fix(provider): preserve anthropic provider-executed tool pairs

packages/opencode/src/provider/transform.ts

@@ -122,7 +122,7 @@ function normalizeMessages(
     })
   }
   if (["@ai-sdk/anthropic", "@ai-sdk/google-vertex/anthropic"].includes(model.api.npm)) {
-    // Anthropic rejects assistant turns where tool_use blocks are followed by non-tool
+    // Anthropic rejects assistant turns where client tool_use blocks are followed by non-tool
     // content, e.g. [tool_use, tool_use, text], with:
     // `tool_use` ids were found without `tool_result` blocks immediately after...
     //
@@ -130,19 +130,26 @@ function normalizeMessages(
     // assistant messages are later merged by the provider/SDK, so preserving the
     // original [tool_use...] then [text] order still produces the invalid payload.
     //
-    // The root cause appears to be somewhere upstream where the stream is originally
-    // processed. We were unable to locate an exact narrower reproduction elsewhere,
-    // so we keep this transform in place for the time being.
+    // Provider-executed tools are different: the AI SDK intentionally represents
+    // their tool-call and tool-result together in assistant content.
     msgs = msgs.flatMap((msg) => {
       if (msg.role !== "assistant" || !Array.isArray(msg.content)) return [msg]
 
       const parts = msg.content
-      const first = parts.findIndex((part) => part.type === "tool-call")
+      const providerExecuted = new Set(
+        parts.flatMap((part) => (part.type === "tool-call" && part.providerExecuted === true ? [part.toolCallId] : [])),
+      )
+      const isClientToolPart = (part: (typeof parts)[number]) => {
+        if (part.type === "tool-call") return part.providerExecuted !== true
+        if (part.type === "tool-result") return !providerExecuted.has(part.toolCallId)
+        return false
+      }
+      const first = parts.findIndex((part) => part.type === "tool-call" && part.providerExecuted !== true)
       if (first === -1) return [msg]
-      if (!parts.slice(first).some((part) => part.type !== "tool-call")) return [msg]
+      if (!parts.slice(first).some((part) => !isClientToolPart(part))) return [msg]
       return [
-        { ...msg, content: parts.filter((part) => part.type !== "tool-call") },
-        { ...msg, content: parts.filter((part) => part.type === "tool-call") },
+        { ...msg, content: parts.filter((part) => !isClientToolPart(part)) },
+        { ...msg, content: parts.filter(isClientToolPart) },
       ]
     })
   }

packages/opencode/src/session/message-v2.ts

@@ -1104,6 +1104,32 @@ export function filterCompacted(msgs: Iterable<WithParts>) {
       completed.add(msg.info.parentID)
   }
   result.reverse()
+  const compactionIndex = result.findLastIndex(
+    (msg) =>
+      msg.info.role === "user" &&
+      msg.parts.some((item): item is CompactionPart => item.type === "compaction" && item.tail_start_id !== undefined),
+  )
+  const compaction = result[compactionIndex]
+  const part = compaction?.parts.find(
+    (item): item is CompactionPart => item.type === "compaction" && item.tail_start_id !== undefined,
+  )
+  const summaryIndex = compaction
+    ? result.findIndex(
+        (msg, index) =>
+          index > compactionIndex &&
+          msg.info.role === "assistant" &&
+          msg.info.summary &&
+          msg.info.parentID === compaction.info.id,
+      )
+    : -1
+  const tailIndex = part?.tail_start_id ? result.findIndex((msg) => msg.info.id === part.tail_start_id) : -1
+  if (tailIndex >= 0 && tailIndex < compactionIndex && summaryIndex > compactionIndex) {
+    return [
+      ...result.slice(compactionIndex, summaryIndex + 1),
+      ...result.slice(tailIndex, compactionIndex),
+      ...result.slice(summaryIndex + 1),
+    ]
+  }
   return result
 }
 

packages/opencode/test/provider/transform.test.ts

@@ -1498,6 +1498,117 @@ describe("ProviderTransform.message - anthropic empty content filtering", () =>
     ])
   })
 
+  test("keeps tool-call and tool-result paired when splitting anthropic messages", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          { type: "tool-call", toolCallId: "toolu_1", toolName: "read", input: { filePath: "/root" } },
+          { type: "tool-result", toolCallId: "toolu_1", toolName: "read", output: { type: "text", value: "ok" } },
+          { type: "text", text: "I checked your home directory." },
+        ],
+      },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {}) as any[]
+
+    expect(result).toHaveLength(2)
+    expect(result[0]).toMatchObject({
+      role: "assistant",
+      content: [{ type: "text", text: "I checked your home directory." }],
+    })
+    expect(result[1]).toMatchObject({
+      role: "assistant",
+      content: [
+        { type: "tool-call", toolCallId: "toolu_1", toolName: "read", input: { filePath: "/root" } },
+        { type: "tool-result", toolCallId: "toolu_1", toolName: "read", output: { type: "text", value: "ok" } },
+      ],
+    })
+  })
+
+  test("leaves provider-executed anthropic tool results with trailing text unchanged", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          {
+            type: "tool-call",
+            toolCallId: "srvtoolu_1",
+            toolName: "code_execution",
+            input: { code: "print('ok')", type: "programmatic-tool-call" },
+            providerExecuted: true,
+          },
+          {
+            type: "tool-result",
+            toolCallId: "srvtoolu_1",
+            toolName: "code_execution",
+            output: {
+              type: "json",
+              value: { type: "code_execution_result", stdout: "ok", stderr: "", return_code: 0 },
+            },
+          },
+          { type: "text", text: "The code ran successfully." },
+        ],
+      },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {}) as any[]
+
+    expect(result).toHaveLength(1)
+    expect(result[0].content).toMatchObject(msgs[0].content)
+  })
+
+  test("keeps provider-executed pairs together when splitting mixed anthropic tool parts", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          { type: "tool-call", toolCallId: "toolu_1", toolName: "read", input: { filePath: "/root" } },
+          {
+            type: "tool-call",
+            toolCallId: "srvtoolu_1",
+            toolName: "code_execution",
+            input: { code: "print('ok')", type: "programmatic-tool-call" },
+            providerExecuted: true,
+          },
+          {
+            type: "tool-result",
+            toolCallId: "srvtoolu_1",
+            toolName: "code_execution",
+            output: {
+              type: "json",
+              value: { type: "code_execution_result", stdout: "ok", stderr: "", return_code: 0 },
+            },
+          },
+          { type: "text", text: "The server-side tool ran successfully." },
+        ],
+      },
+    ] as any[]
+
+    const result = ProviderTransform.message(msgs, anthropicModel, {}) as any[]
+
+    expect(result).toHaveLength(2)
+    expect(result[0].content).toMatchObject([
+      {
+        type: "tool-call",
+        toolCallId: "srvtoolu_1",
+        toolName: "code_execution",
+        input: { code: "print('ok')", type: "programmatic-tool-call" },
+        providerExecuted: true,
+      },
+      {
+        type: "tool-result",
+        toolCallId: "srvtoolu_1",
+        toolName: "code_execution",
+        output: { type: "json", value: { type: "code_execution_result", stdout: "ok", stderr: "", return_code: 0 } },
+      },
+      { type: "text", text: "The server-side tool ran successfully." },
+    ])
+    expect(result[1].content).toMatchObject([
+      { type: "tool-call", toolCallId: "toolu_1", toolName: "read", input: { filePath: "/root" } },
+    ])
+  })
+
   test("splits vertex anthropic assistant messages when text trails tool calls", () => {
     const model = {
       ...anthropicModel,

packages/opencode/test/session/compaction.test.ts

@@ -1218,7 +1218,9 @@ describe("session.compaction.process", () => {
           expect(captured).not.toContain("keep tail")
 
           const filtered = MessageV2.filterCompacted(MessageV2.stream(session.id))
-          expect(filtered[0]?.info.id).toBe(keep.id)
+          expect(filtered.map((msg) => msg.info.id).slice(0, 3)).toEqual([parent!, expect.any(String), keep.id])
+          expect(filtered[1]?.info.role).toBe("assistant")
+          expect(filtered[1]?.info.role === "assistant" ? filtered[1].info.summary : false).toBe(true)
           expect(filtered.map((msg) => msg.info.id)).not.toContain(large.id)
         } finally {
           await rt.dispose()

packages/opencode/test/session/messages-pagination.test.ts

@@ -834,7 +834,7 @@ describe("MessageV2.filterCompacted", () => {
 
         const result = MessageV2.filterCompacted(MessageV2.stream(session.id))
 
-        expect(result.map((item) => item.info.id)).toEqual([u2, a2, c1, s1, u3, a3])
+        expect(result.map((item) => item.info.id)).toEqual([c1, s1, u2, a2, u3, a3])
 
         await svc.remove(session.id)
       },
@@ -889,7 +889,7 @@ describe("MessageV2.filterCompacted", () => {
         })
 
         const parentFiltered = MessageV2.filterCompacted(MessageV2.stream(session.id))
-        expect(parentFiltered.map((item) => item.info.id)).toEqual([u2, a2, c1, s1, u3, a3])
+        expect(parentFiltered.map((item) => item.info.id)).toEqual([c1, s1, u2, a2, u3, a3])
 
         const forked = await svc.fork({ sessionID: session.id })
         const childFiltered = MessageV2.filterCompacted(MessageV2.stream(forked.id))
@@ -964,7 +964,7 @@ describe("MessageV2.filterCompacted", () => {
 
         const result = MessageV2.filterCompacted(MessageV2.stream(session.id))
 
-        expect(result.map((item) => item.info.id)).toEqual([a3, c1, s1, u3, a4])
+        expect(result.map((item) => item.info.id)).toEqual([c1, s1, a3, u3, a4])
 
         await svc.remove(session.id)
       },
@@ -1041,7 +1041,7 @@ describe("MessageV2.filterCompacted", () => {
 
         const result = MessageV2.filterCompacted(MessageV2.stream(session.id))
 
-        expect(result.map((item) => item.info.id)).toEqual([u3, a3, c2, s2, u4, a4])
+        expect(result.map((item) => item.info.id)).toEqual([c2, s2, u3, a3, u4, a4])
 
         await svc.remove(session.id)
       },