diff --git a/packages/opencode/src/cli/cmd/tui/thread.ts b/packages/opencode/src/cli/cmd/tui/thread.ts
index 04037a50f3..8449216f5d 100644
--- a/packages/opencode/src/cli/cmd/tui/thread.ts
+++ b/packages/opencode/src/cli/cmd/tui/thread.ts
@@ -198,7 +198,7 @@ export const TuiThreadCommand = cmd({
           } catch (error) {
             UI.error(errorMessage(error))
             process.exitCode = 1
-            return
+            return false
           }
 
           const config = await TuiConfig.get()
@@ -221,6 +221,7 @@ export const TuiThreadCommand = cmd({
               fork: args.fork,
             },
           }).done
+          return true
         } finally {
           await input.stop?.()
         }
@@ -233,12 +234,15 @@ export const TuiThreadCommand = cmd({
           frame: args.debugFrame,
           directory: cwd,
         })
-        await launch({
-          url: "http://opencode.debug",
-          sessionID: transport.sessionID,
-          fetch: transport.fetch,
-          events: transport.events,
-        })
+        if (
+          !(await launch({
+            url: "http://opencode.debug",
+            sessionID: transport.sessionID,
+            fetch: transport.fetch,
+            events: transport.events,
+          }))
+        )
+          return
         process.exit(0)
         return
       }
@@ -310,17 +314,20 @@ export const TuiThreadCommand = cmd({
         client.call("checkUpgrade", { directory: cwd }).catch(() => {})
       }, 1000).unref?.()
 
-      await launch({
-        ...transport,
-        sessionID: args.session,
-        prompt,
-        stop,
-        onSnapshot: async () => {
-          const tui = writeHeapSnapshot("tui.heapsnapshot")
-          const server = await client.call("snapshot", undefined)
-          return [tui, server]
-        },
-      })
+      if (
+        !(await launch({
+          ...transport,
+          sessionID: args.session,
+          prompt,
+          stop,
+          onSnapshot: async () => {
+            const tui = writeHeapSnapshot("tui.heapsnapshot")
+            const server = await client.call("snapshot", undefined)
+            return [tui, server]
+          },
+        }))
+      )
+        return
     } finally {
       unguard?.()
     }
diff --git a/packages/opencode/test/cli/tui/thread.test.ts b/packages/opencode/test/cli/tui/thread.test.ts
index 53b7488c26..c5dfbb8414 100644
--- a/packages/opencode/test/cli/tui/thread.test.ts
+++ b/packages/opencode/test/cli/tui/thread.test.ts
@@ -1,7 +1,9 @@
 import { describe, expect, test } from "bun:test"
+import { Effect } from "effect"
 import fs from "fs/promises"
 import path from "path"
 import { tmpdir } from "../../fixture/fixture"
+import { cliIt } from "../../lib/cli-process"
 import { resolveThreadDirectory } from "../../../src/cli/cmd/tui/thread"
 
 describe("tui thread", () => {
@@ -25,4 +27,13 @@ describe("tui thread", () => {
   test("uses the real cwd after resolving a relative project from PWD", async () => {
     await check(".")
   })
+
+  cliIt.live("exits nonzero when a requested session ID is invalid", ({ opencode }) =>
+    Effect.gen(function* () {
+      const result = yield* opencode.spawn(["--session", "invalid", "--pure"])
+
+      expect(result.exitCode).not.toBe(0)
+      expect(result.stderr).toContain("Invalid session ID")
+    }),
+  )
 })