@@ -0,0 +1,13 @@
+---
+'@objectstack/cli': patch
+---
+
+fix(cli): `os dev` compiles the config before it boots, so the served connector `baseUrl` is the one dispatch calls
+
+Clause-②: no
+Metadata-protocol: none
+
+- **Before.** `os dev` booted whatever `dist/objectstack.json` already held, and compiled only when it was missing or `--compile` was passed. A host config's dev boot serves the stack from two copies: the config module the server evaluates (what a provider-bound connector is materialized from, so what dispatch calls) and the artifact (what `/api/v1/meta/<type>` serves). A config value read from the environment, such as `examples/app-showcase`'s self URL built from `OS_PORT`, then differed between them. With `OS_PORT=41302` over an artifact built without it, `GET /api/v1/meta/connector/showcase_status_api` served `http://127.0.0.1:3000` while the connector called port 41302.
+- **Now.** `--compile` is on by default: `os dev` compiles `objectstack.config.ts` into the artifact it serves, in its own environment, before the server starts, so both copies come from one evaluation. The watch loop already recompiled in that environment.
+- **`--no-compile`** boots the existing artifact as built, as a bare `os dev` did before (it is still compiled when missing, and the startup warning still says when it is older than the sources). A pinned artifact (`--artifact`, `OS_ARTIFACT_URL`, a remote `OS_ARTIFACT_PATH`) is never rebuilt. With no `objectstack.config.ts`, an existing artifact boots as before.
+- `os serve` and `os start` are unchanged.
@@ -192,7 +192,7 @@ os dev --database file:./data/test.db --auth-secret $(openssl rand -hex 32)
 | `--cert <path>` | — | Path to a TLS certificate (PEM). With `--key`, terminate TLS in the dev process and serve `https://localhost:<port>`. Bring your own certificate — none is generated |
 | `--key <path>` | — | Path to the private key (PEM) for `--cert`. Required with `--cert` |
 | `--ui` | — | Force Console UI on (already on by default in dev) |
-| `--compile` | — | Force compiling `objectstack.config.ts` → `dist/objectstack.json` before starting (auto when the artifact is missing; ignored with `--artifact`) |
+| `--compile` / `--no-compile` | — | Compile `objectstack.config.ts` → `dist/objectstack.json` before starting, under this boot's environment — default on, so a config value read from the environment (such as a self URL built from `OS_PORT`) is the same in the served metadata and in what runs. `--no-compile` boots the existing artifact as built (still compiled when it is missing). Ignored with `--artifact` |
 | `--fresh` | — | Ephemeral `OS_HOME` in the OS tempdir (clean DB, uploads root, and other `OS_HOME`-keyed state), auto-deleted on exit; implies `--seed-admin`. See the scope note below |
 | `--seed-admin` / `--no-seed-admin` | — | Seed a dev admin (`admin@objectos.ai` / `admin123`) on an empty DB — default on; override with `--admin-email` / `--admin-password` |
 | `-v, --verbose` | — | Verbose output |
 
@@ -32,7 +32,10 @@
  * **When this is read matters.** These are ordinary Node modules evaluated at
  * config load, so the read happens in whichever process loads
  * objectstack.config.ts. On the `os dev` / `os serve` path that is the serving
- * process itself, so the value follows the live environment. On the
+ * process itself, so the value follows the live environment; `os dev` also
+ * recompiles `dist/objectstack.json` in that environment before it boots, so
+ * the served connector metadata carries the same value (#26130), except under
+ * `os dev --no-compile`, which serves the metadata as last built. On the
  * artifact-only path (`os build` once, then `os start --artifact`) the
  * connector metadata is serialized into `dist/objectstack.json`, so the value
  * is frozen at BUILD time — set the env for the build, not just the boot.
 
@@ -246,6 +246,48 @@ export function forwardSeedSettledToParent(msg: unknown): boolean {
   return true;
 }
 
+/**
+ * Whether this `os dev` boot compiles the cwd config into the artifact it is
+ * about to serve, before the server starts (#26130).
+ *
+ * Yes by default whenever the boot serves an artifact this command builds and
+ * there is a config to build it from. The reason is the dev boot's two copies
+ * of one stack. A host config's `os dev` boot serves the stack from TWO places:
+ * the config MODULE, evaluated in the `serve` child (the AppPlugin wrap, whose
+ * registry copy is what a provider-bound connector is materialized from, so
+ * what dispatch calls), and the compiled artifact (the dev artifact door, whose
+ * copy is what `/api/v1/meta/<type>` serves). A config that reads the
+ * environment at module evaluation, as `examples/app-showcase`'s self URL reads
+ * `OS_PORT`, gives the module copy THIS boot's value and the artifact copy the
+ * value of whichever environment last compiled it. Measured on the showcase
+ * with `OS_PORT=41302` over an artifact built without it:
+ * `GET /api/v1/meta/connector/showcase_status_api` served
+ * `http://127.0.0.1:3000` while the materialized connector called 41302.
+ *
+ * Compiling here, in this process's environment (the `serve` child inherits
+ * the same one), makes both copies one evaluation's answer, so nothing has to
+ * restate which variables a config reads or in what order. The watch loop's
+ * recompiles already run in that environment, so the two stay one answer for
+ * the whole session.
+ *
+ * `--no-compile` keeps the old shortcut, booting the artifact as built (and
+ * the startup staleness warning says when it is older than the sources); a
+ * missing artifact is still compiled, since there is nothing else to serve. A
+ * pinned artifact (`--artifact`, `OS_ARTIFACT_URL`, a remote
+ * `OS_ARTIFACT_PATH`) is never rebuilt. With no config and a missing artifact
+ * the answer is yes, so the caller refuses there with the one remedy line.
+ */
+export function devCompilesAtBoot(opts: {
+  compile: boolean;
+  pinned: boolean;
+  configExists: boolean;
+  artifactExists: boolean;
+}): boolean {
+  if (opts.pinned) return false;
+  if (!opts.artifactExists) return true;
+  return opts.compile && opts.configExists;
+}
+
 /**
  * Whether this `os dev` boot runs the watch-recompile loop (#20681).
  *
@@ -332,9 +374,11 @@ export default class Dev extends Command {
     preset: Flags.string({
       description: 'Plugin tier preset forwarded to `serve`: minimal | default | full',
     }),
+    // Default ON (#26130): see `devCompilesAtBoot` for why a dev boot over an
+    // artifact it builds always rebuilds it first.
     compile: Flags.boolean({
-      description: 'Compile objectstack.config.ts to dist/objectstack.json before starting (auto if artifact missing). Ignored when --artifact is set.',
-      default: false,
+      description: 'Compile objectstack.config.ts to dist/objectstack.json before starting, under this boot\'s environment (default: on). --no-compile boots the existing artifact as built (still compiled when it is missing). Ignored when --artifact is set.',
+      default: true,
       allowNo: true,
     }),
     restart: Flags.boolean({
@@ -472,9 +516,15 @@ export default class Dev extends Command {
         printKV('Config', configPath, '📂');
       }
 
-      // Auto-compile only when we have a config AND the boot's artifact is one
-      // this command builds. A pinned artifact means "use this, don't rebuild".
-      const needsCompile = !pinnedArtifact && (flags.compile || !fs.existsSync(artifactPath));
+      // Compile only when the boot's artifact is one this command builds — a
+      // pinned artifact means "use this, don't rebuild" — and then by default
+      // (#26130, `devCompilesAtBoot`).
+      const needsCompile = devCompilesAtBoot({
+        compile: flags.compile,
+        pinned: Boolean(pinnedArtifact),
+        configExists,
+        artifactExists: fs.existsSync(artifactPath),
+      });
       if (needsCompile) {
         if (!configExists) {
           printError('No objectstack.config.ts and no --artifact given — nothing to start.');
@@ -531,8 +581,8 @@ export default class Dev extends Command {
       }
 
       // ── Startup staleness warning (#5148 startup variant) ───────────
-      // Without --compile, `os dev` boots whatever dist/objectstack.json
-      // holds. When the sources are NEWER than the artifact (edited while
+      // With --no-compile, `os dev` boots whatever dist/objectstack.json
+      // holds (#26130 made compiling the default). When the sources are NEWER than the artifact (edited while
       // the server was down, stale checkout), the boot silently serves the
       // old build — measured in #5148: the config had gained a capability
       // and dev still printed `Plugins: 38 loaded` until a manual build.
 
@@ -0,0 +1,59 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * PIN (#26130) — a bare `os dev` compiles the cwd config into the artifact it
+ * serves before the server starts, so the served metadata and the config
+ * module the `serve` child evaluates are one environment's answer.
+ *
+ * A PARSE-AND-DECIDE fact, the same instrument `dev-no-watch.pin.test.ts` uses:
+ * oclif's own parser over the command's real declarations, fed into the one
+ * decision the boot reads (`devCompilesAtBoot`). What the decision buys at the
+ * public door (`/api/v1/meta/connector/NAME` agreeing with the materialized
+ * connector on an `OS_PORT` boot) is measured on a real `os dev` boot in
+ * `dev-connector-env-parity.integration.test.ts`.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { Parser } from '@oclif/core';
+import Dev, { devCompilesAtBoot } from '../src/commands/dev.js';
+
+const parseDev = (argv: string[]) =>
+  Parser.parse(argv, { flags: Dev.flags, args: Dev.args, strict: true });
+
+/** The decision for a cwd holding a config and an already-built artifact, from parsed argv. */
+async function overBuiltArtifact(argv: string[]): Promise<boolean> {
+  const { flags } = await parseDev(argv);
+  return devCompilesAtBoot({
+    compile: flags.compile,
+    pinned: Boolean(flags.artifact),
+    configExists: true,
+    artifactExists: true,
+  });
+}
+
+describe('`os dev` compiles before it boots (#26130)', () => {
+  it('bare `os dev` over an already-built artifact compiles it again', async () => {
+    expect(await overBuiltArtifact([])).toBe(true);
+  });
+
+  it('`--no-compile` boots the built artifact as it is', async () => {
+    expect(await overBuiltArtifact(['--no-compile'])).toBe(false);
+  });
+
+  it('a pinned `--artifact` is never rebuilt, whatever `--compile` says', async () => {
+    expect(await overBuiltArtifact(['--artifact', 'elsewhere/objectstack.json'])).toBe(false);
+    expect(await overBuiltArtifact(['--artifact', 'elsewhere/objectstack.json', '--compile'])).toBe(false);
+  });
+
+  it('a missing artifact is compiled even under `--no-compile`', async () => {
+    const { flags } = await parseDev(['--no-compile']);
+    expect(devCompilesAtBoot({ compile: flags.compile, pinned: false, configExists: true, artifactExists: false })).toBe(true);
+  });
+
+  it('with no config, a built artifact boots as it is and a missing one reaches the refusal', async () => {
+    const { flags } = await parseDev([]);
+    expect(devCompilesAtBoot({ compile: flags.compile, pinned: false, configExists: false, artifactExists: true })).toBe(false);
+    // `true` here is what routes the boot to the "nothing to start" refusal.
+    expect(devCompilesAtBoot({ compile: flags.compile, pinned: false, configExists: false, artifactExists: false })).toBe(true);
+  });
+});