diff --git a/ROADMAP.md b/ROADMAP.md
index edca31d..87ddd47 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -107,7 +107,7 @@ _Second external review, this one of the codebase rather than the experience. Ra
 
 - [ ] **Staged resolution with diagnostics** — `normalizeConfig` now applies defaults, coerces conflicts, derives helpers, and encodes framework/target policy in one pass, and **silently** disables what it can't support. Split into ordered stages returning `{ config, changes[], warnings[], errors[] }` so "we turned Storybook off because this isn't a component library" is reported rather than inferred.
 - [ ] **A resolved domain model** — the config carries ~16 derived booleans (`isReact`, `hasApp`, `publishable`, `usesVite`…) that can in principle contradict each other. Features should consume `resolved.targets` / `resolved.build` / `resolved.package` instead of re-interpreting raw selections.
-- [ ] **Make feature ordering explicit** — features merge in array order, so order silently decides who wins. Give them ids, phases, `requires`, `conflictsWith`, and detect collisions rather than relying on position.
+- [x] ~~**Make feature ordering explicit**~~ — **Shipped (3.1).** Rather than build speculative phase/requires/conflictsWith machinery, the real risk — order silently deciding a collision — is now an enforced invariant: `test/feature-registry.test.js` asserts every feature has a unique id and that **no two features collide** on a file or package.json field across the full config matrix (1683 configs). That immediately surfaced a real one — `bundler` and `service` both set `scripts.dev` on `node-service`, resolved only by array position — now fixed by making the service the explicit owner of its `dev` script. Ordering is no longer load-bearing for correctness; a colliding new feature fails the test instead of shipping.
 - [ ] **Pairwise combination testing** — the integration matrix covers presets, which are the *common* paths. The risk is cross-feature interaction (dual + Rollup + Jest + Biome). Generate a matrix where every option pair appears at least once.
 - [ ] **Dependency version catalog** — template versions are embedded across feature modules. Centralize them with compatibility notes and a last-reviewed date; the freshness workflow already treats them as product data, this makes that explicit.
 - [ ] **Unify monorepo and single-package generation** — `generate()` returns early for monorepos, and 2.9 added a second early return inside that. Modelling a project as workspaces (a plain package being a project with one) would stop features having to be implemented twice.
diff --git a/docs/packkit-core.js b/docs/packkit-core.js
index f52ed4b..4641a96 100644
--- a/docs/packkit-core.js
+++ b/docs/packkit-core.js
@@ -641,6 +641,7 @@ var bundler_default = {
       pkg.scripts.build = "tsc";
       pkg.scripts.dev = "tsc --watch";
     }
+    if (cfg.hasService) delete pkg.scripts.dev;
     if (build) pkg.scripts.prepublishOnly = pkg.scripts.build;
     pkg.scripts.clean = "rimraf dist";
     if (build) pkg.devDependencies = { ...pkg.devDependencies, rimraf: "^6.0.0" };
diff --git a/src/core/features/bundler.js b/src/core/features/bundler.js
index ff7f044..9b99976 100644
--- a/src/core/features/bundler.js
+++ b/src/core/features/bundler.js
@@ -73,6 +73,11 @@ export default {
       pkg.scripts.dev = 'tsc --watch';
     }
 
+    // A service owns its `dev` script (tsx/node --watch on the server entry); the
+    // bundler only builds it. Don't also contribute a `dev` — that was a silent
+    // conflict the two features "resolved" purely by array order.
+    if (cfg.hasService) delete pkg.scripts.dev;
+
     if (build) pkg.scripts.prepublishOnly = pkg.scripts.build;
     pkg.scripts.clean = 'rimraf dist';
     if (build) pkg.devDependencies = { ...pkg.devDependencies, rimraf: '^6.0.0' };
diff --git a/src/core/features/index.js b/src/core/features/index.js
index 1156093..a541833 100644
--- a/src/core/features/index.js
+++ b/src/core/features/index.js
@@ -1,5 +1,12 @@
 // Feature registry. Order matters only for how package.json fragments merge
 // (later features deep-merge over earlier ones); files are keyed by path.
+//
+// Ordering contract: no two features may own the same file path or the same
+// package.json field for a given config. That invariant is enforced by
+// test/feature-registry.test.js across the whole config matrix, so ordering is
+// never load-bearing for correctness — if a new feature collides with an
+// existing one, the test fails rather than the winner being decided by position
+// here. Each feature declares a unique `id`, surfaced in collision diagnostics.
 
 import meta from './meta.js';
 import bundler from './bundler.js';
diff --git a/test/feature-registry.test.js b/test/feature-registry.test.js
new file mode 100644
index 0000000..467cef6
--- /dev/null
+++ b/test/feature-registry.test.js
@@ -0,0 +1,60 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import features from '../src/core/features/index.js';
+import { createProject } from '../src/embedded/index.js';
+import { PRESET_NAMES } from '../src/core/index.js';
+
+// Features merge their files and package.json fragments in array order, so a
+// collision between two of them is "resolved" silently by position. These tests
+// make that safe: every feature is uniquely identified, and no two features are
+// allowed to fight over the same output across the whole config matrix — a new
+// feature that collides fails here instead of shipping an order-dependent bug.
+
+test('every feature has a unique id', () => {
+  const ids = features.map((f) => f.id);
+  assert.ok(
+    ids.every((id) => typeof id === 'string' && id.length),
+    'each feature declares a string id',
+  );
+  assert.equal(new Set(ids).size, ids.length, `duplicate feature ids: ${ids.join(', ')}`);
+});
+
+test('no two features collide on a file or package.json field, across the matrix', () => {
+  const toggles = [
+    {},
+    { storybook: true },
+    { knip: true },
+    { jsr: true },
+    { pkgChecks: true },
+    { sizeLimit: true },
+    { e2e: true },
+    { env: true },
+    { canary: true },
+    { doctor: true },
+    { minify: true },
+  ];
+  const linters = ['eslint-prettier', 'biome', 'oxlint'];
+  const hooks = ['simple-git-hooks', 'husky', 'lefthook'];
+
+  const collisions = new Set();
+  for (const preset of PRESET_NAMES) {
+    for (const t of toggles) {
+      for (const lint of linters) {
+        for (const gitHooks of hooks) {
+          let project;
+          try {
+            project = createProject({ preset, name: 'x', overrides: { ...t, lint, gitHooks } });
+          } catch {
+            continue; // an invalid combination — validation covers those elsewhere
+          }
+          for (const d of project.diagnostics) {
+            if (d.code === 'FEATURE_FILE_COLLISION' || d.code === 'PACKAGE_FIELD_CONFLICT') {
+              collisions.add(`${d.code} on ${d.field} — ${d.message}`);
+            }
+          }
+        }
+      }
+    }
+  }
+  assert.deepEqual([...collisions], [], 'features collide (ownership is order-dependent)');
+});