run: defer startup work until first paint

Keep optional initialization off the critical rendering path so the prompt
appears before network and heavy module startup completes. Stop deferred
work when the footer closes to avoid needless requests during early exit.

packages/opencode/test/cli/run/runtime.test.ts

@@ -301,14 +301,17 @@ describe("run interactive runtime", () => {
     expect(legacyCommands).not.toHaveBeenCalled()
   })
 
-  test("paints before resolving the catalog-selected model", async () => {
+  test("defers catalog-selected model resolution until after first paint", async () => {
     const sdk = new OpencodeClient()
     const defaultStarted = defer<void>()
     const releaseDefault = defer<void>()
     const lifecycleStarted = defer<void>()
+    const painted = defer<void>()
     const modelShown = defer<void>()
+    let defaultRequested = false
     const events: FooterEvent[] = []
     const api = footer(events)
+    api.idle = () => painted.promise
     const event = api.event
     api.event = (value) => {
       event(value)
@@ -318,6 +321,7 @@ describe("run interactive runtime", () => {
     }
 
     spyOn(sdk.v2.model, "default").mockImplementation(async () => {
+      defaultRequested = true
       defaultStarted.resolve()
       await releaseDefault.promise
       return ok({
@@ -382,8 +386,10 @@ describe("run interactive runtime", () => {
       },
     )
 
-    await defaultStarted.promise
     await lifecycleStarted.promise
+    expect(defaultRequested).toBe(false)
+    painted.resolve()
+    await defaultStarted.promise
     releaseDefault.resolve()
     await modelShown.promise
     await task
@@ -395,6 +401,49 @@ describe("run interactive runtime", () => {
     })
   })
 
+  test("does not start deferred work after the footer closes", async () => {
+    const sdk = new OpencodeClient()
+    const lifecycleStarted = defer<void>()
+    const painted = defer<void>()
+    const api = footer()
+    api.idle = () => painted.promise
+    const defaultModel = spyOn(sdk.v2.model, "default")
+
+    const task = runInteractiveMode(
+      {
+        sdk,
+        directory: "/tmp",
+        sessionID: "ses-closed",
+        resume: false,
+        agent: "build",
+        model: undefined,
+        variant: undefined,
+        files: [],
+        thinking: false,
+        backgroundSubagents: false,
+      },
+      {
+        createRuntimeLifecycle: async () => {
+          lifecycleStarted.resolve()
+          return {
+            footer: api,
+            onResize: () => () => {},
+            refreshTheme: () => {},
+            resetForReplay: () => Promise.resolve(),
+            close: () => Promise.resolve(),
+          }
+        },
+      },
+    )
+
+    await lifecycleStarted.promise
+    api.close()
+    painted.resolve()
+    await task
+
+    expect(defaultModel).not.toHaveBeenCalled()
+  })
+
   test("retains last-known-good state across failed coalesced refreshes and retries later", async () => {
     const sdk = new OpencodeClient()
     const refreshGate = defer<void>()