chore(cli): changeset for the os dev banner/MCP-block order (#22410)

Claude-Session: https://claude.ai/code/session_01BmsuLyUeuG5CNpZFMH1jzS
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/22410-dev-banner-order.md

@@ -0,0 +1,11 @@
+---
+'@objectstack/cli': patch
+---
+
+fix(cli): `os dev` prints the server's ready banner whole, then the MCP connect block whole, instead of interleaving the two (#22410)
+
+Clause-②: no
+
+- **What a terminal showed.** `os dev` is two processes writing one terminal. The parent prints the MCP connect block (`🤖 MCP server — connect a coding agent:` with its Endpoint, Skill, Connect and Disable rows) when the `serve` child sends `objectstack:listening`, and the child sent that message before it printed its ready banner. Measured under a pty on the Build-with-Claude-Code tutorial project, 6 of 7 boots printed the block above or inside the banner. In 2 of them, banner lines landed between the block's rows, in one case the `➜ Console:` and `➜ MCP:` rows. A setup boot before those seven printed the `🔑 Dev admin` credential lines and the whole plugin section between `Skill` and `Connect`.
+- **What changed.** The child now sends `objectstack:listening` after its ready banner and boot diagnostics have printed. The parent prints the block on that message, so it always comes last, under the banner's `Press Ctrl+C to stop` row. The order follows from the sequence itself, with no timer: the banner is written to the terminal before the message is sent. After the change, every measured boot printed the banner whole and then the block whole.
+- **What did not change.** The message is still `{ type: 'objectstack:listening', port, url }`, carrying the port actually bound. The runtime state file is still written before either announcement, and `objectstack:seed-settled` still follows `objectstack:listening`. A program that spawns `os serve` with an IPC channel receives `objectstack:listening` slightly later than before: after the banner has printed instead of before.

packages/cli/src/commands/serve.ts

@@ -770,7 +770,7 @@ export interface BoundPortChannels {
  * into the terminal this process writes its banner to. Sent BEFORE the banner,
  * the two processes wrote that terminal at once: measured under a pty on the
  * Build-with-Claude-Code tutorial project, 6 of 7 boots printed the block
- * above or inside the banner, 2 of them with banner rows inside the block, and
+ * above or inside the banner, 2 of them with banner lines inside the block, and
  * one probe boot printed the whole credential and plugin section between
  * `Skill` and `Connect`.
  *