onlyterp/prompt-cache-skills/opencode-bedrock-doc-blocks

ValidationException: nothing available to cache

--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ function applyCaching(msgs, model)
+  function hasDocumentBlock(msg: ModelMessage): boolean {
+    if (!Array.isArray(msg.content)) return false;
+    return msg.content.some((b: any) =>
+      b?.type === "document" ||
+      b?.type === "file" ||
+      b?.documentBlock != null
+    );
+  }
+
+  function findLastStableNonDoc(msgs: ModelMessage[], skip: number): number {
+    for (let i = msgs.length - 1 - skip; i >= 0; i--) {
+      if (msgs[i].role !== "system" && !hasDocumentBlock(msgs[i])) {
+        return i;
+      }
+    }
+    return -1;
+  }
@@
-  // Apply to last 2 non-system messages
-  const nonSystemMsgs = msgs.filter(m => m.role !== "system").slice(-2)
-  nonSystemMsgs.forEach(msg => {
-    msg.providerOptions = { /* cachePoint etc. */ }
-  })
+  // For Bedrock, skip DocumentBlock-containing messages — they
+  // can't be cached and produce a hard error.
+  const isBedrock = model.providerID.includes("bedrock");
+  if (isBedrock) {
+    const lastStable = findLastStableNonDoc(msgs, 0);
+    const prevStable = findLastStableNonDoc(msgs, msgs.length - 1 - lastStable + 1);
+    [lastStable, prevStable].forEach(idx => {
+      if (idx < 0) return;
+      msgs[idx].providerOptions = { bedrock: { cachePoint: { type: "default" } } };
+    });
+  } else {
+    // Existing behavior for non-Bedrock providers
+    const nonSystemMsgs = msgs.filter(m => m.role !== "system").slice(-2);
+    nonSystemMsgs.forEach(msg => {
+      msg.providerOptions = { /* cachePoint etc. */ };
+    });
+  }