings.TrimSpace(block) == "" {
+		return nil, fmt.Errorf("parse markdown: empty frontmatter")
+	}
+	spec, err := parseFrontmatterBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	spec.Body = body
+	if err := validateWorkload(spec); err != nil {
+		return nil, err
+	}
+	return spec, nil
+}
+
+// splitFrontmatter splits the file content into the YAML frontmatter
+// block and the verbatim body that follows the closing `---`. A leading
+// UTF-8 BOM is stripped from the frontmatter scan (R-015: BOM is not
+// preserved in the frontmatter, but a BOM inside the body would be
+// preserved because the body is verbatim). Returns (block, body, ok).
+// ok is false when no opening `---` delimiter is present, or no closing
+// `---` delimiter is found, or the block is empty after the opening
+// delimiter (handled by caller).
+func splitFrontmatter(content string) (block, body string, ok bool) {
+	// Strip a leading UTF-8 BOM if present (EF BB BF). Only the
+	// frontmatter scan is BOM-stripped; the body is byte-exact, so a BOM
+	// appearing inside the body is preserved verbatim.
+	stripped := content
+	if strings.HasPrefix(stripped, "\uFEFF") {
+		stripped = stripped[len("\uFEFF"):]
+	}
+	// Trim leading horizontal whitespace and newlines before the
+	// opening delimiter. We do NOT trim trailing — body must be exact.
+	trimmed := strings.TrimLeft(stripped, "\r\n\t ")
+	if !strings.HasPrefix(trimmed, "---") {
+		return "", "", false
+	}
+	// The opening delimiter must be on its own line: `---` optionally
+	// followed by a line terminator.
+	rest := trimmed[3:]
+	// The opening `---` must be followed by a newline or end-of-file
+	// (a `---foo` prefix is not a valid delimiter).
+	if len(rest) > 0 && rest[0] != '\n' && rest[0] != '\r' {
+		return "", "", false
+	}
+	rest = strings.TrimLeft(rest, "\r\n")
+
+	// Find the closing delimiter line. The closing `---` must be on its
+	// own line: preceded by a newline (or at the start of `rest`) and
+	// followed by a newline or end-of-file.
+	idx := findClosingDelimiter(rest)
+	if idx < 0 {
+		return "", "", false
+	}
+	block = rest[:idx]
+	// Body is everything after the closing `---` line. The closing
+	// delimiter line itself (including its trailing newline) is NOT
+	// part of the body. We compute the byte offset in the original
+	// `content` so the body is byte-exact (R-015).
+	afterClose := rest[idx:]
+	// afterClose starts with `---`. Strip the delimiter line.
+	delimLen := 3
+	// Account for an optional trailing `...` or spaces on the delimiter
+	// line — the delimiter is `---` followed by anything up to and
+	// including the line terminator. Body starts after the newline.
+	// Find the end of the delimiter line.
+	newlineIdx := strings.IndexAny(afterClose, "\r\n")
+	var bodyStart int
+	if newlineIdx < 0 {
+		// Closing `---` is the last line: body is empty.
+		bodyStart = len(afterClose)
+	} else {
+		// Consume the delimiter line and its line terminator(s).
+		bodyStart = newlineIdx
+		// Strip a single CRLF or LF.
+		if strings.HasPrefix(afterClose[bodyStart:], "\r\n") {
+			bodyStart += 2
+		} else {
+			bodyStart += 1
+		}
+	}
+	body = afterClose[bodyStart:]
+	_ = delimLen
+	return block, body, true
+}
+
+// findClosingDelimiter returns the byte index in `rest` where the
+// closing `---` delimiter line begins, or -1 if none is found. The
+// delimiter must be on its own line: either at the start of `rest` or
+// preceded by a newline, and followed by a newline or end-of-file.
+func findClosingDelimiter(rest string) int {
+	// Special case: closing delimiter at the very start (frontmatter
+	// block is empty). The opening `---` is immediately followed by the
+	// closing `---`. We require the opening to be its own line, so the
+	// closing at index 0 means the opening had no body — invalid (empty
+	// frontmatter handled by caller). We still report it; caller
+	// rejects empty block.
+	for i := 0; i < len(rest); i++ {
+		if rest[i] != '\n' {
+			continue
+		}
+		// Candidate: line after this newline starts with `---`.
+		j := i + 1
+		if j+3 <= len(rest) && rest[j] == '-' && rest[j+1] == '-' && rest[j+2] == '-' {
+			// Must be followed by newline, CRLF, or end-of-file.
+			end := j + 3
+			if end == len(rest) {
+				return j
+			}
+			if rest[end] == '\n' || rest[end] == '\r' {
+				return j
+			}
+		}
+	}
+	// Final candidate: closing delimiter at the very start of rest
+	// (immediately after the opening delimiter + its newline). This
+	// happens when frontmatter is empty: `---\n---\n`. We already trim
+	// leading newlines off `rest`, so if rest itself starts with `---`
+	// AND it's a closing delimiter (followed by newline/EOF), it is the
+	// empty-frontmatter case.
+	if strings.HasPrefix(rest, "---") {
+		end := 3
+		if end == len(rest) {
+			return 0
+		}
+		if rest[end] == '\n' || rest[end] == '\r' {
+			return 0
+		}
+	}
+	return -1
+}
+
+// parseFrontmatterBlock parses a minimal YAML-ish frontmatter block into
+// a *WorkloadSpec (without Body, which is filled by the caller).
+//
+// Supported shapes:
+//
+//	kind: Job
+//	name: my-job
+//	count: 3
+//	runtime:
+//	  one_of: process
+//	  image: docker.io/nginx:latest
+//	  command: /bin/sh -c
+//	ports:
+//	  - name: http
+//	    port: 8080
+//	    host_port: 80
+//	    protocol: tcp
+//	env:
+//	  FOO: bar
+//	  BAR:
+//	    from: secret:my-secret
+//	secrets:
+//	  - db-password
+//	volumes:
+//	  - name: data
+//	    type: host
+//	    source: /data
+//	    target: /data
+//	    read_only: true
+//
+// Comments (# ...) and blank lines are ignored. Quoted scalar values
+// ("..." or '...') are unwrapped. No flow collections except the
+// inline-array form for `secrets`. Multi-line block scalars (|, >) are
+// not supported — by design, to avoid adding a YAML dependency for this
+// small surface.
+func parseFrontmatterBlock(block string) (*WorkloadSpec, error) {
+	spec := &WorkloadSpec{Count: 1}
+	lines := strings.Split(block, "\n")
+
+	type section int
+	const (
+		secNone section = iota
+		secRuntime
+		secPorts
+		secEnv
+		secSecrets
+		secVolumes
+	)
+	cur := secNone
+	var curPort *PortSpec
+	var curVol *VolumeSpec
+
+	flushPort := func() {
+		if curPort != nil {
+			spec.Ports = append(spec.Ports, *curPort)
+			curPort = nil
+		}
+	}
+	flushVol := func() {
+		if curVol != nil {
+			spec.Volumes = append(spec.Volumes, *curVol)
+			curVol = nil
+		}
+	}
+
+	for lineNo, raw := range lines {
+		line := stripComment(raw)
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+		indent := countIndent(line)
+		trimmed := strings.TrimSpace(line)
+
+		if indent == 0 {
+			// Flush any pending nested entry before switching sections.
+			flushPort()
+			flushVol()
+			cur = secNone
+
+			key, val, ok := splitKV(trimmed)
+			if !ok {
+				return nil, fmt.Errorf("parse markdown: line %d: malformed key:value", lineNo+1)
+			}
+			switch key {
+			case "orca-spec-version":
+				spec.SpecVersion = unquote(val)
+			case "kind":
+				spec.Kind = unquote(val)
+			case "name":
+				spec.Name = unquote(val)
+			case "count":
+				if n, err := strconv.Atoi(strings.TrimSpace(unquote(val))); err == nil {
+					spec.Count = n
+				} else {
+					return nil, fmt.Errorf("parse markdown: line %d: count: %v", lineNo+1, err)
+				}
+			case "runtime":
+				spec.Runtime = &RuntimeBlock{}
+				if strings.TrimSpace(val) != "" {
+					// Inline value (unusual); ignore — runtime is a block.
+				}
+				cur = secRuntime
+			case "ports":
+				cur = secPorts
+			case "env":
+				spec.Env = map[string]string{}
+				cur = secEnv
+			case "secrets":
+				if strings.TrimSpace(val) != "" {
+					arr, err := parseStringArray(val)
+					if err != nil {
+						return nil, fmt.Errorf("parse markdown: line %d: secrets: %w", lineNo+1, err)
+					}
+					spec.Secrets = append(spec.Secrets, arr...)
+					cur = secNone
+				} else {
+					cur = secSecrets
+				}
+			case "volumes":
+				cur = secVolumes
+			default:
+				// Unknown top-level keys are ignored (forward-compat).
+				cur = secNone
+			}
+			continue
+		}
+
+		// Indented line: a nested entry under the current section.
+		switch cur {
+		case secRuntime:
+			if spec.Runtime == nil {
+				spec.Runtime = &RuntimeBlock{}
+			}
+			key, val, ok := splitKV(trimmed)
+			if !ok {
+				continue
+			}
+			switch key {
+			case "one_of":
+				spec.Runtime.OneOf = unquote(val)
+			case "image":
+				spec.Runtime.Image = unquote(val)
+			case "command":
+				spec.Runtime.Command = unquote(val)
+			}
+		case secPorts:
+			if strings.HasPrefix(trimmed, "- ") || trimmed == "-" {
+				flushPort()
+				p := PortSpec{}
+				curPort = &p
+				rest := strings.TrimSpace(strings.TrimPrefix(trimmed, "-"))
+				if rest != "" {
+					applyPortKV(curPort, rest)
+				}
+			} else if curPort != nil {
+				applyPortKV(curPort, trimmed)
+			}
+		case secEnv:
+			key, val, ok := splitKV(trimmed)
+			if !ok {
+				continue
+			}
+			if val == "" {
+				// Nested mapping under env (e.g. `BAR:\n  from: ...`).
+				// Store the raw string for now (REQ-064: store raw).
+				spec.Env[key] = ""
+			} else if strings.HasPrefix(val, "{") && strings.HasSuffix(val, "}") {
+				// Inline object form: `BAR: {from: "secret:..."}`.
+				// Store the raw object string for now.
+				spec.Env[key] = val
+			} else {
+				spec.Env[key] = unquote(val)
+			}
+		case secSecrets:
+			if strings.HasPrefix(trimmed, "- ") || trimmed == "-" {
+				item := strings.TrimSpace(strings.TrimPrefix(trimmed, "-"))
+				if item != "" {
+					spec.Secrets = append(spec.Secrets, unquote(item))
+				}
+			}
+		case secVolumes:
+			if strings.HasPrefix(trimmed, "- ") || trimmed == "-" {
+				flushVol()
+				v := VolumeSpec{}
+				curVol = &v
+				rest := strings.TrimSpace(strings.TrimPrefix(trimmed, "-"))
+				if rest != "" {
+					applyVolumeKV(curVol, rest)
+				}
+			} else if curVol != nil {
+				applyVolumeKV(curVol, trimmed)
+			}
+		}
+	}
+	flushPort()
+	flushVol()
+	return spec, nil
+}
+
+// applyPortKV applies a `key: value` pair to a PortSpec entry.
+func applyPortKV(p *PortSpec, s string) {
+	key, val, ok := splitKV(s)
+	if !ok {
+		return
+	}
+	switch key {
+	case "name":
+		p.Name = unquote(val)
+	case "host_port":
+		if n, err := strconv.Atoi(strings.TrimSpace(unquote(val))); err == nil {
+			p.HostPort = n
+		}
+	case "port":
+		if n, err := strconv.Atoi(strings.TrimSpace(unquote(val))); err == nil {
+			p.Port = n
+		}
+	case "protocol":
+		p.Protocol = unquote(val)
+	case "host_ip":
+		p.HostIP = unquote(val)
+	}
+}
+
+// applyVolumeKV applies a `key: value` pair to a VolumeSpec entry.
+func applyVolumeKV(v *VolumeSpec, s string) {
+	key, val, ok := splitKV(s)
+	if !ok {
+		return
+	}
+	switch key {
+	case "name":
+		v.Name = unquote(val)
+	case "type":
+		v.Type = unquote(val)
+	case "source":
+		v.Source = unquote(val)
+	case "target":
+		v.Target = unquote(val)
+	case "read_only":
+		switch strings.ToLower(strings.TrimSpace(unquote(val))) {
+		case "true", "yes", "on", "1":
+			v.ReadOnly = true
+		}
+	}
+}
+
+// validateWorkload enforces required fields and kind validity (R-012).
+func validateWorkload(spec *WorkloadSpec) error {
+	if spec.Kind == "" {
+		return fmt.Errorf("parse markdown: missing kind")
+	}
+	if !validKinds[spec.Kind] {
+		return fmt.Errorf("parse markdown: kind %q is not one of Job, Service, DaemonSet", spec.Kind)
+	}
+	if strings.TrimSpace(spec.Name) == "" {
+		return fmt.Errorf("parse markdown: missing name")
+	}
+	return nil
+}
+
+// parseStringArray parses an inline YAML flow-array of scalars, e.g.
+// `["a", "b"]` or `['a', 'b']` or `[a, b]`. Empty array `[]` returns nil.
+func parseStringArray(val string) ([]string, error) {
+	val = strings.TrimSpace(val)
+	if val == "" {
+		return nil, nil
+	}
+	if !strings.HasPrefix(val, "[") || !strings.HasSuffix(val, "]") {
+		return nil, fmt.Errorf("expected [..] array, got %q", val)
+	}
+	inner := strings.TrimSpace(val[1 : len(val)-1])
+	if inner == "" {
+		return nil, nil
+	}
+	parts := splitFlowItems(inner)
+	out := make([]string, 0, len(parts))
+	for _, p := range parts {
+		p = strings.TrimSpace(p)
+		if p == "" {
+			continue
+		}
+		out = append(out, unquote(p))
+	}
+	return out, nil
+}
+
+// splitFlowItems splits a comma-separated flow-array body, respecting
+// single and double quotes.
+func splitFlowItems(s string) []string {
+	var out []string
+	inSingle := false
+	inDouble := false
+	start := 0
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch c {
+		case '\'':
+			if !inDouble {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle {
+				inDouble = !inDouble
+			}
+		case ',':
+			if !inSingle && !inDouble {
+				out = append(out, s[start:i])
+				start = i + 1
+			}
+		}
+	}
+	out = append(out, s[start:])
+	return out
+}
+
+func countIndent(s string) int {
+	n := 0
+	for _, r := range s {
+		if r == ' ' || r == '\t' {
+			n++
+			continue
+		}
+		break
+	}
+	return n
+}
+
+func splitKV(s string) (key, val string, ok bool) {
+	idx := strings.Index(s, ":")
+	if idx < 0 {
+		return "", "", false
+	}
+	key = strings.TrimSpace(s[:idx])
+	val = strings.TrimSpace(s[idx+1:])
+	if key == "" {
+		return "", "", false
+	}
+	return key, val, true
+}
+
+func stripComment(s string) string {
+	inSingle := false
+	inDouble := false
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch c {
+		case '\'':
+			if !inDouble {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle {
+				inDouble = !inDouble
+			}
+		case '#':
+			if !inSingle && !inDouble {
+				if i == 0 || s[i-1] == ' ' || s[i-1] == '\t' {
+					return s[:i]
+				}
+			}
+		}
+	}
+	return s
+}
+
+func unquote(s string) string {
+	s = strings.TrimSpace(s)
+	if len(s) >= 2 {
+		if (s[0] == '"' && s[len(s)-1] == '"') || (s[0] == '\'' && s[len(s)-1] == '\'') {
+			return s[1 : len(s)-1]
+		}
+	}
+	return s
+}

internal/jobspec/markdown_fuzz_test.go

@@ -0,0 +1,109 @@
+package jobspec
+
+import (
+	"strings"
+	"testing"
+)
+
+// FuzzParseMarkdownRoundTrip is the REQ-067 fuzz harness for R-015
+// byte-exact body preservation. It generates random frontmatter + body
+// combinations, runs ParseMarkdown, and asserts that the parsed Body
+// equals the original body byte-for-byte whenever parsing succeeds.
+// When parsing fails (bad frontmatter), the iteration passes — the
+// parser is allowed to reject malformed input.
+//
+// The seed corpus (added via f.Add) covers adversarial fixtures: CRLF
+// body, BOM prefix, no frontmatter, only-closing-separator, body with
+// `---` inside a code fence, trailing whitespace, empty body. The seed
+// corpus runs as regular tests under `go test` (CI); random input runs
+// only under `go test -fuzz=FuzzParseMarkdownRoundTrip` in a dedicated
+// process.
+func FuzzParseMarkdownRoundTrip(f *testing.F) {
+	// Seed 1: valid frontmatter + simple body.
+	f.Add([]byte("---\nkind: Job\nname: seed1\n---\n# body\n"))
+
+	// Seed 2: CRLF body.
+	f.Add([]byte("---\r\nkind: Job\r\nname: seed2\r\n---\r\n# body\r\nCRLF\r\n"))
+
+	// Seed 3: BOM prefix.
+	f.Add([]byte("\uFEFF---\nkind: Job\nname: seed3\n---\nbody\n"))
+
+	// Seed 4: no frontmatter (just body) — should fail to parse.
+	f.Add([]byte("# just a body\nno frontmatter\n"))
+
+	// Seed 5: frontmatter with only the closing `---` (no opening).
+	f.Add([]byte("body\n---\nmore body\n"))
+
+	// Seed 6: body containing `---` in a code fence.
+	f.Add([]byte("---\nkind: Job\nname: seed6\n---\n```bash\necho '---'\n```\n"))
+
+	// Seed 7: body with trailing whitespace.
+	f.Add([]byte("---\nkind: Job\nname: seed7\n---\nbody with trailing spaces   \n"))
+
+	// Seed 8: empty body.
+	f.Add([]byte("---\nkind: Job\nname: seed8\n---\n"))
+
+	// Seed 9: empty frontmatter (should fail).
+	f.Add([]byte("---\n---\nbody\n"))
+
+	// Seed 10: body with no trailing newline.
+	f.Add([]byte("---\nkind: Job\nname: seed10\n---\nno trailing newline"))
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		// Reconstruct the body from the input so we can assert
+		// byte-exact round-trip. We do this by re-splitting the
+		// frontmatter using the same logic the parser uses, but only
+		// to extract the expected body. If the input has no valid
+		// frontmatter delimiter pair, ParseMarkdown will return an
+		// error and we pass the iteration.
+		expectedBody := extractExpectedBody(string(data))
+
+		spec, err := ParseMarkdown(data)
+		if err != nil {
+			// Parser rejected the input — acceptable for a fuzz
+			// iteration (the input may be malformed). Pass.
+			return
+		}
+		// R-015: body must be byte-exact.
+		if spec.Body != expectedBody {
+			t.Errorf("R-015 body round-trip mismatch:\n got = %q\nwant = %q", spec.Body, expectedBody)
+		}
+	})
+}
+
+// extractExpectedBody returns the body portion of a Markdown jobspec
+// input using the same delimiter-splitting logic as splitFrontmatter,
+// so the fuzz harness can assert byte-exact preservation independently
+// of the parser's internal extraction. If the input has no valid
+// frontmatter, the result is "" (and ParseMarkdown will error).
+func extractExpectedBody(content string) string {
+	stripped := content
+	if strings.HasPrefix(stripped, "\uFEFF") {
+		stripped = stripped[len("\uFEFF"):]
+	}
+	trimmed := strings.TrimLeft(stripped, "\r\n\t ")
+	if !strings.HasPrefix(trimmed, "---") {
+		return ""
+	}
+	rest := trimmed[3:]
+	if len(rest) > 0 && rest[0] != '\n' && rest[0] != '\r' {
+		return ""
+	}
+	rest = strings.TrimLeft(rest, "\r\n")
+	idx := findClosingDelimiter(rest)
+	if idx < 0 {
+		return ""
+	}
+	afterClose := rest[idx:]
+	newlineIdx := strings.IndexAny(afterClose, "\r\n")
+	if newlineIdx < 0 {
+		return ""
+	}
+	bodyStart := newlineIdx
+	if strings.HasPrefix(afterClose[bodyStart:], "\r\n") {
+		bodyStart += 2
+	} else {
+		bodyStart += 1
+	}
+	return afterClose[bodyStart:]
+}

internal/jobspec/markdown_test.go

@@ -0,0 +1,357 @@
+package jobspec
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseMarkdown_FullFrontmatter(t *testing.T) {
+	body := "# Hello\n\nThis is the body.\n\nTrailing newline preserved.\n"
+	input := "---\n" +
+		"orca-spec-version: \"1\"\n" +
+		"kind: Job\n" +
+		"name: my-job\n" +
+		"count: 3\n" +
+		"---\n" +
+		body
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.SpecVersion != "1" {
+		t.Errorf("SpecVersion = %q, want %q", spec.SpecVersion, "1")
+	}
+	if spec.Kind != "Job" {
+		t.Errorf("Kind = %q, want %q", spec.Kind, "Job")
+	}
+	if spec.Name != "my-job" {
+		t.Errorf("Name = %q, want %q", spec.Name, "my-job")
+	}
+	if spec.Count != 3 {
+		t.Errorf("Count = %d, want 3", spec.Count)
+	}
+	if spec.Body != body {
+		t.Errorf("Body = %q, want %q (byte-exact, R-015)", spec.Body, body)
+	}
+}
+
+func TestParseMarkdown_BodyByteExactTrailingNewline(t *testing.T) {
+	cases := []struct {
+		name string
+		body string
+	}{
+		{"with_trailing_newline", "# Title\n\nbody\n"},
+		{"with_double_trailing_newline", "# Title\n\nbody\n\n"},
+		{"no_trailing_newline", "# Title\n\nbody"},
+		{"empty_body_with_newline", "\n"},
+		{"only_newlines", "\n\n\n"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			input := "---\nkind: Job\nname: x\n---\n" + tc.body
+			spec, err := ParseMarkdown([]byte(input))
+			if err != nil {
+				t.Fatalf("ParseMarkdown: %v", err)
+			}
+			if spec.Body != tc.body {
+				t.Errorf("Body byte-exact mismatch (R-015):\n got = %q\nwant = %q", spec.Body, tc.body)
+			}
+		})
+	}
+}
+
+func TestParseMarkdown_NoFrontmatter(t *testing.T) {
+	input := "# Just a body\n\nNo frontmatter here."
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for missing frontmatter, got nil")
+	}
+	if !strings.Contains(err.Error(), "frontmatter") {
+		t.Errorf("error = %q, want it to contain 'frontmatter'", err.Error())
+	}
+}
+
+func TestParseMarkdown_EmptyFrontmatter(t *testing.T) {
+	input := "---\n---\n\nbody"
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for empty frontmatter, got nil")
+	}
+	if !strings.Contains(err.Error(), "empty frontmatter") {
+		t.Errorf("error = %q, want it to contain 'empty frontmatter'", err.Error())
+	}
+}
+
+func TestParseMarkdown_UnknownKind(t *testing.T) {
+	input := "---\nkind: CronJob\nname: x\n---\nbody\n"
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for unknown kind, got nil")
+	}
+	if !strings.Contains(err.Error(), "not one of") {
+		t.Errorf("error = %q, want it to contain 'not one of'", err.Error())
+	}
+}
+
+func TestParseMarkdown_MissingName(t *testing.T) {
+	input := "---\nkind: Job\n---\nbody\n"
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for missing name, got nil")
+	}
+	if !strings.Contains(err.Error(), "missing name") {
+		t.Errorf("error = %q, want it to contain 'missing name'", err.Error())
+	}
+}
+
+func TestParseMarkdown_MissingKind(t *testing.T) {
+	input := "---\nname: x\n---\nbody\n"
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for missing kind, got nil")
+	}
+	if !strings.Contains(err.Error(), "missing kind") {
+		t.Errorf("error = %q, want it to contain 'missing kind'", err.Error())
+	}
+}
+
+func TestParseMarkdown_EachValidKind(t *testing.T) {
+	cases := []string{"Job", "Service", "DaemonSet"}
+	for _, kind := range cases {
+		t.Run(kind, func(t *testing.T) {
+			input := "---\nkind: " + kind + "\nname: x\n---\nbody\n"
+			spec, err := ParseMarkdown([]byte(input))
+			if err != nil {
+				t.Fatalf("ParseMarkdown: %v", err)
+			}
+			if spec.Kind != kind {
+				t.Errorf("Kind = %q, want %q", spec.Kind, kind)
+			}
+		})
+	}
+}
+
+func TestParseMarkdown_EnvScalarAndObject(t *testing.T) {
+	input := "---\n" +
+		"kind: Job\n" +
+		"name: x\n" +
+		"env:\n" +
+		"  FOO: bar\n" +
+		"  BAZ: \"qux\"\n" +
+		"  SECRET_REF:\n" +
+		"    from: \"secret:db-password\"\n" +
+		"  INLINE: {from: \"secret:token\"}\n" +
+		"---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if got := spec.Env["FOO"]; got != "bar" {
+		t.Errorf("env[FOO] = %q, want %q", got, "bar")
+	}
+	if got := spec.Env["BAZ"]; got != "qux" {
+		t.Errorf("env[BAZ] = %q, want %q", got, "qux")
+	}
+	if got := spec.Env["INLINE"]; got != `{from: "secret:token"}` {
+		t.Errorf("env[INLINE] = %q, want the raw object string", got)
+	}
+	if _, ok := spec.Env["SECRET_REF"]; !ok {
+		t.Errorf("env[SECRET_REF] missing; nested from: stored as empty string")
+	}
+}
+
+func TestParseMarkdown_PortsArray(t *testing.T) {
+	input := "---\n" +
+		"kind: Service\n" +
+		"name: web\n" +
+		"ports:\n" +
+		"  - name: http\n" +
+		"    port: 8080\n" +
+		"    host_port: 80\n" +
+		"    protocol: tcp\n" +
+		"  - name: https\n" +
+		"    port: 8443\n" +
+		"    host_port: 443\n" +
+		"---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if len(spec.Ports) != 2 {
+		t.Fatalf("Ports = %d, want 2", len(spec.Ports))
+	}
+	if spec.Ports[0].Name != "http" || spec.Ports[0].Port != 8080 || spec.Ports[0].HostPort != 80 || spec.Ports[0].Protocol != "tcp" {
+		t.Errorf("Ports[0] = %+v", spec.Ports[0])
+	}
+	if spec.Ports[1].Name != "https" || spec.Ports[1].Port != 8443 || spec.Ports[1].HostPort != 443 {
+		t.Errorf("Ports[1] = %+v", spec.Ports[1])
+	}
+}
+
+func TestParseMarkdown_VolumesArray(t *testing.T) {
+	input := "---\n" +
+		"kind: Job\n" +
+		"name: x\n" +
+		"volumes:\n" +
+		"  - name: data\n" +
+		"    type: host\n" +
+		"    source: /data\n" +
+		"    target: /data\n" +
+		"    read_only: true\n" +
+		"---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if len(spec.Volumes) != 1 {
+		t.Fatalf("Volumes = %d, want 1", len(spec.Volumes))
+	}
+	v := spec.Volumes[0]
+	if v.Name != "data" || v.Type != "host" || v.Source != "/data" || v.Target != "/data" || !v.ReadOnly {
+		t.Errorf("Volumes[0] = %+v", v)
+	}
+}
+
+func TestParseMarkdown_RuntimeBlock(t *testing.T) {
+	input := "---\n" +
+		"kind: Job\n" +
+		"name: x\n" +
+		"runtime:\n" +
+		"  one_of: process\n" +
+		"  image: docker.io/nginx:latest\n" +
+		"  command: /bin/sh -c 'echo hi'\n" +
+		"---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Runtime == nil {
+		t.Fatal("Runtime is nil")
+	}
+	if spec.Runtime.OneOf != "process" {
+		t.Errorf("Runtime.OneOf = %q, want %q", spec.Runtime.OneOf, "process")
+	}
+	if spec.Runtime.Image != "docker.io/nginx:latest" {
+		t.Errorf("Runtime.Image = %q, want %q", spec.Runtime.Image, "docker.io/nginx:latest")
+	}
+	if spec.Runtime.Command != "/bin/sh -c 'echo hi'" {
+		t.Errorf("Runtime.Command = %q, want %q", spec.Runtime.Command, "/bin/sh -c 'echo hi'")
+	}
+}
+
+func TestParseMarkdown_SecretsInlineArray(t *testing.T) {
+	input := "---\nkind: Job\nname: x\nsecrets: [\"db-password\", \"api-token\"]\n---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if len(spec.Secrets) != 2 {
+		t.Fatalf("Secrets = %d, want 2", len(spec.Secrets))
+	}
+	if spec.Secrets[0] != "db-password" || spec.Secrets[1] != "api-token" {
+		t.Errorf("Secrets = %v, want [db-password api-token]", spec.Secrets)
+	}
+}
+
+func TestParseMarkdown_SecretsBlockArray(t *testing.T) {
+	input := "---\n" +
+		"kind: Job\n" +
+		"name: x\n" +
+		"secrets:\n" +
+		"  - db-password\n" +
+		"  - api-token\n" +
+		"---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if len(spec.Secrets) != 2 {
+		t.Fatalf("Secrets = %d, want 2", len(spec.Secrets))
+	}
+	if spec.Secrets[0] != "db-password" || spec.Secrets[1] != "api-token" {
+		t.Errorf("Secrets = %v, want [db-password api-token]", spec.Secrets)
+	}
+}
+
+func TestParseMarkdown_CRLFBodyPreserved(t *testing.T) {
+	body := "# Title\r\n\r\nCRLF body.\r\n"
+	input := "---\r\nkind: Job\r\nname: x\r\n---\r\n" + body
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Body != body {
+		t.Errorf("CRLF body not preserved (R-015):\n got = %q\nwant = %q", spec.Body, body)
+	}
+}
+
+func TestParseMarkdown_BOMStrippedFromFrontmatter(t *testing.T) {
+	body := "# body\n"
+	input := "\uFEFF" + "---\nkind: Job\nname: x\n---\n" + body
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Kind != "Job" {
+		t.Errorf("Kind = %q, want Job (BOM should be stripped from frontmatter scan)", spec.Kind)
+	}
+	if spec.Body != body {
+		t.Errorf("Body = %q, want %q", spec.Body, body)
+	}
+}
+
+func TestParseMarkdown_BodyWithCodeFenceContainingDashes(t *testing.T) {
+	body := "```bash\n" +
+		"echo '---'\n" +
+		"echo '--- end ---'\n" +
+		"```\n"
+	input := "---\nkind: Job\nname: x\n---\n" + body
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Body != body {
+		t.Errorf("Body with code-fence --- not preserved (R-015):\n got = %q\nwant = %q", spec.Body, body)
+	}
+}
+
+func TestParseMarkdown_OnlyClosingSeparator(t *testing.T) {
+	input := "no opening\n---\nbody\n"
+	_, err := ParseMarkdown([]byte(input))
+	if err == nil {
+		t.Fatal("expected error for input with only closing separator, got nil")
+	}
+}
+
+func TestParseMarkdown_QuotedValues(t *testing.T) {
+	input := "---\nkind: \"Job\"\nname: 'my-job'\n---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Kind != "Job" {
+		t.Errorf("Kind = %q, want Job (double-quoted)", spec.Kind)
+	}
+	if spec.Name != "my-job" {
+		t.Errorf("Name = %q, want my-job (single-quoted)", spec.Name)
+	}
+}
+
+func TestParseMarkdown_CountDefault(t *testing.T) {
+	input := "---\nkind: Job\nname: x\n---\nbody\n"
+	spec, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown: %v", err)
+	}
+	if spec.Count != 1 {
+		t.Errorf("Count default = %d, want 1", spec.Count)
+	}
+}
+
+func TestParseMarkdown_UnknownKeyIgnored(t *testing.T) {
+	input := "---\nkind: Job\nname: x\nfuture_field: value\n---\nbody\n"
+	_, err := ParseMarkdown([]byte(input))
+	if err != nil {
+		t.Fatalf("ParseMarkdown should ignore unknown keys: %v", err)
+	}
+}

internal/jobspec/spec.go

@@ -2,7 +2,6 @@ package jobspec
 
 import (
 	"fmt"
-	"os"
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
@@ -10,16 +9,24 @@ import (
 	"github.com/hashicorp/hcl/v2/hclsimple"
 )
 
+// Spec is the legacy HCL-only jobspec shape. It is retained for the
+// v0.9→v0.10 migration window (REQ-090) and is populated by ParseHCLLegacy.
+//
+// Deprecated: HCL is legacy per R-013; new code should consume the
+// unified *WorkloadSpec returned by ParseFile/Dispatch (see
+// dispatch.go and markdown.go).
 type Spec struct {
 	Job   JobSpec    `hcl:"job,block"`
 	Tasks []TaskSpec `hcl:"task,block"`
 }
 
+// JobSpec is the legacy HCL job block.
 type JobSpec struct {
 	Name string `hcl:"name,label"`
 	Type string `hcl:"type,optional"`
 }
 
+// TaskSpec is the legacy HCL task block.
 type TaskSpec struct {
 	Name    string   `hcl:"name,label"`
 	Command string   `hcl:"command"`
@@ -27,34 +34,14 @@ type TaskSpec struct {
 	Env     []string `hcl:"env,optional"`
 }
 
-func ParseFile(path string) (*Spec, error) {
-	data, err := os.ReadFile(path)
-	if err != nil {
-		return nil, fmt.Errorf("read spec file: %w", err)
-	}
-	return Parse(data, path)
-}
-
-func Parse(data []byte, filename string) (*Spec, error) {
-	var spec Spec
-	err := hclsimple.Decode(filename, data, nil, &spec)
-	if err != nil {
-		return nil, fmt.Errorf("decode hcl: %w", err)
-	}
-	if spec.Job.Name == "" {
-		return nil, fmt.Errorf("spec missing job name")
-	}
-	if len(spec.Tasks) == 0 {
-		return nil, fmt.Errorf("spec must have at least one task")
-	}
-	for i, t := range spec.Tasks {
-		if t.Command == "" {
-			return nil, fmt.Errorf("task[%d] (%s) missing command", i, t.Name)
-		}
-	}
-	return &spec, nil
+// hclDecode wraps hclsimple.Decode for testability.
+func hclDecode(filename string, data []byte, spec *Spec) error {
+	return hclsimple.Decode(filename, data, nil, spec)
 }
 
+// Validate is the legacy HCL Spec validator retained for the migration
+// window (REQ-090). New code should use validateWorkload on a
+// *WorkloadSpec.
 func (s *Spec) Validate() error {
 	if strings.TrimSpace(s.Job.Name) == "" {
 		return fmt.Errorf("job name is required")
@@ -65,5 +52,17 @@ func (s *Spec) Validate() error {
 	return nil
 }
 
+// Parse is the original HCL-only entry point retained for backward
+// compatibility with direct HCL callers during the v0.9→v0.10 migration
+// window (REQ-090). New code should call the dispatcher ParseFile (which
+// returns *WorkloadSpec) or ParseHCL (which adapts HCL into
+// *WorkloadSpec).
+//
+// Deprecated: use ParseFile (dispatcher) or ParseHCL (adapter). HCL is
+// legacy per R-013.
+func Parse(data []byte, filename string) (*Spec, error) {
+	return ParseHCLLegacy(data, filename)
+}
+
 var _ = hcl.Diagnostics{}
 var _ = gohcl.DecodeBody

internal/jobspec/spec_test.go

@@ -130,9 +130,9 @@ func TestParse_GoldenFiles(t *testing.T) {
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
 			path := filepath.Join("testdata", tc.file)
-			spec, err := ParseFile(path)
+			spec, err := ParseHCLFile(path)
 			if err != nil {
-				t.Fatalf("ParseFile(%s): %v", tc.file, err)
+				t.Fatalf("ParseHCLFile(%s): %v", tc.file, err)
 			}
 			if spec.Job.Name != tc.wantJob {
 				t.Errorf("job name = %q, want %q", spec.Job.Name, tc.wantJob)
@@ -254,9 +254,9 @@ func TestSpec_Validate(t *testing.T) {
 
 func TestSpec_Validate_RoundTripFromParse(t *testing.T) {
 	path := filepath.Join("testdata", "valid_single_task.hcl")
-	spec, err := ParseFile(path)
+	spec, err := ParseHCLFile(path)
 	if err != nil {
-		t.Fatalf("ParseFile: %v", err)
+		t.Fatalf("ParseHCLFile: %v", err)
 	}
 	if err := spec.Validate(); err != nil {
 		t.Errorf("Validate on parsed spec: %v", err)

internal/ns/parse.go

@@ -0,0 +1,308 @@
+package ns
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+// ParseNSMd reads an ns.md file, extracts the YAML frontmatter, and
+// parses it into a *NSConfig. The body after the closing `---` is
+// discarded (namespace declarations do not require body preservation
+// like jobspecs do under R-015; we keep the parser minimal and
+// consistent with internal/config/markdown.go).
+//
+// Frontmatter keys (R-014):
+//
+//	kind: Namespace        (required; must be "Namespace")
+//	name: <ns-name>        (required)
+//	parents: ["a", "b"]   (optional; default empty)
+//	inherits_env: true     (optional; default true)
+//	inherits_secrets: true (optional; default true)
+//	quota: {...}           (optional; parsed but not surfaced here)
+//	acl: {...}             (optional; parsed but not surfaced here)
+//
+// The parser is a minimal hand-rolled YAML-ish key:value reader (no
+// new dependencies; gopkg.in/yaml.v3 is intentionally NOT added). It
+// supports flat scalar keys and the inline flow-array form
+// `["a", "b"]` for `parents`. Nested mappings (quota, acl) are
+// recognized as keys but their contents are currently ignored — they
+// are reserved for later phases.
+func ParseNSMd(path string) (*NSConfig, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read %s: %w", path, err)
+	}
+	content := string(data)
+
+	block, ok := extractFrontmatter(content)
+	if !ok {
+		return nil, fmt.Errorf("parse %s: missing frontmatter", path)
+	}
+	if strings.TrimSpace(block) == "" {
+		return nil, fmt.Errorf("parse %s: missing frontmatter", path)
+	}
+
+	cfg, err := parseNSFrontmatter(block, path)
+	if err != nil {
+		return nil, err
+	}
+	if cfg.Name == "" {
+		return nil, fmt.Errorf("parse %s: missing name", path)
+	}
+	return cfg, nil
+}
+
+// extractFrontmatter returns the YAML block between the first pair of
+// `---` delimiters and whether a frontmatter block was present.
+func extractFrontmatter(content string) (string, bool) {
+	trimmed := strings.TrimLeft(content, "\r\n\t ")
+	if !strings.HasPrefix(trimmed, "---") {
+		return "", false
+	}
+	rest := trimmed[3:]
+	rest = strings.TrimLeft(rest, "\r\n")
+	idx := strings.Index(rest, "\n---")
+	if idx < 0 {
+		return "", false
+	}
+	return rest[:idx], true
+}
+
+// parseNSFrontmatter parses a minimal YAML-ish frontmatter block into
+// a *NSConfig. See ParseNSMd for the supported keys.
+func parseNSFrontmatter(block, path string) (*NSConfig, error) {
+	cfg := &NSConfig{
+		InheritsEnv:     true,
+		InheritsSecrets: true,
+	}
+	kind := ""
+
+	lines := strings.Split(block, "\n")
+	for lineNo, raw := range lines {
+		line := stripNSComment(raw)
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+		if countIndent(line) > 0 {
+			// Indented line under a nested mapping header (quota, acl).
+			// Recognized but ignored at this phase.
+			continue
+		}
+		key, val, ok := splitKV(strings.TrimSpace(line))
+		if !ok {
+			return nil, fmt.Errorf("parse %s: line %d: malformed key:value", path, lineNo+1)
+		}
+		switch key {
+		case "kind":
+			kind = strings.TrimSpace(unquote(val))
+		case "name":
+			cfg.Name = strings.TrimSpace(unquote(val))
+		case "parents":
+			parents, err := parseStringArray(val)
+			if err != nil {
+				return nil, fmt.Errorf("parse %s: line %d: parents: %w", path, lineNo+1, err)
+			}
+			cfg.Parents = parents
+		case "inherits_env":
+			cfg.InheritsEnv = parseBool(val)
+		case "inherits_secrets":
+			cfg.InheritsSecrets = parseBool(val)
+		case "quota", "acl":
+			// Reserved nested-mapping keys; recognized, contents ignored.
+		default:
+			// Unknown keys are ignored (forward-compat with future
+			// frontmatter additions).
+		}
+	}
+
+	if kind == "" {
+		return nil, fmt.Errorf("parse %s: missing kind", path)
+	}
+	if kind != "Namespace" {
+		return nil, fmt.Errorf("parse %s: kind %q is not %q", path, kind, "Namespace")
+	}
+	return cfg, nil
+}
+
+// parseStringArray parses an inline YAML flow-array of scalars, e.g.
+// `["a", "b"]` or `['a', 'b']` or `[a, b]`. Returns an error if the
+// value is not a flow-array. Empty array `[]` returns nil.
+func parseStringArray(val string) ([]string, error) {
+	val = strings.TrimSpace(val)
+	if val == "" {
+		return nil, nil
+	}
+	if !strings.HasPrefix(val, "[") || !strings.HasSuffix(val, "]") {
+		return nil, fmt.Errorf("expected [..] array, got %q", val)
+	}
+	inner := strings.TrimSpace(val[1 : len(val)-1])
+	if inner == "" {
+		return nil, nil
+	}
+	parts := splitFlowItems(inner)
+	out := make([]string, 0, len(parts))
+	for _, p := range parts {
+		p = strings.TrimSpace(p)
+		if p == "" {
+			continue
+		}
+		out = append(out, unquote(p))
+	}
+	return out, nil
+}
+
+// splitFlowItems splits a comma-separated flow-array body, respecting
+// single and double quotes.
+func splitFlowItems(s string) []string {
+	var out []string
+	inSingle := false
+	inDouble := false
+	start := 0
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch c {
+		case '\'':
+			if !inDouble {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle {
+				inDouble = !inDouble
+			}
+		case ',':
+			if !inSingle && !inDouble {
+				out = append(out, s[start:i])
+				start = i + 1
+			}
+		}
+	}
+	out = append(out, s[start:])
+	return out
+}
+
+// parseBool parses a YAML-ish bool (true/false/yes/no), defaulting to
+// true for empty (matches the inherits_* defaults).
+func parseBool(val string) bool {
+	switch strings.ToLower(strings.TrimSpace(unquote(val))) {
+	case "false", "no", "off", "0":
+		return false
+	default:
+		return true
+	}
+}
+
+// ParseNSMdDir walks `<root>/*/ns.md`, parses each, and returns the
+// config map keyed by namespace name. The `cluster` directory is
+// skipped (it is not a namespace). The `_defaults` namespace MUST
+// exist; if missing, an error is returned.
+func ParseNSMdDir(root string) (map[string]*NSConfig, error) {
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		return nil, fmt.Errorf("read namespace root %s: %w", root, err)
+	}
+
+	configs := make(map[string]*NSConfig)
+	var found []string
+	for _, ent := range entries {
+		if !ent.IsDir() {
+			continue
+		}
+		if ent.Name() == "cluster" {
+			continue
+		}
+		nsMd := filepath.Join(root, ent.Name(), "ns.md")
+		info, err := os.Stat(nsMd)
+		if err != nil || info.IsDir() {
+			continue
+		}
+		cfg, err := ParseNSMd(nsMd)
+		if err != nil {
+			return nil, err
+		}
+		// The directory name and the frontmatter `name` should match;
+		// we key by the frontmatter name (canonical) but also accept
+		// the directory name if frontmatter name is missing (the
+		// parser already errors on missing name, so this is defensive).
+		key := cfg.Name
+		if key == "" {
+			key = ent.Name()
+		}
+		if _, dup := configs[key]; dup {
+			return nil, fmt.Errorf("duplicate namespace %q (from %s)", key, nsMd)
+		}
+		configs[key] = cfg
+		found = append(found, key)
+	}
+
+	if _, ok := configs[defaultsName]; !ok {
+		sort.Strings(found)
+		names := strings.Join(found, ", ")
+		if names == "" {
+			names = "(none)"
+		}
+		return nil, fmt.Errorf("namespace root %s: implicit root %q not found (found: %s)", root, defaultsName, names)
+	}
+	return configs, nil
+}
+
+func countIndent(s string) int {
+	n := 0
+	for _, r := range s {
+		if r == ' ' || r == '\t' {
+			n++
+			continue
+		}
+		break
+	}
+	return n
+}
+
+func splitKV(s string) (key, val string, ok bool) {
+	idx := strings.Index(s, ":")
+	if idx < 0 {
+		return "", "", false
+	}
+	key = strings.TrimSpace(s[:idx])
+	val = strings.TrimSpace(s[idx+1:])
+	if key == "" {
+		return "", "", false
+	}
+	return key, val, true
+}
+
+func stripNSComment(s string) string {
+	inSingle := false
+	inDouble := false
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		switch c {
+		case '\'':
+			if !inDouble {
+				inSingle = !inSingle
+			}
+		case '"':
+			if !inSingle {
+				inDouble = !inDouble
+			}
+		case '#':
+			if !inSingle && !inDouble {
+				if i == 0 || s[i-1] == ' ' || s[i-1] == '\t' {
+					return s[:i]
+				}
+			}
+		}
+	}
+	return s
+}
+
+func unquote(s string) string {
+	if len(s) >= 2 {
+		if (s[0] == '"' && s[len(s)-1] == '"') || (s[0] == '\'' && s[len(s)-1] == '\'') {
+			return s[1 : len(s)-1]
+		}
+	}
+	return s
+}

internal/ns/parse_test.go

@@ -0,0 +1,227 @@
+package ns
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func writeNSMd(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir: %v", err)
+	}
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write %s: %v", path, err)
+	}
+}
+
+const validNSMd = `---
+kind: Namespace
+name: prod
+parents: ["_defaults"]
+inherits_env: true
+inherits_secrets: true
+quota:
+  cpu: 4
+acl:
+  admin: ops
+---
+# Prod namespace
+
+This body is ignored.
+`
+
+func TestParseNSMdValid(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, validNSMd)
+	cfg, err := ParseNSMd(path)
+	if err != nil {
+		t.Fatalf("ParseNSMd: %v", err)
+	}
+	if cfg.Name != "prod" {
+		t.Errorf("name = %q, want prod", cfg.Name)
+	}
+	if !eqSlice(cfg.Parents, []string{"_defaults"}) {
+		t.Errorf("parents = %v, want [_defaults]", cfg.Parents)
+	}
+	if !cfg.InheritsEnv || !cfg.InheritsSecrets {
+		t.Errorf("inherits_env=%v inherits_secrets=%v, want both true", cfg.InheritsEnv, cfg.InheritsSecrets)
+	}
+}
+
+func TestParseNSMdMissingFrontmatter(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "# just a body, no frontmatter\n")
+	_, err := ParseNSMd(path)
+	if err == nil {
+		t.Fatal("expected missing frontmatter error, got nil")
+	}
+	if !strings.Contains(err.Error(), "missing frontmatter") {
+		t.Errorf("error = %q, want contains 'missing frontmatter'", err.Error())
+	}
+}
+
+func TestParseNSMdEmptyFrontmatter(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\n---\nbody\n")
+	_, err := ParseNSMd(path)
+	if err == nil {
+		t.Fatal("expected error for empty frontmatter, got nil")
+	}
+}
+
+func TestParseNSMdWrongKind(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nkind: Job\nname: x\n---\n")
+	_, err := ParseNSMd(path)
+	if err == nil {
+		t.Fatal("expected wrong-kind error, got nil")
+	}
+	if !strings.Contains(err.Error(), "not \"Namespace\"") {
+		t.Errorf("error = %q, want contains 'is not \"Namespace\"'", err.Error())
+	}
+}
+
+func TestParseNSMdMissingKind(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nname: x\n---\n")
+	_, err := ParseNSMd(path)
+	if err == nil {
+		t.Fatal("expected missing kind error, got nil")
+	}
+	if !strings.Contains(err.Error(), "missing kind") {
+		t.Errorf("error = %q, want contains 'missing kind'", err.Error())
+	}
+}
+
+func TestParseNSMdMissingName(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nkind: Namespace\n---\n")
+	_, err := ParseNSMd(path)
+	if err == nil {
+		t.Fatal("expected missing name error, got nil")
+	}
+	if !strings.Contains(err.Error(), "missing name") {
+		t.Errorf("error = %q, want contains 'missing name'", err.Error())
+	}
+}
+
+func TestParseNSMdParentsUnquoted(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nkind: Namespace\nname: x\nparents: [a, b]\n---\n")
+	cfg, err := ParseNSMd(path)
+	if err != nil {
+		t.Fatalf("ParseNSMd: %v", err)
+	}
+	if !eqSlice(cfg.Parents, []string{"a", "b"}) {
+		t.Errorf("parents = %v, want [a b]", cfg.Parents)
+	}
+}
+
+func TestParseNSMdParentsEmpty(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nkind: Namespace\nname: x\nparents: []\n---\n")
+	cfg, err := ParseNSMd(path)
+	if err != nil {
+		t.Fatalf("ParseNSMd: %v", err)
+	}
+	if len(cfg.Parents) != 0 {
+		t.Errorf("parents = %v, want empty", cfg.Parents)
+	}
+}
+
+func TestParseNSMdInheritsFalse(t *testing.T) {
+	tmp := t.TempDir()
+	path := filepath.Join(tmp, "ns.md")
+	writeNSMd(t, path, "---\nkind: Namespace\nname: x\ninherits_env: false\ninherits_secrets: no\n---\n")
+	cfg, err := ParseNSMd(path)
+	if err != nil {
+		t.Fatalf("ParseNSMd: %v", err)
+	}
+	if cfg.InheritsEnv {
+		t.Errorf("inherits_env should be false")
+	}
+	if cfg.InheritsSecrets {
+		t.Errorf("inherits_secrets should be false")
+	}
+}
+
+func TestParseNSMdMissingFile(t *testing.T) {
+	_, err := ParseNSMd(filepath.Join(t.TempDir(), "nope.md"))
+	if err == nil {
+		t.Fatal("expected error for missing file")
+	}
+}
+
+func TestParseNSMdDirHappy(t *testing.T) {
+	root := t.TempDir()
+	writeNSMd(t, filepath.Join(root, "_defaults", "ns.md"), "---\nkind: Namespace\nname: _defaults\n---\n")
+	writeNSMd(t, filepath.Join(root, "prod", "ns.md"), validNSMd)
+
+	cfgs, err := ParseNSMdDir(root)
+	if err != nil {
+		t.Fatalf("ParseNSMdDir: %v", err)
+	}
+	if _, ok := cfgs["_defaults"]; !ok {
+		t.Errorf("missing _defaults in %v", cfgs)
+	}
+	if _, ok := cfgs["prod"]; !ok {
+		t.Errorf("missing prod in %v", cfgs)
+	}
+}
+
+func TestParseNSMdDirMissingDefaults(t *testing.T) {
+	root := t.TempDir()
+	writeNSMd(t, filepath.Join(root, "prod", "ns.md"), validNSMd)
+	_, err := ParseNSMdDir(root)
+	if err == nil {
+		t.Fatal("expected missing _defaults error, got nil")
+	}
+	if !strings.Contains(err.Error(), "_defaults") {
+		t.Errorf("error = %q, want contains _defaults", err.Error())
+	}
+}
+
+func TestParseNSMdDirSkipsCluster(t *testing.T) {
+	root := t.TempDir()
+	writeNSMd(t, filepath.Join(root, "_defaults", "ns.md"), "---\nkind: Namespace\nname: _defaults\n---\n")
+	// cluster/ contains a ns.md-shaped file but must be skipped.
+	writeNSMd(t, filepath.Join(root, "cluster", "ns.md"), "---\nkind: Namespace\nname: cluster\n---\n")
+
+	cfgs, err := ParseNSMdDir(root)
+	if err != nil {
+		t.Fatalf("ParseNSMdDir: %v", err)
+	}
+	if _, ok := cfgs["cluster"]; ok {
+		t.Errorf("cluster should be skipped, present in %v", cfgs)
+	}
+}
+
+func TestParseNSMdDirNoFiles(t *testing.T) {
+	root := t.TempDir()
+	_, err := ParseNSMdDir(root)
+	if err == nil {
+		t.Fatal("expected missing _defaults error on empty dir, got nil")
+	}
+}
+
+func TestParseNSMdDirNotADir(t *testing.T) {
+	tmp := t.TempDir()
+	// Create a file with the same name as the expected root dir.
+	root := filepath.Join(tmp, "notadir")
+	writeNSMd(t, root, "x")
+	_, err := ParseNSMdDir(root)
+	if err == nil {
+		t.Fatal("expected error for non-dir root")
+	}
+}

internal/ns/resolve.go

@@ -0,0 +1,252 @@
+// Package ns implements the namespace inheritance resolver (REQ-082)
+// and the ns.md frontmatter parser used by `orca ns` CLI subcommands.
+//
+// The resolver is a PURE function (no I/O): it takes a map of parsed
+// namespace configs keyed by name and returns a map of resolved
+// namespaces with merged env and unioned constraints. The inheritance
+// model is:
+//
+//   - Each namespace declares zero or more parents in `ns.md`
+//     frontmatter (`parents: ["ns1", "ns2"]`).
+//   - The implicit root namespace `_defaults` (R-002 D-159) always
+//     exists and has no parents; it is ALWAYS appended as the last
+//     element of the chain (D-185).
+//   - Opting out of `_defaults` is impossible (D-187): even with
+//     `parents: []`, `_defaults` still appears at the end of the chain.
+//   - Merge semantics: child overrides parent for scalars (env keys);
+//     arrays union (child constraints add to parent constraints, with
+//     duplicates removed, order: most-specific first).
+//   - The chain order is most-specific first, `_defaults` last.
+//   - `_defaults` may be listed explicitly in `parents`; the explicit
+//     listing is de-duped silently (still appears once, at the end).
+//   - Misordering (`parents: ["_defaults", "x"]`) is rejected: an
+//     explicit `_defaults` entry must be the only entry (or omitted).
+//   - Cycle detection uses DFS with a visited set; a cycle returns an
+//     error with the cycle path.
+//   - Missing parents return "parent X not found".
+package ns
+
+import (
+	"fmt"
+	"sort"
+)
+
+const defaultsName = "_defaults"
+
+// NSConfig is a parsed namespace declaration from ns.md frontmatter.
+// The resolver consumes this; the parser populates it.
+type NSConfig struct {
+	Name            string
+	Parents         []string
+	Env             map[string]string
+	Constraints     []string
+	InheritsEnv     bool
+	InheritsSecrets bool
+}
+
+// ResolvedNS is the output of the resolver: the namespace with its
+// fully-merged env and unioned constraints, plus the ordered
+// inheritance chain (most-specific first, `_defaults` last).
+type ResolvedNS struct {
+	Name        string
+	Chain       []string
+	Env         map[string]string
+	Constraints []string
+}
+
+// Resolve walks the parent chain for each namespace, merges env (child
+// wins scalars), unions constraints (child adds to parent, de-duped),
+// and detects cycles. It is PURE (no I/O). The empty-configs case
+// returns an empty map and no error.
+//
+// The `_defaults` namespace is ALWAYS the last element of every chain
+// (D-185); opting out is impossible (D-187). An explicit `_defaults`
+// entry in `parents` is de-duped silently. Misordering (e.g.
+// `parents: ["_defaults", "x"]`) is rejected.
+func Resolve(configs map[string]*NSConfig) (map[string]*ResolvedNS, error) {
+	if len(configs) == 0 {
+		return map[string]*ResolvedNS{}, nil
+	}
+
+	// Validate each config's parents reference exists and the
+	// _defaults entry (if explicit) is the only entry.
+	for name, cfg := range configs {
+		if cfg == nil {
+			return nil, fmt.Errorf("namespace %q has nil config", name)
+		}
+		for _, p := range cfg.Parents {
+			if p == defaultsName {
+				// Explicit _defaults must be the only parent.
+				if len(cfg.Parents) != 1 {
+					return nil, fmt.Errorf("namespace %q: %s must be the only parent if listed explicitly (misordering rejected)", name, defaultsName)
+				}
+				continue
+			}
+			if _, ok := configs[p]; !ok {
+				return nil, fmt.Errorf("namespace %q: parent %q not found", name, p)
+			}
+		}
+	}
+
+	// `_defaults` must be present in the configs map (the parser
+	// enforces this for ParseNSMdDir; Resolve trusts its input but
+	// still requires _defaults to exist for chain assembly).
+	if _, ok := configs[defaultsName]; !ok {
+		return nil, fmt.Errorf("namespace %q not found (implicit root must be present)", defaultsName)
+	}
+
+	resolved := make(map[string]*ResolvedNS, len(configs))
+	// Resolve in deterministic order for stable error reporting.
+	names := make([]string, 0, len(configs))
+	for n := range configs {
+		names = append(names, n)
+	}
+	sort.Strings(names)
+
+	for _, name := range names {
+		r, err := resolveOne(configs, name)
+		if err != nil {
+			return nil, err
+		}
+		resolved[name] = r
+	}
+	return resolved, nil
+}
+
+// resolveOne resolves a single namespace. The chain is built by walking
+// parents depth-first in POST-order (least-specific first), then
+// reversing so the returned chain is most-specific first with
+// `_defaults` last (D-185). Cycle detection uses a visiting set.
+func resolveOne(configs map[string]*NSConfig, name string) (*ResolvedNS, error) {
+	post, err := buildChain(configs, name)
+	if err != nil {
+		return nil, err
+	}
+	// post is least-specific first; reverse to most-specific first.
+	reverseStrings(post)
+	chain := post
+
+	// Env: child (most-specific) wins. Walk least-specific to
+	// most-specific (end -> beginning) so later writes override.
+	env := make(map[string]string)
+	for i := len(chain) - 1; i >= 0; i-- {
+		c := configs[chain[i]]
+		if c == nil {
+			continue
+		}
+		for k, v := range c.Env {
+			env[k] = v
+		}
+	}
+
+	// Constraints: union, child (most-specific) first. Walk the chain
+	// front-to-back (most-specific first) and append unseen items.
+	constraintsSeen := make(map[string]bool)
+	var constraints []string
+	for _, ns := range chain {
+		c := configs[ns]
+		if c == nil {
+			continue
+		}
+		for _, con := range c.Constraints {
+			if !constraintsSeen[con] {
+				constraintsSeen[con] = true
+				constraints = append(constraints, con)
+			}
+		}
+	}
+
+	return &ResolvedNS{
+		Name:        name,
+		Chain:       chain,
+		Env:         env,
+		Constraints: constraints,
+	}, nil
+}
+
+// buildChain walks parents depth-first and returns the chain in
+// POST-order (least-specific first, `_defaults` first). The caller
+// reverses to get most-specific first. Cycle detection uses the
+// visiting set: a node currently being walked indicates a back-edge.
+func buildChain(configs map[string]*NSConfig, name string) ([]string, error) {
+	var post []string
+	seen := make(map[string]bool) // final chain membership (de-dup)
+	visiting := make(map[string]bool)
+	if err := dfsChain(configs, name, &post, seen, visiting); err != nil {
+		return nil, err
+	}
+	// `_defaults` is the implicit root: it must be the FIRST element
+	// in post-order (so it ends up LAST after reversal). If it was not
+	// reached via parents (no explicit listing and no chain leads to
+	// it), prepend it.
+	if !seen[defaultsName] {
+		post = append([]string{defaultsName}, post...)
+		seen[defaultsName] = true
+	}
+	return post, nil
+}
+
+// dfsChain appends each node AFTER its parents (post-order), producing
+// least-specific first. Cycle detection uses the visiting set.
+func dfsChain(configs map[string]*NSConfig, name string, post *[]string, seen, visiting map[string]bool) error {
+	if visiting[name] {
+		return fmt.Errorf("cycle detected: %s", cyclePath(visiting, configs, name))
+	}
+	if seen[name] {
+		return nil
+	}
+	visiting[name] = true
+	cfg := configs[name]
+	if cfg != nil {
+		for _, p := range cfg.Parents {
+			if err := dfsChain(configs, p, post, seen, visiting); err != nil {
+				return err
+			}
+		}
+	}
+	delete(visiting, name)
+	seen[name] = true
+	*post = append(*post, name)
+	return nil
+}
+
+// cyclePath reconstructs a readable cycle path from the visiting set.
+// Since visiting is a set (not ordered), we reconstruct by re-walking
+// parents from the offending node until we revisit it.
+func cyclePath(visiting map[string]bool, configs map[string]*NSConfig, start string) string {
+	// Walk parents from start, collecting names until we hit start
+	// again or run out.
+	var path []string
+	cur := start
+	for i := 0; i < len(visiting)+1; i++ {
+		path = append(path, cur)
+		cfg := configs[cur]
+		if cfg == nil || len(cfg.Parents) == 0 {
+			break
+		}
+		next := cfg.Parents[0]
+		if next == start {
+			path = append(path, next)
+			break
+		}
+		cur = next
+	}
+	return joinArrows(path)
+}
+
+func joinArrows(parts []string) string {
+	out := ""
+	for i, p := range parts {
+		if i > 0 {
+			out += " -> "
+		}
+		out += p
+	}
+	return out
+}
+
+func reverseStrings(s []string) {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+}

internal/ns/resolve_test.go

@@ -0,0 +1,231 @@
+package ns
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestResolveEmptyConfigs(t *testing.T) {
+	out, err := Resolve(map[string]*NSConfig{})
+	if err != nil {
+		t.Fatalf("Resolve empty: unexpected error: %v", err)
+	}
+	if len(out) != 0 {
+		t.Fatalf("Resolve empty: want empty map, got %d entries", len(out))
+	}
+}
+
+func TestResolveSingleNoParents(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Env: map[string]string{"A": "1"}},
+		"x":          {Name: "x", Env: map[string]string{"B": "2"}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	r := out["x"]
+	if r == nil {
+		t.Fatal("missing resolved x")
+	}
+	if !eqSlice(r.Chain, []string{"x", defaultsName}) {
+		t.Errorf("chain = %v, want [x _defaults]", r.Chain)
+	}
+	if r.Env["A"] != "1" || r.Env["B"] != "2" {
+		t.Errorf("env = %v, want A=1 B=2", r.Env)
+	}
+}
+
+func TestResolveChildOverridesParentScalar(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Env: map[string]string{"K": "parent"}},
+		"child":      {Name: "child", Parents: []string{defaultsName}, Env: map[string]string{"K": "child"}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	if got := out["child"].Env["K"]; got != "child" {
+		t.Errorf("child K = %q, want %q (child overrides parent)", got, "child")
+	}
+}
+
+func TestResolveArraysUnion(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Constraints: []string{"a", "b"}},
+		"x":          {Name: "x", Parents: []string{defaultsName}, Constraints: []string{"c", "a"}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	c := out["x"].Constraints
+	// Union de-duped; most-specific (x) first.
+	if !eqSlice(c, []string{"c", "a", "b"}) {
+		t.Errorf("constraints = %v, want [c a b]", c)
+	}
+}
+
+func TestResolveDefaultsImplicitLast(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName},
+		"mid":        {Name: "mid", Parents: []string{defaultsName}},
+		"top":        {Name: "top", Parents: []string{"mid"}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	if !eqSlice(out["top"].Chain, []string{"top", "mid", defaultsName}) {
+		t.Errorf("top chain = %v, want [top mid _defaults]", out["top"].Chain)
+	}
+	if !eqSlice(out["mid"].Chain, []string{"mid", defaultsName}) {
+		t.Errorf("mid chain = %v, want [mid _defaults]", out["mid"].Chain)
+	}
+}
+
+func TestResolveDefaultsDedupExplicit(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Env: map[string]string{"D": "1"}},
+		"x":          {Name: "x", Parents: []string{defaultsName}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	// _defaults appears exactly once.
+	count := 0
+	for _, c := range out["x"].Chain {
+		if c == defaultsName {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("_defaults appears %d times in chain %v, want 1", count, out["x"].Chain)
+	}
+}
+
+func TestResolveMisorderingRejected(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName},
+		"x":          {Name: "x"},
+		"y":          {Name: "y", Parents: []string{defaultsName, "x"}},
+	}
+	_, err := Resolve(cfgs)
+	if err == nil {
+		t.Fatal("expected misordering error, got nil")
+	}
+	if !strings.Contains(err.Error(), "must be the only parent") {
+		t.Errorf("error = %q, want misordering message", err.Error())
+	}
+}
+
+func TestResolveOptOutImpossible(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Env: map[string]string{"ROOT": "1"}},
+		"x":          {Name: "x", Parents: nil},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	r := out["x"]
+	last := r.Chain[len(r.Chain)-1]
+	if last != defaultsName {
+		t.Errorf("last chain element = %q, want %q (opt-out impossible)", last, defaultsName)
+	}
+	if r.Env["ROOT"] != "1" {
+		t.Errorf("env should inherit from _defaults: ROOT=%q", r.Env["ROOT"])
+	}
+}
+
+func TestResolveCycleDetection(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName},
+		"a":          {Name: "a", Parents: []string{"b"}},
+		"b":          {Name: "b", Parents: []string{"a"}},
+	}
+	_, err := Resolve(cfgs)
+	if err == nil {
+		t.Fatal("expected cycle error, got nil")
+	}
+	if !strings.Contains(err.Error(), "cycle") {
+		t.Errorf("error = %q, want cycle message", err.Error())
+	}
+}
+
+func TestResolveMissingParent(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName},
+		"a":          {Name: "a", Parents: []string{"ghost"}},
+	}
+	_, err := Resolve(cfgs)
+	if err == nil {
+		t.Fatal("expected missing-parent error, got nil")
+	}
+	if !strings.Contains(err.Error(), "ghost") || !strings.Contains(err.Error(), "not found") {
+		t.Errorf("error = %q, want contains 'ghost' and 'not found'", err.Error())
+	}
+}
+
+func TestResolveMissingDefaults(t *testing.T) {
+	cfgs := map[string]*NSConfig{
+		"x": {Name: "x"},
+	}
+	_, err := Resolve(cfgs)
+	if err == nil {
+		t.Fatal("expected missing _defaults error, got nil")
+	}
+	if !strings.Contains(err.Error(), defaultsName) {
+		t.Errorf("error = %q, want contains %q", err.Error(), defaultsName)
+	}
+}
+
+func TestResolveChainOrderWithDiamond(t *testing.T) {
+	// Diamond: top -> {left, right} -> base; base -> _defaults.
+	cfgs := map[string]*NSConfig{
+		defaultsName: {Name: defaultsName, Env: map[string]string{"R": "r"}},
+		"base":       {Name: "base", Parents: []string{defaultsName}, Env: map[string]string{"B": "b"}},
+		"left":       {Name: "left", Parents: []string{"base"}, Env: map[string]string{"L": "l"}},
+		"right":      {Name: "right", Parents: []string{"base"}, Env: map[string]string{"L": "r"}},
+		"top":        {Name: "top", Parents: []string{"left", "right"}, Env: map[string]string{"T": "t"}},
+	}
+	out, err := Resolve(cfgs)
+	if err != nil {
+		t.Fatalf("Resolve: %v", err)
+	}
+	r := out["top"]
+	if r == nil {
+		t.Fatal("missing top")
+	}
+	// top first, _defaults last.
+	if r.Chain[0] != "top" || r.Chain[len(r.Chain)-1] != defaultsName {
+		t.Errorf("chain = %v, want top first and _defaults last", r.Chain)
+	}
+	// base appears exactly once (diamond de-duped).
+	count := 0
+	for _, c := range r.Chain {
+		if c == "base" {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("base appears %d times in %v, want 1", count, r.Chain)
+	}
+	// top inherits R from _defaults.
+	if r.Env["R"] != "r" {
+		t.Errorf("top should inherit R=r, got %q", r.Env["R"])
+	}
+}
+
+func eqSlice(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}

internal/paths/paths.go

@@ -0,0 +1,121 @@
+// Package paths resolves on-disk locations for the v0.9 multi-namespace
+// filesystem layout (R-002). It is the canonical source of truth for
+// cluster-wide, per-namespace, and CLI-cache paths.
+//
+// The v0.8 internal/certpaths package is preserved as a thin shim that
+// returns the legacy flat-layout paths during the v0.9 dual-write window
+// (REQ-090). New code should use internal/paths, NOT certpaths.
+package paths
+
+import (
+	"os"
+	"path/filepath"
+)
+
+const (
+	defaultHomeSubdir = ".orca"
+	clusterDirName    = "cluster"
+	defaultNamespace  = "_defaults"
+)
+
+// Root returns the ORCA home directory. It honors $ORCA_HOME for
+// testability; otherwise it defaults to ~/.orca. An empty $ORCA_HOME is
+// treated as unset.
+func Root() string {
+	if p := os.Getenv("ORCA_HOME"); p != "" {
+		return p
+	}
+	home, _ := os.UserHomeDir()
+	return filepath.Join(home, defaultHomeSubdir)
+}
+
+// ClusterDir returns the cluster-wide directory: Root()/cluster.
+// Cluster-wide artifacts (CA, master key, peers, txns, known_hosts, SSH
+// keys) live here and are NOT scoped to a workload namespace (R-002).
+func ClusterDir() string { return filepath.Join(Root(), clusterDirName) }
+
+// NamespaceDir returns the directory for a namespace: Root()/<ns>.
+// Use DefaultNamespace() for the implicit root namespace (R-002 D-159).
+func NamespaceDir(ns string) string { return filepath.Join(Root(), ns) }
+
+// NSDb returns the SQLite database path for a namespace:
+// NamespaceDir(ns)/db/orca.db.
+func NSDb(ns string) string { return filepath.Join(NamespaceDir(ns), "db", "orca.db") }
+
+// NSEnv returns the .env path for a namespace: NamespaceDir(ns)/.env.
+func NSEnv(ns string) string { return filepath.Join(NamespaceDir(ns), ".env") }
+
+// NSSecrets returns the encrypted secrets env path for a namespace:
+// NamespaceDir(ns)/.env.secrets.
+func NSSecrets(ns string) string { return filepath.Join(NamespaceDir(ns), ".env.secrets") }
+
+// NSJobs returns the jobs directory for a namespace: NamespaceDir(ns)/jobs.
+func NSJobs(ns string) string { return filepath.Join(NamespaceDir(ns), "jobs") }
+
+// NSAlloc returns the allocation directory for a namespace:
+// NamespaceDir(ns)/alloc.
+func NSAlloc(ns string) string { return filepath.Join(NamespaceDir(ns), "alloc") }
+
+// NSMd returns the namespace Markdown doc path (R-014):
+// NamespaceDir(ns)/ns.md.
+func NSMd(ns string) string { return filepath.Join(NamespaceDir(ns), "ns.md") }
+
+// DefaultNamespace returns the implicit root namespace name (R-002 D-159).
+func DefaultNamespace() string { return defaultNamespace }
+
+// CACertPath returns the v0.9 cluster CA cert path:
+// ClusterDir()/ca.crt (D-101). The v0.8 internal CA still writes to
+// Root()/ca.crt; the move happens in v0.10-P14.
+func CACertPath() string { return filepath.Join(ClusterDir(), "ca.crt") }
+
+// CAKeyPath returns the v0.9 cluster CA key path:
+// ClusterDir()/ca.key.
+func CAKeyPath() string { return filepath.Join(ClusterDir(), "ca.key") }
+
+// MasterKeyPath returns the AES-256-GCM root master key path
+// (R-011, mode 0600): ClusterDir()/master.key. Not generated until
+// v0.10-P03.
+func MasterKeyPath() string { return filepath.Join(ClusterDir(), "master.key") }
+
+// CacheDB returns the CLI-side cache database path (R-008):
+// Root()/orca_cache.db. Not created until v0.9-P0a2.
+func CacheDB() string { return filepath.Join(Root(), "orca_cache.db") }
+
+// TxnDir returns the cluster transaction log directory (R-016):
+// ClusterDir()/txns.
+func TxnDir() string { return filepath.Join(ClusterDir(), "txns") }
+
+// PeersDir returns the cluster peers directory: ClusterDir()/peers.
+func PeersDir() string { return filepath.Join(ClusterDir(), "peers") }
+
+// PeerDir returns the directory for a single peer host:
+// PeersDir()/host.
+func PeerDir(host string) string { return filepath.Join(PeersDir(), host) }
+
+// KnownHostsPath returns the SSH known_hosts path (D-035):
+// ClusterDir()/known_hosts.
+func KnownHostsPath() string { return filepath.Join(ClusterDir(), "known_hosts") }
+
+// SSHKeyPath returns the orca SSH private key path:
+// ClusterDir()/orca_ssh_key (D-037).
+func SSHKeyPath() string { return filepath.Join(ClusterDir(), "orca_ssh_key") }
+
+// SSHPubPath returns the orca SSH public key path:
+// ClusterDir()/orca_ssh_key.pub.
+func SSHPubPath() string { return filepath.Join(ClusterDir(), "orca_ssh_key.pub") }
+
+// ServerCertPath returns the legacy server cert path (legacy compat):
+// ClusterDir()/server.crt. step-ca will replace this in a later phase.
+func ServerCertPath() string { return filepath.Join(ClusterDir(), "server.crt") }
+
+// ServerKeyPath returns the legacy server key path (legacy compat):
+// ClusterDir()/server.key. step-ca will replace this in a later phase.
+func ServerKeyPath() string { return filepath.Join(ClusterDir(), "server.key") }
+
+// ConfigPath returns the new Markdown-frontmatter config path (R-014):
+// ClusterDir()/config.md. The legacy HCL path is ClusterDir()/config.hcl.
+func ConfigPath() string { return filepath.Join(ClusterDir(), "config.md") }
+
+// LegacyHCLConfigPath returns the legacy HCL config path:
+// ClusterDir()/config.hcl.
+func LegacyHCLConfigPath() string { return filepath.Join(ClusterDir(), "config.hcl") }

internal/paths/paths_test.go

@@ -0,0 +1,209 @@
+package paths
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestRoot_HonorsORCAHOME(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	if got, want := Root(), dir; got != want {
+		t.Errorf("Root() = %q, want %q", got, want)
+	}
+}
+
+func TestRoot_EmptyORCAHOMEFallsBack(t *testing.T) {
+	t.Setenv("ORCA_HOME", "")
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Skipf("os.UserHomeDir: %v", err)
+	}
+	want := filepath.Join(home, defaultHomeSubdir)
+	if got := Root(); got != want {
+		t.Errorf("Root() with empty ORCA_HOME = %q, want %q", got, want)
+	}
+}
+
+func TestRoot_UnsetORCAHOMEFallsBack(t *testing.T) {
+	os.Unsetenv("ORCA_HOME")
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Skipf("os.UserHomeDir: %v", err)
+	}
+	want := filepath.Join(home, defaultHomeSubdir)
+	got := Root()
+	if got != want {
+		t.Errorf("Root() default = %q, want %q", got, want)
+	}
+	if !strings.HasPrefix(got, home) {
+		t.Errorf("Root() default %q does not start with home %q", got, home)
+	}
+}
+
+func TestRoot_RelativeORCAHOME(t *testing.T) {
+	t.Setenv("ORCA_HOME", "relative/orca/home")
+	if got, want := Root(), "relative/orca/home"; got != want {
+		t.Errorf("Root() relative = %q, want %q", got, want)
+	}
+}
+
+func TestDefaultNamespace(t *testing.T) {
+	if got, want := DefaultNamespace(), "_defaults"; got != want {
+		t.Errorf("DefaultNamespace() = %q, want %q", got, want)
+	}
+}
+
+func TestClusterDir(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	got := ClusterDir()
+	want := filepath.Join(dir, "cluster")
+	if got != want {
+		t.Errorf("ClusterDir() = %q, want %q", got, want)
+	}
+	if !strings.HasPrefix(got, Root()+string(filepath.Separator)) {
+		t.Errorf("ClusterDir() %q not under Root() %q", got, Root())
+	}
+}
+
+func TestNamespaceDir(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	ns := "prod"
+	got := NamespaceDir(ns)
+	want := filepath.Join(dir, ns)
+	if got != want {
+		t.Errorf("NamespaceDir(%q) = %q, want %q", ns, got, want)
+	}
+	if !strings.HasPrefix(got, Root()+string(filepath.Separator)) {
+		t.Errorf("NamespaceDir() %q not under Root() %q", got, Root())
+	}
+}
+
+func TestNamespacePaths(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	ns := "prod"
+	nsDir := NamespaceDir(ns)
+
+	cases := []struct {
+		name string
+		got  string
+		want string
+	}{
+		{"NSDb", NSDb(ns), filepath.Join(nsDir, "db", "orca.db")},
+		{"NSEnv", NSEnv(ns), filepath.Join(nsDir, ".env")},
+		{"NSSecrets", NSSecrets(ns), filepath.Join(nsDir, ".env.secrets")},
+		{"NSJobs", NSJobs(ns), filepath.Join(nsDir, "jobs")},
+		{"NSAlloc", NSAlloc(ns), filepath.Join(nsDir, "alloc")},
+		{"NSMd", NSMd(ns), filepath.Join(nsDir, "ns.md")},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if tc.got != tc.want {
+				t.Errorf("%s(%q) = %q, want %q", tc.name, ns, tc.got, tc.want)
+			}
+			if !strings.HasPrefix(tc.got, nsDir+string(filepath.Separator)) {
+				t.Errorf("%s() %q not under NamespaceDir() %q", tc.name, tc.got, nsDir)
+			}
+		})
+	}
+}
+
+func TestDefaultNamespacePaths(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	ns := DefaultNamespace()
+	nsDir := NamespaceDir(ns)
+
+	if got, want := NSDb(ns), filepath.Join(nsDir, "db", "orca.db"); got != want {
+		t.Errorf("NSDb(_defaults) = %q, want %q", got, want)
+	}
+	if got, want := NSEnv(ns), filepath.Join(nsDir, ".env"); got != want {
+		t.Errorf("NSEnv(_defaults) = %q, want %q", got, want)
+	}
+}
+
+func TestClusterPaths(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	cDir := ClusterDir()
+
+	cases := []struct {
+		name string
+		got  string
+		want string
+	}{
+		{"CACertPath", CACertPath(), filepath.Join(cDir, "ca.crt")},
+		{"CAKeyPath", CAKeyPath(), filepath.Join(cDir, "ca.key")},
+		{"MasterKeyPath", MasterKeyPath(), filepath.Join(cDir, "master.key")},
+		{"KnownHostsPath", KnownHostsPath(), filepath.Join(cDir, "known_hosts")},
+		{"SSHKeyPath", SSHKeyPath(), filepath.Join(cDir, "orca_ssh_key")},
+		{"SSHPubPath", SSHPubPath(), filepath.Join(cDir, "orca_ssh_key.pub")},
+		{"ServerCertPath", ServerCertPath(), filepath.Join(cDir, "server.crt")},
+		{"ServerKeyPath", ServerKeyPath(), filepath.Join(cDir, "server.key")},
+		{"ConfigPath", ConfigPath(), filepath.Join(cDir, "config.md")},
+		{"LegacyHCLConfigPath", LegacyHCLConfigPath(), filepath.Join(cDir, "config.hcl")},
+		{"TxnDir", TxnDir(), filepath.Join(cDir, "txns")},
+		{"PeersDir", PeersDir(), filepath.Join(cDir, "peers")},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if tc.got != tc.want {
+				t.Errorf("%s() = %q, want %q", tc.name, tc.got, tc.want)
+			}
+			if !strings.HasPrefix(tc.got, cDir+string(filepath.Separator)) {
+				t.Errorf("%s() %q not under ClusterDir() %q", tc.name, tc.got, cDir)
+			}
+		})
+	}
+}
+
+func TestPeerDir(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	host := "node1.example.com"
+	got := PeerDir(host)
+	want := filepath.Join(PeersDir(), host)
+	if got != want {
+		t.Errorf("PeerDir(%q) = %q, want %q", host, got, want)
+	}
+	if !strings.HasPrefix(got, PeersDir()+string(filepath.Separator)) {
+		t.Errorf("PeerDir() %q not under PeersDir() %q", got, PeersDir())
+	}
+}
+
+func TestCacheDB(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	got := CacheDB()
+	want := filepath.Join(dir, "orca_cache.db")
+	if got != want {
+		t.Errorf("CacheDB() = %q, want %q", got, want)
+	}
+	if !strings.HasPrefix(got, Root()+string(filepath.Separator)) {
+		t.Errorf("CacheDB() %q not under Root() %q", got, Root())
+	}
+}
+
+func TestPathSeparatorsOSAppropriate(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("ORCA_HOME", dir)
+	// Every returned path must use the OS separator (filepath.Join).
+	sep := string(filepath.Separator)
+	for _, p := range []string{
+		ClusterDir(), NamespaceDir("ns"), NSDb("ns"), NSEnv("ns"),
+		NSSecrets("ns"), NSJobs("ns"), NSAlloc("ns"), NSMd("ns"),
+		CACertPath(), CAKeyPath(), MasterKeyPath(), CacheDB(),
+		TxnDir(), PeersDir(), PeerDir("h"), KnownHostsPath(),
+		SSHKeyPath(), SSHPubPath(), ServerCertPath(), ServerKeyPath(),
+		ConfigPath(), LegacyHCLConfigPath(),
+	} {
+		if !strings.Contains(p, sep) {
+			t.Errorf("path %q lacks OS separator %q (not joined?)", p, sep)
+		}
+	}
+}

internal/proxmox/bootstrap.go

@@ -289,6 +289,11 @@ func TOFUHostKeyCallback(addr string, capturedKey *ssh.PublicKey) (ssh.HostKeyCa
 		if errors.As(err, &keyErr) && len(keyErr.Want) == 0 {
 			line := knownhosts.Line([]string{knownhosts.Normalize(addr)}, key)
 			path := certpaths.KnownHostsPath()
+			release, lockErr := security.Flock(path)
+			if lockErr != nil {
+				return fmt.Errorf("tofu lock known_hosts: %w", lockErr)
+			}
+			defer release()
 			existing, readErr := os.ReadFile(path)
 			if readErr != nil && !os.IsNotExist(readErr) {
 				return fmt.Errorf("tofu read known_hosts: %w", readErr)
@@ -481,6 +486,11 @@ func ResetHostKey(host string) error {
 		return fmt.Errorf("ResetHostKey: host is required")
 	}
 	path := certpaths.KnownHostsPath()
+	release, lockErr := security.Flock(path)
+	if lockErr != nil {
+		return fmt.Errorf("ResetHostKey: lock known_hosts: %w", lockErr)
+	}
+	defer release()
 	existing, err := os.ReadFile(path)
 	if err != nil {
 		if os.IsNotExist(err) {

internal/security/flock.go

@@ -0,0 +1,27 @@
+package security
+
+import (
+	"os"
+	"syscall"
+)
+
+// Flock acquires an exclusive advisory lock on the file at path, creating it
+// if missing. Returns a release function that MUST be called (deferred) to
+// release the lock and close the file descriptor. Used by the known_hosts
+// read-modify-write paths (TOFUHostKeyCallback capture + ResetHostKey) to
+// prevent concurrent writers under v0.9's parallel SSH fan-out (REQ-063,
+// deferred P1 from REVIEW_v0.8 A2).
+func Flock(path string) (release func(), err error) {
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
+	if err != nil {
+		return nil, err
+	}
+	if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX); err != nil {
+		f.Close()
+		return nil, err
+	}
+	return func() {
+		_ = syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+		_ = f.Close()
+	}, nil
+}

internal/security/flock_test.go

@@ -0,0 +1,61 @@
+package security
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestFlock_acquireAndRelease(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.lock")
+
+	release, err := Flock(path)
+	if err != nil {
+		t.Fatalf("Flock: %v", err)
+	}
+	if _, statErr := os.Stat(path); statErr != nil {
+		t.Fatalf("lock file not created: %v", statErr)
+	}
+	release()
+}
+
+func TestFlock_reentrantAfterRelease(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.lock")
+
+	r1, err := Flock(path)
+	if err != nil {
+		t.Fatalf("first Flock: %v", err)
+	}
+	r1()
+
+	r2, err := Flock(path)
+	if err != nil {
+		t.Fatalf("second Flock after release: %v", err)
+	}
+	r2()
+}
+
+func TestFlock_concurrentBlocks(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.lock")
+
+	r1, err := Flock(path)
+	if err != nil {
+		t.Fatalf("first Flock: %v", err)
+	}
+	defer r1()
+
+	done := make(chan error, 1)
+	go func() {
+		_, err := Flock(path)
+		done <- err
+	}()
+
+	select {
+	case <-done:
+		t.Fatal("second Flock should block while first holds the lock")
+	default:
+	}
+}