Fix rebuild generation reconciliation (Refs #155)

docs/guides/collections.md

@@ -304,6 +304,27 @@ before continuing eligible interrupted startups. Unknown command results retain
 their original command ID and occupied slots until the host confirms the outcome.
 Missing server registrations and later destruction attempts require inspection.
 
+### Recovering a completed rebuild generation
+
+A completed rebuild records the replacement generation before EC verifies health.
+If fresh host inventory disagrees, verification pauses with the controller and
+host generations in the operation's recovery message.
+
+For an existing mismatch, open the **completed rebuild's Provisioning detail**
+(even if that operation was later cancelled), then choose **Reconcile replacement
+generation**. EC requires a completed command for the original host and immutable
+instance ID, the command's requested replacement generation, and matching host
+inventory observed within the last 30 seconds. Wait for that host to reconnect
+and report fresh inventory if the action is unavailable. A server name alone is
+not sufficient evidence.
+
+Reconciliation preserves cancellation and submitted commands. Use **Resume health
+verification** when offered, or request a new lifecycle operation after resolving
+any remaining active operation. Fresh health checks, log reads, and new lifecycle
+commands use the replacement generation. EC requires fresh container and game
+evidence before reporting the server online. The agent continues to reject stale
+commands; an admin player-safety override does not bypass generation checks.
+
 ## API
 
 Collections retain the existing `/api/blueprints` endpoints and `blueprintId` /
@@ -351,6 +372,9 @@ there while preserving query parameters.
 - `GET /api/deployments/:id`: includes `recipe`, `blueprintName`, and
   `canResumeVerification` and `canRetryWithRebuild` for lifecycle operations.
 - `POST /api/deployments/:id/resume`: resume eligible creation health checks.
+- `POST /api/provisioning/:id/reconcile-generation`: reconcile a completed rebuild
+  using fresh inventory from its original host. Returns 409 when identity or
+  completion evidence cannot be validated; repeated application is safe.
 - `POST /api/provisioning/:id/retry-rebuild`: request a new rebuild for an eligible
   failed creation and link it from the original operation.