build: development server builds for solid-js and @solidjs/web; uniform <entry>.dev.js naming

.changeset/dev-artifact-naming.md

@@ -0,0 +1,7 @@
+---
+"solid-js": patch
+"@solidjs/web": patch
+"@solidjs/universal": patch
+---
+
+Rename the three legacy client dev artifacts to the `<entry>.dev.{js,cjs}` convention every other dev build already uses: `solid-js/dist/dev.*` → `dist/solid.dev.*`, `@solidjs/web/dist/dev.*` → `dist/web.dev.*`, `@solidjs/universal/dist/dev.*` → `dist/universal.dev.*`. With server dev builds now shipping as `dist/server.dev.*`, a bare `dev.js` no longer says which entry it is the dev build of. The `exports` maps are updated; only code deep-importing `dist/dev.js` directly (bypassing `exports`) is affected.

.changeset/server-dev-build.md

@@ -0,0 +1,12 @@
+---
+"solid-js": patch
+"@solidjs/web": patch
+---
+
+Add development server builds — `dist/server.dev.*` for `solid-js` and `@solidjs/web`, and `frames/dist/server.dev.*` — selected by the `development` export condition nested under `node`/`worker`/`deno` (nesting is required: those conditions precede the top-level `development` key, so a top-level entry never matched on a server). Until now SSR had no dev build: the only server artifact was built with `_SOLID_DEV_` stripped, so the server runtime's dev checks (head/preload descriptor validation, `useHead` warnings, the committed-response header guard) never ran outside the test suite.
+
+The server entries now gate their public dev flags on the same `_SOLID_DEV_` replace as their internals instead of hard-coding them: `solid-js`'s server `DEV` is `@solidjs/signals`' `DEV` object in the dev artifact (so `DEV.diagnostics.subscribe`/`capture` work server-side) and `undefined` in prod; `@solidjs/web`'s server `isDev` is `true` in the dev artifact and `false` in prod.
+
+Behavior change for dev SSR hosts that pass the `development` condition (Vite dev does by default): a header write after the response has committed now **throws** with the offending header named, where the production artifact continues to `console.error` and drop the write.
+
+Also runs `replaceDev(false)` on `solid-js`'s production server build so a future `_SOLID_DEV_` gate in `src/server/` cannot constant-fold into the dev branch in production.

.changeset/signals-dev-cjs.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/signals": patch
+---
+
+Add a development CJS build, `dist/node.dev.cjs`, selected by the `development` condition on the `require` branch of `exports`. Previously `require` always resolved to the production `dist/node.cjs` (`__DEV__` false), so a CJS host that resolved `solid-js`'s dev server artifact would get `DEV === undefined` from its `@solidjs/signals` dependency — a dev server runtime whose diagnostics channel was silently absent. Dev CJS is the unmangled twin of `dist/dev.js`; the production CJS is unchanged.

.cursor/rules/web.mdc

@@ -64,7 +64,10 @@ Browser-safe stubs that log errors if server APIs are accidentally used in brows
 ## Build Outputs
 
 - `dist/web.js` — production browser
-- `dist/dev.js` — development browser (with `_SOLID_DEV_` enabled)
-- `dist/server.js` — server (Node/Deno/Worker)
+- `dist/web.dev.js` — development browser (with `_SOLID_DEV_` enabled)
+- `dist/server.js` — production server (Node/Deno/Worker)
+- `dist/server.dev.js` — development server (`development` export condition, nested under `node`/`worker`/`deno`)
+
+Every dev artifact is `<entry>.dev.{js,cjs}` beside its prod `<entry>.{js,cjs}` — the same rule for `frames/`, `server-functions/`, and the other packages. Dev-ness is a build mode, not an entry.
 
 Rollup with Babel for JSX transformation, `@rollup/plugin-replace` for dev/prod flags.

packages/signals/package.json

@@ -34,14 +34,15 @@
       },
       "require": {
         "types": "./dist/types-cjs/index.d.cts",
+        "development": "./dist/node.dev.cjs",
         "default": "./dist/node.cjs"
       }
     },
     "./package.json": "./package.json"
   },
   "scripts": {
     "build": "npm-run-all -nl build:* && pnpm types",
-    "build:clean": "rimraf dist/dev dist/prod dist/node dist/dev.js dist/prod.js dist/node.cjs",
+    "build:clean": "rimraf dist/dev dist/prod dist/node dist/dev.js dist/prod.js dist/node.cjs dist/node.dev.cjs",
     "build:js": "rollup -c && node ./scripts/mangle-props.mjs dist/prod dist/node.cjs && node ./scripts/check-pure.mjs dist/prod",
     "types": "tsc -p tsconfig.build.json && node ../../scripts/sync-dual-types.mjs ./dist/types ./dist/types-cjs",
     "test": "vitest run",

packages/signals/rollup.config.js

@@ -6,7 +6,7 @@ import prettier from "rollup-plugin-prettier";
 // consumed exclusively by bundlers, which can drop whole feature modules —
 // including their top-level GlobalQueue hook installs, which statement-level
 // shaking of a flat file can never remove (#2883) — and scope-hoist the rest
-// back into one module. Dev and node stay flat single files: dev bundle size
+// back into one module. Dev and node (prod + dev CJS) stay flat single files: dev bundle size
 // doesn't matter (and vitest's per-module SSR transform makes a chunked tree
 // ~2x slower in the flush hot path, poisoning CI benches), and CJS `require`
 // can't tree-shake, so a tree would charge unbundled SSR the per-module-
@@ -95,5 +95,38 @@ export default [
         parser: "typescript"
       })
     ]
+  },
+  {
+    // Dev CJS — the `require` twin of dist/dev.js, selected by the
+    // `development` condition on the `require` branch. Without it a CJS host
+    // that resolved solid-js's `dist/server.dev.cjs` would `require` the prod
+    // `dist/node.cjs` (`__DEV__` false) and get `DEV === undefined` from a dev
+    // artifact — a lie that goes unnoticed until something emits into
+    // `DEV.diagnostics`. Flat single file like node.cjs; not mangled (dev
+    // outputs never are — see build:js).
+    input: "src/index.ts",
+    output: {
+      file: "dist/node.dev.cjs",
+      format: "cjs",
+      exports: "named"
+    },
+    plugins: [
+      replace({
+        __DEV__: "true",
+        __TEST__: "false",
+        preventAssignment: true
+      }),
+      typescript({
+        declaration: false,
+        outDir: "dist",
+        module: "esnext",
+        target: "esnext",
+        moduleResolution: "bundler",
+        verbatimModuleSyntax: true
+      }),
+      prettier({
+        parser: "typescript"
+      })
+    ]
   }
 ];

packages/signals/tests/dist-cjs-artifacts.test.ts

@@ -0,0 +1,35 @@
+/**
+ * Direct coverage of the built CJS artifacts — dist/node.cjs (prod, the
+ * `require` default) and dist/node.dev.cjs (the `development` condition on
+ * the `require` branch). The suite otherwise imports source under vitest's
+ * `__DEV__: true` define, so it cannot see whether each artifact's replace
+ * ran. `DEV` is the observable: defined in dev, `undefined` in prod. The dev
+ * CJS exists so a CJS host that resolves solid-js's `dist/server.dev.cjs`
+ * also gets a signals with a live `DEV.diagnostics` — one dev flag per
+ * process, not one per module format. Requires a prior build (the turbo
+ * `test` task depends on `build`).
+ */
+import { createRequire } from "node:module";
+import { describe, expect, test } from "vitest";
+
+const require = createRequire(import.meta.url);
+
+describe("@solidjs/signals CJS artifacts", () => {
+  test("dist/node.cjs (prod) exports DEV as undefined", () => {
+    const prod = require("../dist/node.cjs");
+    expect(prod.DEV).toBeUndefined();
+  });
+
+  test("dist/node.dev.cjs exports a live DEV with the diagnostics channel", () => {
+    const dev = require("../dist/node.dev.cjs");
+    expect(dev.DEV).toBeDefined();
+    expect(typeof dev.DEV.diagnostics.subscribe).toBe("function");
+    expect(typeof dev.DEV.diagnostics.capture).toBe("function");
+  });
+
+  test("the two artifacts export the same surface", () => {
+    const prod = require("../dist/node.cjs");
+    const dev = require("../dist/node.dev.cjs");
+    expect(Object.keys(dev).sort()).toEqual(Object.keys(prod).sort());
+  });
+});

packages/solid/package.json

@@ -28,6 +28,16 @@
   "exports": {
     ".": {
       "worker": {
+        "development": {
+          "import": {
+            "types": "./types/index.d.ts",
+            "default": "./dist/server.dev.js"
+          },
+          "require": {
+            "types": "./types-cjs/index.d.cts",
+            "default": "./dist/server.dev.cjs"
+          }
+        },
         "import": {
           "types": "./types/index.d.ts",
           "default": "./dist/server.js"
@@ -41,11 +51,11 @@
         "development": {
           "import": {
             "types": "./types/index.d.ts",
-            "default": "./dist/dev.js"
+            "default": "./dist/solid.dev.js"
           },
           "require": {
             "types": "./types-cjs/index.d.cts",
-            "default": "./dist/dev.cjs"
+            "default": "./dist/solid.dev.cjs"
           }
         },
         "import": {
@@ -58,6 +68,16 @@
         }
       },
       "deno": {
+        "development": {
+          "import": {
+            "types": "./types/index.d.ts",
+            "default": "./dist/server.dev.js"
+          },
+          "require": {
+            "types": "./types-cjs/index.d.cts",
+            "default": "./dist/server.dev.cjs"
+          }
+        },
         "import": {
           "types": "./types/index.d.ts",
           "default": "./dist/server.js"
@@ -68,6 +88,16 @@
         }
       },
       "node": {
+        "development": {
+          "import": {
+            "types": "./types/index.d.ts",
+            "default": "./dist/server.dev.js"
+          },
+          "require": {
+            "types": "./types-cjs/index.d.cts",
+            "default": "./dist/server.dev.cjs"
+          }
+        },
         "import": {
           "types": "./types/index.d.ts",
           "default": "./dist/server.js"
@@ -80,11 +110,11 @@
       "development": {
         "import": {
           "types": "./types/index.d.ts",
-          "default": "./dist/dev.js"
+          "default": "./dist/solid.dev.js"
         },
         "require": {
           "types": "./types-cjs/index.d.cts",
-          "default": "./dist/dev.cjs"
+          "default": "./dist/solid.dev.cjs"
         }
       },
       "import": {

packages/solid/rollup.config.js

@@ -44,6 +44,10 @@ export default [
     plugins: [replaceDev(false)].concat(plugins)
   },
   {
+    // Prod server build. `src/server/` has no `"_SOLID_DEV_"` gates today, but
+    // the replace must run anyway: without it babel constant-folds the truthy
+    // string literal and the first gate anyone adds takes the dev branch in
+    // production (the #2982 failure @solidjs/web's server entry shipped with).
     input: "src/server/index.ts",
     output: [
       {
@@ -56,17 +60,37 @@ export default [
       }
     ],
     external: ["@solidjs/signals", "stream"],
-    plugins
+    plugins: [replaceDev(false)].concat(plugins)
+  },
+  {
+    // Dev server build, selected by the `development` condition nested under
+    // `node`/`worker`/`deno` in package.json exports (nested on purpose: at the
+    // top level `node` precedes `development` and would win). Until this
+    // existed, SSR had no dev build at all — server-side dev diagnostics had
+    // nowhere to run. Mirrors `@solidjs/web/server-functions`'s server.dev.
+    input: "src/server/index.ts",
+    output: [
+      {
+        file: "dist/server.dev.cjs",
+        format: "cjs"
+      },
+      {
+        file: "dist/server.dev.js",
+        format: "es"
+      }
+    ],
+    external: ["@solidjs/signals", "stream"],
+    plugins: [replaceDev(true)].concat(plugins)
   },
   {
     input: "src/index.ts",
     output: [
       {
-        file: "dist/dev.cjs",
+        file: "dist/solid.dev.cjs",
         format: "cjs"
       },
       {
-        file: "dist/dev.js",
+        file: "dist/solid.dev.js",
         format: "es"
       }
     ],

packages/solid/src/server/index.ts

@@ -1,3 +1,5 @@
+import { DEV as _DEV, type Dev } from "@solidjs/signals";
+
 // From mock signals (same exports that index.ts pulls from @solidjs/signals)
 export {
   $PROXY,
@@ -126,5 +128,11 @@ export function materializeContainerTrace(marker: unknown): unknown {
   return marker;
 }
 
-// Dev — no dev mode on server
-export const DEV = undefined;
+// Dev — same shape as the client entry. `"_SOLID_DEV_"` is replaced per build
+// (dist/server.dev.* → true, dist/server.* → false), so the dev artifact
+// exposes @solidjs/signals' DEV object — its `diagnostics` channel is the bus
+// server-side dev findings report through — and prod exports `undefined`.
+// The server reimplements reactivity, so `DEV.attribution`/graph helpers
+// have nothing to introspect here; the channel is what's shared.
+const IS_DEV = "_SOLID_DEV_" as string | boolean;
+export const DEV: Dev | undefined = IS_DEV ? _DEV : undefined;

packages/solid/test/server/dist-server-artifact.spec.ts

@@ -0,0 +1,39 @@
+/** @vitest-environment node */
+/**
+ * Direct coverage of the built server artifacts — dist/server.js (prod) and
+ * dist/server.dev.js (the `development` export condition, nested under
+ * node/worker/deno). The rest of the suite imports source, where the
+ * `"_SOLID_DEV_"` literal is truthy, so it cannot see whether the replace
+ * ran per artifact. `DEV` is the observable: the server entry gates it the
+ * same way the client does, so the dev artifact must expose @solidjs/signals'
+ * DEV object (the diagnostics channel server-side findings report through)
+ * and the prod artifact must export `undefined`. A string scan can't pin
+ * this — babel's constant folding erases the marker either way.
+ * Requires a prior `pnpm build`.
+ */
+import { describe, expect, test } from "vitest";
+// Relative imports on purpose: they bypass the `solid-js` → source alias in
+// vite.config.mjs so the built artifacts themselves are under test.
+// @ts-ignore — dist files have no adjacent type declarations.
+import * as prod from "../../dist/server.js";
+// @ts-ignore
+import * as dev from "../../dist/server.dev.js";
+import { DEV as signalsDEV } from "@solidjs/signals";
+
+describe("solid-js server artifacts", () => {
+  test("dist/server.js (prod) exports DEV as undefined", () => {
+    expect(prod.DEV).toBeUndefined();
+  });
+
+  test("dist/server.dev.js exports @solidjs/signals' DEV object", () => {
+    expect(dev.DEV).toBeDefined();
+    // Not a copy or a stub: the very object signals exports, so a subscriber
+    // on `DEV.diagnostics` sees server findings without a second channel.
+    expect(dev.DEV).toBe(signalsDEV);
+    expect(typeof dev.DEV.diagnostics.subscribe).toBe("function");
+  });
+
+  test("the two artifacts export the same surface", () => {
+    expect(Object.keys(dev).sort()).toEqual(Object.keys(prod).sort());
+  });
+});

packages/solid/test/server/export-parity.spec.ts

@@ -15,10 +15,15 @@ describe("Export parity: server mirrors client", () => {
     expect(missingFromServer).toEqual([]);
   });
 
-  test("all function exports are functions (or undefined for DEV)", () => {
+  test("all function exports are functions (DEV is the same signals object as the client's)", () => {
     for (const [key, value] of Object.entries(server)) {
       if (key === "DEV") {
-        expect(value).toBeUndefined();
+        // Both entries gate on `"_SOLID_DEV_"` (truthy here — source, not
+        // dist) and re-export @solidjs/signals' DEV, so the server's dev
+        // diagnostics channel IS the client's. dist/server.js exports
+        // `undefined`; the dist artifact specs pin that.
+        expect(value).toBeDefined();
+        expect(value).toBe(client.DEV);
         continue;
       }
       if (typeof (client as any)[key] === "function") {

packages/universal/package.json

@@ -29,11 +29,11 @@
       "development": {
         "import": {
           "types": "./types/index.d.ts",
-          "default": "./dist/dev.js"
+          "default": "./dist/universal.dev.js"
         },
         "require": {
           "types": "./types-cjs/index.d.cts",
-          "default": "./dist/dev.cjs"
+          "default": "./dist/universal.dev.cjs"
         }
       },
       "import": {

packages/universal/rollup.config.js

@@ -47,11 +47,11 @@ export default [
     input: "src/index.ts",
     output: [
       {
-        file: "dist/dev.cjs",
+        file: "dist/universal.dev.cjs",
         format: "cjs"
       },
       {
-        file: "dist/dev.js",
+        file: "dist/universal.dev.js",
         format: "es"
       }
     ],

packages/web/frames/package.json

@@ -17,6 +17,16 @@
           "default": "./dist/client.cjs"
         }
       },
+      "development": {
+        "import": {
+          "types": "../types/frames/server.d.ts",
+          "default": "./dist/server.dev.js"
+        },
+        "require": {
+          "types": "../types-cjs/frames/server.d.cts",
+          "default": "./dist/server.dev.cjs"
+        }
+      },
       "import": {
         "types": "../types/frames/server.d.ts",
         "default": "./dist/server.js"