Add retry resilience to Agent365 exporter

A365_DOCUMENTATION.md

@@ -42,6 +42,8 @@ use_microsoft_opentelemetry(
 | `a365_scheduled_delay_ms` | `int` | `5000` | — | Delay between A365 export batches in milliseconds. |
 | `a365_exporter_timeout_ms` | `int` | `30000` | — | Timeout for a single A365 export operation in milliseconds. |
 | `a365_max_export_batch_size` | `int` | `512` | — | Maximum batch size for a single A365 export operation. |
+| `a365_exporter_disable_offline_storage` | `bool` | `False` | — | Disable durable offline storage. When `True`, failed exports are not persisted to disk and at-least-once delivery is not guaranteed. Defaults to `False` (storage enabled). |
+| `a365_exporter_storage_directory` | `str` | `None` | — | Custom directory for durable offline storage. When `None`, a platform default path is used. Choose a path that only the current user or service account can read, because stored OTLP payloads may contain prompts or completions when sensitive-data capture is enabled. |
 
 ### Resource / Service Name
 
@@ -83,6 +85,52 @@ use_microsoft_opentelemetry(
 )
 ```
 
+### Durable Delivery (Offline Storage)
+
+When `a365_enable_observability_exporter=True`, the A365 exporter persists failed export payloads to disk and replays them once connectivity is restored — providing **at-least-once delivery** semantics.
+
+Key defaults and limits:
+
+| Property | Value |
+|---|---|
+| Enabled by default | Yes (when exporter is active) |
+| Retention window | 2 days |
+| Maximum storage size | 50 MB |
+| Storage path | Platform default (see below) |
+
+The default path is a sub-directory of the platform's local app data folder,
+derived from the user, executable, and working directory. Processes for the
+same application can share the SQLite queue; leases coordinate replay across
+those processes.
+
+**Replay behavior:**
+
+- Each queued record stores only its identity (tenant, agent, agentic user, S2S flag) and payload — not a fixed URL. On replay, the exporter reconstructs the export endpoint from the exporter's *current* configuration and re-resolves a fresh bearer token, so records queued before an endpoint or credential change are still delivered correctly, and any endpoint that would not resolve to HTTPS is rejected rather than replayed.
+- Records that are permanently rejected by the service (e.g. `400 Bad Request`) or that fail internal validation (unsupported schema version, blank tenant/agent id, or blank payload — "poison" records) are discarded from the durable queue instead of being retried forever.
+- `shutdown()` is drain-safe: it signals the background replay loop to stop and blocks until any in-flight replay send actually finishes before closing the durable store and HTTP session, so an in-progress send is never left holding a closed resource and no accepted span is dropped mid-flight. Concurrent `shutdown()` callers all wait for that same cleanup to complete.
+
+**To disable durable storage** (no disk writes, best-effort delivery only):
+
+```python
+use_microsoft_opentelemetry(
+    enable_a365=True,
+    a365_enable_observability_exporter=True,
+    a365_exporter_disable_offline_storage=True,
+)
+```
+
+**To specify a custom storage directory:**
+
+```python
+use_microsoft_opentelemetry(
+    enable_a365=True,
+    a365_enable_observability_exporter=True,
+    a365_exporter_storage_directory="/var/lib/my-agent/telemetry",
+)
+```
+
+> **Security note:** Stored OTLP payloads are unencrypted. When sensitive-data capture is enabled (`enable_sensitive_data=True`), payloads may include prompts, completions, or tool arguments. Restrict the storage directory to the service account running the agent (e.g., `chmod 700`).
+
 ## Auto-Instrumented Libraries
 
 It auto-discovers and activates supported instrumentors via OpenTelemetry entry points. No manual `instrument()` calls are needed.

CHANGELOG.md

@@ -7,6 +7,18 @@
 ### Features Added
 - Add support for agent identity propagation for compiled agents in nested graph
   ([#245](https://github.com/microsoft/opentelemetry-distro-python/pull/245))
+- Expose A365 offline storage options: `a365_exporter_disable_offline_storage` (default `False`)
+  and `a365_exporter_storage_directory` (default `None`) on `use_microsoft_opentelemetry`,
+  `Agent365ExporterOptions`, and `create_a365_components`.
+  When `a365_enable_observability_exporter=True`, the exporter provides at-least-once delivery
+  by persisting failed payloads to disk (up to 2 days / 50 MB) and replaying them on recovery.
+  Set `a365_exporter_disable_offline_storage=True` to opt out.
+  Stored payloads are unencrypted; restrict the storage path to the service account, especially
+  when `enable_sensitive_data=True` (payloads may contain prompts or completions).
+  Replay reconstructs the current HTTPS export endpoint and bearer token at send time rather
+  than reusing a stale URL, permanently-rejected or malformed ("poison") records are discarded
+  instead of retried forever, and `shutdown()` is drain-safe: it waits for any in-flight replay
+  send to finish before closing the durable store and HTTP session (parity with `.NET` PR #137).
 
 # 1.3.7 (2026-08-05)
 ### Features Added

README.md

@@ -117,6 +117,8 @@ See the [A365 guide](https://github.com/microsoft/opentelemetry-distro-python/bl
 | `a365_scheduled_delay_ms` | `int` | `5000` | Delay between A365 export batches (ms). |
 | `a365_exporter_timeout_ms` | `int` | `30000` | Timeout for a single A365 export operation (ms). |
 | `a365_max_export_batch_size` | `int` | `512` | Maximum batch size for a single A365 export operation. |
+| `a365_exporter_disable_offline_storage` | `bool` | `False` | Disable durable offline storage. When `True`, failed exports are not persisted to disk. |
+| `a365_exporter_storage_directory` | `str` | `None` | Custom directory for durable offline storage. Restrict to the service account; payloads may contain prompts or completions when sensitive-data capture is enabled. |
 
 > For A365 token resolver patterns, baggage, and scope classes, see the [A365 guide](https://github.com/microsoft/opentelemetry-distro-python/blob/main/A365_DOCUMENTATION.md).