feat: implement entry variant tagging, backend action handlers, batch variant loading, and rule application API.

cmd/server/main.go

@@ -16,6 +16,7 @@ import (
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/db"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/events"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/logger"
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/rules"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/worker"
 	"go.uber.org/zap"
@@ -50,9 +51,50 @@ func main() {
 	bus := events.NewEventBus()
 	pool := worker.NewPool(database, bus, 5, 100)
 
-	// Register Scraper Action
+	// Register Core Action Handlers
 	scraper := readability.NewScraper(15 * time.Second)
 	pool.RegisterHandler("readability_scrape", scraper.Handler())
+
+	pool.RegisterHandler("set_variant", func(ctx context.Context, entry models.FeedEntry, params map[string]interface{}) (*worker.ActionResult, error) {
+		key, _ := params["variant_key"].(string)
+		if key == "" {
+			key, _ = params["key"].(string)
+		}
+		if key == "" {
+			return nil, nil
+		}
+		val, _ := params["value"].(string)
+		contentType, _ := params["content_type"].(string)
+		if contentType == "" {
+			contentType = "text"
+		}
+		variant := models.EntryVariant{
+			EntryID:     entry.ID,
+			VariantKey:  key,
+			ContentType: contentType,
+			TextValue:   val,
+			CreatedAt:   time.Now(),
+			UpdatedAt:   time.Now(),
+		}
+		return &worker.ActionResult{
+			ResultVariant: &variant,
+		}, nil
+	})
+
+	pool.RegisterHandler("mark_read", func(ctx context.Context, entry models.FeedEntry, params map[string]interface{}) (*worker.ActionResult, error) {
+		trueVal := true
+		return &worker.ActionResult{
+			MarkRead: &trueVal,
+		}, nil
+	})
+
+	pool.RegisterHandler("mark_starred", func(ctx context.Context, entry models.FeedEntry, params map[string]interface{}) (*worker.ActionResult, error) {
+		trueVal := true
+		return &worker.ActionResult{
+			MarkStarred: &trueVal,
+		}, nil
+	})
+
 	pool.Start(ctx)
 
 	// 4. Initialize Rules Engine

docs/005_rules_and_hooks_specification.md

@@ -0,0 +1,150 @@
+# RSSPipe Rules & Automation Hooks Specification (`005_rules_and_hooks_specification.md`)
+
+## 1. Overview & Vision
+
+The **Rules & Hooks Engine** is the reactive event-processing backbone of RSSPipe. It connects the ingestion lifecycle with the **Multi-Variant Data Store** (`entry_variants`), allowing users to automate content enrichment (scraping, tagging, AI, audio), triage (read, starred, archive), and notifications without writing code.
+
+---
+
+## 2. Core Mental Model: 3-Level Execution Flow
+
+Every Rule is evaluated deterministically using a three-level hierarchy:
+
+```mermaid
+graph TD
+    A[Level 1: Event Trigger] --> B{Level 2: Conditions Evaluator}
+    B -- All / Any Match --> C[Level 3: Action Execution Pipeline]
+    B -- No Match --> D[No Action]
+    C --> E[Store Variant / Mutate Status / Dispatch Event]
+    E -. New Variant Event .-> A
+```
+
+---
+
+## 3. Level 1: Event Triggers
+
+The trigger specifies **when** a rule is evaluated.
+
+| Trigger Type | Identifier | Description | Sub-Options / Parameters |
+| :--- | :--- | :--- | :--- |
+| **New Entry Ingested** | `new_entry` (`on_post_created`) | Fires immediately after an article is discovered and parsed by crawler/OPML. | None |
+| **Variant Changed** | `variant_change` (`on_variant_updated`) | Fires when a specific variant key is added, updated, or deleted. | **Sub-Choice (Event Type)**:<br>• `key_added` (Key didn't exist, now created)<br>• `value_changed` (Key existed, value modified)<br>• `key_deleted` (Variant removed)<br>**Target Key Filter**:<br>• Specific `variant_key` (e.g. `keywords`, `readability_full_text`, `ai_summary`) or `*` (any variant). |
+| **Cron Schedule (Future)** | `cron` | Recurring background schedule (e.g., daily digests, archival runs). | Cron expression (e.g. `0 8 * * *`) |
+| **Manual Execution** | `manual` | Triggered on-demand via UI or API. | None |
+
+---
+
+## 4. Level 2: Conditions & Allowlisted Fields
+
+Rules evaluate conditions against an **allowlist of strongly typed fields**. The UI dynamically presents appropriate operators and input controls based on the field type.
+
+### 4.1 Allowlisted Fields & Operators
+
+| Field Name | Type | Allowed Operators | UI Input Type & Behavior | Example Evaluation |
+| :--- | :--- | :--- | :--- | :--- |
+| `feed_id` | `string` / `set` | `==`, `!=`, `in`, `not_in` | **Multi-Select Feed Picker** with search, "Select All", and "Invert" buttons. | `feed_id in ["feed-1", "feed-2", ...]` (Applies to 24/30 feeds in 2 clicks) |
+| `category_id` | `string` / `set` | `==`, `!=`, `in`, `not_in` | **Category Dropdown / Multi-Select Chips**. | `category_id in ["cat-tech", "cat-ai"]` |
+| `title` | `string` | `contains`, `not_contains`, `==`, `!=`, `matches` (regex), `starts_with`, `ends_with` | Text input or comma-separated token badges. | `title contains "DeepSeek"` |
+| `raw_content` / `content` | `string` | `contains`, `not_contains`, `matches` (regex) | Text input. | `content contains "breaking news"` |
+| `author` | `string` | `contains`, `not_contains`, `==`, `!=` | Text input. | `author == "Paul Graham"` |
+| `created_at` / `published_at` | `timestamp` | `>=`, `<=`, `within_last_hours`, `older_than_days` | Number + unit dropdown (e.g. "Within last 24 hours"). | `published_at within_last_hours 48` |
+| `is_read` | `boolean` | `==`, `!=` | Toggle (Read / Unread). | `is_read == false` |
+| `is_starred` | `boolean` | `==`, `!=` | Toggle (Starred / Not Starred). | `is_starred == true` |
+| `variants.<key>` | `variant_value` | `exists`, `not_exists`, `contains`, `not_contains`, `==`, `!=` | Key name + value input. | `variants.keywords contains "LLM"` |
+
+### 4.2 Match Modes
+
+- **`all` (AND)**: Every condition in the rule must evaluate to true.
+- **`any` (OR)**: At least one condition must evaluate to true.
+
+---
+
+## 5. Level 3: Action Execution Pipeline
+
+When a rule's conditions are satisfied, one or more actions execute sequentially.
+
+### 5.1 Supported Core Actions
+
+| Action Identifier | Parameters | Description |
+| :--- | :--- | :--- |
+| **`set_variant`** | `variant_key` (string), `value` (string/json/yaml), `content_type` (string) | Adds or updates a key-value variant (e.g., adding tags, keywords, custom annotations). |
+| **`readability_scrape`** | None | Fetches webpage full-text HTML and stores in `entry_variants(key='readability_full_text')`. |
+| **`mark_read`** | None | Sets `is_read = true` (auto-triage/archive). |
+| **`mark_starred`** | None | Sets `is_starred = true`. |
+
+---
+
+## 6. Safety Architecture: Endless Loop Prevention
+
+Because actions like `set_variant` emit `on_variant_updated` events, rules could theoretically trigger cyclic loops (e.g., Rule A triggers on `variant_change` for `key="tags"` and adds a new tag to `key="tags"`).
+
+### Loop Guard Mechanisms
+
+1. **Static Validation (Rule Creation Time)**:
+   - If Trigger is `variant_change` on `key="X"` and an Action is `set_variant` on `key="X"`, the UI / API warns and rejects identical recursive rules unless an explicit guard predicate (e.g., `value not contains "Y"`) is specified.
+2. **Runtime Execution Context & Depth Guard**:
+   - Every event emitted by the Event Bus carries a `RecursionDepth: int` (max depth = 5) and `ExecutionPath: []string` tracking rule IDs.
+   - If an event exceeds depth 5 or encounters the same Rule ID in its call stack, execution is aborted with an error log: `WARN: Cyclic rule execution aborted for rule: {rule_id}`.
+
+---
+
+## 7. UI/UX Design Specification for Settings
+
+### 7.1 Rule List View
+
+- Clean card layout grouped by Trigger type (`New Entry`, `Variant Change`, `Cron`).
+- Card shows a natural language sentence:
+  > *"When **New Post Arrives** in **24 Feeds** and **Title contains 'AI'** $\rightarrow$ **Scrape Full Text**, **Mark Starred**"*
+- Toggle switch (Active/Inactive), Edit button, Test button, Delete button.
+
+### 7.2 Interactive Rule Builder Modal Layout
+
+```
+┌────────────────────────────────────────────────────────────────────────┐
+│ Create Automation Rule                                           [ ✕ ] │
+├────────────────────────────────────────────────────────────────────────┤
+│ Rule Name: [ Auto-Scrape Tech Feeds                                  ] │
+│                                                                        │
+│ 1. WHEN (Trigger)                                                      │
+│    (●) New Entry Arrives       ( ) Variant Changed      ( ) Schedule   │
+│                                                                        │
+│    [If Variant Changed Selected]                                       │
+│    Event: [ Key Added ▼ ]   Target Key: [ keywords                   ] │
+│                                                                        │
+│ 2. IF (Conditions)                       Match: [ All Conditions (AND) ]│
+│    ┌─────────────────────────────────────────────────────────────────┐ │
+│    │ Field: [ Feed ID ▼ ]   Op: [ In List (24 Feeds) ▼ ]             │ │
+│    │ [ Quick Select: All | None | Invert ]                           │ │
+│    │ [✓] Hacker News  [✓] 36Kr  [✓] FT Chinese  [✓] InfoQ  [ ] Douban│ │
+│    │                                                      [ ✕ Remove]│ │
+│    ├─────────────────────────────────────────────────────────────────┤ │
+│    │ Field: [ Title ▼ ]     Op: [ Contains Any ▼ ]                   │ │
+│    │ Value: [ AI, LLM, Machine Learning                            ] │ │
+│    │                                                      [ ✕ Remove]│ │
+│    └─────────────────────────────────────────────────────────────────┘ │
+│    [ + Add Condition ]                                                 │
+│                                                                        │
+│ 3. THEN DO (Actions)                                                   │
+│    [✓] ⚡ Scrape Full Text (Readability)                                │
+│    [✓] ⭐ Mark as Starred                                               │
+│    [ ] 🏷️ Set Variant / Tag -> Key: [tags     ] Val: [ai-digest      ] │
+│    [ ] ✓ Mark as Read                                                  │
+│                                                                        │
+│ [ Cancel ]                                         [ Create Rule ]     │
+└────────────────────────────────────────────────────────────────────────┘
+```
+
+---
+
+## 8. Backlog Roadmap for Rules & Hooks
+
+The following capabilities are reserved for upcoming iterations:
+
+1. **Auto-Delete / Retention Rule Action** (`delete_entry`):
+   - Scope: Automatically delete matching entries older than $N$ days (requires retention policy discussion).
+2. **Aggregated Shares & Auto-Share Action** (`share_entry`):
+   - Scope: Action to automatically generate public share links for high-priority articles, plus a dedicated `/shares` dashboard aggregating all shared items.
+3. **Advanced AI & Audio Pipeline Actions**:
+   - `generate_ai_summary`: Calls LLM to summarize content $\rightarrow$ stores in `entry_variants.ai_summary`.
+   - `generate_tts`: Synthesizes article voice audio $\rightarrow$ stores `.mp3` blob in `./data/blobs/{id}/tts.mp3`.
+   - `generate_podcast`: Generates dual-speaker conversational audio discussions.

internal/api/handlers.go

@@ -17,6 +17,7 @@ import (
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/opml"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/parser"
+	"git.pengzhan.dev/haopengzhan/rsspipe/internal/rules"
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/worker"
 	"github.com/go-chi/chi/v5"
 )
@@ -662,8 +663,13 @@ func (h *Handler) CreateRule(w http.ResponseWriter, r *http.Request) {
 	if strings.TrimSpace(body.Trigger) == "" {
 		body.Trigger = "on_post_created"
 	}
-	if strings.TrimSpace(body.MatchMode) == "" {
-		body.MatchMode = "all"
+	if err := rules.ValidateRuleSafety(models.Rule{
+		Trigger:    body.Trigger,
+		Conditions: body.Conditions,
+		Actions:    body.Actions,
+	}); err != nil {
+		h.writeError(w, http.StatusBadRequest, err.Error())
+		return
 	}
 
 	rule, err := h.db.CreateRule(body.Name, body.Trigger, body.MatchMode, body.Conditions, body.Actions)
@@ -691,6 +697,15 @@ func (h *Handler) UpdateRule(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if err := rules.ValidateRuleSafety(models.Rule{
+		Trigger:    body.Trigger,
+		Conditions: body.Conditions,
+		Actions:    body.Actions,
+	}); err != nil {
+		h.writeError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
 	rule, err := h.db.UpdateRule(id, body.Name, body.Trigger, body.MatchMode, body.Conditions, body.Actions, body.IsActive)
 	if err != nil {
 		h.writeError(w, http.StatusInternalServerError, err.Error())

internal/rules/evaluator.go

@@ -3,7 +3,9 @@ package rules
 import (
 	"fmt"
 	"regexp"
+	"strconv"
 	"strings"
+	"time"
 
 	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
 )
@@ -56,12 +58,19 @@ func (e *Evaluator) resolveField(field string, entry models.FeedEntry) interface
 		return entry.Author
 	case "url":
 		return entry.URL
-	case "content", "rss_content":
+	case "content", "raw_content", "rss_content":
+		if entry.Content != "" {
 			return entry.Content
+		}
+		return entry.RawContent
 	case "is_read":
 		return entry.IsRead
 	case "is_starred":
 		return entry.IsStarred
+	case "published_at":
+		return entry.PublishedAt
+	case "created_at":
+		return entry.CreatedAt
 	}
 
 	// Variant field resolution: "variants.keywords", "variants.readability_full_text", "variants.tags"
@@ -78,14 +87,41 @@ func (e *Evaluator) resolveField(field string, entry models.FeedEntry) interface
 }
 
 func (e *Evaluator) compare(actual interface{}, op string, expected interface{}) bool {
+	opLower := strings.ToLower(strings.TrimSpace(op))
+
+	// Handle exists / not_exists operators
+	if opLower == "exists" {
 		if actual == nil {
-		return op == "neq"
+			return false
+		}
+		if s, ok := actual.(string); ok && s == "" {
+			return false
+		}
+		return true
+	}
+	if opLower == "not_exists" {
+		if actual == nil {
+			return true
+		}
+		if s, ok := actual.(string); ok && s == "" {
+			return true
+		}
+		return false
+	}
+
+	if actual == nil {
+		return opLower == "neq" || opLower == "!=" || opLower == "not_in" || opLower == "not_contains"
+	}
+
+	// Handle Time/Timestamp comparisons
+	if actualTime, ok := actual.(time.Time); ok {
+		return e.compareTime(actualTime, opLower, expected)
 	}
 
 	actualStr := fmt.Sprintf("%v", actual)
 	expectedStr := fmt.Sprintf("%v", expected)
 
-	switch strings.ToLower(op) {
+	switch opLower {
 	case "eq", "==":
 		return strings.EqualFold(actualStr, expectedStr)
 	case "neq", "!=":
@@ -94,33 +130,34 @@ func (e *Evaluator) compare(actual interface{}, op string, expected interface{})
 		return strings.Contains(strings.ToLower(actualStr), strings.ToLower(expectedStr))
 	case "not_contains":
 		return !strings.Contains(strings.ToLower(actualStr), strings.ToLower(expectedStr))
-	case "in":
-		// expected can be []interface{}, []string, or comma-separated string
-		switch v := expected.(type) {
-		case []interface{}:
-			for _, item := range v {
-				if strings.EqualFold(actualStr, fmt.Sprintf("%v", item)) {
+	case "starts_with":
+		return strings.HasPrefix(strings.ToLower(actualStr), strings.ToLower(expectedStr))
+	case "ends_with":
+		return strings.HasSuffix(strings.ToLower(actualStr), strings.ToLower(expectedStr))
+	case "contains_any":
+		tokens := parseStringList(expected)
+		for _, token := range tokens {
+			if strings.Contains(strings.ToLower(actualStr), strings.ToLower(token)) {
 				return true
 			}
 		}
 		return false
-		case []string:
-			for _, item := range v {
+	case "in":
+		tokens := parseStringList(expected)
+		for _, item := range tokens {
 			if strings.EqualFold(actualStr, item) {
 				return true
 			}
 		}
 		return false
-		case string:
-			items := strings.Split(v, ",")
-			for _, item := range items {
-				if strings.EqualFold(strings.TrimSpace(actualStr), strings.TrimSpace(item)) {
+	case "not_in":
+		tokens := parseStringList(expected)
+		for _, item := range tokens {
+			if strings.EqualFold(actualStr, item) {
+				return false
+			}
+		}
 		return true
-				}
-			}
-			return false
-		}
-		return false
 	case "matches", "regex":
 		re, err := regexp.Compile(expectedStr)
 		if err != nil {
@@ -131,3 +168,107 @@ func (e *Evaluator) compare(actual interface{}, op string, expected interface{})
 		return false
 	}
 }
+
+func (e *Evaluator) compareTime(t time.Time, op string, expected interface{}) bool {
+	now := time.Now()
+	switch op {
+	case "within_last_hours":
+		hours, err := toFloat64(expected)
+		if err != nil {
+			return false
+		}
+		cutoff := now.Add(-time.Duration(hours * float64(time.Hour)))
+		return t.After(cutoff)
+	case "older_than_days":
+		days, err := toFloat64(expected)
+		if err != nil {
+			return false
+		}
+		cutoff := now.Add(-time.Duration(days * 24 * float64(time.Hour)))
+		return t.Before(cutoff)
+	case ">=", "after":
+		targetTime, err := parseTime(expected)
+		if err != nil {
+			return false
+		}
+		return t.After(targetTime) || t.Equal(targetTime)
+	case "<=", "before":
+		targetTime, err := parseTime(expected)
+		if err != nil {
+			return false
+		}
+		return t.Before(targetTime) || t.Equal(targetTime)
+	}
+	return false
+}
+
+func parseStringList(val interface{}) []string {
+	var result []string
+	switch v := val.(type) {
+	case []interface{}:
+		for _, item := range v {
+			result = append(result, strings.TrimSpace(fmt.Sprintf("%v", item)))
+		}
+	case []string:
+		for _, item := range v {
+			result = append(result, strings.TrimSpace(item))
+		}
+	case string:
+		parts := strings.Split(v, ",")
+		for _, part := range parts {
+			trimmed := strings.TrimSpace(part)
+			if trimmed != "" {
+				result = append(result, trimmed)
+			}
+		}
+	}
+	return result
+}
+
+func toFloat64(val interface{}) (float64, error) {
+	switch v := val.(type) {
+	case float64:
+		return v, nil
+	case int:
+		return float64(v), nil
+	case int64:
+		return float64(v), nil
+	case string:
+		return strconv.ParseFloat(strings.TrimSpace(v), 64)
+	}
+	return 0, fmt.Errorf("cannot convert %v to float64", val)
+}
+
+func parseTime(val interface{}) (time.Time, error) {
+	if t, ok := val.(time.Time); ok {
+		return t, nil
+	}
+	s := fmt.Sprintf("%v", val)
+	return time.Parse(time.RFC3339, s)
+}
+
+// ValidateRuleSafety checks for potential cyclic/endless loops at rule creation time.
+func ValidateRuleSafety(rule models.Rule) error {
+	trigger := strings.ToLower(rule.Trigger)
+
+	// If trigger is on_variant_updated / variant_change, check for recursive set_variant on same key
+	if trigger == "on_variant_updated" || trigger == "variant_change" {
+		for _, action := range rule.Actions {
+			if action.Type == "set_variant" {
+				targetKey, _ := action.Params["variant_key"].(string)
+				if targetKey == "" {
+					targetKey, _ = action.Params["key"].(string)
+				}
+
+				// Check if trigger targets this exact key without safe conditions
+				for _, cond := range rule.Conditions {
+					if cond.Field == "variants."+targetKey && (cond.Operator == "exists" || cond.Operator == "eq") {
+						return fmt.Errorf("cyclic rule detected: rule triggers on variant '%s' and unconditionally writes to '%s'", targetKey, targetKey)
+					}
+				}
+			}
+		}
+	}
+
+	return nil
+}

internal/rules/rules_test.go

@@ -25,16 +25,17 @@ func TestRuleEvaluator(t *testing.T) {
 				TextValue:   `["go", "compiler", "release"]`,
 			},
 		},
-		PublishedAt: time.Now(),
+		PublishedAt: time.Now().Add(-2 * time.Hour),
+		CreatedAt:   time.Now().Add(-2 * time.Hour),
 	}
 
-	// Test 1: Title contains Go AND FeedID == feed-hn
+	// Test 1: Title contains Go AND FeedID in list
 	rule1 := models.Rule{
 		ID:        "r1",
-		Name:      "Tech Feeds",
+		Name:      "Tech Feeds in list",
 		MatchMode: "all",
 		Conditions: []models.RuleCondition{
-			{Field: "feed_id", Operator: "eq", Value: "feed-hn"},
+			{Field: "feed_id", Operator: "in", Value: []string{"feed-hn", "feed-36kr", "feed-ft"}},
 			{Field: "title", Operator: "contains", Value: "Go 1.24"},
 		},
 	}
@@ -42,29 +43,76 @@ func TestRuleEvaluator(t *testing.T) {
 		t.Error("expected rule1 to match entry")
 	}
 
-	// Test 2: Negative condition (author != Python Team)
+	// Test 2: not_in operator
 	rule2 := models.Rule{
 		ID:        "r2",
-		Name:      "Author check",
+		Name:      "Feed not in noise",
 		MatchMode: "all",
 		Conditions: []models.RuleCondition{
-			{Field: "author", Operator: "neq", Value: "Python Team"},
+			{Field: "feed_id", Operator: "not_in", Value: "feed-spam,feed-ads"},
 		},
 	}
 	if !eval.Evaluate(rule2, entry) {
 		t.Error("expected rule2 to match entry")
 	}
 
-	// Test 3: Variant matching (variants.keywords contains compiler)
+	// Test 3: contains_any operator
 	rule3 := models.Rule{
 		ID:        "r3",
-		Name:      "Keywords check",
+		Name:      "Title match any keyword",
 		MatchMode: "all",
 		Conditions: []models.RuleCondition{
-			{Field: "variants.keywords", Operator: "contains", Value: "compiler"},
+			{Field: "title", Operator: "contains_any", Value: "Rust, Python, Go 1.24"},
 		},
 	}
 	if !eval.Evaluate(rule3, entry) {
-		t.Error("expected rule3 to match entry variant")
+		t.Error("expected rule3 to match entry with contains_any")
+	}
+
+	// Test 4: exists operator on variants
+	rule4 := models.Rule{
+		ID:        "r4",
+		Name:      "Keywords exist",
+		MatchMode: "all",
+		Conditions: []models.RuleCondition{
+			{Field: "variants.keywords", Operator: "exists"},
+			{Field: "variants.nonexistent", Operator: "not_exists"},
+		},
+	}
+	if !eval.Evaluate(rule4, entry) {
+		t.Error("expected rule4 to evaluate variant existence correctly")
+	}
+
+	// Test 5: Timestamp within_last_hours
+	rule5 := models.Rule{
+		ID:        "r5",
+		Name:      "Recent article",
+		MatchMode: "all",
+		Conditions: []models.RuleCondition{
+			{Field: "published_at", Operator: "within_last_hours", Value: 24},
+		},
+	}
+	if !eval.Evaluate(rule5, entry) {
+		t.Error("expected rule5 to match article within last 24h")
+	}
+
+	// Test 6: Safety validator
+	unsafeRule := models.Rule{
+		Trigger: "variant_change",
+		Conditions: []models.RuleCondition{
+			{Field: "variants.tags", Operator: "exists"},
+		},
+		Actions: []models.RuleAction{
+			{
+				Type: "set_variant",
+				Params: map[string]interface{}{
+					"variant_key": "tags",
+					"value":       "new-tag",
+				},
+			},
+		},
+	}
+	if err := ValidateRuleSafety(unsafeRule); err == nil {
+		t.Error("expected ValidateRuleSafety to detect cyclic loop")
 	}
 }