diff --git a/README.md b/README.md
index 95c5970..becdf4f 100644
--- a/README.md
+++ b/README.md
@@ -316,6 +316,19 @@ aliases resolve to their base. Explicit `-cluster` flags are applied last, so
 they override or extend the manifest (e.g. `-cluster events_recent=@absent`).
 A cluster that references an undeclared role is rejected.
 
+#### Validating a whole environment
+
+With `-manifest`/`-env` and **no** `-layer`/`-config`, validate runs in
+manifest-driven mode: it validates **every role** in the manifest for that env,
+each against the cluster set derived from the whole manifest. One command checks
+the entire environment instead of a shell loop over nodes; failures are prefixed
+with the role they came from.
+
+```sh
+hclexp validate -manifest roles.hcl -env prod-us -layer-root .
+# validation error: [role data] posthog.web_stats: Distributed table column ...
+```
+
 ### Distributed proxy columns
 
 Once a `Distributed` remote resolves to an inspectable table (locally or via a
diff --git a/cmd/hclexp/hclexp.go b/cmd/hclexp/hclexp.go
index affc56b..36fd019 100644
--- a/cmd/hclexp/hclexp.go
+++ b/cmd/hclexp/hclexp.go
@@ -193,41 +193,108 @@ func buildManifestClusters(cs *hclload.ClusterSet, path, env, layerRoot string)
 	if err != nil {
 		return err
 	}
-	layersByRole := make(map[string][]string, len(roles))
+	clusters, err := parseManifestClusters(path)
+	if err != nil {
+		return err
+	}
+	// Load only the roles some cluster references (single-node mode needs the
+	// mappings, not every role's schema).
+	referenced := map[string]bool{}
+	for _, cl := range clusters {
+		for _, role := range cl.Roles {
+			referenced[role] = true
+		}
+	}
+	needed := make([]manifestRole, 0, len(referenced))
 	for _, r := range roles {
-		layersByRole[r.Role] = r.Layers
+		if referenced[r.Role] {
+			needed = append(needed, r)
+		}
 	}
-
-	clusters, err := parseManifestClusters(path)
+	schemas, err := loadManifestRoleSchemas(needed, layerRoot)
 	if err != nil {
 		return err
 	}
+	clusterSetFromRoles(cs, clusters, schemas)
+	return nil
+}
+
+// loadManifestRoleSchemas loads and resolves each role's composition for the
+// selected env (layer paths under layerRoot) into a schema, keyed by role name.
+func loadManifestRoleSchemas(roles []manifestRole, layerRoot string) (map[string]*hclload.Schema, error) {
+	schemas := make(map[string]*hclload.Schema, len(roles))
+	for _, r := range roles {
+		dirs := make([]string, len(r.Layers))
+		for i, l := range r.Layers {
+			dirs[i] = filepath.Join(layerRoot, l)
+		}
+		schema, err := hclload.LoadLayers(dirs)
+		if err != nil {
+			return nil, fmt.Errorf("role %q: loading %v: %w", r.Role, dirs, err)
+		}
+		if err := hclload.Resolve(schema); err != nil {
+			return nil, fmt.Errorf("role %q: resolving %v: %w", r.Role, dirs, err)
+		}
+		schemas[r.Role] = schema
+	}
+	return schemas, nil
+}
+
+// clusterSetFromRoles registers each cluster's mapping in cs: its schema is the
+// union of its member roles' (preloaded) compositions, and each alias maps to
+// @alias=cluster. A member role absent from schemas (not deployed in the env)
+// contributes nothing.
+func clusterSetFromRoles(cs *hclload.ClusterSet, clusters []manifestClusterBlock, schemas map[string]*hclload.Schema) {
 	for _, cl := range clusters {
 		var dbs []hclload.DatabaseSpec
 		for _, role := range cl.Roles {
-			layers, ok := layersByRole[role]
-			if !ok {
-				continue // role not deployed in this env
-			}
-			dirs := make([]string, len(layers))
-			for i, l := range layers {
-				dirs[i] = filepath.Join(layerRoot, l)
-			}
-			schema, err := hclload.LoadLayers(dirs)
-			if err != nil {
-				return fmt.Errorf("cluster %q role %q: loading %v: %w", cl.Name, role, dirs, err)
+			if s, ok := schemas[role]; ok {
+				dbs = append(dbs, s.Databases...)
 			}
-			if err := hclload.Resolve(schema); err != nil {
-				return fmt.Errorf("cluster %q role %q: resolving %v: %w", cl.Name, role, dirs, err)
-			}
-			dbs = append(dbs, schema.Databases...)
 		}
 		cs.Add(cl.Name, dbs)
 		for _, alias := range cl.Aliases {
 			cs.AddAlias(alias, cl.Name)
 		}
 	}
-	return nil
+}
+
+// roleValidation holds the validation errors for one role's composition.
+type roleValidation struct {
+	Role string
+	Errs []hclload.ValidationError
+}
+
+// validateManifest validates every role's composition in the manifest for env,
+// each against the cluster set derived from the whole manifest (member-role
+// unions + aliases, with flagEntries applied last). Results are returned per
+// role in manifest order.
+func validateManifest(path, env, layerRoot string, skip hclload.SkipSet, opts hclload.ValidateOptions, flagEntries []clusterEntry) ([]roleValidation, error) {
+	roles, err := parseManifest(path, env)
+	if err != nil {
+		return nil, err
+	}
+	clusters, err := parseManifestClusters(path)
+	if err != nil {
+		return nil, err
+	}
+	schemas, err := loadManifestRoleSchemas(roles, layerRoot)
+	if err != nil {
+		return nil, err
+	}
+
+	cs := hclload.NewClusterSet()
+	clusterSetFromRoles(&cs, clusters, schemas)
+	if err := applyClusterEntries(&cs, flagEntries); err != nil {
+		return nil, err
+	}
+
+	results := make([]roleValidation, 0, len(roles))
+	for _, r := range roles {
+		errs := hclload.ValidateOpts(schemas[r.Role].Databases, skip, cs, opts)
+		results = append(results, roleValidation{Role: r.Role, Errs: errs})
+	}
+	return results, nil
 }
 
 // runValidate loads an HCL config (single file or layers), resolves it, and
@@ -249,16 +316,22 @@ func buildManifestClusters(cs *hclload.ClusterSet, path, env, layerRoot string)
 // additionally requires the remote's columns to all exist on the proxy.
 //
 // Instead of listing every cluster as a -cluster flag, -manifest/-env derive the
-// mappings from the same role manifest `plan` uses: each role's `cluster` (and
-// `aliases`) maps to its composed layer stack for -env. Explicit -cluster flags
-// are applied last, so they override or extend the manifest (e.g. NAME=@absent).
+// mappings from the same role manifest `plan` uses: each `cluster` block maps to
+// the union of its member roles' composed layer stacks for -env. Explicit
+// -cluster flags are applied last, so they override or extend the manifest
+// (e.g. NAME=@absent).
+//
+// With -manifest/-env and no explicit node (-layer/-config), validate runs in
+// manifest-driven mode: it validates every role in the manifest, each against
+// the cluster set derived from the whole manifest — one command to check a
+// whole environment.
 func runValidate(args []string) {
 	fs := flag.NewFlagSet("hclexp validate", flag.ExitOnError)
 	configFlag := fs.String("config", "./cmd/hclexp/node.conf", "path to a single HCL config file (mutually exclusive with -layer)")
 	layersFlag := fs.String("layer", "", "comma-separated list of layer directories (loaded in order)")
 	skipFlag := fs.String("skip-validation", "", "comma-separated dependent object names to skip, or \"*\" for all")
 	strictProxyCols := fs.Bool("strict-proxy-columns", false, "require Distributed proxy and remote to have exactly the same columns (default: proxy columns need only be a subset)")
-	manifestFlag := fs.String("manifest", "", "HCL role manifest to derive -cluster mappings from (each role's cluster/aliases -> its -env layer stack); requires -env")
+	manifestFlag := fs.String("manifest", "", "HCL role manifest to derive -cluster mappings from; requires -env. With no -layer/-config, validates every role in the manifest")
 	envFlag := fs.String("env", "", "environment selecting each role's layer stack in -manifest")
 	layerRootFlag := fs.String("layer-root", ".", "root directory the manifest's layer paths resolve under")
 	var clusters clusterFlag
@@ -270,6 +343,15 @@ func runValidate(args []string) {
 		os.Exit(2)
 	}
 
+	// Manifest-driven mode: -manifest/-env with no explicit node (-layer or
+	// -config) validates every role in the manifest, each against the clusters
+	// derived from the whole manifest.
+	if *manifestFlag != "" && *layersFlag == "" && !flagWasSet(fs, "config") {
+		runValidateManifest(*manifestFlag, *envFlag, *layerRootFlag,
+			hclload.ParseSkipSet(*skipFlag), hclload.ValidateOptions{StrictProxyColumns: *strictProxyCols}, clusters.entries)
+		return
+	}
+
 	schema, err := load(*configFlag, *layersFlag)
 	if err != nil {
 		slog.Error("failed to load config", "err", err)
@@ -307,6 +389,42 @@ func runValidate(args []string) {
 	slog.Info("schema validation passed", "databases", len(schema.Databases))
 }
 
+// flagWasSet reports whether the named flag was explicitly provided on the
+// command line (as opposed to left at its default).
+func flagWasSet(fs *flag.FlagSet, name string) bool {
+	set := false
+	fs.Visit(func(f *flag.Flag) {
+		if f.Name == name {
+			set = true
+		}
+	})
+	return set
+}
+
+// runValidateManifest validates every role in the manifest for env, each
+// against the cluster set derived from the whole manifest. Errors are printed
+// per role and it exits non-zero if any role fails.
+func runValidateManifest(manifestPath, env, layerRoot string, skip hclload.SkipSet, opts hclload.ValidateOptions, flagEntries []clusterEntry) {
+	results, err := validateManifest(manifestPath, env, layerRoot, skip, opts, flagEntries)
+	if err != nil {
+		slog.Error("failed to validate manifest", "file", manifestPath, "env", env, "err", err)
+		os.Exit(1)
+	}
+
+	total := 0
+	for _, r := range results {
+		for _, e := range r.Errs {
+			fmt.Fprintf(os.Stderr, "validation error: [role %s] %s\n", r.Role, e.Error())
+		}
+		total += len(r.Errs)
+	}
+	if total > 0 {
+		slog.Error("schema validation failed", "env", env, "roles", len(results), "errors", total)
+		os.Exit(1)
+	}
+	slog.Info("schema validation passed", "env", env, "roles", len(results))
+}
+
 // runLoad loads an HCL config (single file or layers), resolves it, and
 // optionally writes the resolved schema back out as canonical HCL.
 func runLoad(args []string) {
diff --git a/cmd/hclexp/hclexp_test.go b/cmd/hclexp/hclexp_test.go
index b07618f..b68896f 100644
--- a/cmd/hclexp/hclexp_test.go
+++ b/cmd/hclexp/hclexp_test.go
@@ -641,6 +641,99 @@ cluster "aux" {
 		"manifest alias resolves via its base cluster")
 }
 
+// validateManifest validates every role's composition, resolving cross-cluster
+// references against the manifest-derived cluster set. Clean roles pass; a role
+// with a broken reference reports it, while its cross-cluster proxy resolves.
+func TestValidateManifest_AllRoles(t *testing.T) {
+	root := t.TempDir()
+	// aux role: a clean storage table.
+	writeLayer(t, root, "layers/aux/aux.hcl", `
+database "posthog" {
+  table "sharded_web_stats" {
+    order_by = ["day"]
+    column "day" { type = "Date" }
+    engine "merge_tree" {}
+  }
+}`)
+	// data role: a Distributed proxy into aux (resolves cross-cluster) plus a
+	// view referencing a table that exists nowhere (an error).
+	writeLayer(t, root, "layers/data/data.hcl", `
+database "posthog" {
+  table "web_stats" {
+    engine "distributed" {
+      cluster_name    = "aux"
+      remote_database = "posthog"
+      remote_table    = "sharded_web_stats"
+    }
+    column "day" { type = "Date" }
+  }
+  view "broken" {
+    query = "SELECT day FROM posthog.nonexistent"
+  }
+}`)
+	manifest := writeTemp(t, "roles.hcl", `
+role "data" {
+  env "prod-us" { layers = ["layers/data"] }
+}
+role "aux" {
+  env "prod-us" { layers = ["layers/aux"] }
+}
+cluster "aux"     { roles = ["aux"] }
+cluster "posthog" { roles = ["data"] }`)
+
+	results, err := validateManifest(manifest, "prod-us", root, hclload.ParseSkipSet(""), hclload.ValidateOptions{}, nil)
+	require.NoError(t, err)
+	require.Len(t, results, 2, "every deployed role is validated")
+
+	byRole := map[string][]hclload.ValidationError{}
+	for _, r := range results {
+		byRole[r.Role] = r.Errs
+	}
+	require.Empty(t, byRole["aux"], "aux role is clean")
+	require.Len(t, byRole["data"], 1, "data role has exactly the broken view (its proxy resolved cross-cluster)")
+	require.Equal(t, "broken", byRole["data"][0].Object.Name)
+	require.Equal(t, "nonexistent", byRole["data"][0].Missing.Name)
+}
+
+// A fully consistent manifest yields no errors on any role.
+func TestValidateManifest_AllClean(t *testing.T) {
+	root := t.TempDir()
+	writeLayer(t, root, "layers/aux/aux.hcl", `
+database "posthog" {
+  table "sharded_web_stats" {
+    order_by = ["day"]
+    column "day" { type = "Date" }
+    engine "merge_tree" {}
+  }
+}`)
+	writeLayer(t, root, "layers/data/data.hcl", `
+database "posthog" {
+  table "web_stats" {
+    engine "distributed" {
+      cluster_name    = "aux"
+      remote_database = "posthog"
+      remote_table    = "sharded_web_stats"
+    }
+    column "day" { type = "Date" }
+  }
+}`)
+	manifest := writeTemp(t, "roles.hcl", `
+role "data" {
+  env "prod-us" { layers = ["layers/data"] }
+}
+role "aux" {
+  env "prod-us" { layers = ["layers/aux"] }
+}
+cluster "aux" { roles = ["aux"] }`)
+
+	results, err := validateManifest(manifest, "prod-us", root, hclload.ParseSkipSet(""), hclload.ValidateOptions{}, nil)
+	require.NoError(t, err)
+	require.Len(t, results, 2)
+	for _, r := range results {
+		require.Empty(t, r.Errs, "role %s should be clean", r.Role)
+	}
+}
+
 // writeLayer writes content to root/rel, creating parent dirs.
 func writeLayer(t *testing.T, root, rel, content string) {
 	t.Helper()
diff --git a/docs/plans/2026-07-08-validate-manifest-driven.md b/docs/plans/2026-07-08-validate-manifest-driven.md
new file mode 100644
index 0000000..6463cce
--- /dev/null
+++ b/docs/plans/2026-07-08-validate-manifest-driven.md
@@ -0,0 +1,49 @@
+# validate: manifest-driven mode (validate a whole environment)
+
+Status: implemented 2026-07-08.
+Origin: `validate -manifest` (the prior change) validates **one** node passed via
+`-layer`/`-config`, using the manifest only as cross-cluster resolution context.
+To check a whole environment you had to loop `validate` per node in a shell. This
+adds a first-class mode that validates every role in the manifest in one command.
+
+## Behavior
+
+`hclexp validate -manifest roles.hcl -env prod-us [-layer-root .]` with **no**
+`-layer`/`-config`:
+
+- Loads and resolves every role's composition for `-env`.
+- Builds the cluster set from the manifest (member-role unions + aliases), plus
+  any `-cluster` flags applied last.
+- Runs the full validation on **each** role's schema against that cluster set,
+  and reports errors prefixed with the role: `[role data] ...`.
+- Exits non-zero if any role has errors.
+
+Mode is selected when `-manifest` is set and neither `-layer` nor an explicit
+`-config` is given (detected via `flag.FlagSet.Visit`). With `-layer`/`-config`,
+the existing single-node behavior (manifest as context) is unchanged.
+
+## Implementation (`cmd/hclexp/hclexp.go`)
+
+Shared helpers factored so both modes load role schemas once:
+
+- `loadManifestRoleSchemas(roles, layerRoot)` — role name → resolved `*Schema`.
+- `clusterSetFromRoles(cs, clusters, schemas)` — union member-role databases per
+  cluster + aliases. `buildManifestClusters` (single-node) reuses these, loading
+  only cluster-referenced roles.
+- `validateManifest(...) []roleValidation` — loads all roles, builds the cluster
+  set, validates each; returns per-role errors (testable, no `os.Exit`).
+- `runValidateManifest(...)` — prints per-role errors and sets the exit code.
+- `flagWasSet(fs, name)` — detects an explicit `-config`.
+
+## Tests
+
+- `validateManifest`: every role validated; a clean role passes while a role with
+  a broken reference reports it *and* its cross-cluster proxy still resolves.
+- all-clean manifest → no errors on any role.
+- Binary end-to-end: one command flags `[role data]` for a broken view, then
+  passes for the whole env once fixed.
+
+## Downstream
+
+posthog `check.sh` collapses its per-node validate loop into a single
+`validate -manifest -env` per environment.