diff --git a/sdk/guides/agent-acp.mdx b/sdk/guides/agent-acp.mdx
index 38a40007..99fc18c1 100644
--- a/sdk/guides/agent-acp.mdx
+++ b/sdk/guides/agent-acp.mdx
@@ -158,6 +158,38 @@ When the ACP server advertises authentication methods, `ACPAgent` automatically
 
 If no supported credential source is found, the server may proceed without authentication (some servers don't require it).
 
+## Session Recovery
+
+`ACPAgent` persists the provider's session ID in the conversation state and uses
+`session/load` to resume it after a process restart. The provider's own session
+files must also remain available. Saving the OpenHands event history alone does
+not preserve the provider's native context.
+
+If `session/load` fails, the conversation enters an error state and retains its
+previous session ID. It does not automatically call `session/new` or send the
+pending message to an empty session. The error includes the provider's failure
+details and asks you to retry or explicitly start a new conversation.
+
+To recover:
+
+1. Resolve the reported provider error. For example, restore missing credentials
+   or session files, or shut down a confirmed stale process that owns the session.
+2. Retry the same conversation using the same working directory and provider data
+   directory. The SDK attempts to load the original session again.
+3. If the original session cannot be recovered, explicitly create a new
+   conversation and provide the context it needs.
+
+`acp_resume_session_id` can supply an explicit provider session ID when it was
+stored separately from OpenHands conversation state. A failed load of this ID
+also raises an error instead of falling back to a fresh session. Treat this ID as
+a secret.
+
+<Note>
+This recovery behavior applies to `session/load` failures. Moving a persisted
+conversation to a different working directory still follows the existing
+working-directory mismatch behavior, which can start a fresh session.
+</Note>
+
 ## Metrics
 
 Token usage and cost data are automatically captured from the ACP server's responses. You can inspect them through the standard `LLM.metrics` interface: