I read this as a read-only failure investigation - I’ll trace the disposable E2E restart path and return exactly three code-grounded causes, each paired with one decisive runtime query.


The evidence narrows the stop to startup between the fourth child’s `sendChatAction` and its first `setMyCommands`/`getUpdates`; I’m now separating a true startup stall from a child exit hidden by the launcher.


I read this as a read-only failure investigation - I traced the exact startup boundary and ranked three code-supported causes.

1. **Blocked membership-journal lock**
   - Fourth child reaches the final readiness API call, `sendChatAction`, at `fake-api-calls.jsonl:70`.
   - That call is the last await inside `verify_subscription_readiness()` (`gateway/platforms/telegram_staff_membership_gate.py:302`).
   - The next blocking operation is `journal.append()` (`gateway/platforms/telegram.py:2433`), which takes an unbounded exclusive `flock` (`gateway/platforms/telegram_staff_membership_gate.py:381`).
   - This exactly explains a live child that never reaches polling.
   - **Decisive runtime query:** During the stall, run `py-spy dump --pid <normal-restart-child-pid>`; a main-thread stack at `MembershipJournal.append` line 381 confirms it.

2. **`sendChatAction` was recorded but its response never completed**
   - The fake records an action before dispatch finishes (`scripts/dualcoach_v111_fake_telegram_engine.py:293-306`); therefore line 70 proves request arrival, not that PTB received the response.
   - The child cannot leave `verify_subscription_readiness()` until `await bot.send_chat_action(...)` returns (`gateway/platforms/telegram_staff_membership_gate.py:302`).
   - Earlier identical calls succeeded at action sequences 4, 27, and 47, making this lower-ranked but still the exact preceding boundary.
   - **Decisive runtime query:** During the stall, run `py-spy dump --pid <harness-pid>` and inspect the `dualcoach-v111-fake-telegram` thread; a stack inside `_TelegramHandler._reply` or request handling identifies an incomplete response.

3. **The harness waits for a late milestone with a startup-wide 20-second budget**
   - `_start_and_wait_for_poll()` starts the child and waits only for `getUpdates` (`scripts/run_dualcoach_v111_disposable_e2e.py:224-245`).
   - Before polling, startup performs membership readiness, application startup, all nutrition recovery, and production command registration (`gateway/platforms/telegram.py:3055-3057`); only afterward does `start_polling()` run (`gateway/platforms/telegram.py:3128`).
   - The fourth restart has more durable state than earlier starts, but the same fixed 20-second timeout applies. The action log has no timestamps, so action 70 may simply have occurred near expiry.
   - **Decisive runtime query:** During the stall, run `py-spy dump --pid <normal-restart-child-pid>`; a stack in `_recover_task26_nutrition_background` or command registration, rather than polling, confirms startup ordering exhausted the budget.

The strongest immediate suspect is the unbounded membership-journal `flock`; the current evidence cannot distinguish it from an unfinished `sendChatAction` because child stderr is discarded at `scripts/run_dualcoach_v111_disposable_e2e.py:173`.