SIENTIAPDE-1811

Enhance OPC UA communication and metrics tracking

- Updated README.md to include new OPC UA Communication section and detailed metrics for session and write diagnostics.
- Added new metrics in laborious/metrics.py for tracking OPC UA session states and write attempts.
- Refactored OPC activity in laborious/activities/opc.py to handle session errors and improve error reporting.
- Updated e2e tests to cover new scenarios for OPC session/channel errors and reconnect handling.
- Modified .gitignore to include relatorio files and mlruns directory.
- Added ipykernel to requirements-dev.txt for Jupyter notebook support.

docs/opc-communication.md

@@ -12,7 +12,7 @@ Worker (long-lived)
         ├── connect / disconnect / validate_connection (read-only)
         ├── _connect_locked / _reconnect_locked (under _connection_lock)
         ├── write_data (single attempt per call)
-        └── background reconnect on Tier-1 Bad*
+        └── background reconnect on Tier-1 Bad*, closed protocol, or stale session
 
 Temporal activity write_opc_data
   └── OPC.manage_output_tags → write_data per tag (sequential per activity)
@@ -26,9 +26,9 @@ One worker process holds one `OpcRepository` instance per configured server. Mul
 |-------|----------|
 | Startup | `init_opc()` creates repositories and calls `connect()` → `_connect_locked()` |
 | Steady state | `validate_connection()` is read-only (`protocol.state` only); `_session_ready` is checked in `write_data` |
-| Tier-1 Bad* | `_start_reconnect_on_bad` → `_run_reconnect_on_bad` → `_reconnect_locked()` (respects `reconnection_interval`) |
-| Write | `write_data()` checks `_session_ready`, validates, then one `get_node` + `write_value` |
-| Shutdown | `close()` disconnects all repositories |
+| Tier-1 Bad* / protocol closed / session not ready | `_start_reconnect(reason)` → `_run_reconnect` (thread) → `_reconnect_locked()` (respects `reconnection_interval`) |
+| Write | `write_data()` checks in-flight reconnect thread, `_session_ready`, validates, then one `get_node` + `write_value` |
+| Shutdown | `disconnect()` sets `_allow_reconnect = False`, then tears down session |
 
 ### Session and channel timeouts
 
@@ -44,8 +44,9 @@ To allow **multiple concurrent writes** when the session is healthy, but **block
 
 | Primitive | Role |
 |-----------|------|
-| `_connection_lock` (`asyncio.Lock`) | Held for the entire `disconnect` → `connect` path. Only one connection-maintenance task at a time. |
-| `_session_ready` (`asyncio.Event`) | Set when a session is ready for writes; cleared before reconnect starts and set again after a successful connect. |
+| `_connection_lock` (`threading.Lock`) | Held for the entire `disconnect` → `connect` path. Only one connection-maintenance task at a time. |
+| `_session_ready` (`threading.Event`) | Set when a session is ready for writes; cleared before reconnect starts and set again after a successful connect. |
+| `_allow_reconnect` | Cleared in `disconnect()` so shutdown does not spawn reconnect threads |
 
 **Connection methods (caller holds `_connection_lock` for `_*_locked` helpers):**
 
@@ -61,21 +62,20 @@ Public `connect()` / `disconnect()` acquire the lock and call `_connect_locked()
 
 **Write path (`write_data`):**
 
-1. If `_session_ready` is cleared → **fail immediately** (`opc_error_kind=reconnect_in_progress`).
-2. `validate_connection()` checks `protocol.state` only (read-only).
-3. Single `get_node` + `write_value` (no retry).
+1. If a reconnect **thread** is alive → `reconnect_in_progress`.
+2. If `_session_ready` is cleared → schedule `SessionNotReady` reconnect; return `reconnect_in_progress` or `connection_lost`.
+3. If `validate_connection()` fails (protocol closed) → schedule `ProtocolClosed` reconnect; return `connection_lost`.
+4. Single `get_node` + `write_value` (no retry in the same call).
 
-**Reconnect path (`_run_reconnect_on_bad`):**
+**Reconnect path (`_run_reconnect`):**
 
-1. `_start_reconnect_on_bad` clears `_session_ready` and schedules the task when the interval allows.
-2. `async with _connection_lock:` → `_reconnect_locked()`.
+1. `_start_reconnect` clears `_session_ready` and starts a daemon thread when the interval allows and `_allow_reconnect` is true.
+2. `with _connection_lock:` → `_reconnect_locked()`.
 3. `_session_ready` is set on successful `_open_session()`.
 
 A second `_connect_locked()` while a session is already open raises `OpcSessionAlreadyConnectedError` (disconnect first).
 
-**asyncua note:** Concurrent `write_value` on the same session is only safe if the stack tolerates it. If production shows issues, serialize writes with an optional `asyncio.Semaphore(1)` while keeping the connection lock semantics above.
-
-**Future threads:** replace `asyncio.Lock` / `Event` with `threading` primitives or route all OPC I/O through one dedicated loop.
+**asyncua note:** Concurrent `write_value` on the same session is only safe if the stack tolerates it. If production shows issues, serialize writes while keeping the connection lock semantics above.
 
 ## Tier-1 `Bad*` errors and reconnect