René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Send() blocks indefinitely when ReadyForInitialPrompt returns false despite Status() reporting \"stable\"","articleBody":"## Bug\n\n`POST /message` with `type: \"user\"` hangs indefinitely when `ReadyForInitialPrompt` never returns `true` for the current screen, even though `GET /status` returns `\"stable\"`.\n\n## Root cause\n\n`statusLocked()` does not check `initialPromptReady`. It returns `\"stable\"` when the screen is stable and the queue is empty. `Send()` passes the status validation and enqueues the message. But the `stableSignal` (which the send loop waits on) requires `initialPromptReady` to be `true`. If `ReadyForInitialPrompt` never returns `true`, the signal never fires and `Send()` blocks forever.\n\n```\nstatusLocked() = \"stable\"   →  Send() passes status check, enqueues\nstableSignal requires:       →  initialPromptReady \u0026\u0026 queue \u003e 0 \u0026\u0026 screenStable\ninitialPromptReady = false   →  signal never fires\nSend() blocks on errCh       →  forever\n```\n\n## Real-world trigger\n\nClaude Code v2.1.87 shows a theme selection onboarding screen that uses `╌╌╌` (Unicode dashed lines) instead of `───` (box-drawing characters). The message box detection in `findGreaterThanMessageBox` / `findGenericSlimMessageBox` fails because it looks for `───────────────` and `\u003e` which aren't present on this screen. `initialPromptReady` stays `false` and all `user`-type messages hang.\n\nLast 6 lines of the actual screen content:\n```\n  1  function greet() {                                                         \n  2 -  console.log(\"Hello, World!\");                                            \n  2 +  console.log(\"Hello, Claude!\");                                           \n  3  }                                                                          \n ╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌ \n  Syntax theme: Monokai Extended (ctrl+t to disable)                            \n```\n\nNote: `╌` (U+254C, BOX DRAWINGS LIGHT DOUBLE DASH HORIZONTAL) vs `─` (U+2500, BOX DRAWINGS LIGHT HORIZONTAL).\n\n## Reproducing test\n\n```go\nfunc TestSendBlocksWhenInitialPromptNotReady(t *testing.T) {\n\tctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)\n\tt.Cleanup(cancel)\n\n\tmClock := quartz.NewMock(t)\n\tagent := \u0026testAgent{screen: \"onboarding screen without message box\"}\n\tcfg := st.PTYConversationConfig{\n\t\tClock:                 mClock,\n\t\tSnapshotInterval:      100 * time.Millisecond,\n\t\tScreenStabilityLength: 200 * time.Millisecond,\n\t\tAgentIO:               agent,\n\t\tReadyForInitialPrompt: func(screen string) bool {\n\t\t\treturn false // Simulates failed message box detection.\n\t\t},\n\t\tLogger: slog.New(slog.NewTextHandler(io.Discard, nil)),\n\t}\n\tc := st.NewPTY(ctx, cfg, \u0026testEmitter{})\n\tc.Start(ctx)\n\n\t// Fill snapshot buffer to reach stability.\n\tadvanceFor(ctx, t, mClock, 300*time.Millisecond)\n\n\t// Status reports \"stable\" — Send() will pass the status check.\n\tassert.Equal(t, st.ConversationStatusStable, c.Status())\n\n\t// But Send() blocks forever because stableSignal requires\n\t// initialPromptReady, which is false.\n\tvar sendDone atomic.Bool\n\tgo func() {\n\t\t_ = c.Send(st.MessagePartText{Content: \"hello\"})\n\t\tsendDone.Store(true)\n\t}()\n\tadvanceFor(ctx, t, mClock, 20*time.Second)\n\n\tassert.False(t, sendDone.Load(),\n\t\t\"Send() blocks forever: status said stable but stableSignal never fires\")\n}\n```\n\n## Possible fixes\n\n1. **Make `statusLocked()` check `initialPromptReady`**: return `\"initializing\"` or `\"changing\"` when `initialPromptReady` is false. This would cause `Send()` to reject the message with `ErrMessageValidationChanging` instead of hanging.\n2. **Improve message box detection**: add `╌╌╌` as an alternative to `───` in `findGreaterThanMessageBox` / `findGenericSlimMessageBox`.\n3. **Both**: fix the detection AND add the safety check in `statusLocked()`.\n\nOption 3 is likely the right approach — fix the detection for this specific Claude Code version, and add the statusLocked guard so future detection failures fail fast instead of hanging.\n\nDiscovered while smoke-testing #208.\n\n\u003e 🤖 This response was generated by Coder Agents.","author":{"url":"https://github.com/johnstcn","@type":"Person","name":"johnstcn"},"datePublished":"2026-03-31T13:36:06.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/209/agentapi/issues/209"}