feat: add two-layer tool call validation system (proactive + reactive) (#249)

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/hooks/tool-call-validator/index.ts

@@ -0,0 +1,98 @@
+import type { Part } from "@opencode-ai/sdk"
+import type { ToolRegistry } from "../../shared/tool-registry"
+import type { MessageWithParts, ToolUsePart, ToolResultPart, TextPart } from "./types"
+import {
+  INVALID_TOOL_PLACEHOLDER_PREFIX,
+  INVALID_TOOL_PLACEHOLDER_SUFFIX,
+  PAIRED_RESULT_PLACEHOLDER,
+} from "./constants"
+
+type MessagesTransformHook = {
+  "experimental.chat.messages.transform"?: (
+    input: Record<string, never>,
+    output: { messages: MessageWithParts[] }
+  ) => Promise<void>
+}
+
+function isToolUsePart(part: Part): part is ToolUsePart {
+  const type = part.type as string
+  return type === "tool_use" || type === "tool"
+}
+
+function isToolResultPart(part: Part): part is ToolResultPart {
+  const type = part.type as string
+  return type === "tool_result"
+}
+
+function getToolName(part: ToolUsePart): string | undefined {
+  return part.name || part.tool
+}
+
+function getToolUseIdFromResult(part: Part): string | undefined {
+  return (part as { tool_use_id?: string }).tool_use_id
+}
+
+function createInvalidToolPlaceholder(toolName: string): TextPart {
+  return {
+    type: "text",
+    text: `${INVALID_TOOL_PLACEHOLDER_PREFIX}${toolName}${INVALID_TOOL_PLACEHOLDER_SUFFIX}`,
+    synthetic: true,
+  } as TextPart
+}
+
+function createPairedResultPlaceholder(): TextPart {
+  return {
+    type: "text",
+    text: PAIRED_RESULT_PLACEHOLDER,
+    synthetic: true,
+  } as TextPart
+}
+
+export function createToolCallValidatorHook(
+  registry: ToolRegistry
+): MessagesTransformHook {
+  return {
+    "experimental.chat.messages.transform": async (_input, output) => {
+      const { messages } = output
+
+      if (!messages || messages.length === 0) {
+        return
+      }
+
+      const invalidatedToolUseIds = new Set<string>()
+
+      for (const message of messages) {
+        if (message.info.role === "user") {
+          continue
+        }
+
+        const parts = message.parts
+        if (!parts || parts.length === 0) {
+          continue
+        }
+
+        for (let i = 0; i < parts.length; i++) {
+          const part = parts[i]
+
+          if (isToolUsePart(part)) {
+            const toolName = getToolName(part)
+
+            if (toolName && !registry.isValidTool(toolName)) {
+              if (part.id) {
+                invalidatedToolUseIds.add(part.id)
+              }
+
+              parts[i] = createInvalidToolPlaceholder(toolName)
+            }
+          } else if (isToolResultPart(part)) {
+            const toolUseId = getToolUseIdFromResult(part)
+
+            if (toolUseId && invalidatedToolUseIds.has(toolUseId)) {
+              parts[i] = createPairedResultPlaceholder()
+            }
+          }
+        }
+      }
+    },
+  }
+}