secrets: encrypt the evidence snapshot heads at rest

traffic_evidence_snapshots.req_head and resp_head join the secret column registry (AAD per column, enc:v1:). Heads are sealed at insert and opened on every read; the startup key check, the no-key refusal and the idempotent backfill cover them. Archives keep the heads sealed; the import opens them to check the snapshot ID and the insert seals them once.

README.md

@@ -183,7 +183,7 @@ gunzip -c backups/artex-db-<timestamp>.sql.gz | docker compose exec -T postgres
 
 Stored secrets (LLM API keys and proxies, MCP env, task credentials,
 notification channel config, the Brave and Tavily search keys, the web search
-and global proxies) are encrypted in the database with the key in `keys/secret.key`
+and global proxies, the execution spec of custom tools) are encrypted in the database with the key in `keys/secret.key`
 (generated at first start, mode 0600, next to `jwt.key`). **A database backup
 without that key can no longer restore those secrets**: back up `keys/` with the
 dump, separately. Deployments without a persistent disk set `ARTEX_SECRET_KEY`

db/evidence_secrets_test.go

@@ -0,0 +1,245 @@
+package db
+
+import (
+	"database/sql"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+)
+
+const (
+	evCookie = "session=ev-cookie-secret"
+	evBearer = "Bearer ev-auth-secret"
+)
+
+// evidenceFixture records a finding. With legacy=false the snapshot goes through
+// the normal insert path; with legacy=true it is written in clear by raw SQL.
+func evidenceFixture(t *testing.T, d *DB, tag string, legacy bool) (*Task, int64, TrafficEvidenceSnapshot) {
+	t.Helper()
+	task, err := d.CreateTask("evidence heads at rest "+tag, "goal", nil, 0, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := TrafficEvidenceSnapshot{SourceTrafficID: "t-sec-ev-" + tag, CapturedAt: 1, URL: "http://ev.example/" + tag, Method: "GET", Status: 200,
+		ReqHead:  "GET /" + tag + " HTTP/1.1\nCookie: " + evCookie + "\nAuthorization: " + evBearer + "\n",
+		RespHead: "HTTP/1.1 200 OK\nSet-Cookie: " + evCookie + "\n", ReqHash: "rh-" + tag, RespHash: "ph-" + tag}
+	s.ID = TrafficSnapshotID(s)
+	t.Cleanup(func() {
+		d.Exec(`DELETE FROM task_archives WHERE task_id=$1`, task.ID)
+		d.DeleteTaskCascade(task.ID, false, true) // findings and their bindings too
+		if _, err := d.Exec(`DELETE FROM traffic_evidence_snapshots WHERE id=$1`, s.ID); err != nil {
+			t.Errorf("cleanup snapshot: %v", err)
+		}
+	})
+	f, err := d.Exploration(task.ExplorationID).RecordFinding(t.Context(), RecordFindingInput{TaskID: task.ID, ExplorationID: task.ExplorationID, Summary: "evidence " + tag, Severity: "low"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if legacy {
+		_, err = d.Exec(`INSERT INTO traffic_evidence_snapshots(id,source_traffic_id,captured_at,url,method,status,req_head,resp_head,req_hash,resp_hash,req_len,resp_len)
+VALUES($1,$2,1,$3,'GET',200,$4,$5,$6,$7,0,0)`, s.ID, s.SourceTrafficID, s.URL, s.ReqHead, s.RespHead, s.ReqHash, s.RespHash)
+		if err == nil {
+			_, err = d.Exec(`INSERT INTO finding_traffic_bindings(finding_id,snapshot_id,position) VALUES($1,$2,0)`, f.FindingID, s.ID)
+		}
+	} else {
+		err = d.WithEvidenceTx(t.Context(), func(tx *sql.Tx) error {
+			return AddFindingTrafficTx(tx, f.FindingID, []PreparedTrafficEvidence{{Ref: TrafficRef{TrafficID: s.SourceTrafficID, Role: "proof"}, Snapshot: s}})
+		})
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return task, f.FindingID, s
+}
+
+// rawHeads reads the stored heads; both must be sealed and hide the secrets.
+func rawHeads(t *testing.T, d *DB, id string) (req, resp string) {
+	t.Helper()
+	if err := d.QueryRow(`SELECT req_head,resp_head FROM traffic_evidence_snapshots WHERE id=$1`, id).Scan(&req, &resp); err != nil {
+		t.Fatal(err)
+	}
+	for _, v := range []string{req, resp} {
+		if !isEncrypted(v) || strings.Contains(v, evCookie) || strings.Contains(v, evBearer) {
+			t.Fatalf("head stored in clear: %q", v)
+		}
+	}
+	return req, resp
+}
+
+// assertClearHeads checks the application read and that the stored value is
+// sealed exactly once.
+func assertClearHeads(t *testing.T, d *DB, findingID int64, want TrafficEvidenceSnapshot) {
+	t.Helper()
+	got, err := d.GetFindingTraffic(t.Context(), findingID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got.Bindings) != 1 || got.Bindings[0].Snapshot.ReqHead != want.ReqHead || got.Bindings[0].Snapshot.RespHead != want.RespHead || got.Bindings[0].SnapshotID != want.ID {
+		t.Fatalf("read back: %+v", got.Bindings)
+	}
+	req, resp := rawHeads(t, d, want.ID)
+	box := activeSecretBox.Load()
+	if p, err := box.decrypt(colEvReqHead.aad(), req); err != nil || p != want.ReqHead {
+		t.Fatalf("req_head not sealed once: %q %v", p, err)
+	}
+	if p, err := box.decrypt(colEvRespHead.aad(), resp); err != nil || p != want.RespHead {
+		t.Fatalf("resp_head not sealed once: %q %v", p, err)
+	}
+}
+
+func TestEvidenceHeadsSealedAtInsert(t *testing.T) {
+	d, err := Open(testDSN(t))
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	t.Cleanup(func() { d.Close() })
+	_, fid, s := evidenceFixture(t, d, "insert", false)
+	assertClearHeads(t, d, fid, s)
+	var url, method string
+	if err := d.QueryRow(`SELECT url,method FROM traffic_evidence_snapshots WHERE id=$1`, s.ID).Scan(&url, &method); err != nil || url != s.URL || method != "GET" {
+		t.Fatalf("metadata must stay in clear: %q %q %v", url, method, err)
+	}
+}
+
+func TestEvidenceHeadsBackfillAndKeyChecks(t *testing.T) {
+	d, err := Open(testDSN(t))
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	t.Cleanup(func() { d.Close() })
+	_, fid, s := evidenceFixture(t, d, "legacy", true)
+	t.Setenv(secretKeyEnv, base64.StdEncoding.EncodeToString(testSecretKey))
+	if err := d.InitSecrets(t.TempDir()); err != nil {
+		t.Fatal(err)
+	}
+	assertClearHeads(t, d, fid, s)
+	req, resp := rawHeads(t, d, s.ID)
+	if err := d.InitSecrets(t.TempDir()); err != nil {
+		t.Fatal(err)
+	}
+	if r2, p2 := rawHeads(t, d, s.ID); r2 != req || p2 != resp {
+		t.Fatal("second backfill must leave the ciphertexts untouched")
+	}
+
+	// A head sealed under another key: the read and the startup check fail and
+	// name the column. The startup check samples one sealed row per column, so
+	// this row must be the only sealed snapshot.
+	var sealedRows int
+	if err := d.QueryRow(`SELECT count(*) FROM traffic_evidence_snapshots WHERE req_head LIKE 'enc:v1:%' OR resp_head LIKE 'enc:v1:%'`).Scan(&sealedRows); err != nil || sealedRows != 1 {
+		t.Fatalf("want only this fixture's snapshot sealed, got %d (%v)", sealedRows, err)
+	}
+	other, _ := newSecretBox([]byte("ffffffffffffffffffffffffffffffff"))
+	for _, c := range []secretColumn{colEvReqHead, colEvRespHead} {
+		bad, _ := other.encrypt(c.aad(), "GET / HTTP/1.1\nCookie: other\n")
+		if _, err := d.Exec(`UPDATE traffic_evidence_snapshots SET `+c.col+`=$1 WHERE id=$2`, bad, s.ID); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := d.GetFindingTraffic(t.Context(), fid); err == nil || !strings.Contains(err.Error(), c.aad()) {
+			t.Fatalf("want a read failure naming %s, got %v", c.aad(), err)
+		}
+		if err := d.InitSecrets(t.TempDir()); err == nil || !strings.Contains(err.Error(), "secret key check") || !strings.Contains(err.Error(), c.aad()) {
+			t.Fatalf("want a key-check failure naming %s, got %v", c.aad(), err)
+		}
+		if _, err := d.Exec(`UPDATE traffic_evidence_snapshots SET req_head=$1,resp_head=$2 WHERE id=$3`, req, resp, s.ID); err != nil {
+			t.Fatal(err)
+		}
+	}
+	assertClearHeads(t, d, fid, s)
+
+	// No key with sealed heads: refuse, and each head counts. One head stays
+	// sealed so the refusal never turns into a new key.
+	t.Setenv(secretKeyEnv, "")
+	dir := t.TempDir()
+	withHeads := encryptedCount(t, d, dir)
+	for _, c := range []secretColumn{colEvReqHead, colEvRespHead} {
+		if _, err := d.Exec(`UPDATE traffic_evidence_snapshots SET req_head=$1,resp_head=$2 WHERE id=$3`, req, resp, s.ID); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := d.Exec(`UPDATE traffic_evidence_snapshots SET `+c.col+`='' WHERE id=$1`, s.ID); err != nil {
+			t.Fatal(err)
+		}
+		if n := encryptedCount(t, d, dir); withHeads-n != 1 {
+			t.Fatalf("no-key refusal counted %d then %d encrypted values; %s must count", withHeads, n, c.aad())
+		}
+	}
+}
+
+// Export keeps the heads sealed; import opens them to check the snapshot ID,
+// then the insert seals them once. A legacy clear archive is sealed on import.
+func TestEvidenceHeadsArchiveRoundTrip(t *testing.T) {
+	d, err := Open(testDSN(t))
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	t.Cleanup(func() { d.Close() })
+	if err = d.EnsureLLMRecordsTable(); err != nil {
+		t.Fatal(err)
+	}
+	if err = d.EnsureLLMUsageTable(); err != nil {
+		t.Fatal(err)
+	}
+	for _, legacy := range []bool{false, true} {
+		t.Run(fmt.Sprint("legacy=", legacy), func(t *testing.T) {
+			task, fid, s := evidenceFixture(t, d, fmt.Sprint("archive-", legacy), false)
+			if err := d.SetPaused(task.ID, true); err != nil {
+				t.Fatal(err)
+			}
+			archive, err := d.QueueTaskArchive(task.ID)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if _, err = d.ClaimTaskArchiveJob(t.Context()); err != nil {
+				t.Fatal(err)
+			}
+			snapshot, err := d.SnapshotTaskArchive(task.ID)
+			if err != nil {
+				t.Fatal(err)
+			}
+			exported := string(snapshot.Tables["traffic_evidence_snapshots"])
+			if !strings.Contains(exported, secretPrefix) || strings.Contains(exported, evCookie) || strings.Contains(exported, evBearer) {
+				t.Fatalf("archive must keep the heads sealed: %s", exported)
+			}
+			if err = d.CompleteTaskArchive(archive.ID, snapshot, "/tmp/evidence-heads-test.tar.zst", "fixture", 1, 1); err != nil {
+				t.Fatal(err)
+			}
+			var rows []map[string]any
+			if err = json.Unmarshal(snapshot.Tables["traffic_evidence_snapshots"], &rows); err != nil || len(rows) != 1 {
+				t.Fatal(rows, err)
+			}
+			if legacy { // an archive written before the heads were sealed
+				rows[0]["req_head"], rows[0]["resp_head"] = s.ReqHead, s.RespHead
+				snapshot.Tables["traffic_evidence_snapshots"], _ = json.Marshal(rows)
+			} else { // a head sealed under another key fails the import, naming the column
+				other, _ := newSecretBox([]byte("ffffffffffffffffffffffffffffffff"))
+				bad, _ := other.encrypt(colEvReqHead.aad(), s.ReqHead)
+				good := rows[0]["req_head"]
+				rows[0]["req_head"] = bad
+				raw, _ := json.Marshal(rows)
+				if _, err := ArchiveEvidenceSnapshots(&TaskArchiveSnapshot{FormatVersion: snapshot.FormatVersion, Tables: map[string]json.RawMessage{"traffic_evidence_snapshots": raw}}); err == nil || !strings.Contains(err.Error(), colEvReqHead.aad()) {
+					t.Fatalf("want an import failure naming %s, got %v", colEvReqHead.aad(), err)
+				}
+				rows[0]["req_head"] = good
+			}
+			list, err := ArchiveEvidenceSnapshots(snapshot)
+			if err != nil || len(list) != 1 || list[0].ReqHead != s.ReqHead || list[0].RespHead != s.RespHead {
+				t.Fatalf("archive snapshots: %+v %v", list, err)
+			}
+			// The hot row is gone (GC), so the restore inserts it again.
+			if _, err = d.Exec(`DELETE FROM traffic_evidence_snapshots WHERE id=$1`, s.ID); err != nil {
+				t.Fatal(err)
+			}
+			if _, err = d.QueueTaskArchiveRestore(archive.ID); err != nil {
+				t.Fatal(err)
+			}
+			if _, err = d.ClaimTaskArchiveJob(t.Context()); err != nil {
+				t.Fatal(err)
+			}
+			if _, err = d.RestoreTaskArchive(archive.ID, snapshot, 0); err != nil {
+				t.Fatal(err)
+			}
+			assertClearHeads(t, d, fid, s)
+		})
+	}
+}

db/finding_traffic.go

@@ -195,10 +195,29 @@ func InsertEvidenceSnapshotTx(tx *sql.Tx, s TrafficEvidenceSnapshot) error {
 	if s.CreatedAt.IsZero() {
 		s.CreatedAt = time.Now().UTC()
 	}
-	_, err := tx.Exec(`INSERT INTO traffic_evidence_snapshots
+	// The ID hashes the clear heads; only the stored heads are sealed.
+	reqHead, err := sealSecret(colEvReqHead, s.ReqHead)
+	if err != nil {
+		return err
+	}
+	respHead, err := sealSecret(colEvRespHead, s.RespHead)
+	if err != nil {
+		return err
+	}
+	_, err = tx.Exec(`INSERT INTO traffic_evidence_snapshots
 (id,source_traffic_id,captured_at,url,method,status,content_type,req_head,resp_head,req_hash,resp_hash,req_len,resp_len,created_at)
 VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14) ON CONFLICT(id) DO NOTHING`,
-		s.ID, s.SourceTrafficID, s.CapturedAt, s.URL, s.Method, s.Status, s.ContentType, s.ReqHead, s.RespHead, s.ReqHash, s.RespHash, s.ReqLen, s.RespLen, s.CreatedAt)
+		s.ID, s.SourceTrafficID, s.CapturedAt, s.URL, s.Method, s.Status, s.ContentType, reqHead, respHead, s.ReqHash, s.RespHash, s.ReqLen, s.RespLen, s.CreatedAt)
+	return err
+}
+
+// openHeads decrypts the heads of a snapshot read from the table or an archive.
+// Clear legacy values pass through; a value that fails to decrypt is an error.
+func (s *TrafficEvidenceSnapshot) openHeads() (err error) {
+	if s.ReqHead, err = openSecret(colEvReqHead, s.ReqHead); err != nil {
+		return err
+	}
+	s.RespHead, err = openSecret(colEvRespHead, s.RespHead)
 	return err
 }
 
@@ -263,6 +282,9 @@ FROM finding_traffic_bindings b JOIN traffic_evidence_snapshots s ON s.id=b.snap
 		if err := json.Unmarshal(raw, &b.Snapshot); err != nil {
 			return nil, err
 		}
+		if err := b.Snapshot.openHeads(); err != nil {
+			return nil, err
+		}
 		out.Bindings = append(out.Bindings, b)
 	}
 	return out, rows.Err()

db/finding_traffic_archive.go

@@ -15,8 +15,17 @@ func ArchiveEvidenceSnapshots(snapshot *TaskArchiveSnapshot) ([]TrafficEvidenceS
 	if snapshot.FormatVersion < 3 {
 		return nil, ErrTaskArchiveFormatMismatch
 	}
-	err := json.Unmarshal(snapshot.Tables["traffic_evidence_snapshots"], &out)
-	return out, err
+	// The archive keeps the heads as stored (sealed). They are opened here so the
+	// restore can check each content-addressed ID; the insert then seals them once.
+	if err := json.Unmarshal(snapshot.Tables["traffic_evidence_snapshots"], &out); err != nil {
+		return nil, err
+	}
+	for i := range out {
+		if err := out[i].openHeads(); err != nil {
+			return nil, err
+		}
+	}
+	return out, nil
 }
 
 func restoreFindingTrafficTx(tx *sql.Tx, snapshot *TaskArchiveSnapshot) error {

db/secrets.go

@@ -46,17 +46,21 @@ func (c secretColumn) aad() string {
 }
 
 // rowFilter limits a settings entry to its own row; the key is a code-owned
-// constant from secretSettingKeys, never input.
+// constant from secretSettingKeys, never input. tools.exec covers the
+// user-created tools only: the seeds rewrite the built-in rows in clear.
 func (c secretColumn) rowFilter() string {
 	if c.setting != "" {
 		return ` AND key='` + c.setting + `'`
 	}
+	if c == colToolExec {
+		return ` AND system=false`
+	}
 	return ""
 }
 
-// idCol names the row key: settings rows are keyed by name, the rest by id.
+// idCol names the row key: settings and tools rows are keyed by name, the rest by id.
 func (c secretColumn) idCol() string {
-	if c.setting != "" {
+	if c.setting != "" || c == colToolExec {
 		return "key"
 	}
 	return "id"
@@ -76,7 +80,11 @@ var (
 	colMCPEnv      = secretColumn{"mcp_servers", "env", true, ""}
 	colCredPass    = secretColumn{"task_credentials", "password", false, ""}
 	colNotifConfig = secretColumn{"notification_channels", "config", true, ""}
-	secretColumns  = append([]secretColumn{colLLMKey, colLLMProxy, colMCPEnv, colCredPass, colNotifConfig}, secretSettingColumns()...)
+	colToolExec    = secretColumn{"tools", "exec", true, ""} // system=false rows: headers, proxy, body, code, command
+	// Evidence head blocks carry the captured Cookie and Authorization headers.
+	colEvReqHead  = secretColumn{"traffic_evidence_snapshots", "req_head", false, ""}
+	colEvRespHead = secretColumn{"traffic_evidence_snapshots", "resp_head", false, ""}
+	secretColumns = append([]secretColumn{colLLMKey, colLLMProxy, colMCPEnv, colCredPass, colNotifConfig, colToolExec, colEvReqHead, colEvRespHead}, secretSettingColumns()...)
 )
 
 // secretSettingKeys are the settings stored encrypted, AAD "settings.<key>".

db/tools.go

@@ -110,6 +110,13 @@ func scanTool(rows interface{ Scan(...any) error }) (*Tool, error) {
 	if err := rows.Scan(&t.Key, &t.System, &t.Description, &t.Schema, &agents, &t.Enabled, &t.Kind, &t.Exec, &t.Deferred); err != nil {
 		return nil, err
 	}
+	if !t.System { // a custom tool's exec is sealed at rest
+		plain, err := openSecret(colToolExec, string(t.Exec))
+		if err != nil {
+			return nil, err
+		}
+		t.Exec = json.RawMessage(plain)
+	}
 	if len(agents) > 0 {
 		_ = json.Unmarshal(agents, &t.Agents)
 	}
@@ -154,15 +161,15 @@ func (d *DB) CreateCustomTool(t *Tool) error {
 	if len(schema) == 0 {
 		schema = json.RawMessage("{}")
 	}
-	exec := t.Exec
-	if len(exec) == 0 {
-		exec = json.RawMessage("{}")
+	exec, err := sealToolExec(t.Exec)
+	if err != nil {
+		return err
 	}
 	agents, _ := json.Marshal(t.Agents)
 	if len(agents) == 0 {
 		agents = json.RawMessage("[]")
 	}
-	_, err := d.Exec(`
+	_, err = d.Exec(`
 INSERT INTO tools(key, system, description, schema, agents, enabled, kind, exec, deferred)
 VALUES ($1, false, $2, $3, $4, $5, $6, $7, $8)`,
 		t.Key, t.Description, schema, agents, t.Enabled, t.Kind, exec, t.Deferred)
@@ -176,21 +183,29 @@ func (d *DB) UpdateCustomTool(t *Tool) error {
 	if len(schema) == 0 {
 		schema = json.RawMessage("{}")
 	}
-	exec := t.Exec
-	if len(exec) == 0 {
-		exec = json.RawMessage("{}")
+	exec, err := sealToolExec(t.Exec)
+	if err != nil {
+		return err
 	}
 	agents, _ := json.Marshal(t.Agents)
 	if len(agents) == 0 {
 		agents = json.RawMessage("[]")
 	}
-	_, err := d.Exec(`
+	_, err = d.Exec(`
 UPDATE tools SET description=$2, schema=$3, agents=$4, enabled=$5, kind=$6, exec=$7, deferred=$8
 WHERE key=$1 AND system=false`,
 		t.Key, t.Description, schema, agents, t.Enabled, t.Kind, exec, t.Deferred)
 	return err
 }
 
+// sealToolExec encrypts a custom tool's exec spec for storage; empty means {}.
+func sealToolExec(exec json.RawMessage) (string, error) {
+	if len(exec) == 0 {
+		exec = json.RawMessage("{}")
+	}
+	return sealSecret(colToolExec, string(exec))
+}
+
 // DeleteCustomTool removes a custom tool (system=false only; built-ins protected).
 func (d *DB) DeleteCustomTool(key string) error {
 	_, err := d.Exec(`DELETE FROM tools WHERE key=$1 AND system=false`, key)

db/tools_secrets_test.go

@@ -0,0 +1,184 @@
+package db
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// toolExecPlain is a custom http tool's exec carrying a secret in every field
+// the phase 3 encryption covers.
+const toolExecPlain = `{"method":"GET","url":"https://api.example/x","headers":{"Authorization":"Bearer tool-hdr-plain"},` +
+	`"body":"tool-body-plain","proxy":"http://u:tool-proxy-plain@p.example:3128"}`
+
+var toolPlainSecrets = []string{"tool-hdr-plain", "tool-body-plain", "tool-proxy-plain", "tool-cmd-plain"}
+
+func rawToolExec(t *testing.T, d *DB, key string) string {
+	t.Helper()
+	var v string
+	if err := d.QueryRow(`SELECT exec::text FROM tools WHERE key=$1`, key).Scan(&v); err != nil {
+		t.Fatal(err)
+	}
+	return v
+}
+
+// assertToolExecSealed checks a custom tool's exec is sealed at rest and read
+// back in clear, equal to want, by every db getter.
+func assertToolExecSealed(t *testing.T, d *DB, key, want string) {
+	t.Helper()
+	raw := rawToolExec(t, d, key)
+	if !isSealed(colToolExec, raw) {
+		t.Fatalf("tools.exec of %s not sealed at rest: %s", key, raw)
+	}
+	for _, p := range toolPlainSecrets {
+		if strings.Contains(raw, p) {
+			t.Fatalf("plaintext %q found at rest", p)
+		}
+	}
+	var got []json.RawMessage
+	if tl, err := d.GetTool(key); err != nil || tl == nil {
+		t.Fatalf("GetTool: %v", err)
+	} else {
+		got = append(got, tl.Exec)
+	}
+	for _, list := range []func() ([]*Tool, error){d.ListTools, d.ListCustomTools} {
+		ts, err := list()
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, tl := range ts {
+			if tl.Key == key {
+				got = append(got, tl.Exec)
+			}
+		}
+	}
+	if len(got) != 3 {
+		t.Fatalf("tool %s read by %d getters, want 3", key, len(got))
+	}
+	for _, g := range got {
+		if !jsonEqual(t, string(g), want) {
+			t.Fatalf("exec read back as %s, want %s", g, want)
+		}
+	}
+}
+
+func jsonEqual(t *testing.T, a, b string) bool {
+	t.Helper()
+	var x, y any
+	if json.Unmarshal([]byte(a), &x) != nil || json.Unmarshal([]byte(b), &y) != nil {
+		return false
+	}
+	ca, _ := json.Marshal(x)
+	cb, _ := json.Marshal(y)
+	return string(ca) == string(cb)
+}
+
+func TestToolExecSealedAtRest(t *testing.T) {
+	d, err := Open(testDSN(t))
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	t.Cleanup(func() {
+		d.Exec(`DELETE FROM tools WHERE key LIKE 't_secexec%'`)
+		d.Close()
+	})
+	if err := d.CreateCustomTool(&Tool{Key: "t_secexec", Kind: "http", Exec: json.RawMessage(toolExecPlain), Enabled: true}); err != nil {
+		t.Fatal(err)
+	}
+	assertToolExecSealed(t, d, "t_secexec", toolExecPlain)
+	first := rawToolExec(t, d, "t_secexec")
+
+	cmd := `{"command":"curl -H 'X-Key: tool-cmd-plain' {args}","timeout_ms":5000}`
+	if err := d.UpdateCustomTool(&Tool{Key: "t_secexec", Kind: "command", Exec: json.RawMessage(cmd), Enabled: true}); err != nil {
+		t.Fatal(err)
+	}
+	assertToolExecSealed(t, d, "t_secexec", cmd)
+	if err := d.UpdateCustomTool(&Tool{Key: "t_secexec", Kind: "http", Exec: json.RawMessage(toolExecPlain), Enabled: true}); err != nil {
+		t.Fatal(err)
+	}
+	if rawToolExec(t, d, "t_secexec") == first {
+		t.Fatal("the same exec must seal under a fresh nonce")
+	}
+
+	// A shell tool has no exec: {} stays {}.
+	if err := d.CreateCustomTool(&Tool{Key: "t_secexec_shell", Kind: "shell", Enabled: true}); err != nil {
+		t.Fatal(err)
+	}
+	if raw := rawToolExec(t, d, "t_secexec_shell"); raw != "{}" {
+		t.Fatalf("empty exec stored as %s, want {}", raw)
+	}
+	if err := d.CreateCustomTool(&Tool{Key: "t_secexec_resv", Kind: "command", Exec: json.RawMessage(`{"__artex_enc":"x"}`)}); err == nil {
+		t.Fatal("reserved key must be refused on write")
+	}
+
+	// A value sealed under another key fails the read (fail closed).
+	other, _ := newSecretBox([]byte("ffffffffffffffffffffffffffffffff"))
+	foreign, _ := other.seal(colToolExec, toolExecPlain)
+	if _, err := d.Exec(`UPDATE tools SET exec=$1::jsonb WHERE key='t_secexec'`, foreign); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := d.GetTool("t_secexec"); err == nil || !strings.Contains(err.Error(), "tools.exec") {
+		t.Fatalf("a foreign ciphertext must fail the read, got %v", err)
+	}
+	if _, err := d.ListCustomTools(); err == nil {
+		t.Fatal("ListCustomTools must fail on a foreign ciphertext")
+	}
+}
+
+func TestToolExecBackfillAndKeyChecks(t *testing.T) {
+	d, err := Open(testDSN(t))
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	t.Cleanup(func() {
+		d.Exec(`DELETE FROM tools WHERE key LIKE 't_secexec%'`)
+		d.Close()
+	})
+	sysExec := `{"command":"echo system-plain"}`
+	for _, q := range []struct {
+		key, exec string
+		system    bool
+	}{{"t_secexec_legacy", toolExecPlain, false}, {"t_secexec_sys", sysExec, true}, {"t_secexec_empty", `{}`, false}} {
+		if _, err := d.Exec(`INSERT INTO tools(key, system, kind, exec) VALUES ($1, $2, 'http', $3::jsonb)`, q.key, q.system, q.exec); err != nil {
+			t.Fatal(err)
+		}
+	}
+	t.Setenv(secretKeyEnv, base64.StdEncoding.EncodeToString(testSecretKey))
+	if err := d.InitSecrets(t.TempDir()); err != nil {
+		t.Fatal(err)
+	}
+	assertToolExecSealed(t, d, "t_secexec_legacy", toolExecPlain)
+	first := rawToolExec(t, d, "t_secexec_legacy")
+	if raw := rawToolExec(t, d, "t_secexec_sys"); !jsonEqual(t, raw, sysExec) {
+		t.Fatalf("a system tool's exec must stay in clear, got %s", raw)
+	}
+	if raw := rawToolExec(t, d, "t_secexec_empty"); raw != "{}" {
+		t.Fatalf("an empty exec must stay {}, got %s", raw)
+	}
+	if err := d.InitSecrets(t.TempDir()); err != nil || rawToolExec(t, d, "t_secexec_legacy") != first {
+		t.Fatalf("second backfill must leave the ciphertext untouched (%v)", err)
+	}
+
+	// Missing key: the sealed exec counts in the refusal.
+	t.Setenv(secretKeyEnv, "")
+	dir := t.TempDir()
+	withTool := encryptedCount(t, d, dir)
+	if _, err := d.Exec(`UPDATE tools SET exec='{}'::jsonb WHERE key='t_secexec_legacy'`); err != nil {
+		t.Fatal(err)
+	}
+	if n := encryptedCount(t, d, dir); withTool-n != 1 {
+		t.Fatalf("no-key refusal counted %d then %d encrypted values; tools.exec must count", withTool, n)
+	}
+
+	// Wrong key: an exec sealed under another key fails the startup key check.
+	other, _ := newSecretBox([]byte("ffffffffffffffffffffffffffffffff"))
+	foreign, _ := other.seal(colToolExec, toolExecPlain)
+	if _, err := d.Exec(`UPDATE tools SET exec=$1::jsonb WHERE key='t_secexec_legacy'`, foreign); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv(secretKeyEnv, base64.StdEncoding.EncodeToString(testSecretKey))
+	if err := d.InitSecrets(t.TempDir()); err == nil || !strings.Contains(err.Error(), "tools.exec") {
+		t.Fatalf("want a key-check failure on tools.exec, got %v", err)
+	}
+}

evidence/testmain_test.go

@@ -34,5 +34,10 @@ func runEvidenceSuite(m *testing.M) int {
 		panic(err)
 	}
 	defer conn.ExecContext(context.Background(), `SELECT pg_advisory_unlock(7337741002)`)
+	// Snapshot inserts seal the heads: load a fixed test key (env, no key file).
+	os.Setenv("ARTEX_SECRET_KEY", "MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWY=")
+	if err = pg.InitSecrets(""); err != nil {
+		panic(err)
+	}
 	return m.Run()
 }

server/customtool.go

@@ -21,6 +21,7 @@ import (
 	"github.com/Autumn-27/artex/egress"
 	"github.com/Autumn-27/artex/guard"
 	"github.com/Autumn-27/artex/intercept"
+	"github.com/Autumn-27/artex/notify"
 	"github.com/Autumn-27/norma/permission"
 	actool "github.com/Autumn-27/norma/tool"
 )
@@ -72,6 +73,11 @@ func (s *Server) pgCreateCustomTool(w http.ResponseWriter, r *http.Request) {
 		writeErr(w, 409, "this key already exists (built-in or custom tool)")
 		return
 	}
+	var err error
+	if req.Exec, err = unmaskToolExec("", nil, req.Kind, req.Exec); err != nil { // nothing stored: a placeholder is refused
+		writeErr(w, 400, err.Error())
+		return
+	}
 	if err := pg.CreateCustomTool(&db.Tool{
 		Key: req.Key, Description: req.Description, Schema: req.Schema, Agents: req.Agents,
 		Enabled: req.Enabled, Kind: req.Kind, Exec: req.Exec, Deferred: req.Deferred,
@@ -110,6 +116,10 @@ func (s *Server) pgUpdateCustomTool(w http.ResponseWriter, r *http.Request) {
 		writeErr(w, 400, "http tools must provide a parameter JSON Schema (cannot be left empty)")
 		return
 	}
+	if req.Exec, err = unmaskToolExec(existing.Kind, existing.Exec, req.Kind, req.Exec); err != nil {
+		writeErr(w, 400, err.Error())
+		return
+	}
 	if err := pg.UpdateCustomTool(&db.Tool{
 		Key: key, Description: req.Description, Schema: req.Schema, Agents: req.Agents,
 		Enabled: req.Enabled, Kind: req.Kind, Exec: req.Exec, Deferred: req.Deferred,
@@ -138,6 +148,7 @@ func (s *Server) pgDeleteCustomTool(w http.ResponseWriter, r *http.Request) {
 // real tool call — it runs arbitrary command/script/http on the server, which the
 // custom-tool feature already allows, so no new capability is granted.
 type testToolReq struct {
+	Key    string          `json:"key"`  // the saved tool being edited, if any: its stored values replace placeholders
 	Kind   string          `json:"kind"` // command | script | http
 	Exec   json.RawMessage `json:"exec"`
 	Params map[string]any  `json:"params"`
@@ -156,6 +167,23 @@ func (s *Server) pgTestCustomTool(w http.ResponseWriter, r *http.Request) {
 		writeErr(w, 400, "invalid request body")
 		return
 	}
+	var storedKind string
+	var stored json.RawMessage
+	if req.Key != "" {
+		t, err := pg.GetTool(req.Key)
+		if err != nil {
+			writeErr(w, 500, err.Error())
+			return
+		}
+		if t != nil && !t.System {
+			storedKind, stored = t.Kind, t.Exec
+		}
+	}
+	var err error
+	if req.Exec, err = unmaskToolExec(storedKind, stored, req.Kind, req.Exec); err != nil {
+		writeErr(w, 400, err.Error())
+		return
+	}
 	params := req.Params
 	if params == nil {
 		params = map[string]any{}
@@ -236,6 +264,86 @@ type httpExec struct {
 	UseRecordingProxy bool              `json:"use_recording_proxy"`
 }
 
+// toolExecFlags are the response-only *_set flags of maskToolExec; never stored.
+var toolExecFlags = []string{"headers_set", "proxy_set", "body_set"}
+
+// maskToolExec is what the API shows of a custom tool's exec: every header value,
+// the proxy and the body become the placeholder, each with a *_set flag.
+func maskToolExec(raw json.RawMessage) json.RawMessage {
+	var e map[string]any
+	if json.Unmarshal(raw, &e) != nil || e == nil {
+		return raw
+	}
+	if h, ok := e["headers"].(map[string]any); ok {
+		set := false
+		for k, v := range h {
+			if v != "" {
+				h[k], set = notify.MaskedPrefix, true
+			}
+		}
+		e["headers_set"] = set
+	}
+	for _, k := range []string{"proxy", "body"} {
+		if s, ok := e[k].(string); ok {
+			e[k], e[k+"_set"] = maskedSecret(s), s != ""
+		}
+	}
+	out, _ := json.Marshal(e)
+	return out
+}
+
+// unmaskToolExec puts the stored value back for every header, proxy or body sent
+// as the placeholder, so a client echoing the list response keeps the stored
+// secret; an explicit value replaces it and "" clears it. A placeholder with
+// nothing stored to keep (stored nil on create) is refused. As for the MCP env,
+// a stored secret is only kept for the destination it was configured for: when
+// the url (exact string) or the kind changes, a placeholder is refused.
+func unmaskToolExec(storedKind string, stored json.RawMessage, kind string, in json.RawMessage) (json.RawMessage, error) {
+	var e, old map[string]any
+	if json.Unmarshal(in, &e) != nil || e == nil {
+		return in, nil // not an object: stored or refused as before
+	}
+	_ = json.Unmarshal(stored, &old)
+	changed, kept := false, false
+	for _, k := range toolExecFlags {
+		if _, ok := e[k]; ok {
+			delete(e, k)
+			changed = true
+		}
+	}
+	oldHeaders, _ := old["headers"].(map[string]any)
+	headers, _ := e["headers"].(map[string]any)
+	for k, v := range headers {
+		if s, ok := v.(string); !ok || !isMaskedSecret(s) {
+			continue
+		}
+		prev, ok := oldHeaders[k]
+		if !ok {
+			return nil, fmt.Errorf("header %q: masked value but nothing stored to keep", k)
+		}
+		headers[k], changed, kept = prev, true, true
+	}
+	for _, k := range []string{"proxy", "body"} {
+		if s, ok := e[k].(string); !ok || !isMaskedSecret(s) {
+			continue
+		}
+		prev, _ := old[k].(string)
+		if prev == "" {
+			return nil, fmt.Errorf("%s: masked value but nothing stored to keep", k)
+		}
+		e[k], changed, kept = prev, true, true
+	}
+	oldURL, _ := old["url"].(string)
+	newURL, _ := e["url"].(string)
+	if kept && (oldURL != newURL || storedKind != kind) {
+		return nil, fmt.Errorf("destination changed (url or kind) while a stored secret was kept: re-enter the masked header/proxy/body or clear it; stored secrets are not sent to a new destination")
+	}
+	if !changed {
+		return in, nil
+	}
+	return json.Marshal(e)
+}
+
 func timeoutOr(ms, def int) time.Duration {
 	if ms <= 0 {
 		return time.Duration(def) * time.Millisecond

server/finding_traffic_test.go

@@ -172,6 +172,11 @@ func TestFindingTrafficAPIAndExport(t *testing.T) {
 	if w = req("GET", fmt.Sprintf("%s/%d", base, first), ""); w.Code != 200 || !strings.Contains(w.Body.String(), `"binary":true`) {
 		t.Fatal(w.Code, w.Body)
 	}
+	// The viewer reads the heads in clear; the table stores them sealed.
+	var rawHead string
+	if err := s.m.pg.QueryRow(`SELECT req_head FROM traffic_evidence_snapshots WHERE id=$1`, list.Bindings[0].SnapshotID).Scan(&rawHead); err != nil || !strings.HasPrefix(rawHead, "enc:v1:") || !strings.Contains(w.Body.String(), `"req_head":"POST / HTTP/1.1"`) {
+		t.Fatalf("head at rest %q (%v), viewer %s", rawHead, err, w.Body)
+	}
 	if w = req("GET", fmt.Sprintf("%s/%d/body?side=response&offset=20001", base, first), ""); w.Code != 422 {
 		t.Fatal(w.Code, w.Body)
 	}

server/platform_tools.go

@@ -216,6 +216,10 @@ func (s *Server) toolCreateCustomTool() actool.CoreTool {
 			if exist, _ := s.m.pg.GetTool(a.Key); exist != nil {
 				return actool.Errorf("this key already exists: " + a.Key), nil
 			}
+			var err error
+			if a.Exec, err = unmaskToolExec("", nil, a.Kind, a.Exec); err != nil { // nothing stored: a placeholder is refused
+				return actool.Errorf(err.Error()), nil
+			}
 			if err := s.m.pg.CreateCustomTool(toDBTool(a)); err != nil {
 				return actool.Errorf(err.Error()), nil
 			}
@@ -239,6 +243,10 @@ func (s *Server) toolUpdateCustomTool() actool.CoreTool {
 			if a.Kind == "http" && !hasSchemaProps(a.Schema) {
 				return actool.Errorf("http tools must provide a parameter JSON Schema (cannot be empty)"), nil
 			}
+			var err error
+			if a.Exec, err = unmaskToolExec(existing.Kind, existing.Exec, a.Kind, a.Exec); err != nil {
+				return actool.Errorf(err.Error()), nil
+			}
 			if err := s.m.pg.UpdateCustomTool(toDBTool(a)); err != nil {
 				return actool.Errorf(err.Error()), nil
 			}

server/server_mgmt.go

@@ -754,6 +754,11 @@ func (s *Server) pgListTools(w http.ResponseWriter, r *http.Request) {
 	if ts == nil {
 		ts = []*db.Tool{}
 	}
+	for _, tool := range ts {
+		if !tool.System {
+			tool.Exec = maskToolExec(tool.Exec)
+		}
+	}
 	// Usage is best-effort decoration. Runtime tool resolution keeps using the plain
 	// catalog query, so agent assembly never pays for this aggregate.
 	counts, countErr := pg.ToolUsageCounts()

server/tools_secrets_api_test.go

@@ -0,0 +1,248 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync/atomic"
+	"testing"
+)
+
+// A placeholder keeps the stored secret only for the url and kind it was saved
+// with: a changed destination is refused before any write or request.
+func TestCustomToolExecDestinationGuard(t *testing.T) {
+	s, _, request := trafficEvidenceServer(t)
+	pg := s.m.PG()
+	var hits atomic.Int32
+	echo := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		hits.Add(1)
+		io.WriteString(w, "auth="+r.Header.Get("Authorization"))
+	}))
+	t.Cleanup(echo.Close)
+	t.Cleanup(func() { pg.Exec(`DELETE FROM tools WHERE key LIKE 't_secguard%'`) })
+	const secret = "Bearer guard-plain-0001"
+	schema := `{"type":"object","properties":{"q":{"type":"string"}}}`
+	body := func(kind, url, hdr string) string {
+		e, _ := json.Marshal(map[string]any{"method": "GET", "url": url, "headers": map[string]string{"Authorization": hdr}})
+		return `{"key":"t_secguard","kind":"` + kind + `","enabled":true,"schema":` + schema + `,"exec":` + string(e) + `}`
+	}
+	storedExec := func() (url, auth string) {
+		tl, err := pg.GetTool("t_secguard")
+		if err != nil || tl == nil {
+			t.Fatalf("GetTool: %v", err)
+		}
+		var e struct {
+			URL     string            `json:"url"`
+			Headers map[string]string `json:"headers"`
+		}
+		_ = json.Unmarshal(tl.Exec, &e)
+		return e.URL, e.Headers["Authorization"]
+	}
+	if resp := request("POST", "/api/tools/custom", body("http", echo.URL, secret)); resp.Code != 200 {
+		t.Fatalf("create: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	moved := echo.URL + "/elsewhere"
+
+	// 1. Masked header, changed url: refused, nothing written.
+	if resp := request("PUT", "/api/tools/custom/t_secguard", body("http", moved, "__masked__")); resp.Code != 400 {
+		t.Fatalf("masked header with a changed url must be refused, got HTTP %d", resp.Code)
+	}
+	if url, auth := storedExec(); url != echo.URL || auth != secret {
+		t.Fatalf("a refused update changed the stored exec: %s %s", url, auth)
+	}
+	// An empty url against a stored one is a change too.
+	if resp := request("PUT", "/api/tools/custom/t_secguard", body("http", "", "__masked__")); resp.Code != 400 {
+		t.Fatalf("masked header with an emptied url must be refused, got HTTP %d", resp.Code)
+	}
+
+	// 2. Masked header, same url: kept.
+	if resp := request("PUT", "/api/tools/custom/t_secguard", body("http", echo.URL, "__masked__")); resp.Code != 200 {
+		t.Fatalf("masked header with the same url: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	if url, auth := storedExec(); url != echo.URL || auth != secret {
+		t.Fatalf("the stored secret was not kept: %s %s", url, auth)
+	}
+
+	// 3. Test endpoint, masked header, changed url: refused, no request sent.
+	e, _ := json.Marshal(map[string]any{"method": "GET", "url": moved, "headers": map[string]string{"Authorization": "__masked__"}})
+	if resp := request("POST", "/api/tools/custom/test", `{"key":"t_secguard","kind":"http","exec":`+string(e)+`}`); resp.Code != 400 {
+		t.Fatalf("test endpoint with a changed url must be refused, got HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	if n := hits.Load(); n != 0 {
+		t.Fatalf("the echo server received %d request(s); the stored secret left", n)
+	}
+
+	// 4. Kind change while keeping a placeholder: refused.
+	if resp := request("PUT", "/api/tools/custom/t_secguard", body("command", echo.URL, "__masked__")); resp.Code != 400 {
+		t.Fatalf("a kind change with a placeholder must be refused, got HTTP %d", resp.Code)
+	}
+	if tl, _ := pg.GetTool("t_secguard"); tl == nil || tl.Kind != "http" {
+		t.Fatalf("a refused kind change was written: %v", tl)
+	}
+
+	// 5. An explicit value with a changed url is allowed.
+	if resp := request("PUT", "/api/tools/custom/t_secguard", body("http", moved, "Bearer typed-0002")); resp.Code != 200 {
+		t.Fatalf("explicit header with a changed url: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	if url, auth := storedExec(); url != moved || auth != "Bearer typed-0002" {
+		t.Fatalf("explicit replace not stored: %s %s", url, auth)
+	}
+}
+
+// A custom tool's exec: headers, proxy and body are masked by GET /api/tools;
+// the placeholder keeps the stored value on update and in the test endpoint, a
+// create with it is refused, and the executor runs on the clear exec.
+func TestCustomToolExecMasking(t *testing.T) {
+	s, _, request := trafficEvidenceServer(t)
+	pg := s.m.PG()
+	echo := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		b, _ := io.ReadAll(r.Body)
+		io.WriteString(w, "auth="+r.Header.Get("Authorization")+" body="+string(b))
+	}))
+	t.Cleanup(echo.Close)
+	t.Cleanup(func() { pg.Exec(`DELETE FROM tools WHERE key LIKE 't_secexec%'`) })
+	secrets := []string{"hdr-plain-0001", "body-plain-0002", "proxy-plain-0003"}
+	schema := `{"type":"object","properties":{"q":{"type":"string"}}}`
+	execOf := func(hdr, body, proxy string) string {
+		e, _ := json.Marshal(map[string]any{"method": "POST", "url": echo.URL,
+			"headers": map[string]string{"Authorization": hdr, "X-Empty": ""}, "body": body, "proxy": proxy})
+		return string(e)
+	}
+	toolBody := func(key, exec string) string {
+		return `{"key":"` + key + `","kind":"http","enabled":true,"schema":` + schema + `,"exec":` + exec + `}`
+	}
+	stored := func() map[string]any {
+		tl, err := pg.GetTool("t_secexec")
+		if err != nil || tl == nil {
+			t.Fatalf("GetTool: %v", err)
+		}
+		var e map[string]any
+		_ = json.Unmarshal(tl.Exec, &e)
+		return e
+	}
+
+	plain := execOf("Bearer "+secrets[0], secrets[1], "http://u:"+secrets[2]+"@127.0.0.1:1")
+	if resp := request("POST", "/api/tools/custom", toolBody("t_secexec", plain)); resp.Code != 200 {
+		t.Fatalf("create: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	var raw string
+	if err := pg.QueryRow(`SELECT exec::text FROM tools WHERE key='t_secexec'`).Scan(&raw); err != nil || !strings.Contains(raw, "__artex_enc") {
+		t.Fatalf("exec not sealed at rest: %s %v", raw, err)
+	}
+
+	// List: masked with *_set flags, nothing in clear.
+	resp := request("GET", "/api/tools", "")
+	for _, sec := range secrets {
+		if resp.Code != 200 || strings.Contains(resp.Body.String(), sec) {
+			t.Fatalf("GET /api/tools: HTTP %d or a secret returned in clear", resp.Code)
+		}
+	}
+	var list struct {
+		Tools []struct {
+			Key  string          `json:"key"`
+			Exec json.RawMessage `json:"exec"`
+		}
+	}
+	_ = json.Unmarshal(resp.Body.Bytes(), &list)
+	var masked json.RawMessage
+	for _, tl := range list.Tools {
+		if tl.Key == "t_secexec" {
+			masked = tl.Exec
+		}
+	}
+	var m map[string]any
+	_ = json.Unmarshal(masked, &m)
+	h, _ := m["headers"].(map[string]any)
+	if h["Authorization"] != "__masked__" || h["X-Empty"] != "" || m["body"] != "__masked__" || m["proxy"] != "__masked__" ||
+		m["headers_set"] != true || m["body_set"] != true || m["proxy_set"] != true || m["url"] != echo.URL {
+		t.Fatalf("exec not masked as expected: %s", masked)
+	}
+
+	// Update echoing the masked exec: every stored value is kept, no flag stored.
+	if resp := request("PUT", "/api/tools/custom/t_secexec", toolBody("t_secexec", string(masked))); resp.Code != 200 {
+		t.Fatalf("update with placeholders: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	e := stored()
+	if e["headers"].(map[string]any)["Authorization"] != "Bearer "+secrets[0] || e["body"] != secrets[1] ||
+		!strings.Contains(e["proxy"].(string), secrets[2]) || e["body_set"] != nil {
+		t.Fatalf("placeholders did not keep the stored exec: %v", e)
+	}
+
+	// Test endpoint: the saved tool's key resolves the placeholders.
+	noProxy := execOf("__masked__", "__masked__", "")
+	if resp := request("POST", "/api/tools/custom/test", `{"kind":"http","exec":`+noProxy+`}`); resp.Code != 400 {
+		t.Fatalf("a placeholder without a saved tool must be refused, got HTTP %d", resp.Code)
+	}
+	resp = request("POST", "/api/tools/custom/test", `{"key":"t_secexec","kind":"http","exec":`+noProxy+`}`)
+	if resp.Code != 200 || !strings.Contains(resp.Body.String(), "auth=Bearer "+secrets[0]+" body="+secrets[1]) {
+		t.Fatalf("test endpoint did not use the stored values: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+
+	// Replace the header, keep the body, clear the proxy.
+	if resp := request("PUT", "/api/tools/custom/t_secexec", toolBody("t_secexec", execOf("Bearer new-0004", "__masked__", ""))); resp.Code != 200 {
+		t.Fatalf("update: HTTP %d %s", resp.Code, resp.Body.String())
+	}
+	e = stored()
+	if e["headers"].(map[string]any)["Authorization"] != "Bearer new-0004" || e["body"] != secrets[1] || e["proxy"] != "" {
+		t.Fatalf("replace/keep/clear: %v", e)
+	}
+	if resp := request("GET", "/api/tools", ""); strings.Contains(resp.Body.String(), "new-0004") {
+		t.Fatal("a replaced secret is returned in clear")
+	}
+
+	// Create with a placeholder: refused, nothing written.
+	for _, ex := range []string{execOf("__masked__", "", ""), execOf("", "__masked__", ""), execOf("", "", "__masked__")} {
+		if resp := request("POST", "/api/tools/custom", toolBody("t_secexec_new", ex)); resp.Code != 400 {
+			t.Fatalf("create with a placeholder must be refused, got HTTP %d", resp.Code)
+		}
+	}
+	if tl, _ := pg.GetTool("t_secexec_new"); tl != nil {
+		t.Fatal("a refused create wrote a row")
+	}
+
+	// The executor receives the clear exec from the sealed row.
+	tools, err := s.customTools()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, tl := range tools {
+		if tl.Name() != "t_secexec" {
+			continue
+		}
+		res, err := tl.Call(context.Background(), json.RawMessage(`{"q":"x"}`), nil)
+		if err != nil || !strings.Contains(res.Flatten(), "auth=Bearer new-0004 body="+secrets[1]) {
+			t.Fatalf("executor output %q %v", res.Flatten(), err)
+		}
+		return
+	}
+	t.Fatal("t_secexec not built by customTools")
+}
+
+// The platform tools follow the API: create refuses a placeholder, update keeps the stored value.
+func TestPlatformCustomToolPlaceholders(t *testing.T) {
+	s, _, _ := trafficEvidenceServer(t)
+	pg := s.m.PG()
+	t.Cleanup(func() { pg.Exec(`DELETE FROM tools WHERE key LIKE 't_secexec%'`) })
+	in := func(exec string) json.RawMessage {
+		return json.RawMessage(`{"key":"t_secexec_pt","kind":"command","exec":` + exec + `}`)
+	}
+	create, update := s.toolCreateCustomTool(), s.toolUpdateCustomTool()
+	if res, _ := create.Call(context.Background(), in(`{"command":"echo","proxy":"__masked__"}`), nil); !res.IsError {
+		t.Fatalf("create with a placeholder must fail: %s", res.Flatten())
+	}
+	if res, _ := create.Call(context.Background(), in(`{"command":"echo","body":"pt-body-plain"}`), nil); res.IsError {
+		t.Fatalf("create: %s", res.Flatten())
+	}
+	if res, _ := update.Call(context.Background(), in(`{"command":"echo 2","body":"__masked__"}`), nil); res.IsError {
+		t.Fatalf("update: %s", res.Flatten())
+	}
+	tl, err := pg.GetTool("t_secexec_pt")
+	if err != nil || tl == nil || !jsonHas(tl.Exec, "pt-body-plain") || !jsonHas(tl.Exec, "echo 2") {
+		t.Fatalf("update with a placeholder must keep the stored body: %v %v", tl, err)
+	}
+}
+
+func jsonHas(raw json.RawMessage, s string) bool { return strings.Contains(string(raw), s) }

web/src/app/(main)/system/tools/page.tsx

@@ -662,7 +662,8 @@ function CustomToolDialog({
     setTesting(true);
     setTestResult(null);
     try {
-      const r = await api.testCustomTool({ kind, exec: buildExec(), params });
+      // key: a saved tool's stored secrets replace the masked placeholders.
+      const r = await api.testCustomTool({ key: tool?.key, kind, exec: buildExec(), params });
       setTestResult(r);
     } catch (e) {
       setTestResult({ output: (e as Error).message, is_error: true });

web/src/lib/api.ts

@@ -1113,7 +1113,7 @@ export const api = {
     t: Pick<Tool, "description" | "schema" | "agents" | "enabled" | "kind" | "exec" | "deferred">,
   ) => put<{ ok: boolean }>(`/tools/custom/${key}`, t),
   deleteCustomTool: (key: string) => del<{ deleted: string }>(`/tools/custom/${key}`),
-  testCustomTool: (body: { kind: string; exec: Record<string, unknown>; params: Record<string, unknown> }) =>
+  testCustomTool: (body: { key?: string; kind: string; exec: Record<string, unknown>; params: Record<string, unknown> }) =>
     post<{ output: string; is_error: boolean }>("/tools/custom/test", body),
   detectPython: () => post<{ python_interpreter: string }>("/settings/python/detect", {}),