arcrun — AI workflow execution engine (clean history)

Self-hosted 開源：WASM 零件 + recipe + cypher-executor，跑在你自己的 Cloudflare。

此為重建的乾淨歷史起點（移除曾誤 commit 的 GCP SA 金鑰，舊歷史保留在
richblack/arcrun 與本地 backup 分支）。含：
- acr init --self-hosted installer（建 KV/R2 + codeload 拉預編譯 wasm + wrangler deploy + seed recipe）
- recipe push 把關（資料外流提醒 + 打通檢查）
- 19 個正當零件預編譯 wasm（claude_api/km_writer/kbdb_upsert_block 排除：違反 DECISIONS §1）
- CLI / cypher-executor / registry / 完整 SDD

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

registry/components/set/component.contract.yaml

@@ -0,0 +1,64 @@
+canonical_id: "set"
+display_name: "設定變數"
+category: "logic"
+version: "v1"
+wasi_target: "preview1"
+stability: "floating"
+runtime_compat:
+  - "cf-workers"
+  - "workerd"
+  - "wazero"
+constraints:
+  max_size_kb: 2048
+  max_cold_start_ms: 50
+  no_network_syscall: true
+  no_filesystem_syscall: true
+  io_model: "stdin_stdout_json"
+input_schema:
+  type: object
+  properties:
+    assignments:
+      type: array
+      description: 賦值清單，每筆含 key 與 value（與 values 擇一必填）
+      items:
+        type: object
+        required: [key, value]
+        properties:
+          key:
+            type: string
+          value: {}
+    values:
+      type: object
+      description: 鍵值對物件，與 assignments 擇一必填
+    context:
+      type: object
+      description: 上游傳入的上下文，設定結果會合併覆寫
+output_schema:
+  type: object
+  properties:
+    success:
+      type: boolean
+    data:
+      type: object
+      description: context 加上所有設定後的變數
+gherkin_tests:
+  - scenario: "用 assignments 設定變數"
+    given: '{"assignments":[{"key":"name","value":"Alice"}]}'
+    then_contains: '"name":"Alice"'
+  - scenario: "用 values 設定變數"
+    given: '{"values":{"name":"Bob","age":30}}'
+    then_contains: '"name":"Bob"'
+  - scenario: "未提供 assignments 或 values 時失敗"
+    given: '{"context":{"x":1}}'
+    then_contains: '{"success":false'
+tags: [builtin, set, assign, variable, context]
+description: "設定或覆寫變數，支援 assignments 陣列或 values 物件兩種格式，結果合併自 context。"
+config_example: |
+  my_set:                                 # 節點名稱（可自訂）
+    assignments:                          # 賦值清單（與 values 擇一必填）
+      - key: status
+        value: active
+      - key: count
+        value: 0
+    context:                              # 上游上下文，設定結果會合併覆寫（選填）
+      payload: "{{upstream.data}}"

registry/components/set/go.mod

@@ -0,0 +1,3 @@
+module component
+
+go 1.21

registry/components/set/main.go

@@ -0,0 +1,59 @@
+// set — 設定/覆寫變數，傳遞到下一個節點
+// 支援 assignments 陣列或 values 物件兩種格式
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+)
+
+type Input struct {
+	Assignments []Assignment           `json:"assignments"`
+	Values      map[string]interface{} `json:"values"`
+	Context     map[string]interface{} `json:"context"`
+}
+
+type Assignment struct {
+	Key   string      `json:"key"`
+	Value interface{} `json:"value"`
+}
+
+func main() {
+	raw, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		writeError("failed to read stdin: " + err.Error())
+		return
+	}
+	var input Input
+	if err := json.Unmarshal(raw, &input); err != nil {
+		writeError("invalid input JSON: " + err.Error())
+		return
+	}
+
+	result := make(map[string]interface{})
+	for k, v := range input.Context {
+		result[k] = v
+	}
+
+	if len(input.Assignments) > 0 {
+		for _, a := range input.Assignments {
+			result[a.Key] = a.Value
+		}
+	} else if len(input.Values) > 0 {
+		for k, v := range input.Values {
+			result[k] = v
+		}
+	} else {
+		writeError("需提供 assignments 陣列或 values 物件")
+		return
+	}
+
+	out, _ := json.Marshal(map[string]interface{}{"success": true, "data": result})
+	os.Stdout.Write(out)
+}
+
+func writeError(msg string) {
+	out, _ := json.Marshal(map[string]interface{}{"success": false, "error": msg})
+	os.Stdout.Write(out)
+}