diff --git a/internal/builder/builder.go b/internal/builder/builder.go
index 5fcbf54..1bc99d9 100644
--- a/internal/builder/builder.go
+++ b/internal/builder/builder.go
@@ -593,6 +593,12 @@ func one(ctx context.Context, run Runner, publish Publisher,
 		if err != nil {
 			return catalogue.Built{}, fmt.Errorf("%s: writing %s's launchers failed: %w", module, a.Name, err)
 		}
+		if chain.Bundler != "" {
+			say("bundle", "bundling each entrypoint into one file")
+			if compiled, err = bundled(ctx, run, tree, chain, base, a, launchers); err != nil {
+				return catalogue.Built{}, fmt.Errorf("%s: bundling %s failed: %w", module, a.Name, err)
+			}
+		}
 		say("bundle", "compiled, packing")
 		body, err := pack(compiled)
 		if err != nil {
@@ -974,7 +980,7 @@ func compile(ctx context.Context, run Runner, tree string, chain Toolchain,
 	if _, err := run(ctx, tree, "docker", invocation...); err != nil {
 		return "", err
 	}
-	if chain.Dependencies != "" {
+	if chain.Dependencies != "" && chain.Bundler == "" {
 		// **What the bundle runs with, from the image it was compiled in** (Toolchain.Dependencies).
 		// A second run in the same image rather than a shell wrapped around the compiler: the
 		// compile line stays a plain command a reader can run by hand, and the copy is one more
@@ -1224,3 +1230,94 @@ func writeLaunchers(root string, chain Toolchain, a catalogue.Artifact) (map[str
 	}
 	return out, nil
 }
+
+// bundledSuffix is where a bundle's one-file output is written, beside what the compiler wrote.
+const bundledSuffix = ".bundled"
+
+// bundled makes every entrypoint and every launcher of a compiled bundle ONE file, in the toolchain
+// image's bundler, and answers the directory to pack (novox/hq ADR 0193).
+//
+// **What a launched bundle runs is what it imports, and nothing else.** Every served bundle is its
+// own process, so it carries its own copy of the SDK and its own dependencies inlined — the
+// toolchain's whole node_modules no longer travels in every bundle. An entrypoint a process runs by
+// name (`node daemon/index.js`) is bundled in place under its own name; a launcher keeps its name
+// and its first line, and stays executable. A package the bundler cannot inline is named by the
+// artifact (`external`), kept as an import, and only then is the toolchain's runtime directory
+// copied beside the files. CommonJS inlined into an ES module still finds `require`.
+func bundled(ctx context.Context, run Runner, tree string, chain Toolchain, base string,
+	a catalogue.Artifact, launchers map[string]string) (string, error) {
+	const within = "/app/modules/module"
+	out, final := Out(a.Name), Out(a.Name)+bundledSuffix
+	if err := os.RemoveAll(filepath.Join(tree, final)); err != nil {
+		return "", err
+	}
+	if err := os.MkdirAll(filepath.Join(tree, final), 0o755); err != nil {
+		return "", err
+	}
+	common := []string{"--bundle", "--platform=node", "--format=esm", "--target=node22",
+		"--outbase=" + out, "--outdir=" + final, "--log-level=warning",
+		"--banner:js=import { createRequire as __meshRequire } from 'node:module'; const require = __meshRequire(import.meta.url);"}
+	for _, x := range a.External {
+		common = append(common, "--external:"+x)
+	}
+	var plain []string
+	for _, e := range a.Entrypoints {
+		if strings.HasSuffix(e, ".js") {
+			plain = append(plain, out+"/"+e)
+		}
+	}
+	var launch []string
+	for _, l := range sortedValues(launchers) {
+		launch = append(launch, out+"/"+l)
+	}
+	// Refused by name in an image that predates the bundler, as the dependencies copy is: a bundle
+	// packed without it would carry nothing it imports.
+	guard := `test -x "$0" || { echo "the toolchain image carries no bundler at $0: it predates one-file bundles, rebuild mesh-tools first" >&2; exit 1; }; exec node "$0" "$@"`
+	step := func(entries []string, extra ...string) error {
+		if len(entries) == 0 {
+			return nil
+		}
+		invocation := []string{"run", "--rm", "--volume", tree + ":" + within, "--workdir", within, base,
+			"sh", "-c", guard, chain.Bundler}
+		invocation = append(invocation, entries...)
+		invocation = append(invocation, common...)
+		invocation = append(invocation, extra...)
+		_, err := run(ctx, tree, "docker", invocation...)
+		return err
+	}
+	if err := step(plain); err != nil {
+		return "", err
+	}
+	if err := step(launch, "--out-extension:.js=.mjs"); err != nil {
+		return "", err
+	}
+	// Plain `.js` output is an ES module; said once, as the runtime directory used to say it.
+	if err := os.WriteFile(filepath.Join(tree, final, "package.json"), []byte(`{"type":"module","private":true}`+"\n"), 0o644); err != nil {
+		return "", err
+	}
+	for _, l := range launchers {
+		path := filepath.Join(tree, final, filepath.FromSlash(l))
+		if _, err := os.Stat(path); err == nil {
+			if err := os.Chmod(path, 0o755); err != nil {
+				return "", err
+			}
+		}
+	}
+	if len(a.External) > 0 && chain.Dependencies != "" {
+		copying := []string{"run", "--rm", "--volume", tree + ":" + within, "--workdir", within, base,
+			"sh", "-c", `cp -a "$0/node_modules" "$1/"`, chain.Dependencies, final}
+		if _, err := run(ctx, tree, "docker", copying...); err != nil {
+			return "", fmt.Errorf("copying the packages %s keeps external: %w", a.Name, err)
+		}
+	}
+	return filepath.Join(tree, final), nil
+}
+
+func sortedValues(m map[string]string) []string {
+	out := make([]string, 0, len(m))
+	for _, v := range m {
+		out = append(out, v)
+	}
+	sort.Strings(out)
+	return out
+}
diff --git a/internal/builder/bundle_test.go b/internal/builder/bundle_test.go
index 7872da2..a29225e 100644
--- a/internal/builder/bundle_test.go
+++ b/internal/builder/bundle_test.go
@@ -83,25 +83,49 @@ func TestABundleIsCompiledAndPackedWithNoDockerfile(t *testing.T) {
 		t.Fatalf("the bundle was not pinned: %v", got.Manifest.Resources[0])
 	}
 
-	// **And what it runs with, from the image it was compiled in** (novox/hq to-be 38 WP3). A
-	// second run in the same toolchain image copies the toolchain's runtime directory — the
-	// `"type": "module"` package.json and the pruned node_modules — into the output's root, and
-	// refuses by name when the image carries none rather than packing a bundle that starts nowhere.
-	var copied string
+	// **One file per entrypoint and launcher, in the toolchain's bundler** (novox/hq ADR 0193). A
+	// second run in the same toolchain image bundles each into the artifact's bundled output, the SDK
+	// inlined, refusing by name in an image that predates the bundler; and the toolchain's
+	// node_modules is no longer copied into a bundle that keeps nothing external.
+	var bundling []string
 	for _, line := range r.ran {
-		if strings.HasPrefix(line, "docker run") && strings.Contains(line, "/app/runtime") {
-			copied = line
+		if strings.HasPrefix(line, "docker run") && strings.Contains(line, "esbuild") {
+			bundling = append(bundling, line)
 		}
 	}
-	if copied == "" {
-		t.Fatalf("the bundle's dependencies were not copied in after the compile:\n%s", strings.Join(r.ran, "\n"))
+	if len(bundling) != 2 {
+		t.Fatalf("want one bundling run for the entrypoints and one for the launchers:\n%s", strings.Join(r.ran, "\n"))
 	}
-	if !strings.Contains(copied, "mesh-tools/build@sha256:") || !strings.Contains(copied, "predates") ||
-		!strings.Contains(copied, Out("code")) {
-		t.Fatalf("the copy does not run in the same toolchain, refuse an older image by name, or land in the artifact's output: %s", copied)
+	for _, want := range []string{"mesh-tools/build@sha256:", "predates one-file bundles", "--bundle", "--format=esm",
+		"--platform=node", "--outdir=" + Out("code") + ".bundled", Out("code") + "/index.js"} {
+		if !strings.Contains(bundling[0], want) {
+			t.Errorf("the entrypoints' bundling lacks %q: %s", want, bundling[0])
+		}
 	}
-	if strings.Index(strings.Join(r.ran, "\n"), "--outDir") > strings.Index(strings.Join(r.ran, "\n"), "/app/runtime") {
-		t.Fatal("the dependencies were copied before the compile wrote its output")
+	if !strings.Contains(bundling[1], Out("code")+"/index.serve.mjs") || !strings.Contains(bundling[1], "--out-extension:.js=.mjs") {
+		t.Errorf("the launcher is not bundled under its own name: %s", bundling[1])
+	}
+	if strings.Contains(strings.Join(r.ran, "\n"), "/app/runtime") {
+		t.Errorf("the toolchain's node_modules was copied into a bundle that keeps nothing external:\n%s", strings.Join(r.ran, "\n"))
+	}
+	if strings.Index(strings.Join(r.ran, "\n"), "--outDir") > strings.Index(strings.Join(r.ran, "\n"), "esbuild") {
+		t.Fatal("the bundler ran before the compile wrote its output")
+	}
+}
+
+// A bundle naming packages it keeps external is bundled with them as imports, and carries the
+// toolchain's node_modules for them — the one case it still does.
+func TestABundleKeepingAPackageExternalCarriesTheToolchainsModules(t *testing.T) {
+	manifest := strings.Replace(aBundle, `"entrypoints":["index.js"]`, `"entrypoints":["index.js"],"external":["sharp"]`, 1)
+	r, workspace := aRepository(t, manifest, map[string]string{"index.ts": "console.log(1)"})
+	held := map[string]string{"mesh-tools/build": "registry.invalid/mesh-tools/build@sha256:" + strings.Repeat("b", 64)}
+	if _, err := Build(context.Background(), compiling{r}.run, r,
+		"https://forge.invalid/greeter.git", "", "", workspace, held, Npmrc{}, GitCredential{}, nil); err != nil {
+		t.Fatal(err)
+	}
+	all := strings.Join(r.ran, "\n")
+	if !strings.Contains(all, "--external:sharp") || !strings.Contains(all, "/app/runtime") {
+		t.Errorf("an external package was not kept as an import with the toolchain's modules beside it:\n%s", all)
 	}
 }
 
diff --git a/internal/builder/standing_on_test.go b/internal/builder/standing_on_test.go
index 615ce2b..d6462d9 100644
--- a/internal/builder/standing_on_test.go
+++ b/internal/builder/standing_on_test.go
@@ -200,3 +200,23 @@ func TestWhatABuildReadIsTheRepositoriesItsRecipesName(t *testing.T) {
 		t.Fatal("a module whose recipes name no other repository read one")
 	}
 }
+
+// novox/hq 04-ISSUES/212: a toolchain stands on the SDK's published package, and is built with the
+// exact version the mesh published — an argument that changes when the SDK does, so a rebuild after
+// a release never reuses an install of the version before it.
+func TestAPackageTheMeshPublishedIsPassedByItsExactVersion(t *testing.T) {
+	manifest := catalogue.Manifest{
+		Module: "mesh-tools",
+		Build: &catalogue.Build{
+			On: []catalogue.BuildsOn{{Arg: "MESH_SDK", Module: "mesh-sdk", Artifact: "lib"}},
+		},
+	}
+	held := map[string]string{"mesh-sdk/lib": "@novox/mesh-sdk@0.1.6"}
+	args, resolved, err := standingOn(context.Background(), manifest, held, noMirror)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fmt.Sprint(args) != "[--build-arg MESH_SDK=@novox/mesh-sdk@0.1.6]" || fmt.Sprint(resolved) != "[@novox/mesh-sdk@0.1.6]" {
+		t.Errorf("the package was passed as %v, recorded as %v", args, resolved)
+	}
+}
diff --git a/internal/builder/toolchain.go b/internal/builder/toolchain.go
index 5df2d3f..72abad6 100644
--- a/internal/builder/toolchain.go
+++ b/internal/builder/toolchain.go
@@ -73,7 +73,16 @@ type Toolchain struct {
 	//
 	// A toolchain image without the directory fails the build by name rather than packing a bundle
 	// that starts nowhere: the image predates this and must be rebuilt first.
+	//
+	// *Since the bundler (below):* copied only for a bundle that names packages it keeps external,
+	// which cannot be inlined; a bundle with none carries no node_modules at all.
 	Dependencies string
+	// Bundler is the bundler inside the toolchain image that makes each compiled entrypoint and each
+	// launcher ONE self-contained file (novox/hq ADR 0193): every served bundle is its own process
+	// now, so each carries its own copy of what it imports — the SDK included — and nothing else.
+	// A bundle shrinks from the toolchain's whole node_modules to the code it runs. Empty for a
+	// language whose build is already one file.
+	Bundler string
 	// SystemStamp is the variable this language's linker fills with the artifact's declared system,
 	// for a language whose binaries are pinned to one at link time (novox/hq ADR 0005).
 	//
@@ -139,6 +148,7 @@ var toolchains = []Toolchain{
 		Unit:         UnitSources,
 		SourceExt:    ".ts",
 		Dependencies: "/app/runtime",
+		Bundler:      "/app/node_modules/esbuild/bin/esbuild",
 	},
 	{
 		Language: "go",
diff --git a/internal/catalogue/build.go b/internal/catalogue/build.go
index 23d3aa6..4db55a1 100644
--- a/internal/catalogue/build.go
+++ b/internal/catalogue/build.go
@@ -214,6 +214,11 @@ func (b *Build) problems(module string) []string {
 		// A bundle's source is the module's own directory by definition, and what it needs to say
 		// is which compiler — because the mesh chooses that, and cannot choose for a module that
 		// has not said.
+		if len(a.External) > 0 && (a.Kind != ArtifactBundle || a.Language != "typescript") {
+			problems = append(problems, fmt.Sprintf(
+				"%s: %q names packages it keeps external, and only a TypeScript bundle is bundled into "+
+					"one file with some kept out (novox/hq ADR 0193)", module, a.Name))
+		}
 		if len(a.Env) > 0 && a.Kind != ArtifactBundle {
 			problems = append(problems, fmt.Sprintf(
 				"%s: %q is a %q and says what it is given (env). Only a bundle the node's runtime "+
diff --git a/internal/catalogue/manifest.go b/internal/catalogue/manifest.go
index aef8497..4c55564 100644
--- a/internal/catalogue/manifest.go
+++ b/internal/catalogue/manifest.go
@@ -757,6 +757,11 @@ type Artifact struct {
 	// list twice. A module declaring no tools has nothing the runtime loads, whatever it compiles.
 	Loads []string `json:"loads,omitempty"`
 
+	// External are packages a TypeScript bundle keeps as imports rather than inlining — a native
+	// addon, a package that reads its own files — and so carries the toolchain's node_modules for
+	// (novox/hq ADR 0193). Absent for nearly every bundle, which is then one file per entrypoint.
+	External []string `json:"external,omitempty"`
+
 	// Env is what a tools bundle is given on a machine (novox/hq ADR 0192): words and their values,
 	// paths and constants composed with ${dir:…} and ${port:…} exactly as a container's environment
 	// is, never a secret's content. The node's runtime hands it to this bundle and to no other.
diff --git a/internal/inventory/dependencies_test.go b/internal/inventory/dependencies_test.go
index 144595a..32c3615 100644
--- a/internal/inventory/dependencies_test.go
+++ b/internal/inventory/dependencies_test.go
@@ -100,3 +100,23 @@ func TestABundleStandsOnTheToolchainItIsCompiledIn(t *testing.T) {
 		}
 	}
 }
+
+// novox/hq 04-ISSUES/212: a toolchain standing on the SDK's package is planned after the SDK, so a
+// release of the SDK rebuilds the toolchain, and every bundle compiled in it after that.
+func TestAToolchainStandingOnTheSDKFollowsIt(t *testing.T) {
+	entries := []Entry{
+		{Manifest: catalogue.Manifest{Module: "mesh-sdk"}},
+		{Manifest: catalogue.Manifest{Module: "mesh-tools", Build: &catalogue.Build{
+			On: []catalogue.BuildsOn{{Arg: "MESH_SDK", Module: "mesh-sdk", Artifact: "lib"}}}}},
+	}
+	edges := dependenciesOf(entries, nil, nil)
+	found := false
+	for _, e := range edges {
+		if e.From == "mesh-tools" && e.To == "mesh-sdk" {
+			found = true
+		}
+	}
+	if !found {
+		t.Errorf("no edge from the toolchain to the SDK: %v", edges)
+	}
+}