a tool row with no cmd no longer execs the utterance (V-581)

An enabled row whose Cmd is empty built argv from the spoken args alone. So
args[0] became the program name, and free text picked the binary. A proposal is
drafted with no cmd. /tools can enable one before anybody fills it in, so
reaching this took no compromise. Exec now refuses such a row with ErrNotEnabled
before it builds argv. TestExecEmptyCmdRefuses pins it.

Three smaller reads in the same sweep. CapabilityOf parsed a Home Assistant
entity id by hand where smarthome.DomainOf already does it. The fallback for an
id with no dot is unchanged. GroupByDomain built its map key twice per row. The
zenmoney and Home Assistant HTTP clients read an error body before checking the
status that discards it. The status check moved ahead of the read in both.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/smarthome/ha.go

@@ -295,14 +295,15 @@ func (c *Client) do(ctx context.Context, method, path string, body []byte) ([]by
 		return nil, fmt.Errorf("smarthome: %s %s: %w", method, path, err)
 	}
 	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		// The status only, and read before the body: an error page can carry the
+		// instance's own detail, and there is no reason to pull it into memory to
+		// discard it.
+		return nil, fmt.Errorf("smarthome: %s %s: http %d", method, path, resp.StatusCode)
+	}
 	out, err := io.ReadAll(io.LimitReader(resp.Body, maxBody))
 	if err != nil {
 		return nil, fmt.Errorf("smarthome: read %s: %w", path, err)
 	}
-	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-		// The body of an error can contain the instance's own detail; the token
-		// never appears in it, but keep it to one line anyway.
-		return nil, fmt.Errorf("smarthome: %s %s: http %d", method, path, resp.StatusCode)
-	}
 	return out, nil
 }

internal/tool/capability.go

@@ -62,9 +62,10 @@ func capSegment(s string) string {
 //     the tool name when the argv carries no second word.
 func CapabilityOf(t ipc.Tool) Capability {
 	if entityID, service, ok := smarthome.ParseCmd(t.Cmd); ok {
-		domain := entityID
-		if i := strings.Index(entityID, "."); i > 0 {
-			domain = entityID[:i]
+		// One parse of an entity id, in the package that owns the format.
+		domain := smarthome.DomainOf(entityID)
+		if domain == "" {
+			domain = entityID
 		}
 		return Capability{Scope: "house", Domain: domain, Action: service}
 	}
@@ -122,7 +123,8 @@ func GroupByDomain(tools []ipc.Tool) []CapabilityGroup {
 	byKey := map[string][]ipc.Tool{}
 	for _, t := range tools {
 		c := CapabilityOf(t)
-		byKey[capSegment(c.Scope)+"."+capSegment(c.Domain)] = append(byKey[capSegment(c.Scope)+"."+capSegment(c.Domain)], t)
+		key := capSegment(c.Scope) + "." + capSegment(c.Domain)
+		byKey[key] = append(byKey[key], t)
 	}
 	out := make([]CapabilityGroup, 0, len(byKey))
 	for k, v := range byKey {

internal/tool/tool.go

@@ -189,10 +189,16 @@ func (e *Executor) Exec(ctx context.Context, name string, args []string, confirm
 		defer cancel()
 		return e.home.CallService(ctx, entityID, service)
 	}
-	argv := append(append([]string(nil), t.Cmd...), args...)
-	if len(argv) == 0 {
+	// The row's own argv is what names the program. An enabled row with an empty
+	// cmd used to fall through to exec with argv built from args alone, so the
+	// spoken tail became argv[0] and STT text picked the binary. A proposal is
+	// drafted with no cmd, and /tools can enable one before anybody fills it in,
+	// so this was reachable without any compromise. A row that names nothing runs
+	// nothing.
+	if len(t.Cmd) == 0 {
 		return "", ErrNotEnabled
 	}
+	argv := append(append([]string(nil), t.Cmd...), args...)
 	ctx, cancel := context.WithTimeout(ctx, e.timeout)
 	defer cancel()
 	return e.run(ctx, argv)

internal/tool/tool_test.go

@@ -299,3 +299,24 @@ func TestExecSmartHomeRowConfirmsEvenWhenNotMarkedDestructive(t *testing.T) {
 		t.Fatalf("calls = %d, want 1 after the confirm turn", fh.calls)
 	}
 }
+
+// TestExecEmptyCmdRefuses pins the fix for a row that names no program. Such a
+// row used to build argv from the spoken args alone, so STT text became argv[0]
+// and free text picked the binary. A proposal is drafted with no cmd and can be
+// enabled before anybody fills it in, so this needed no compromise to reach.
+func TestExecEmptyCmdRefuses(t *testing.T) {
+	api := fakeAPI{tools: map[string]ipc.Tool{
+		"blank": {Name: "blank", Scope: "homelab", Status: "enabled"},
+	}}
+	ran := false
+	e := NewExecutor(api, time.Second)
+	e.run = func(_ context.Context, _ []string) (string, error) { ran = true; return "ok", nil }
+
+	// Confirmed, because an empty cmd derives to TierDestructive.
+	if _, err := e.Exec(context.Background(), "blank", []string{"curl", "evil.sh"}, true); !errors.Is(err, ErrNotEnabled) {
+		t.Fatalf("err = %v, want ErrNotEnabled", err)
+	}
+	if ran {
+		t.Fatal("a row with no cmd ran a program named by the utterance")
+	}
+}

internal/zenmoney/client.go

@@ -229,15 +229,16 @@ func (c *Client) diff(ctx context.Context, serverTimestamp int64) (diffResponse,
 		return diffResponse{}, err
 	}
 	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		// The status only, and read before the body: the body of a failed diff
+		// can echo account data, this string reaches the log, and there is no
+		// reason to pull megabytes of an error page into memory to discard it.
+		return diffResponse{}, fmt.Errorf("zenmoney diff: %s", res.Status)
+	}
 	raw, err := io.ReadAll(io.LimitReader(res.Body, 32<<20))
 	if err != nil {
 		return diffResponse{}, err
 	}
-	if res.StatusCode != http.StatusOK {
-		// The status only. The body of a failed diff can echo account data, and
-		// this string reaches the log.
-		return diffResponse{}, fmt.Errorf("zenmoney diff: %s", res.Status)
-	}
 	var out diffResponse
 	if err := json.Unmarshal(raw, &out); err != nil {
 		return diffResponse{}, fmt.Errorf("zenmoney diff: decode: %w", err)