## Summary
Increase the external currentTime/read request timeout from 5 seconds to
10 seconds.
## Validation
- just fmt
- Focused app-server test build was stopped to defer validation to CI.
## Summary
- make the external app-server time provider establish sleep deadlines
using `currentTime/read`
- poll the external clock once per second and complete `clock.sleep`
when the deadline is reached
- keep the system-clock timer and existing steer/agent-message
interruption behavior unchanged
## Why
This lets training control `clock.sleep` through its existing external
simulated clock without adding separate sleep/wake protocol methods.
## Testing
- `just fmt`
- `just test -p codex-app-server
external_sleep_polls_current_time_and_emits_items`
## Summary
- add a cancellable sleep operation to `TimeProvider`
- route `clock.sleep` through the configured provider
- extend the supported sleep duration to 12 hours
- complete the sleep turn item before propagating provider failures
## Why
This isolates the core clock abstraction needed by external clock
integrations. Existing system and app-server behavior remains wall-clock
based in this PR; the stacked follow-up supplies app-server sleeps from
an external clock.
## What
Server should request:
```
{
"id": 42,
"method": "currentTime/read",
"params": {
"threadId": "11111111-1111-1111-1111-aaaaafdc2c11"
}
}
```
Client should respond with something like:
```rust
{
"id": 42,
"result": {
"currentTimeAt": 1781717655
}
}
```
## Why
Sessions configured with `clock_source = "external"` need a
thread-specific external time source before inference. The system clock
remains the default production provider.
## Validation
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-app-server --test all
current_time_read_round_trip_adds_reminder_to_model_input`
- `cargo test -p codex-app-server
first_attestation_capable_connection_for_thread_only_uses_thread_subscribers`
- `cargo test -p codex-analytics`
- `just fix -p codex-app-server-protocol`
- `just fix -p codex-app-server`
Stacked on #28824.
rka-oai