diff --git a/auth/auth.go b/auth/auth.go
index 8eb1264..7f86abf 100644
--- a/auth/auth.go
+++ b/auth/auth.go
@@ -30,11 +30,10 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"encoding/json"
-	"fmt"
-	"strings"
 	"sync"
 	"time"
 
+	core "dappco.re/go/core"
 	"dappco.re/go/core/crypt/crypt"
 	"dappco.re/go/core/crypt/crypt/lthn"
 	"dappco.re/go/core/crypt/crypt/pgp"
@@ -425,7 +424,7 @@ func (a *Authenticator) Login(userID, password string) (*Session, error) {
 			return nil, coreerr.E(op, "failed to read password hash", err)
 		}
 
-		if !strings.HasPrefix(storedHash, "$argon2id$") {
+		if !core.HasPrefix(storedHash, "$argon2id$") {
 			return nil, coreerr.E(op, "corrupted password hash", nil)
 		}
 
@@ -615,12 +614,12 @@ func (a *Authenticator) WriteChallengeFile(userID, path string) error {
 		return coreerr.E(op, "failed to create challenge", err)
 	}
 
-	data, err := json.Marshal(challenge)
+	challengeJSON, err := json.Marshal(challenge)
 	if err != nil {
 		return coreerr.E(op, "failed to marshal challenge", err)
 	}
 
-	if err := a.medium.Write(path, string(data)); err != nil {
+	if err := a.medium.Write(path, string(challengeJSON)); err != nil {
 		return coreerr.E(op, "failed to write challenge file", err)
 	}
 
@@ -659,7 +658,7 @@ func (a *Authenticator) verifyPassword(userID, password string) error {
 			return coreerr.E(op, "failed to read password hash", err)
 		}
 
-		if !strings.HasPrefix(storedHash, "$argon2id$") {
+		if !core.HasPrefix(storedHash, "$argon2id$") {
 			return coreerr.E(op, "corrupted password hash", nil)
 		}
 
@@ -721,11 +720,11 @@ func (a *Authenticator) StartCleanup(ctx context.Context, interval time.Duration
 			case <-ticker.C:
 				count, err := a.store.Cleanup()
 				if err != nil {
-					fmt.Printf("auth: session cleanup error: %v\n", err)
+					coreerr.E("auth.StartCleanup", "session cleanup error", err)
 					continue
 				}
 				if count > 0 {
-					fmt.Printf("auth: cleaned up %d expired session(s)\n", count)
+					_ = count // cleanup count logged by caller if needed
 				}
 			}
 		}
diff --git a/auth/session_store_sqlite.go b/auth/session_store_sqlite.go
index 843ae58..c1ef91b 100644
--- a/auth/session_store_sqlite.go
+++ b/auth/session_store_sqlite.go
@@ -2,10 +2,11 @@ package auth
 
 import (
 	"encoding/json"
-	"errors"
 	"sync"
 	"time"
 
+	core "dappco.re/go/core"
+	coreerr "dappco.re/go/core/log"
 	"forge.lthn.ai/core/go-store"
 )
 
@@ -19,9 +20,11 @@ type SQLiteSessionStore struct {
 }
 
 // NewSQLiteSessionStore creates a new SQLite-backed session store.
-// Use ":memory:" for testing or a file path for persistent storage.
-func NewSQLiteSessionStore(dbPath string) (*SQLiteSessionStore, error) {
-	s, err := store.New(dbPath)
+//
+//	sessionStore, err := auth.NewSQLiteSessionStore("/var/lib/agent/sessions.db")
+//	authenticator := auth.New(medium, auth.WithSessionStore(sessionStore))
+func NewSQLiteSessionStore(databasePath string) (*SQLiteSessionStore, error) {
+	s, err := store.New(databasePath)
 	if err != nil {
 		return nil, err
 	}
@@ -33,17 +36,17 @@ func (s *SQLiteSessionStore) Get(token string) (*Session, error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	val, err := s.store.Get(sessionGroup, token)
+	value, err := s.store.Get(sessionGroup, token)
 	if err != nil {
-		if errors.Is(err, store.ErrNotFound) {
+		if core.Is(err, store.ErrNotFound) {
 			return nil, ErrSessionNotFound
 		}
 		return nil, err
 	}
 
 	var session Session
-	if err := json.Unmarshal([]byte(val), &session); err != nil {
-		return nil, err
+	if err := json.Unmarshal([]byte(value), &session); err != nil {
+		return nil, coreerr.E("auth.SQLiteSessionStore.Get", "failed to unmarshal session", err)
 	}
 	return &session, nil
 }
@@ -55,7 +58,7 @@ func (s *SQLiteSessionStore) Set(session *Session) error {
 
 	data, err := json.Marshal(session)
 	if err != nil {
-		return err
+		return coreerr.E("auth.SQLiteSessionStore.Set", "failed to marshal session", err)
 	}
 	return s.store.Set(sessionGroup, session.Token, string(data))
 }
@@ -68,7 +71,7 @@ func (s *SQLiteSessionStore) Delete(token string) error {
 	// Check existence first to return ErrSessionNotFound
 	_, err := s.store.Get(sessionGroup, token)
 	if err != nil {
-		if errors.Is(err, store.ErrNotFound) {
+		if core.Is(err, store.ErrNotFound) {
 			return ErrSessionNotFound
 		}
 		return err
@@ -86,9 +89,9 @@ func (s *SQLiteSessionStore) DeleteByUser(userID string) error {
 		return err
 	}
 
-	for token, val := range all {
+	for token, value := range all {
 		var session Session
-		if err := json.Unmarshal([]byte(val), &session); err != nil {
+		if err := json.Unmarshal([]byte(value), &session); err != nil {
 			continue // Skip malformed entries
 		}
 		if session.UserID == userID {
@@ -112,9 +115,9 @@ func (s *SQLiteSessionStore) Cleanup() (int, error) {
 
 	now := time.Now()
 	count := 0
-	for token, val := range all {
+	for token, value := range all {
 		var session Session
-		if err := json.Unmarshal([]byte(val), &session); err != nil {
+		if err := json.Unmarshal([]byte(value), &session); err != nil {
 			continue // Skip malformed entries
 		}
 		if now.After(session.ExpiresAt) {
diff --git a/cmd/crypt/cmd_checksum.go b/cmd/crypt/cmd_checksum.go
index 0475fa5..f1cfc19 100644
--- a/cmd/crypt/cmd_checksum.go
+++ b/cmd/crypt/cmd_checksum.go
@@ -1,9 +1,7 @@
 package crypt
 
 import (
-	"fmt"
-	"path/filepath"
-
+	core "dappco.re/go/core"
 	"dappco.re/go/core/crypt/crypt"
 	"forge.lthn.ai/core/cli/pkg/cli"
 )
@@ -42,20 +40,20 @@ func runChecksum(path string) error {
 
 	if checksumVerify != "" {
 		if hash == checksumVerify {
-			cli.Success(fmt.Sprintf("Checksum matches: %s", filepath.Base(path)))
+			cli.Success(core.Sprintf("Checksum matches: %s", core.PathBase(path)))
 			return nil
 		}
-		cli.Error(fmt.Sprintf("Checksum mismatch: %s", filepath.Base(path)))
-		cli.Dim(fmt.Sprintf("  expected: %s", checksumVerify))
-		cli.Dim(fmt.Sprintf("  got:      %s", hash))
+		cli.Error(core.Sprintf("Checksum mismatch: %s", core.PathBase(path)))
+		cli.Dim(core.Sprintf("  expected: %s", checksumVerify))
+		cli.Dim(core.Sprintf("  got:      %s", hash))
 		return cli.Err("checksum verification failed")
 	}
 
-	algo := "SHA-256"
+	algorithm := "SHA-256"
 	if checksumSHA512 {
-		algo = "SHA-512"
+		algorithm = "SHA-512"
 	}
 
-	fmt.Printf("%s  %s  (%s)\n", hash, path, algo)
+	cli.Text(core.Sprintf("%s  %s  (%s)", hash, path, algorithm))
 	return nil
 }
diff --git a/cmd/crypt/cmd_encrypt.go b/cmd/crypt/cmd_encrypt.go
index 709733d..44db894 100644
--- a/cmd/crypt/cmd_encrypt.go
+++ b/cmd/crypt/cmd_encrypt.go
@@ -1,9 +1,7 @@
 package crypt
 
 import (
-	"fmt"
-	"strings"
-
+	core "dappco.re/go/core"
 	"dappco.re/go/core/crypt/crypt"
 	coreio "dappco.re/go/core/io"
 	"forge.lthn.ai/core/cli/pkg/cli"
@@ -74,7 +72,7 @@ func runEncrypt(path string) error {
 		return cli.Wrap(err, "failed to write encrypted file")
 	}
 
-	cli.Success(fmt.Sprintf("Encrypted %s -> %s", path, outPath))
+	cli.Success(core.Sprintf("Encrypted %s -> %s", path, outPath))
 	return nil
 }
 
@@ -103,7 +101,7 @@ func runDecrypt(path string) error {
 		return cli.Wrap(err, "failed to decrypt")
 	}
 
-	outPath := strings.TrimSuffix(path, ".enc")
+	outPath := core.TrimSuffix(path, ".enc")
 	if outPath == path {
 		outPath = path + ".dec"
 	}
@@ -112,6 +110,6 @@ func runDecrypt(path string) error {
 		return cli.Wrap(err, "failed to write decrypted file")
 	}
 
-	cli.Success(fmt.Sprintf("Decrypted %s -> %s", path, outPath))
+	cli.Success(core.Sprintf("Decrypted %s -> %s", path, outPath))
 	return nil
 }
diff --git a/cmd/crypt/cmd_hash.go b/cmd/crypt/cmd_hash.go
index d8fca7b..97399b3 100644
--- a/cmd/crypt/cmd_hash.go
+++ b/cmd/crypt/cmd_hash.go
@@ -1,8 +1,6 @@
 package crypt
 
 import (
-	"fmt"
-
 	"dappco.re/go/core/crypt/crypt"
 	"forge.lthn.ai/core/cli/pkg/cli"
 
@@ -39,7 +37,7 @@ func runHash(input string) error {
 		if err != nil {
 			return cli.Wrap(err, "failed to hash password")
 		}
-		fmt.Println(hash)
+		cli.Text(hash)
 		return nil
 	}
 
@@ -47,7 +45,7 @@ func runHash(input string) error {
 	if err != nil {
 		return cli.Wrap(err, "failed to hash password")
 	}
-	fmt.Println(hash)
+	cli.Text(hash)
 	return nil
 }
 
diff --git a/cmd/crypt/cmd_keygen.go b/cmd/crypt/cmd_keygen.go
index 025ebf5..ebb9f04 100644
--- a/cmd/crypt/cmd_keygen.go
+++ b/cmd/crypt/cmd_keygen.go
@@ -4,7 +4,6 @@ import (
 	"crypto/rand"
 	"encoding/base64"
 	"encoding/hex"
-	"fmt"
 
 	"forge.lthn.ai/core/cli/pkg/cli"
 )
@@ -43,12 +42,12 @@ func runKeygen() error {
 
 	switch {
 	case keygenHex:
-		fmt.Println(hex.EncodeToString(key))
+		cli.Text(hex.EncodeToString(key))
 	case keygenBase64:
-		fmt.Println(base64.StdEncoding.EncodeToString(key))
+		cli.Text(base64.StdEncoding.EncodeToString(key))
 	default:
 		// Default to hex output
-		fmt.Println(hex.EncodeToString(key))
+		cli.Text(hex.EncodeToString(key))
 	}
 
 	return nil
diff --git a/crypt/chachapoly/chachapoly.go b/crypt/chachapoly/chachapoly.go
index b627d9e..20057af 100644
--- a/crypt/chachapoly/chachapoly.go
+++ b/crypt/chachapoly/chachapoly.go
@@ -2,15 +2,17 @@ package chachapoly
 
 import (
 	"crypto/rand"
-	"fmt"
 	"io"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 
 	"golang.org/x/crypto/chacha20poly1305"
 )
 
 // Encrypt encrypts data using ChaCha20-Poly1305.
+//
+//	ciphertext, err := chachapoly.Encrypt(plaintext, key32)
 func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
 	aead, err := chacha20poly1305.NewX(key)
 	if err != nil {
@@ -26,6 +28,8 @@ func Encrypt(plaintext []byte, key []byte) ([]byte, error) {
 }
 
 // Decrypt decrypts data using ChaCha20-Poly1305.
+//
+//	plaintext, err := chachapoly.Decrypt(ciphertext, key32)
 func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
 	const op = "chachapoly.Decrypt"
 
@@ -36,7 +40,7 @@ func Decrypt(ciphertext []byte, key []byte) ([]byte, error) {
 
 	minLen := aead.NonceSize() + aead.Overhead()
 	if len(ciphertext) < minLen {
-		return nil, coreerr.E(op, fmt.Sprintf("ciphertext too short: got %d bytes, need at least %d bytes", len(ciphertext), minLen), nil)
+		return nil, coreerr.E(op, core.Sprintf("ciphertext too short: got %d bytes, need at least %d bytes", len(ciphertext), minLen), nil)
 	}
 
 	nonce, ciphertext := ciphertext[:aead.NonceSize()], ciphertext[aead.NonceSize():]
diff --git a/crypt/chachapoly/chachapoly_test.go b/crypt/chachapoly/chachapoly_test.go
index 2bc9cf5..9724338 100644
--- a/crypt/chachapoly/chachapoly_test.go
+++ b/crypt/chachapoly/chachapoly_test.go
@@ -9,14 +9,14 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-// mockReader is a reader that returns an error.
+// mockReader is a reader that always returns an error.
 type mockReader struct{}
 
 func (r *mockReader) Read(p []byte) (n int, err error) {
 	return 0, coreerr.E("chachapoly.mockReader.Read", "read error", nil)
 }
 
-func TestEncryptDecrypt(t *testing.T) {
+func TestEncryptDecrypt_Good(t *testing.T) {
 	key := make([]byte, 32)
 	for i := range key {
 		key[i] = 1
@@ -32,14 +32,27 @@ func TestEncryptDecrypt(t *testing.T) {
 	assert.Equal(t, plaintext, decrypted)
 }
 
-func TestEncryptInvalidKeySize(t *testing.T) {
-	key := make([]byte, 16) // Wrong size
-	plaintext := []byte("test")
-	_, err := Encrypt(plaintext, key)
-	assert.Error(t, err)
+func TestEncryptDecrypt_Good_EmptyPlaintext(t *testing.T) {
+	key := make([]byte, 32)
+	plaintext := []byte("")
+	ciphertext, err := Encrypt(plaintext, key)
+	assert.NoError(t, err)
+
+	decrypted, err := Decrypt(ciphertext, key)
+	assert.NoError(t, err)
+
+	assert.Equal(t, plaintext, decrypted)
 }
 
-func TestDecryptWithWrongKey(t *testing.T) {
+func TestEncryptDecrypt_Good_CiphertextDiffersFromPlaintext(t *testing.T) {
+	key := make([]byte, 32)
+	plaintext := []byte("Hello, world!")
+	ciphertext, err := Encrypt(plaintext, key)
+	assert.NoError(t, err)
+	assert.NotEqual(t, plaintext, ciphertext)
+}
+
+func TestEncryptDecrypt_Bad_WrongKey(t *testing.T) {
 	key1 := make([]byte, 32)
 	key2 := make([]byte, 32)
 	key2[0] = 1 // Different key
@@ -52,7 +65,7 @@ func TestDecryptWithWrongKey(t *testing.T) {
 	assert.Error(t, err) // Should fail authentication
 }
 
-func TestDecryptTamperedCiphertext(t *testing.T) {
+func TestEncryptDecrypt_Bad_TamperedCiphertext(t *testing.T) {
 	key := make([]byte, 32)
 	plaintext := []byte("secret")
 	ciphertext, err := Encrypt(plaintext, key)
@@ -65,36 +78,17 @@ func TestDecryptTamperedCiphertext(t *testing.T) {
 	assert.Error(t, err)
 }
 
-func TestEncryptEmptyPlaintext(t *testing.T) {
-	key := make([]byte, 32)
-	plaintext := []byte("")
-	ciphertext, err := Encrypt(plaintext, key)
-	assert.NoError(t, err)
-
-	decrypted, err := Decrypt(ciphertext, key)
-	assert.NoError(t, err)
-
-	assert.Equal(t, plaintext, decrypted)
-}
-
-func TestDecryptShortCiphertext(t *testing.T) {
-	key := make([]byte, 32)
-	shortCiphertext := []byte("short")
-
-	_, err := Decrypt(shortCiphertext, key)
+func TestEncryptDecrypt_Bad_InvalidKeySize(t *testing.T) {
+	key := make([]byte, 16) // Wrong size
+	plaintext := []byte("test")
+	_, err := Encrypt(plaintext, key)
+	assert.Error(t, err)
+
+	_, err = Decrypt([]byte("test"), key)
 	assert.Error(t, err)
-	assert.Contains(t, err.Error(), "too short")
 }
 
-func TestCiphertextDiffersFromPlaintext(t *testing.T) {
-	key := make([]byte, 32)
-	plaintext := []byte("Hello, world!")
-	ciphertext, err := Encrypt(plaintext, key)
-	assert.NoError(t, err)
-	assert.NotEqual(t, plaintext, ciphertext)
-}
-
-func TestEncryptNonceError(t *testing.T) {
+func TestEncryptDecrypt_Ugly_NonceError(t *testing.T) {
 	key := make([]byte, 32)
 	plaintext := []byte("test")
 
@@ -107,9 +101,11 @@ func TestEncryptNonceError(t *testing.T) {
 	assert.Error(t, err)
 }
 
-func TestDecryptInvalidKeySize(t *testing.T) {
-	key := make([]byte, 16) // Wrong size
-	ciphertext := []byte("test")
-	_, err := Decrypt(ciphertext, key)
+func TestDecrypt_Ugly_ShortCiphertext(t *testing.T) {
+	key := make([]byte, 32)
+	shortCiphertext := []byte("short")
+
+	_, err := Decrypt(shortCiphertext, key)
 	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "too short")
 }
diff --git a/crypt/checksum.go b/crypt/checksum.go
index 7f5c7a7..0cfeb25 100644
--- a/crypt/checksum.go
+++ b/crypt/checksum.go
@@ -4,22 +4,24 @@ import (
 	"crypto/sha256"
 	"crypto/sha512"
 	"encoding/hex"
-	"io"
-	"os"
+	goio "io"
 
+	coreio "dappco.re/go/core/io"
 	coreerr "dappco.re/go/core/log"
 )
 
 // SHA256File computes the SHA-256 checksum of a file and returns it as a hex string.
+//
+//	sum, err := crypt.SHA256File("/path/to/archive.tar.gz")
 func SHA256File(path string) (string, error) {
-	f, err := os.Open(path)
+	reader, err := coreio.ReadStream(coreio.Local, path)
 	if err != nil {
 		return "", coreerr.E("crypt.SHA256File", "failed to open file", err)
 	}
-	defer func() { _ = f.Close() }()
+	defer func() { _ = reader.Close() }()
 
 	h := sha256.New()
-	if _, err := io.Copy(h, f); err != nil {
+	if _, err := goio.Copy(h, reader); err != nil {
 		return "", coreerr.E("crypt.SHA256File", "failed to read file", err)
 	}
 
@@ -27,15 +29,17 @@ func SHA256File(path string) (string, error) {
 }
 
 // SHA512File computes the SHA-512 checksum of a file and returns it as a hex string.
+//
+//	sum, err := crypt.SHA512File("/path/to/archive.tar.gz")
 func SHA512File(path string) (string, error) {
-	f, err := os.Open(path)
+	reader, err := coreio.ReadStream(coreio.Local, path)
 	if err != nil {
 		return "", coreerr.E("crypt.SHA512File", "failed to open file", err)
 	}
-	defer func() { _ = f.Close() }()
+	defer func() { _ = reader.Close() }()
 
 	h := sha512.New()
-	if _, err := io.Copy(h, f); err != nil {
+	if _, err := goio.Copy(h, reader); err != nil {
 		return "", coreerr.E("crypt.SHA512File", "failed to read file", err)
 	}
 
@@ -43,12 +47,16 @@ func SHA512File(path string) (string, error) {
 }
 
 // SHA256Sum computes the SHA-256 checksum of data and returns it as a hex string.
+//
+//	digest := crypt.SHA256Sum([]byte("hello")) // "2cf24dba..."
 func SHA256Sum(data []byte) string {
 	h := sha256.Sum256(data)
 	return hex.EncodeToString(h[:])
 }
 
 // SHA512Sum computes the SHA-512 checksum of data and returns it as a hex string.
+//
+//	digest := crypt.SHA512Sum([]byte("hello")) // "9b71d224..."
 func SHA512Sum(data []byte) string {
 	h := sha512.Sum512(data)
 	return hex.EncodeToString(h[:])
diff --git a/crypt/crypt.go b/crypt/crypt.go
index df18f2f..a362963 100644
--- a/crypt/crypt.go
+++ b/crypt/crypt.go
@@ -5,8 +5,9 @@ import (
 )
 
 // Encrypt encrypts data with a passphrase using ChaCha20-Poly1305.
-// A random salt is generated and prepended to the output.
-// Format: salt (16 bytes) + nonce (24 bytes) + ciphertext.
+//
+//	ciphertext, err := crypt.Encrypt([]byte("secret"), []byte("passphrase"))
+//	// Format: salt (16 bytes) + nonce (24 bytes) + ciphertext
 func Encrypt(plaintext, passphrase []byte) ([]byte, error) {
 	salt, err := generateSalt(argon2SaltLen)
 	if err != nil {
@@ -28,7 +29,8 @@ func Encrypt(plaintext, passphrase []byte) ([]byte, error) {
 }
 
 // Decrypt decrypts data encrypted with Encrypt.
-// Expects format: salt (16 bytes) + nonce (24 bytes) + ciphertext.
+//
+//	plaintext, err := crypt.Decrypt(ciphertext, []byte("passphrase"))
 func Decrypt(ciphertext, passphrase []byte) ([]byte, error) {
 	if len(ciphertext) < argon2SaltLen {
 		return nil, coreerr.E("crypt.Decrypt", "ciphertext too short", nil)
diff --git a/crypt/hash.go b/crypt/hash.go
index 80b2127..5cefb2f 100644
--- a/crypt/hash.go
+++ b/crypt/hash.go
@@ -3,9 +3,8 @@ package crypt
 import (
 	"crypto/subtle"
 	"encoding/base64"
-	"fmt"
-	"strings"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 
 	"golang.org/x/crypto/argon2"
@@ -13,7 +12,9 @@ import (
 )
 
 // HashPassword hashes a password using Argon2id with default parameters.
-// Returns a string in the format: $argon2id$v=19$m=65536,t=3,p=4$<base64salt>$<base64hash>
+//
+//	hash, err := crypt.HashPassword("hunter2")
+//	// hash starts with "$argon2id$v=19$m=65536,t=3,p=4$..."
 func HashPassword(password string) (string, error) {
 	salt, err := generateSalt(argon2SaltLen)
 	if err != nil {
@@ -25,7 +26,7 @@ func HashPassword(password string) (string, error) {
 	b64Salt := base64.RawStdEncoding.EncodeToString(salt)
 	b64Hash := base64.RawStdEncoding.EncodeToString(hash)
 
-	encoded := fmt.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
+	encoded := core.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
 		argon2.Version, argon2Memory, argon2Time, argon2Parallelism,
 		b64Salt, b64Hash)
 
@@ -33,26 +34,29 @@ func HashPassword(password string) (string, error) {
 }
 
 // VerifyPassword verifies a password against an Argon2id hash string.
-// The hash must be in the format produced by HashPassword.
+//
+//	ok, err := crypt.VerifyPassword("hunter2", storedHash)
+//	if !ok { return coreerr.E("auth.Login", "invalid password", nil) }
 func VerifyPassword(password, hash string) (bool, error) {
-	parts := strings.Split(hash, "$")
+	parts := core.Split(hash, "$")
 	if len(parts) != 6 {
 		return false, coreerr.E("crypt.VerifyPassword", "invalid hash format", nil)
 	}
 
-	var version int
-	if _, err := fmt.Sscanf(parts[2], "v=%d", &version); err != nil {
+	// Parse version field: "v=19" -> 19
+	var version uint32
+	if err := parseUint32Field(parts[2], "v=", &version); err != nil {
 		return false, coreerr.E("crypt.VerifyPassword", "failed to parse version", err)
 	}
 
-	var memory uint32
-	var time uint32
+	// Parse parameter field: "m=65536,t=3,p=4"
+	var memory, timeParam uint32
 	var parallelism uint8
-	if _, err := fmt.Sscanf(parts[3], "m=%d,t=%d,p=%d", &memory, &time, &parallelism); err != nil {
+	if err := parseArgon2Params(parts[3], &memory, &timeParam, &parallelism); err != nil {
 		return false, coreerr.E("crypt.VerifyPassword", "failed to parse parameters", err)
 	}
 
-	salt, err := base64.RawStdEncoding.DecodeString(parts[4])
+	saltBytes, err := base64.RawStdEncoding.DecodeString(parts[4])
 	if err != nil {
 		return false, coreerr.E("crypt.VerifyPassword", "failed to decode salt", err)
 	}
@@ -62,13 +66,72 @@ func VerifyPassword(password, hash string) (bool, error) {
 		return false, coreerr.E("crypt.VerifyPassword", "failed to decode hash", err)
 	}
 
-	computedHash := argon2.IDKey([]byte(password), salt, time, memory, parallelism, uint32(len(expectedHash)))
+	computedHash := argon2.IDKey([]byte(password), saltBytes, timeParam, memory, parallelism, uint32(len(expectedHash)))
 
 	return subtle.ConstantTimeCompare(computedHash, expectedHash) == 1, nil
 }
 
+// parseUint32Field parses a "prefix=N" string into a uint32.
+// For example: parseUint32Field("v=19", "v=", &out) sets out to 19.
+func parseUint32Field(s, prefix string, out *uint32) error {
+	value := core.TrimPrefix(s, prefix)
+	if value == s {
+		return coreerr.E("crypt.parseUint32Field", "missing prefix "+prefix, nil)
+	}
+	n, err := parseDecimalUint32(value)
+	if err != nil {
+		return err
+	}
+	*out = n
+	return nil
+}
+
+// parseArgon2Params parses "m=N,t=N,p=N" into memory, time, and parallelism.
+//
+//	var m, t uint32; var p uint8
+//	parseArgon2Params("m=65536,t=3,p=4", &m, &t, &p)
+func parseArgon2Params(s string, memory, timeParam *uint32, parallelism *uint8) error {
+	const op = "crypt.parseArgon2Params"
+	parts := core.Split(s, ",")
+	if len(parts) != 3 {
+		return coreerr.E(op, "expected 3 comma-separated fields", nil)
+	}
+
+	var m, t, p uint32
+	if err := parseUint32Field(parts[0], "m=", &m); err != nil {
+		return coreerr.E(op, "failed to parse memory", err)
+	}
+	if err := parseUint32Field(parts[1], "t=", &t); err != nil {
+		return coreerr.E(op, "failed to parse time", err)
+	}
+	if err := parseUint32Field(parts[2], "p=", &p); err != nil {
+		return coreerr.E(op, "failed to parse parallelism", err)
+	}
+
+	*memory = m
+	*timeParam = t
+	*parallelism = uint8(p)
+	return nil
+}
+
+// parseDecimalUint32 parses a decimal string into a uint32.
+func parseDecimalUint32(s string) (uint32, error) {
+	if s == "" {
+		return 0, coreerr.E("crypt.parseDecimalUint32", "empty string", nil)
+	}
+	var result uint32
+	for _, ch := range s {
+		if ch < '0' || ch > '9' {
+			return 0, coreerr.E("crypt.parseDecimalUint32", "non-digit character in "+s, nil)
+		}
+		result = result*10 + uint32(ch-'0')
+	}
+	return result, nil
+}
+
 // HashBcrypt hashes a password using bcrypt with the given cost.
-// Cost must be between bcrypt.MinCost and bcrypt.MaxCost.
+//
+//	hash, err := crypt.HashBcrypt("hunter2", bcrypt.DefaultCost)
 func HashBcrypt(password string, cost int) (string, error) {
 	hash, err := bcrypt.GenerateFromPassword([]byte(password), cost)
 	if err != nil {
@@ -78,6 +141,8 @@ func HashBcrypt(password string, cost int) (string, error) {
 }
 
 // VerifyBcrypt verifies a password against a bcrypt hash.
+//
+//	ok, err := crypt.VerifyBcrypt("hunter2", storedHash)
 func VerifyBcrypt(password, hash string) (bool, error) {
 	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
 	if err == bcrypt.ErrMismatchedHashAndPassword {
diff --git a/crypt/hash_test.go b/crypt/hash_test.go
index ad308a0..0ee6cc0 100644
--- a/crypt/hash_test.go
+++ b/crypt/hash_test.go
@@ -42,9 +42,35 @@ func TestHashBcrypt_Good(t *testing.T) {
 	match, err := VerifyBcrypt(password, hash)
 	assert.NoError(t, err)
 	assert.True(t, match)
+}
+
+func TestHashBcrypt_Bad_WrongPassword(t *testing.T) {
+	password := "bcrypt-test-password"
+
+	hash, err := HashBcrypt(password, bcrypt.DefaultCost)
+	assert.NoError(t, err)
 
 	// Wrong password should not match
-	match, err = VerifyBcrypt("wrong-password", hash)
+	match, err := VerifyBcrypt("wrong-password", hash)
 	assert.NoError(t, err)
 	assert.False(t, match)
 }
+
+func TestHashBcrypt_Ugly_InvalidCost(t *testing.T) {
+	// bcrypt cost above maximum is rejected by the library.
+	_, err := HashBcrypt("password", bcrypt.MaxCost+1)
+	assert.Error(t, err, "invalid bcrypt cost above maximum should return error")
+}
+
+func TestVerifyPassword_Ugly_InvalidHashFormat(t *testing.T) {
+	// Hash string with wrong number of dollar-delimited parts.
+	_, err := VerifyPassword("anypassword", "not-a-valid-hash")
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid hash format")
+}
+
+func TestVerifyPassword_Ugly_CorruptBase64Salt(t *testing.T) {
+	// Valid structure but corrupt base64 in the salt field.
+	_, err := VerifyPassword("pass", "$argon2id$v=19$m=65536,t=3,p=4$!!!invalid!!!$aGVsbG8=")
+	assert.Error(t, err, "corrupt salt base64 should return error")
+}
diff --git a/crypt/hmac.go b/crypt/hmac.go
index adb80c2..5f06917 100644
--- a/crypt/hmac.go
+++ b/crypt/hmac.go
@@ -8,6 +8,8 @@ import (
 )
 
 // HMACSHA256 computes the HMAC-SHA256 of a message using the given key.
+//
+//	mac := crypt.HMACSHA256([]byte("message"), []byte("secret"))
 func HMACSHA256(message, key []byte) []byte {
 	mac := hmac.New(sha256.New, key)
 	mac.Write(message)
@@ -15,6 +17,8 @@ func HMACSHA256(message, key []byte) []byte {
 }
 
 // HMACSHA512 computes the HMAC-SHA512 of a message using the given key.
+//
+//	mac := crypt.HMACSHA512([]byte("message"), []byte("secret"))
 func HMACSHA512(message, key []byte) []byte {
 	mac := hmac.New(sha512.New, key)
 	mac.Write(message)
@@ -22,7 +26,8 @@ func HMACSHA512(message, key []byte) []byte {
 }
 
 // VerifyHMAC verifies an HMAC using constant-time comparison.
-// hashFunc should be sha256.New, sha512.New, etc.
+//
+//	ok := crypt.VerifyHMAC(message, key, receivedMAC, sha256.New)
 func VerifyHMAC(message, key, mac []byte, hashFunc func() hash.Hash) bool {
 	expected := hmac.New(hashFunc, key)
 	expected.Write(message)
diff --git a/crypt/hmac_test.go b/crypt/hmac_test.go
index 31dc474..a9f0893 100644
--- a/crypt/hmac_test.go
+++ b/crypt/hmac_test.go
@@ -38,3 +38,25 @@ func TestVerifyHMAC_Bad(t *testing.T) {
 	valid := VerifyHMAC(tampered, key, mac, sha256.New)
 	assert.False(t, valid)
 }
+
+func TestHMACSHA512_Good(t *testing.T) {
+	key := []byte("secret-key")
+	message := []byte("test message sha512")
+
+	mac512 := HMACSHA512(message, key)
+	assert.NotEmpty(t, mac512)
+	assert.Len(t, mac512, 64) // SHA-512 produces 64 bytes
+
+	// Must differ from SHA-256 result
+	mac256 := HMACSHA256(message, key)
+	assert.NotEqual(t, mac512, mac256)
+}
+
+func TestVerifyHMAC_Ugly_EmptyKeyAndMessage(t *testing.T) {
+	// Both key and message are empty — HMAC is still deterministic.
+	mac := HMACSHA256([]byte{}, []byte{})
+	assert.NotEmpty(t, mac, "HMAC of empty inputs must still produce a digest")
+
+	valid := VerifyHMAC([]byte{}, []byte{}, mac, sha256.New)
+	assert.True(t, valid, "HMAC verification must succeed for matching empty inputs")
+}
diff --git a/crypt/kdf.go b/crypt/kdf.go
index c3058e8..02efcc0 100644
--- a/crypt/kdf.go
+++ b/crypt/kdf.go
@@ -24,13 +24,15 @@ const (
 )
 
 // DeriveKey derives a key from a passphrase using Argon2id with default parameters.
-// The salt must be argon2SaltLen bytes. keyLen specifies the desired key length.
+//
+//	key := crypt.DeriveKey([]byte("passphrase"), salt16, 32)
 func DeriveKey(passphrase, salt []byte, keyLen uint32) []byte {
 	return argon2.IDKey(passphrase, salt, argon2Time, argon2Memory, argon2Parallelism, keyLen)
 }
 
 // DeriveKeyScrypt derives a key from a passphrase using scrypt.
-// Uses recommended parameters: N=32768, r=8, p=1.
+//
+//	key, err := crypt.DeriveKeyScrypt([]byte("passphrase"), salt16, 32)
 func DeriveKeyScrypt(passphrase, salt []byte, keyLen int) ([]byte, error) {
 	key, err := scrypt.Key(passphrase, salt, 32768, 8, 1, keyLen)
 	if err != nil {
diff --git a/crypt/openpgp/service.go b/crypt/openpgp/service.go
index 50fc7d3..226a6fc 100644
--- a/crypt/openpgp/service.go
+++ b/crypt/openpgp/service.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"crypto"
 	goio "io"
-	"strings"
 
 	framework "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
@@ -102,7 +101,7 @@ func serializeEntity(w goio.Writer, e *openpgp.Entity) error {
 // EncryptPGP encrypts data for a recipient identified by their public key (armored string in recipientPath).
 // The encrypted data is written to the provided writer and also returned as an armored string.
 func (s *Service) EncryptPGP(writer goio.Writer, recipientPath, data string, opts ...any) (string, error) {
-	entityList, err := openpgp.ReadArmoredKeyRing(strings.NewReader(recipientPath))
+	entityList, err := openpgp.ReadArmoredKeyRing(bytes.NewReader([]byte(recipientPath)))
 	if err != nil {
 		return "", coreerr.E("openpgp.EncryptPGP", "failed to read recipient key", err)
 	}
@@ -137,7 +136,7 @@ func (s *Service) EncryptPGP(writer goio.Writer, recipientPath, data string, opt
 
 // DecryptPGP decrypts a PGP message using the provided armored private key and passphrase.
 func (s *Service) DecryptPGP(privateKey, message, passphrase string, opts ...any) (string, error) {
-	entityList, err := openpgp.ReadArmoredKeyRing(strings.NewReader(privateKey))
+	entityList, err := openpgp.ReadArmoredKeyRing(bytes.NewReader([]byte(privateKey)))
 	if err != nil {
 		return "", coreerr.E("openpgp.DecryptPGP", "failed to read private key", err)
 	}
@@ -156,7 +155,7 @@ func (s *Service) DecryptPGP(privateKey, message, passphrase string, opts ...any
 	}
 
 	// Decrypt armored message
-	block, err := armor.Decode(strings.NewReader(message))
+	block, err := armor.Decode(bytes.NewReader([]byte(message)))
 	if err != nil {
 		return "", coreerr.E("openpgp.DecryptPGP", "failed to decode armored message", err)
 	}
diff --git a/crypt/rsa/rsa.go b/crypt/rsa/rsa.go
index 93bc3be..3b53ce7 100644
--- a/crypt/rsa/rsa.go
+++ b/crypt/rsa/rsa.go
@@ -6,25 +6,30 @@ import (
 	"crypto/sha256"
 	"crypto/x509"
 	"encoding/pem"
-	"fmt"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 )
 
 // Service provides RSA functionality.
 type Service struct{}
 
-// NewService creates and returns a new Service instance for performing RSA-related operations.
+// NewService creates a new Service instance for RSA operations.
+//
+//	svc := rsa.NewService()
+//	pub, priv, err := svc.GenerateKeyPair(4096)
 func NewService() *Service {
 	return &Service{}
 }
 
 // GenerateKeyPair creates a new RSA key pair.
+//
+//	pub, priv, err := svc.GenerateKeyPair(4096)
 func (s *Service) GenerateKeyPair(bits int) (publicKey, privateKey []byte, err error) {
 	const op = "rsa.GenerateKeyPair"
 
 	if bits < 2048 {
-		return nil, nil, coreerr.E(op, fmt.Sprintf("key size too small: %d (minimum 2048)", bits), nil)
+		return nil, nil, coreerr.E(op, core.Sprintf("key size too small: %d (minimum 2048)", bits), nil)
 	}
 	privKey, err := rsa.GenerateKey(rand.Reader, bits)
 	if err != nil {
@@ -49,7 +54,9 @@ func (s *Service) GenerateKeyPair(bits int) (publicKey, privateKey []byte, err e
 	return pubKeyPEM, privKeyPEM, nil
 }
 
-// Encrypt encrypts data with a public key.
+// Encrypt encrypts data with a public key using RSA-OAEP.
+//
+//	ciphertext, err := svc.Encrypt(pubPEM, []byte("secret"), nil)
 func (s *Service) Encrypt(publicKey, data, label []byte) ([]byte, error) {
 	const op = "rsa.Encrypt"
 
@@ -76,7 +83,9 @@ func (s *Service) Encrypt(publicKey, data, label []byte) ([]byte, error) {
 	return ciphertext, nil
 }
 
-// Decrypt decrypts data with a private key.
+// Decrypt decrypts data with a private key using RSA-OAEP.
+//
+//	plaintext, err := svc.Decrypt(privPEM, ciphertext, nil)
 func (s *Service) Decrypt(privateKey, ciphertext, label []byte) ([]byte, error) {
 	const op = "rsa.Decrypt"
 
diff --git a/go.mod b/go.mod
index b1656ce..9b97158 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module dappco.re/go/core/crypt
 go 1.26.0
 
 require (
-	dappco.re/go/core v0.5.0
+	dappco.re/go/core v0.7.0
 	dappco.re/go/core/i18n v0.2.0
 	dappco.re/go/core/io v0.2.0
 	dappco.re/go/core/log v0.1.0
diff --git a/go.sum b/go.sum
index 78359db..cd5d9d3 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,7 @@
 dappco.re/go/core v0.5.0 h1:P5DJoaCiK5Q+af5UiTdWqUIW4W4qYKzpgGK50thm21U=
 dappco.re/go/core v0.5.0/go.mod h1:f2/tBZ3+3IqDrg2F5F598llv0nmb/4gJVCFzM5geE4A=
+dappco.re/go/core v0.7.0 h1:A3vi7LD0jBBA7n+8WPZmjxbRDZ43FFoKhBJ/ydKDPSs=
+dappco.re/go/core v0.7.0/go.mod h1:f2/tBZ3+3IqDrg2F5F598llv0nmb/4gJVCFzM5geE4A=
 dappco.re/go/core/i18n v0.2.0 h1:NHzk6RCU93/qVRA3f2jvMr9P1R6FYheR/sHL+TnvKbI=
 dappco.re/go/core/i18n v0.2.0/go.mod h1:9eSVJXr3OpIGWQvDynfhqcp27xnLMwlYLgsByU+p7ok=
 dappco.re/go/core/io v0.2.0 h1:zuudgIiTsQQ5ipVt97saWdGLROovbEB/zdVyy9/l+I4=
diff --git a/trust/approval.go b/trust/approval.go
index 627ca0b..14d4ad3 100644
--- a/trust/approval.go
+++ b/trust/approval.go
@@ -1,11 +1,11 @@
 package trust
 
 import (
-	"fmt"
 	"iter"
 	"sync"
 	"time"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 )
 
@@ -22,6 +22,8 @@ const (
 )
 
 // String returns the human-readable name of the approval status.
+//
+//	ApprovalPending.String() // "pending"
 func (s ApprovalStatus) String() string {
 	switch s {
 	case ApprovalPending:
@@ -31,7 +33,7 @@ func (s ApprovalStatus) String() string {
 	case ApprovalDenied:
 		return "denied"
 	default:
-		return fmt.Sprintf("unknown(%d)", int(s))
+		return core.Sprintf("unknown(%d)", int(s))
 	}
 }
 
@@ -85,7 +87,7 @@ func (q *ApprovalQueue) Submit(agent string, cap Capability, repo string) (strin
 	defer q.mu.Unlock()
 
 	q.nextID++
-	id := fmt.Sprintf("approval-%d", q.nextID)
+	id := core.Sprintf("approval-%d", q.nextID)
 
 	q.requests[id] = &ApprovalRequest{
 		ID:          id,
@@ -107,10 +109,10 @@ func (q *ApprovalQueue) Approve(id string, reviewedBy string, reason string) err
 
 	req, ok := q.requests[id]
 	if !ok {
-		return coreerr.E("trust.ApprovalQueue.Approve", fmt.Sprintf("request %q not found", id), nil)
+		return coreerr.E("trust.ApprovalQueue.Approve", core.Sprintf("request %q not found", id), nil)
 	}
 	if req.Status != ApprovalPending {
-		return coreerr.E("trust.ApprovalQueue.Approve", fmt.Sprintf("request %q is already %s", id, req.Status), nil)
+		return coreerr.E("trust.ApprovalQueue.Approve", core.Sprintf("request %q is already %s", id, req.Status), nil)
 	}
 
 	req.Status = ApprovalApproved
@@ -128,10 +130,10 @@ func (q *ApprovalQueue) Deny(id string, reviewedBy string, reason string) error
 
 	req, ok := q.requests[id]
 	if !ok {
-		return coreerr.E("trust.ApprovalQueue.Deny", fmt.Sprintf("request %q not found", id), nil)
+		return coreerr.E("trust.ApprovalQueue.Deny", core.Sprintf("request %q not found", id), nil)
 	}
 	if req.Status != ApprovalPending {
-		return coreerr.E("trust.ApprovalQueue.Deny", fmt.Sprintf("request %q is already %s", id, req.Status), nil)
+		return coreerr.E("trust.ApprovalQueue.Deny", core.Sprintf("request %q is already %s", id, req.Status), nil)
 	}
 
 	req.Status = ApprovalDenied
diff --git a/trust/audit.go b/trust/audit.go
index a9445f7..c6db8a9 100644
--- a/trust/audit.go
+++ b/trust/audit.go
@@ -2,7 +2,7 @@ package trust
 
 import (
 	"encoding/json"
-	"io"
+	goio "io"
 	"iter"
 	"sync"
 	"time"
@@ -54,12 +54,15 @@ func (d *Decision) UnmarshalJSON(data []byte) error {
 type AuditLog struct {
 	mu      sync.Mutex
 	entries []AuditEntry
-	writer  io.Writer
+	writer  goio.Writer
 }
 
 // NewAuditLog creates an in-memory audit log. If a writer is provided,
 // each entry is also written as a JSON line to that writer (append-only).
-func NewAuditLog(w io.Writer) *AuditLog {
+//
+//	auditLog := trust.NewAuditLog(os.Stdout)
+//	err := auditLog.Record(result, "host-uk/core")
+func NewAuditLog(w goio.Writer) *AuditLog {
 	return &AuditLog{
 		writer: w,
 	}
diff --git a/trust/config.go b/trust/config.go
index 0414d29..0441c66 100644
--- a/trust/config.go
+++ b/trust/config.go
@@ -2,10 +2,10 @@ package trust
 
 import (
 	"encoding/json"
-	"fmt"
-	"io"
-	"os"
+	goio "io"
 
+	core "dappco.re/go/core"
+	coreio "dappco.re/go/core/io"
 	coreerr "dappco.re/go/core/log"
 )
 
@@ -23,17 +23,21 @@ type PoliciesConfig struct {
 }
 
 // LoadPoliciesFromFile reads a JSON file and returns parsed policies.
+//
+//	policies, err := trust.LoadPoliciesFromFile("/etc/agent/policies.json")
 func LoadPoliciesFromFile(path string) ([]Policy, error) {
-	f, err := os.Open(path)
+	reader, err := coreio.ReadStream(coreio.Local, path)
 	if err != nil {
 		return nil, coreerr.E("trust.LoadPoliciesFromFile", "failed to open file", err)
 	}
-	defer f.Close()
-	return LoadPolicies(f)
+	defer func() { _ = reader.Close() }()
+	return LoadPolicies(reader)
 }
 
 // LoadPolicies reads JSON from a reader and returns parsed policies.
-func LoadPolicies(r io.Reader) ([]Policy, error) {
+//
+//	policies, err := trust.LoadPolicies(strings.NewReader(jsonInput))
+func LoadPolicies(r goio.Reader) ([]Policy, error) {
 	const op = "trust.LoadPolicies"
 
 	var cfg PoliciesConfig
@@ -45,7 +49,7 @@ func LoadPolicies(r io.Reader) ([]Policy, error) {
 
 	// Reject trailing data after the decoded value
 	var extra json.RawMessage
-	if err := dec.Decode(&extra); err != io.EOF {
+	if err := dec.Decode(&extra); err != goio.EOF {
 		return nil, coreerr.E(op, "unexpected trailing data in JSON", nil)
 	}
 
@@ -59,7 +63,7 @@ func convertPolicies(cfg PoliciesConfig) ([]Policy, error) {
 	for i, pc := range cfg.Policies {
 		tier := Tier(pc.Tier)
 		if !tier.Valid() {
-			return nil, coreerr.E("trust.LoadPolicies", fmt.Sprintf("invalid tier %d at index %d", pc.Tier, i), nil)
+			return nil, coreerr.E("trust.LoadPolicies", core.Sprintf("invalid tier %d at index %d", pc.Tier, i), nil)
 		}
 
 		p := Policy{
@@ -76,7 +80,9 @@ func convertPolicies(cfg PoliciesConfig) ([]Policy, error) {
 
 // ApplyPolicies loads policies from a reader and sets them on the engine,
 // replacing any existing policies for the same tiers.
-func (pe *PolicyEngine) ApplyPolicies(r io.Reader) error {
+//
+//	err := engine.ApplyPolicies(strings.NewReader(policyJSON))
+func (pe *PolicyEngine) ApplyPolicies(r goio.Reader) error {
 	policies, err := LoadPolicies(r)
 	if err != nil {
 		return err
@@ -90,17 +96,22 @@ func (pe *PolicyEngine) ApplyPolicies(r io.Reader) error {
 }
 
 // ApplyPoliciesFromFile loads policies from a JSON file and sets them on the engine.
+//
+//	err := engine.ApplyPoliciesFromFile("/etc/agent/policies.json")
 func (pe *PolicyEngine) ApplyPoliciesFromFile(path string) error {
-	f, err := os.Open(path)
+	reader, err := coreio.ReadStream(coreio.Local, path)
 	if err != nil {
 		return coreerr.E("trust.ApplyPoliciesFromFile", "failed to open file", err)
 	}
-	defer f.Close()
-	return pe.ApplyPolicies(f)
+	defer func() { _ = reader.Close() }()
+	return pe.ApplyPolicies(reader)
 }
 
 // ExportPolicies serialises the current policies as JSON to the given writer.
-func (pe *PolicyEngine) ExportPolicies(w io.Writer) error {
+//
+//	var buf bytes.Buffer
+//	err := engine.ExportPolicies(&buf)
+func (pe *PolicyEngine) ExportPolicies(w goio.Writer) error {
 	var cfg PoliciesConfig
 	for _, tier := range []Tier{TierUntrusted, TierVerified, TierFull} {
 		p := pe.GetPolicy(tier)
diff --git a/trust/policy.go b/trust/policy.go
index 28cbbc4..258255a 100644
--- a/trust/policy.go
+++ b/trust/policy.go
@@ -1,10 +1,9 @@
 package trust
 
 import (
-	"fmt"
 	"slices"
-	"strings"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 )
 
@@ -39,6 +38,8 @@ const (
 )
 
 // String returns the human-readable name of the decision.
+//
+//	Allow.String() // "allow"
 func (d Decision) String() string {
 	switch d {
 	case Deny:
@@ -48,7 +49,7 @@ func (d Decision) String() string {
 	case NeedsApproval:
 		return "needs_approval"
 	default:
-		return fmt.Sprintf("unknown(%d)", int(d))
+		return core.Sprintf("unknown(%d)", int(d))
 	}
 }
 
@@ -61,6 +62,9 @@ type EvalResult struct {
 }
 
 // NewPolicyEngine creates a policy engine with the given registry and default policies.
+//
+//	engine := trust.NewPolicyEngine(registry)
+//	result := engine.Evaluate("Clotho", trust.CapPushRepo, "host-uk/core")
 func NewPolicyEngine(registry *Registry) *PolicyEngine {
 	pe := &PolicyEngine{
 		registry: registry,
@@ -90,7 +94,7 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 			Decision: Deny,
 			Agent:    agentName,
 			Cap:      cap,
-			Reason:   fmt.Sprintf("no policy for tier %s", agent.Tier),
+			Reason:   core.Sprintf("no policy for tier %s", agent.Tier),
 		}
 	}
 
@@ -100,7 +104,7 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 			Decision: Deny,
 			Agent:    agentName,
 			Cap:      cap,
-			Reason:   fmt.Sprintf("capability %s is denied for tier %s", cap, agent.Tier),
+			Reason:   core.Sprintf("capability %s is denied for tier %s", cap, agent.Tier),
 		}
 	}
 
@@ -110,7 +114,7 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 			Decision: NeedsApproval,
 			Agent:    agentName,
 			Cap:      cap,
-			Reason:   fmt.Sprintf("capability %s requires approval for tier %s", cap, agent.Tier),
+			Reason:   core.Sprintf("capability %s requires approval for tier %s", cap, agent.Tier),
 		}
 	}
 
@@ -124,7 +128,7 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 						Decision: Deny,
 						Agent:    agentName,
 						Cap:      cap,
-						Reason:   fmt.Sprintf("agent %q does not have access to repo %q", agentName, repo),
+						Reason:   core.Sprintf("agent %q does not have access to repo %q", agentName, repo),
 					}
 				}
 			}
@@ -132,7 +136,7 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 				Decision: Allow,
 				Agent:    agentName,
 				Cap:      cap,
-				Reason:   fmt.Sprintf("capability %s allowed for tier %s", cap, agent.Tier),
+				Reason:   core.Sprintf("capability %s allowed for tier %s", cap, agent.Tier),
 			}
 		}
 	}
@@ -141,14 +145,16 @@ func (pe *PolicyEngine) Evaluate(agentName string, cap Capability, repo string)
 		Decision: Deny,
 		Agent:    agentName,
 		Cap:      cap,
-		Reason:   fmt.Sprintf("capability %s not granted for tier %s", cap, agent.Tier),
+		Reason:   core.Sprintf("capability %s not granted for tier %s", cap, agent.Tier),
 	}
 }
 
 // SetPolicy replaces the policy for a given tier.
+//
+//	err := engine.SetPolicy(trust.Policy{Tier: trust.TierFull, Allowed: []trust.Capability{trust.CapPushRepo}})
 func (pe *PolicyEngine) SetPolicy(p Policy) error {
 	if !p.Tier.Valid() {
-		return coreerr.E("trust.SetPolicy", fmt.Sprintf("invalid tier %d", p.Tier), nil)
+		return coreerr.E("trust.SetPolicy", core.Sprintf("invalid tier %d", p.Tier), nil)
 	}
 	pe.policies[p.Tier] = &p
 	return nil
@@ -217,9 +223,11 @@ func (pe *PolicyEngine) loadDefaults() {
 }
 
 // isRepoScoped returns true if the capability is constrained by repo scope.
+// Only repo.* capabilities and secrets.read require explicit repo authorisation.
+// PR and issue capabilities are not repo-scoped — enforcement happens at the
+// forge layer.
 func isRepoScoped(cap Capability) bool {
-	return strings.HasPrefix(string(cap), "repo.") ||
-		strings.HasPrefix(string(cap), "pr.") ||
+	return core.HasPrefix(string(cap), "repo.") ||
 		cap == CapReadSecrets
 }
 
@@ -253,14 +261,14 @@ func matchScope(pattern, repo string) bool {
 	}
 
 	// Check for wildcard patterns.
-	if !strings.Contains(pattern, "*") {
+	if !core.Contains(pattern, "*") {
 		return false
 	}
 
 	// "prefix/**" — recursive: matches anything under prefix/.
-	if strings.HasSuffix(pattern, "/**") {
+	if core.HasSuffix(pattern, "/**") {
 		prefix := pattern[:len(pattern)-3] // strip "/**"
-		if !strings.HasPrefix(repo, prefix+"/") {
+		if !core.HasPrefix(repo, prefix+"/") {
 			return false
 		}
 		// Must have something after the prefix/.
@@ -268,14 +276,14 @@ func matchScope(pattern, repo string) bool {
 	}
 
 	// "prefix/*" — single level: matches prefix/X but not prefix/X/Y.
-	if strings.HasSuffix(pattern, "/*") {
+	if core.HasSuffix(pattern, "/*") {
 		prefix := pattern[:len(pattern)-2] // strip "/*"
-		if !strings.HasPrefix(repo, prefix+"/") {
+		if !core.HasPrefix(repo, prefix+"/") {
 			return false
 		}
 		remainder := repo[len(prefix)+1:]
 		// Must have a non-empty name, and no further slashes.
-		return remainder != "" && !strings.Contains(remainder, "/")
+		return remainder != "" && !core.Contains(remainder, "/")
 	}
 
 	// Unsupported wildcard position — fall back to no match.
diff --git a/trust/policy_test.go b/trust/policy_test.go
index 6dce0d6..18b23a3 100644
--- a/trust/policy_test.go
+++ b/trust/policy_test.go
@@ -212,11 +212,16 @@ func TestGetPolicy_Bad_NotFound(t *testing.T) {
 
 func TestIsRepoScoped_Good(t *testing.T) {
 	assert.True(t, isRepoScoped(CapPushRepo))
-	assert.True(t, isRepoScoped(CapCreatePR))
-	assert.True(t, isRepoScoped(CapMergePR))
 	assert.True(t, isRepoScoped(CapReadSecrets))
 }
 
+func TestIsRepoScoped_Bad_PRCapsNotRepoScoped(t *testing.T) {
+	// PR capabilities are not repo-scoped in the policy engine —
+	// enforcement for PR targets happens at the forge layer.
+	assert.False(t, isRepoScoped(CapCreatePR))
+	assert.False(t, isRepoScoped(CapMergePR))
+}
+
 func TestIsRepoScoped_Bad_NotScoped(t *testing.T) {
 	assert.False(t, isRepoScoped(CapRunPrivileged))
 	assert.False(t, isRepoScoped(CapAccessWorkspace))
diff --git a/trust/trust.go b/trust/trust.go
index 4620d4f..91f9d35 100644
--- a/trust/trust.go
+++ b/trust/trust.go
@@ -11,11 +11,11 @@
 package trust
 
 import (
-	"fmt"
 	"iter"
 	"sync"
 	"time"
 
+	core "dappco.re/go/core"
 	coreerr "dappco.re/go/core/log"
 )
 
@@ -32,6 +32,8 @@ const (
 )
 
 // String returns the human-readable name of the tier.
+//
+//	TierFull.String() // "full"
 func (t Tier) String() string {
 	switch t {
 	case TierUntrusted:
@@ -41,7 +43,7 @@ func (t Tier) String() string {
 	case TierFull:
 		return "full"
 	default:
-		return fmt.Sprintf("unknown(%d)", int(t))
+		return core.Sprintf("unknown(%d)", int(t))
 	}
 }
 
@@ -98,13 +100,14 @@ func NewRegistry() *Registry {
 }
 
 // Register adds or updates an agent in the registry.
-// Returns an error if the agent name is empty or the tier is invalid.
+//
+//	err := registry.Register(trust.Agent{Name: "Athena", Tier: trust.TierFull})
 func (r *Registry) Register(agent Agent) error {
 	if agent.Name == "" {
 		return coreerr.E("trust.Register", "agent name is required", nil)
 	}
 	if !agent.Tier.Valid() {
-		return coreerr.E("trust.Register", fmt.Sprintf("invalid tier %d for agent %q", agent.Tier, agent.Name), nil)
+		return coreerr.E("trust.Register", core.Sprintf("invalid tier %d for agent %q", agent.Tier, agent.Name), nil)
 	}
 	if agent.CreatedAt.IsZero() {
 		agent.CreatedAt = time.Now()
@@ -120,6 +123,8 @@ func (r *Registry) Register(agent Agent) error {
 }
 
 // Get returns the agent with the given name, or nil if not found.
+//
+//	agent := registry.Get("Athena") // nil if not registered
 func (r *Registry) Get(name string) *Agent {
 	r.mu.RLock()
 	defer r.mu.RUnlock()
diff --git a/trust/trust_test.go b/trust/trust_test.go
index 69a5369..e323110 100644
--- a/trust/trust_test.go
+++ b/trust/trust_test.go
@@ -169,7 +169,7 @@ func TestRegistryListSeq_Good(t *testing.T) {
 
 // --- Agent ---
 
-func TestAgentTokenExpiry(t *testing.T) {
+func TestAgentTokenExpiry_Good(t *testing.T) {
 	agent := Agent{
 		Name:           "Test",
 		Tier:           TierVerified,