diff --git a/apps/api/cmd/seed-platform-admin/main.go b/apps/api/cmd/seed-platform-admin/main.go
index 0445761..4db11dd 100644
--- a/apps/api/cmd/seed-platform-admin/main.go
+++ b/apps/api/cmd/seed-platform-admin/main.go
@@ -1,22 +1,16 @@
-// Command seed-platform-admin upserts the first (or additional) platform admin
-// for greenfield / production deploys where no legacy admin_users cutover ran
-// and seed-demo must not be used.
+// Command seed-platform-admin upserts a platform admin with a tenant company
+// (membership admin + Free plan), matching self-serve register. Without a
+// company, login leaves session company empty and every /api/* tenant call
+// returns 400 "company not selected".
 //
 // Usage:
 //
-//	cd apps/api
-//	go run ./cmd/seed-platform-admin \
-//	  -postgres "$env:DATABASE_URL" \
-//	  -email you@example.com \
-//	  -password 'choose-a-strong-password' \
-//	  -confirm
+//	npm run seed:platform-admin -- --email you@example.com --password '…'
+//	npm run seed:platform-admin -- --email you@example.com --promote-only
+//	npm run seed:platform-admin -- --email you@example.com --password '…' --company 'Acme Ops'
 //
-// Env aliases: none for credentials — pass -email / -password (or use
-// `npm run seed:platform-admin -- --email … --password …`). DATABASE_URL may
-// come from the shell or monorepo-root .env via config.LoadDotEnv.
-//
-// -promote-only grants admin on an existing user without changing the password
-// (-password is ignored). Always requires -confirm.
+// Credentials are CLI-only (never from .env). DATABASE_URL may come from the
+// shell or monorepo-root .env via config.LoadDotEnv. Always requires -confirm.
 package main
 
 import (
@@ -30,6 +24,7 @@ import (
 	"time"
 
 	"github.com/descrybe/descrybe-v2/apps/api/internal/auth"
+	"github.com/descrybe/descrybe-v2/apps/api/internal/billing"
 	"github.com/descrybe/descrybe-v2/apps/api/internal/config"
 	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5"
@@ -43,11 +38,13 @@ func main() {
 	email := flag.String("email", "", "Platform admin email (required; do not put in .env)")
 	password := flag.String("password", "", "Password (min 8; ignored with -promote-only; do not put in .env)")
 	name := flag.String("name", "", "Display name (defaults to email local-part)")
+	company := flag.String("company", "", "Company/workspace name (default: \"<name> workspace\")")
+	noCompany := flag.Bool("no-company", false, "Skip company creation (staff-only; dashboard tenant APIs will 400)")
 	promoteOnly := flag.Bool("promote-only", false, "Grant platform admin on an existing user; do not set password")
-	confirm := flag.Bool("confirm", false, "Required: acknowledge this writes is_platform_admin + staff_role=admin")
+	confirm := flag.Bool("confirm", false, "Required: acknowledge privilege + optional company writes")
 	flag.Parse()
 
-	opts, err := parseOptions(*postgresURL, *email, *password, *name, *promoteOnly, *confirm, os.Getenv("APP_ENV"))
+	opts, err := parseOptions(*postgresURL, *email, *password, *name, *company, *promoteOnly, *noCompany, *confirm, os.Getenv("APP_ENV"))
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -80,8 +77,30 @@ func main() {
 	} else {
 		fmt.Println("  password:           set (argon2id)")
 	}
+
+	if opts.NoCompany {
+		fmt.Println("  company:            skipped (-no-company)")
+		fmt.Println()
+		fmt.Println("WARNING: without a company, dashboard /api/* calls return 400 company not selected.")
+		return
+	}
+
+	companyID, companyName, companyCreated, err := ensureAdminCompany(ctx, pg, userID, opts.CompanyName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	billingSvc := &billing.Service{Pool: pg}
+	if err := billingSvc.ProvisionFreePlan(ctx, companyID); err != nil {
+		log.Fatalf("provision Free plan: %v", err)
+	}
+	companyAction := "existing"
+	if companyCreated {
+		companyAction = "created"
+	}
+	fmt.Printf("  company:            %s (%s) [%s]\n", companyName, companyID, companyAction)
+	fmt.Println("  plan:               Free (provisioned)")
 	fmt.Println()
-	fmt.Println("Sign in on the web app, then open /admin.")
+	fmt.Println("Sign in on the web app (company is selected on login). Platform panel: /admin.")
 }
 
 type options struct {
@@ -89,10 +108,12 @@ type options struct {
 	Email       string
 	Password    string
 	Name        string
+	CompanyName string
 	PromoteOnly bool
+	NoCompany   bool
 }
 
-func parseOptions(postgresURL, email, password, name string, promoteOnly, confirm bool, appEnv string) (options, error) {
+func parseOptions(postgresURL, email, password, name, company string, promoteOnly, noCompany, confirm bool, appEnv string) (options, error) {
 	if !confirm {
 		return options{}, fmt.Errorf("-confirm is required (refuses silent privilege grants)")
 	}
@@ -116,11 +137,18 @@ func parseOptions(postgresURL, email, password, name string, promoteOnly, confir
 		}
 	}
 
+	companyName := strings.TrimSpace(company)
+	if !noCompany && companyName == "" {
+		companyName = display + " workspace"
+	}
+
 	opts := options{
 		PostgresURL: pg,
 		Email:       emailNorm,
 		Name:        display,
+		CompanyName: companyName,
 		PromoteOnly: promoteOnly,
+		NoCompany:   noCompany,
 	}
 	if promoteOnly {
 		return opts, nil
@@ -225,3 +253,61 @@ func upsertPlatformAdmin(ctx context.Context, pg *pgxpool.Pool, opts options) (u
 	}
 	return userID, !existed, nil
 }
+
+// ensureAdminCompany attaches the user to a company as membership admin.
+// If they already have any active membership, reuses the first company (idempotent repair).
+func ensureAdminCompany(ctx context.Context, pg *pgxpool.Pool, userID uuid.UUID, companyName string) (uuid.UUID, string, bool, error) {
+	var existingID uuid.UUID
+	var existingName string
+	err := pg.QueryRow(ctx, `
+		SELECT c.id, c.name
+		FROM memberships m
+		JOIN companies c ON c.id = m.company_id
+		WHERE m.user_id = $1 AND m.status = 'active'
+		ORDER BY m.created_at NULLS LAST, c.name
+		LIMIT 1`, userID).Scan(&existingID, &existingName)
+	if err == nil {
+		_, _ = pg.Exec(ctx, `
+			UPDATE memberships
+			SET role = 'admin', status = 'active', updated_at = now()
+			WHERE user_id = $1 AND company_id = $2`, userID, existingID)
+		return existingID, existingName, false, nil
+	}
+	if !errors.Is(err, pgx.ErrNoRows) {
+		return uuid.Nil, "", false, fmt.Errorf("lookup memberships: %w", err)
+	}
+
+	tx, err := pg.Begin(ctx)
+	if err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("begin company: %w", err)
+	}
+	defer tx.Rollback(ctx)
+
+	var companyID uuid.UUID
+	err = tx.QueryRow(ctx, `INSERT INTO companies (name) VALUES ($1) RETURNING id`, companyName).Scan(&companyID)
+	if err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("insert company: %w", err)
+	}
+	_, err = tx.Exec(ctx, `
+		INSERT INTO memberships (company_id, user_id, role, status)
+		VALUES ($1, $2, 'admin', 'active')`, companyID, userID)
+	if err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("insert membership: %w", err)
+	}
+	_, err = tx.Exec(ctx, `
+		INSERT INTO company_settings (company_id) VALUES ($1)
+		ON CONFLICT DO NOTHING`, companyID)
+	if err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("company_settings: %w", err)
+	}
+	_, err = tx.Exec(ctx, `
+		INSERT INTO credit_balances (company_id) VALUES ($1)
+		ON CONFLICT DO NOTHING`, companyID)
+	if err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("credit_balances: %w", err)
+	}
+	if err := tx.Commit(ctx); err != nil {
+		return uuid.Nil, "", false, fmt.Errorf("commit company: %w", err)
+	}
+	return companyID, companyName, true, nil
+}
diff --git a/apps/api/cmd/seed-platform-admin/main_test.go b/apps/api/cmd/seed-platform-admin/main_test.go
index e3a5b08..b627844 100644
--- a/apps/api/cmd/seed-platform-admin/main_test.go
+++ b/apps/api/cmd/seed-platform-admin/main_test.go
@@ -7,7 +7,7 @@ import (
 
 func TestParseOptionsRequiresPostgres(t *testing.T) {
 	t.Parallel()
-	_, err := parseOptions("", "a@b.com", "password1", "", false, true, "development")
+	_, err := parseOptions("", "a@b.com", "password1", "", "", false, false, true, "development")
 	if err == nil || !strings.Contains(err.Error(), "DATABASE_URL") {
 		t.Fatalf("err = %v, want DATABASE_URL required", err)
 	}
@@ -15,7 +15,7 @@ func TestParseOptionsRequiresPostgres(t *testing.T) {
 
 func TestParseOptionsRequiresConfirm(t *testing.T) {
 	t.Parallel()
-	_, err := parseOptions("postgres://x", "a@b.com", "password1", "", false, false, "development")
+	_, err := parseOptions("postgres://x", "a@b.com", "password1", "", "", false, false, false, "development")
 	if err == nil || !strings.Contains(err.Error(), "-confirm") {
 		t.Fatalf("err = %v, want -confirm required", err)
 	}
@@ -23,19 +23,37 @@ func TestParseOptionsRequiresConfirm(t *testing.T) {
 
 func TestParseOptionsRequiresEmailAndPassword(t *testing.T) {
 	t.Parallel()
-	_, err := parseOptions("postgres://x", "", "password1", "", false, true, "development")
+	_, err := parseOptions("postgres://x", "", "password1", "", "", false, false, true, "development")
 	if err == nil {
 		t.Fatal("expected email error")
 	}
-	_, err = parseOptions("postgres://x", "a@b.com", "short", "", false, true, "development")
+	_, err = parseOptions("postgres://x", "a@b.com", "short", "", "", false, false, true, "development")
 	if err == nil || !strings.Contains(err.Error(), "8") {
 		t.Fatalf("err = %v, want min length", err)
 	}
 }
 
+func TestParseOptionsDefaultCompanyName(t *testing.T) {
+	t.Parallel()
+	opts, err := parseOptions("postgres://x", "ops@example.com", "password1", "Ops", "", false, false, true, "development")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if opts.CompanyName != "Ops workspace" {
+		t.Fatalf("company = %q", opts.CompanyName)
+	}
+	opts, err = parseOptions("postgres://x", "ops@example.com", "password1", "Ops", "Acme", false, false, true, "development")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if opts.CompanyName != "Acme" {
+		t.Fatalf("company = %q", opts.CompanyName)
+	}
+}
+
 func TestParseOptionsPromoteOnlySkipsPassword(t *testing.T) {
 	t.Parallel()
-	opts, err := parseOptions("postgres://x", "Ops@Example.COM", "", "Ops", true, true, "production")
+	opts, err := parseOptions("postgres://x", "Ops@Example.COM", "", "Ops", "Acme", true, false, true, "production")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -45,18 +63,18 @@ func TestParseOptionsPromoteOnlySkipsPassword(t *testing.T) {
 	if opts.Password != "" || !opts.PromoteOnly {
 		t.Fatalf("promote-only opts = %+v", opts)
 	}
-	if opts.Name != "Ops" {
-		t.Fatalf("name = %q", opts.Name)
+	if opts.CompanyName != "Acme" {
+		t.Fatalf("company = %q", opts.CompanyName)
 	}
 }
 
 func TestParseOptionsRejectsDemoInProduction(t *testing.T) {
 	t.Parallel()
-	_, err := parseOptions("postgres://x", "demo@descrybe.local", "securepass", "", false, true, "production")
+	_, err := parseOptions("postgres://x", "demo@descrybe.local", "securepass", "", "", false, false, true, "production")
 	if err == nil || !strings.Contains(err.Error(), "demo/local") {
 		t.Fatalf("err = %v, want demo/local refuse", err)
 	}
-	_, err = parseOptions("postgres://x", "you@example.com", "DemoPass123!", "", false, true, "prod")
+	_, err = parseOptions("postgres://x", "you@example.com", "DemoPass123!", "", "", false, false, true, "prod")
 	if err == nil || !strings.Contains(err.Error(), "seed-demo password") {
 		t.Fatalf("err = %v, want demo password refuse", err)
 	}
@@ -64,7 +82,7 @@ func TestParseOptionsRejectsDemoInProduction(t *testing.T) {
 
 func TestParseOptionsAllowsDemoLocally(t *testing.T) {
 	t.Parallel()
-	opts, err := parseOptions("postgres://x", "demo@descrybe.local", "DemoPass123!", "", false, true, "development")
+	opts, err := parseOptions("postgres://x", "demo@descrybe.local", "DemoPass123!", "", "", false, false, true, "development")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/scripts/seed-local.mjs b/scripts/seed-local.mjs
index 6480ef7..4246315 100644
--- a/scripts/seed-local.mjs
+++ b/scripts/seed-local.mjs
@@ -46,6 +46,8 @@ run([
   adminPass,
   "-name",
   "Local Admin",
+  "-company",
+  "Local Admin Co",
   "-confirm",
 ]);
 
diff --git a/scripts/seed-platform-admin.mjs b/scripts/seed-platform-admin.mjs
index c0db8e9..27eabd6 100644
--- a/scripts/seed-platform-admin.mjs
+++ b/scripts/seed-platform-admin.mjs
@@ -1,14 +1,13 @@
 #!/usr/bin/env node
 /**
- * Upsert a platform admin (is_platform_admin + staff_role=admin).
- * Loads monorepo-root `.env` only for DATABASE_URL (same as the API).
+ * Upsert a platform admin with a tenant company (fixes empty-company 400s).
+ * Loads monorepo-root `.env` only for DATABASE_URL.
  * Email/password are CLI flags only — never read from .env.
  *
  * Usage (from repo root):
  *   npm run seed:platform-admin -- --email you@example.com --password '…'
  *   npm run seed:platform-admin -- --email you@example.com --promote-only
- *
- * Optional: --name "Display Name"
+ *   npm run seed:platform-admin -- --email you@example.com --password '…' --company 'Acme Ops'
  */
 import { spawnSync } from "node:child_process";
 import path from "node:path";
@@ -22,22 +21,34 @@ function usage(msg) {
   console.error(`Usage:
   npm run seed:platform-admin -- --email you@example.com --password 'strong-password'
   npm run seed:platform-admin -- --email you@example.com --promote-only
-  npm run seed:platform-admin -- --email you@example.com --password '…' --name 'Ops'
+  npm run seed:platform-admin -- --email you@example.com --password '…' --company 'Acme Ops'
 
 Email/password must be passed on the CLI (not stored in .env).
-DATABASE_URL comes from the shell or monorepo-root .env.`);
+DATABASE_URL comes from the shell or monorepo-root .env.
+Creates a company + admin membership + Free plan unless --no-company.`);
   process.exit(1);
 }
 
 /** Parse `--key value` / `--flag` from argv after npm's `--`. */
 function parseArgs(argv) {
-  const out = { email: "", password: "", name: "", promoteOnly: false };
+  const out = {
+    email: "",
+    password: "",
+    name: "",
+    company: "",
+    promoteOnly: false,
+    noCompany: false,
+  };
   for (let i = 0; i < argv.length; i++) {
     const a = argv[i];
     if (a === "--promote-only") {
       out.promoteOnly = true;
       continue;
     }
+    if (a === "--no-company") {
+      out.noCompany = true;
+      continue;
+    }
     if (a === "--email" || a === "-email") {
       out.email = String(argv[++i] || "").trim();
       continue;
@@ -50,6 +61,10 @@ function parseArgs(argv) {
       out.name = String(argv[++i] || "").trim();
       continue;
     }
+    if (a === "--company" || a === "-company") {
+      out.company = String(argv[++i] || "").trim();
+      continue;
+    }
     if (a === "--help" || a === "-h") usage();
     usage(`Unknown argument: ${a}`);
   }
@@ -78,9 +93,9 @@ const args = [
   opts.email,
   "-confirm",
 ];
-if (opts.name) {
-  args.push("-name", opts.name);
-}
+if (opts.name) args.push("-name", opts.name);
+if (opts.company) args.push("-company", opts.company);
+if (opts.noCompany) args.push("-no-company");
 if (opts.promoteOnly) {
   args.push("-promote-only");
 } else {