Retrieve Message Batch results

 
   - `string`
 
-  - `"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 31 more`
+  - `"message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 38 more`
 
     - `"message-batches-2024-09-24"`
 

 
     - `"mid-conversation-tool-changes-2026-07-01"`
 
+    - `"compact-2026-01-12"`
+
+    - `"computer-use-2025-11-24"`
+
+    - `"mcp-tunnels-2026-06-22"`
+
+    - `"structured-outputs-2025-11-13"`
+
+    - `"task-budgets-2026-03-13"`
+
+    - `"thinking-display-updates-2026-08-18"`
+
+    - `"ce-user-management-2026-07-13"`
+
 ## Returns
 
 - `BetaMessageBatchIndividualResponse object`

 
             Per-iteration token usage breakdown.
 
-            Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:
+            Each entry represents one sampling iteration, with its own input/output token counts and cache statistics, discriminated by `type`. For `message` entries (model sampling iterations, such as the turns of a server-side tool use loop), this allows you to:
 
             - Determine which iterations exceeded long context thresholds (>=200k tokens)
-            - Calculate the true context window size from the last iteration
+            - Calculate the context window size from the last `message` entry
             - Understand token accumulation across server-side tool use loops
+
+            A `compaction` entry reports the token usage of the compaction operation itself — the server-side request that summarizes the context being closed — NOT the size of the context that was compacted away, and its token counts can be much smaller than that closed context (for example, a compaction that closes a ~200k-token context can report only a few thousand tokens). Do not derive the context window size from a `compaction` entry, even when it is the last entry. A `compaction` entry's tokens are not included in the top-level `usage` fields. When an input-token trigger is in effect (the default — 150,000 tokens unless configured otherwise), each `compaction` entry closes a context that had reached at least that threshold, though the context can exceed it by the final iteration's output and tool results.
 
             - `BetaMessageIterationUsage object`