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/if_control/component.contract.yaml

@@ -0,0 +1,56 @@
+canonical_id: "if_control"
+display_name: "條件判斷"
+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
+  required: [condition]
+  properties:
+    condition:
+      type: string
+      description: 條件運算式，支援 key（truthy）、key == value、key > number、key < number
+    input:
+      type: object
+      description: 條件運算式中參照的變數字典
+output_schema:
+  type: object
+  properties:
+    success:
+      type: boolean
+    data:
+      type: object
+      properties:
+        result:
+          type: boolean
+        branch:
+          type: string
+          enum: ["true", "false"]
+gherkin_tests:
+  - scenario: "條件成立走 true 分支"
+    given: '{"condition":"status == active","input":{"status":"active"}}'
+    then_contains: '"branch":"true"'
+  - scenario: "條件不成立走 false 分支"
+    given: '{"condition":"status == active","input":{"status":"inactive"}}'
+    then_contains: '"branch":"false"'
+  - scenario: "缺少 condition"
+    given: '{"input":{"status":"active"}}'
+    then_contains: '{"success":false'
+tags: [builtin, control, if, condition, branch]
+description: "評估條件運算式，依結果路由到 true 或 false 分支。"
+config_example: |
+  my_if:                                    # 節點名稱（可自訂）
+    condition: "status == active"           # 條件運算式（必填）
+    input:                                  # 條件運算式中參照的變數字典（選填）
+      status: "{{upstream.status}}"

registry/components/if_control/go.mod

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

registry/components/if_control/main.go

@@ -0,0 +1,138 @@
+// if_control — 單一條件判斷，true/false 兩個出口
+// condition 支援：key（truthy）、key == value、key > number、key < number
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Input struct {
+	Condition string                 `json:"condition"`
+	Input     map[string]interface{} `json:"input"`
+}
+
+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
+	}
+	if input.Condition == "" {
+		writeError("condition 必填")
+		return
+	}
+
+	result := evaluateCondition(input.Condition, input.Input)
+	branch := "false"
+	if result {
+		branch = "true"
+	}
+
+	out, _ := json.Marshal(map[string]interface{}{
+		"success": true,
+		"data":    map[string]interface{}{"result": result, "branch": branch},
+	})
+	os.Stdout.Write(out)
+}
+
+func toString(v interface{}) string {
+	switch val := v.(type) {
+	case string:
+		return val
+	case float64:
+		return strconv.FormatFloat(val, 'f', -1, 64)
+	case bool:
+		if val {
+			return "true"
+		}
+		return "false"
+	case nil:
+		return ""
+	default:
+		b, _ := json.Marshal(val)
+		return string(b)
+	}
+}
+
+func evaluateCondition(condition string, ctx map[string]interface{}) bool {
+	if ctx == nil {
+		return false
+	}
+	expr := strings.TrimSpace(condition)
+
+	// key == value
+	if idx := strings.Index(expr, "=="); idx > 0 {
+		key := strings.TrimSpace(expr[:idx])
+		expected := strings.Trim(strings.TrimSpace(expr[idx+2:]), `"'`)
+		v, ok := ctx[key]
+		if !ok {
+			return false
+		}
+		return toString(v) == expected
+	}
+	// key > number
+	if idx := strings.Index(expr, ">"); idx > 0 {
+		key := strings.TrimSpace(expr[:idx])
+		threshold, err := strconv.ParseFloat(strings.TrimSpace(expr[idx+1:]), 64)
+		if err != nil {
+			return false
+		}
+		v, ok := ctx[key]
+		if !ok {
+			return false
+		}
+		n, err := strconv.ParseFloat(toString(v), 64)
+		if err != nil {
+			return false
+		}
+		return n > threshold
+	}
+	// key < number
+	if idx := strings.Index(expr, "<"); idx > 0 {
+		key := strings.TrimSpace(expr[:idx])
+		threshold, err := strconv.ParseFloat(strings.TrimSpace(expr[idx+1:]), 64)
+		if err != nil {
+			return false
+		}
+		v, ok := ctx[key]
+		if !ok {
+			return false
+		}
+		n, err := strconv.ParseFloat(toString(v), 64)
+		if err != nil {
+			return false
+		}
+		return n < threshold
+	}
+	// truthy check
+	v, ok := ctx[expr]
+	if !ok {
+		return false
+	}
+	switch val := v.(type) {
+	case bool:
+		return val
+	case string:
+		return val != ""
+	case float64:
+		return val != 0
+	case nil:
+		return false
+	default:
+		return true
+	}
+}
+
+func writeError(msg string) {
+	out, _ := json.Marshal(map[string]interface{}{"success": false, "error": msg})
+	os.Stdout.Write(out)
+}