feat(task): refactor to Claude Code style individual tools

- Split unified Task tool into individual tools (TaskCreate, TaskGet, TaskList, TaskUpdate)
- Update schema to Claude Code field names (subject, blockedBy, blocks, activeForm, owner, metadata)
- Add OpenCode Todo API sync layer (todo-sync.ts)
- Implement Todo sync on task create/update for continuation enforcement
- Add comprehensive tests for all tools (96 tests total)
- Update AGENTS.md documentation

Breaking Changes:
- Field names changed: title→subject, dependsOn→blockedBy, open→pending
- Tool names changed: task→task_create, task_get, task_list, task_update

Closes: todo-continuation-enforcer now sees Task-created items

src/tools/task/task-get.ts

@@ -0,0 +1,48 @@
+import { tool, type ToolDefinition } from "@opencode-ai/plugin/tool"
+import { join } from "path"
+import type { OhMyOpenCodeConfig } from "../../config/schema"
+import type { TaskGetInput } from "./types"
+import { TaskGetInputSchema, TaskObjectSchema } from "./types"
+import { getTaskDir, readJsonSafe } from "../../features/claude-tasks/storage"
+
+const TASK_ID_PATTERN = /^T-[A-Za-z0-9-]+$/
+
+function parseTaskId(id: string): string | null {
+  if (!TASK_ID_PATTERN.test(id)) return null
+  return id
+}
+
+export function createTaskGetTool(config: Partial<OhMyOpenCodeConfig>): ToolDefinition {
+  return tool({
+    description: `Retrieve a task by ID.
+
+Returns the full task object including all fields: id, subject, description, status, activeForm, blocks, blockedBy, owner, metadata, repoURL, parentID, and threadID.
+
+Returns null if the task does not exist or the file is invalid.`,
+    args: {
+      id: tool.schema.string().describe("Task ID to retrieve (format: T-{uuid})"),
+    },
+    execute: async (args: Record<string, unknown>): Promise<string> => {
+      try {
+        const validatedArgs = TaskGetInputSchema.parse(args)
+        const taskId = parseTaskId(validatedArgs.id)
+
+        if (!taskId) {
+          return JSON.stringify({ error: "invalid_task_id" })
+        }
+
+        const taskDir = getTaskDir(config)
+        const taskPath = join(taskDir, `${taskId}.json`)
+
+         const task = readJsonSafe(taskPath, TaskObjectSchema)
+
+        return JSON.stringify({ task: task ?? null })
+      } catch (error) {
+        if (error instanceof Error && error.message.includes("validation")) {
+          return JSON.stringify({ error: "invalid_arguments" })
+        }
+        return JSON.stringify({ error: "unknown_error" })
+      }
+    },
+  })
+}