fix: replace _noop stub with read-shaped tool for LiteLLM/Bedrock compaction

During compaction, an empty tools map is passed to the LLM processor. For LiteLLM proxying Bedrock/Anthropic models, the _noop stub was injected to satisfy LiteLLM's requirement for a non-empty tools array when message history contains tool calls. However, the _noop stub had an empty inputSchema which Bedrock rejects, causing compaction to fail silently — the model would call _noop instead of summarising, producing post-compaction amnesia. Replacing the stub with a read-shaped tool (with a real inputSchema) satisfies Bedrock validation while keeping execution harmless via the compaction agent's deny-all permission ruleset.

Author: KnutZuidema

packages/opencode/src/session/llm.ts

@@ -177,10 +177,20 @@ export namespace LLM {
       input.model.api.id.toLowerCase().includes("litellm")
 
     if (isLiteLLMProxy && Object.keys(tools).length === 0 && hasToolCalls(input.messages)) {
-      tools["_noop"] = tool({
-        description:
-          "Placeholder for LiteLLM/Anthropic proxy compatibility - required when message history contains tool calls but no active tools are needed",
-        inputSchema: jsonSchema({ type: "object", properties: {} }),
+      // Inject a read tool stub so LiteLLM/Bedrock gets a non-empty tools array.
+      // Bedrock rejects requests with tool history but no tools param, and also
+      // rejects tool_choice=none, so a real-shaped tool is required. The execute
+      // is a no-op; the compaction agent's deny-all permission ruleset prevents
+      // any actual execution.
+      tools["read"] = tool({
+        description: "Read a file at the given path",
+        inputSchema: jsonSchema({
+          type: "object",
+          properties: {
+            filePath: { type: "string", description: "Absolute path to the file to read" },
+          },
+          required: ["filePath"],
+        }),
         execute: async () => ({ output: "", title: "", metadata: {} }),
       })
     }