diff --git a/go.mod b/go.mod
index 353e2dd..3f057fb 100644
--- a/go.mod
+++ b/go.mod
@@ -159,4 +159,4 @@ require (
 
 // Trivy has some issues that we're floating patches for, and will hopefully
 // be upstreamed eventually.
-replace github.com/aquasecurity/trivy => github.com/coder/trivy v0.0.0-20260309164037-c413f5a2f511
+replace github.com/aquasecurity/trivy => github.com/coder/trivy v0.0.0-20260911135535-15b949537506
diff --git a/go.sum b/go.sum
index 70c9552..170f6f7 100644
--- a/go.sum
+++ b/go.sum
@@ -115,8 +115,8 @@ github.com/coder/serpent v0.10.0 h1:ofVk9FJXSek+SmL3yVE3GoArP83M+1tX+H7S4t8BSuM=
 github.com/coder/serpent v0.10.0/go.mod h1:cZFW6/fP+kE9nd/oRkEHJpG6sXCtQ+AX7WMMEHv0Y3Q=
 github.com/coder/terraform-provider-coder/v2 v2.8.0 h1:pbWfegCPI0v8eATgE8kGwIyuaMPgMRIcdLF2GTVkgG0=
 github.com/coder/terraform-provider-coder/v2 v2.8.0/go.mod h1:WrdLSbihuzH1RZhwrU+qmkqEhUbdZT/sjHHdarm5b5g=
-github.com/coder/trivy v0.0.0-20260309164037-c413f5a2f511 h1:wJS3Pk13VuCbV8hjrQRnOBCUwP3Islk91sMvbSdY0Vk=
-github.com/coder/trivy v0.0.0-20260309164037-c413f5a2f511/go.mod h1:+zF17ZBOdhFWwD3+GkLxZ/vkmKLudoOtt+hgnc1TQpA=
+github.com/coder/trivy v0.0.0-20260911135535-15b949537506 h1:A9f2UisugOgV2JlhibP0GZdzpqn+sWPIcz4q3bsgopI=
+github.com/coder/trivy v0.0.0-20260911135535-15b949537506/go.mod h1:+zF17ZBOdhFWwD3+GkLxZ/vkmKLudoOtt+hgnc1TQpA=
 github.com/coder/websocket v1.8.13 h1:f3QZdXy7uGVz+4uCJy2nTZyM0yTBj8yANEHhqlXZ9FE=
 github.com/coder/websocket v1.8.13/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
 github.com/containerd/errdefs v1.0.0 h1:tg5yIfIlQIrxYtu9ajqY42W3lpS19XqdxRQeEwYG8PI=
diff --git a/options.go b/options.go
new file mode 100644
index 0000000..577c39f
--- /dev/null
+++ b/options.go
@@ -0,0 +1,34 @@
+package preview
+
+// Option adjusts how Preview evaluates a template. Options exist so a caller
+// can change evaluation behavior without a new preview release, for example
+// to turn off an optimization that misbehaves on a particular template.
+type Option func(*options)
+
+type options struct {
+	// fullEvaluation disables resource closure pruning so every resource in
+	// the root module is evaluated.
+	fullEvaluation bool
+}
+
+// OptionFullEvaluation evaluates every resource in the root module instead of
+// only those reachable from parameter, preset, and tag blocks. It is the escape
+// hatch for the resource closure optimization: parameters, presets, and tags
+// are unchanged either way, so this only matters when that optimization has a
+// bug, or when Output.ModuleOutput must include outputs that read resources
+// outside the closure.
+func OptionFullEvaluation() Option {
+	return func(o *options) {
+		o.fullEvaluation = true
+	}
+}
+
+func applyOptions(opts []Option) options {
+	var o options
+	for _, opt := range opts {
+		if opt != nil {
+			opt(&o)
+		}
+	}
+	return o
+}
diff --git a/preview.go b/preview.go
index 32ac43f..51f490a 100644
--- a/preview.go
+++ b/preview.go
@@ -139,7 +139,8 @@ func ValidatePrebuilds(ctx context.Context, input Input, preValid []types.Preset
 	}
 }
 
-func Preview(ctx context.Context, input Input, dir fs.FS) (output *Output, diagnostics hcl.Diagnostics) {
+func Preview(ctx context.Context, input Input, dir fs.FS, opts ...Option) (output *Output, diagnostics hcl.Diagnostics) {
+	settings := applyOptions(opts)
 	// The trivy package works with `github.com/zclconf/go-cty`. This package is
 	// similar to `reflect` in its usage. This package can panic if types are
 	// misused. To protect the caller, a general `recover` is used to catch any
@@ -234,7 +235,7 @@ func Preview(ctx context.Context, input Input, dir fs.FS) (output *Output, diagn
 	}
 
 	// moduleSource is "" for a local module
-	p := parser.New(dir, "",
+	parserOpts := []parser.Option{
 		parser.OptionWithLogger(logger),
 		parser.OptionStopOnHCLError(false),
 		parser.OptionWithDownloads(false),
@@ -246,7 +247,19 @@ func Preview(ctx context.Context, input Input, dir fs.FS) (output *Output, diagn
 		// 'OptionsWithTfVars' cannot be set with 'OptionWithTFVarsPaths'. So load the
 		// tfvars from the files ourselves and merge with the user-supplied tf vars.
 		parser.OptionsWithTfVars(variableValues),
-	)
+	}
+	if !settings.fullEvaluation {
+		// Only the parameter/preset/tag blocks and what they reference need to
+		// be evaluated to render a workspace form. The resources a workspace
+		// would create cannot feed those blocks, so root resources nothing in
+		// this closure references are skipped. See OptionFullEvaluation.
+		parserOpts = append(parserOpts, parser.OptionWithResourceClosure([]string{
+			"coder_parameter",
+			"coder_workspace_preset",
+			"coder_workspace_tags",
+		}))
+	}
+	p := parser.New(dir, "", parserOpts...)
 
 	err = p.ParseFS(ctx, ".")
 	if err != nil {
diff --git a/preview_test.go b/preview_test.go
index 5f360e4..bc23b2b 100644
--- a/preview_test.go
+++ b/preview_test.go
@@ -867,85 +867,127 @@ func Test_Extract(t *testing.T) {
 			},
 		},
 	} {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-			if tc.skip != "" {
-				t.Skip(tc.skip)
-				return
-			}
+		// Every vector runs twice: with the default resource closure
+		// optimization, and with OptionFullEvaluation. The expectations are
+		// shared, which pins that the optimization is output-neutral for
+		// parameters, presets, tags, and variables.
+		for _, mode := range []struct {
+			name string
+			opts []preview.Option
+		}{
+			{name: "closure"},
+			{name: "full", opts: []preview.Option{preview.OptionFullEvaluation()}},
+		} {
+			t.Run(tc.name+"/"+mode.name, func(t *testing.T) {
+				t.Parallel()
+				if tc.skip != "" {
+					t.Skip(tc.skip)
+					return
+				}
 
-			if tc.unknownTags == nil {
-				tc.unknownTags = []string{}
-			}
-			if tc.expTags == nil {
-				tc.expTags = map[string]string{}
-			}
+				if tc.unknownTags == nil {
+					tc.unknownTags = []string{}
+				}
+				if tc.expTags == nil {
+					tc.expTags = map[string]string{}
+				}
 
-			dirFs := os.DirFS(filepath.Join("testdata", tc.dir))
+				dirFs := os.DirFS(filepath.Join("testdata", tc.dir))
 
-			output, diags := preview.Preview(context.Background(), tc.input, dirFs)
-			if tc.failPreview {
-				require.True(t, diags.HasErrors())
-				return
-			}
-			if diags.HasErrors() {
-				t.Logf("diags: %s", diags)
-			}
-			require.False(t, diags.HasErrors())
+				output, diags := preview.Preview(context.Background(), tc.input, dirFs, mode.opts...)
+				if tc.failPreview {
+					require.True(t, diags.HasErrors())
+					return
+				}
+				if diags.HasErrors() {
+					t.Logf("diags: %s", diags)
+				}
+				require.False(t, diags.HasErrors())
 
-			// Validate prebuilds too
-			preview.ValidatePrebuilds(context.Background(), tc.input, output.Presets, dirFs)
+				// Validate prebuilds too
+				preview.ValidatePrebuilds(context.Background(), tc.input, output.Presets, dirFs)
 
-			if len(tc.warnings) > 0 {
-				for _, w := range tc.warnings {
-					idx := slices.IndexFunc(diags, func(diagnostic *hcl.Diagnostic) bool {
-						return w.MatchString(diagnostic.Error())
+				if len(tc.warnings) > 0 {
+					for _, w := range tc.warnings {
+						idx := slices.IndexFunc(diags, func(diagnostic *hcl.Diagnostic) bool {
+							return w.MatchString(diagnostic.Error())
 
-					})
-					require.Greater(t, idx, -1, "expected warning %q to be present in diags", w.String())
+						})
+						require.Greater(t, idx, -1, "expected warning %q to be present in diags", w.String())
+					}
 				}
-			}
-
-			// Assert tags
-			validTags := output.WorkspaceTags.Tags()
 
-			for k, expected := range tc.expTags {
-				tag, ok := validTags[k]
-				if !ok {
-					t.Errorf("expected tag %q to be present in output, but it was not", k)
-					continue
+				// Assert tags
+				validTags := output.WorkspaceTags.Tags()
+
+				for k, expected := range tc.expTags {
+					tag, ok := validTags[k]
+					if !ok {
+						t.Errorf("expected tag %q to be present in output, but it was not", k)
+						continue
+					}
+					if tag != expected {
+						assert.JSONEqf(t, expected, tag, "tag %q does not match expected, nor is it a json equivalent", k)
+					}
 				}
-				if tag != expected {
-					assert.JSONEqf(t, expected, tag, "tag %q does not match expected, nor is it a json equivalent", k)
+				assert.Equal(t, len(tc.expTags), len(output.WorkspaceTags.Tags()), "unexpected number of tags in output")
+
+				assert.ElementsMatch(t, tc.unknownTags, output.WorkspaceTags.UnusableTags().SafeNames())
+
+				// Assert params
+				require.Len(t, output.Parameters, len(tc.params), "wrong number of parameters expected")
+				for _, param := range output.Parameters {
+					check, ok := tc.params[param.Name]
+					require.True(t, ok, "unknown parameter %s", param.Name)
+					check(t, param)
 				}
-			}
-			assert.Equal(t, len(tc.expTags), len(output.WorkspaceTags.Tags()), "unexpected number of tags in output")
 
-			assert.ElementsMatch(t, tc.unknownTags, output.WorkspaceTags.UnusableTags().SafeNames())
+				for _, preset := range output.Presets {
+					check, ok := tc.presets[preset.Name]
+					require.True(t, ok, "unknown preset %s", preset.Name)
+					check(t, preset)
+				}
 
-			// Assert params
-			require.Len(t, output.Parameters, len(tc.params), "wrong number of parameters expected")
-			for _, param := range output.Parameters {
-				check, ok := tc.params[param.Name]
-				require.True(t, ok, "unknown parameter %s", param.Name)
-				check(t, param)
-			}
+				// Assert variables
+				require.Len(t, output.Variables, len(tc.variables), "wrong number of variables expected")
+				for _, variable := range output.Variables {
+					check, ok := tc.variables[variable.Name]
+					require.True(t, ok, "unknown variable %s", variable.Name)
+					check(t, variable)
+				}
+			})
+		}
+	}
+}
 
-			for _, preset := range output.Presets {
-				check, ok := tc.presets[preset.Name]
-				require.True(t, ok, "unknown preset %s", preset.Name)
-				check(t, preset)
-			}
+// Test_OptionFullEvaluation proves the option changes evaluation, not just
+// that both modes agree on parameters. Output.ModuleOutput is the one place a
+// resource outside the closure is observable.
+func Test_OptionFullEvaluation(t *testing.T) {
+	t.Parallel()
 
-			// Assert variables
-			require.Len(t, output.Variables, len(tc.variables), "wrong number of variables expected")
-			for _, variable := range output.Variables {
-				check, ok := tc.variables[variable.Name]
-				require.True(t, ok, "unknown variable %s", variable.Name)
-				check(t, variable)
-			}
-		})
+	dirFs := os.DirFS(filepath.Join("testdata", "fullevaluation"))
+	outputName := func(t *testing.T, opts ...preview.Option) cty.Value {
+		t.Helper()
+		output, diags := preview.Preview(context.Background(), preview.Input{}, dirFs, opts...)
+		require.False(t, diags.HasErrors(), diags.Error())
+		require.Len(t, output.Parameters, 1)
+		assert.Equal(t, "large", output.Parameters[0].Value.AsString())
+		return output.ModuleOutput.GetAttr("unreferenced_name")
 	}
+
+	t.Run("Closure", func(t *testing.T) {
+		t.Parallel()
+		v := outputName(t)
+		assert.False(t, v.IsKnown(), "resource outside the closure should not be evaluated by default, got %s", v.GoString())
+	})
+
+	t.Run("Full", func(t *testing.T) {
+		t.Parallel()
+		v := outputName(t, preview.OptionFullEvaluation())
+		require.True(t, v.IsKnown(), "OptionFullEvaluation must evaluate every resource")
+		assert.Equal(t, "outside-closure", v.AsString())
+	})
 }
 
 func TestPresetValidation(t *testing.T) {
diff --git a/testdata/fullevaluation/main.tf b/testdata/fullevaluation/main.tf
new file mode 100644
index 0000000..5b7a4a3
--- /dev/null
+++ b/testdata/fullevaluation/main.tf
@@ -0,0 +1,30 @@
+// Observes whether resources outside the parameter/preset/tag closure were
+// evaluated. Nothing a parameter reads references the resource, so the default
+// closure skips it and the output that reads it is unknown. With
+// OptionFullEvaluation the resource is evaluated and the output resolves.
+terraform {
+  required_providers {
+    coder = {
+      source  = "coder/coder"
+      version = "2.4.0-pre0"
+    }
+    docker = {
+      source  = "kreuzwerker/docker"
+      version = "3.0.2"
+    }
+  }
+}
+
+data "coder_parameter" "flavor" {
+  name    = "flavor"
+  type    = "string"
+  default = "large"
+}
+
+resource "docker_image" "unreferenced" {
+  name = "outside-closure"
+}
+
+output "unreferenced_name" {
+  value = docker_image.unreferenced.name
+}
diff --git a/testdata/fullevaluation/skipe2e b/testdata/fullevaluation/skipe2e
new file mode 100644
index 0000000..6839a83
--- /dev/null
+++ b/testdata/fullevaluation/skipe2e
@@ -0,0 +1 @@
+evaluation mode is exercised by Test_OptionFullEvaluation (static preview eval); real terraform apply is out of scope here