diff --git a/lib/jmap/client.ts b/lib/jmap/client.ts
index ee589d72..56ba6402 100644
--- a/lib/jmap/client.ts
+++ b/lib/jmap/client.ts
@@ -1502,17 +1502,22 @@ export class JMAPClient {
     throw new Error('Invalid upload response: blobId not found');
   }
 
-  async createSieveScript(name: string, content: string): Promise<SieveScript> {
+  async createSieveScript(name: string, content: string, activate?: boolean): Promise<SieveScript> {
     const blobId = await this.uploadSieveBlob(content);
     const accountId = this.getSieveAccountId();
 
+    const setArgs: Record<string, unknown> = {
+      accountId,
+      create: {
+        "new-script": { name, blobId }
+      },
+    };
+    if (activate) {
+      setArgs.onSuccessActivateScript = "#new-script";
+    }
+
     const response = await this.request([
-      ["SieveScript/set", {
-        accountId,
-        create: {
-          "new-script": { name, blobId }
-        }
-      }, "0"]
+      ["SieveScript/set", setArgs, "0"]
     ], this.sieveUsing());
 
     if (response.methodResponses?.[0]?.[0] === "SieveScript/set") {
@@ -1531,17 +1536,22 @@ export class JMAPClient {
     throw new Error("Failed to create sieve script");
   }
 
-  async updateSieveScript(scriptId: string, content: string): Promise<void> {
+  async updateSieveScript(scriptId: string, content: string, activate?: boolean): Promise<void> {
     const blobId = await this.uploadSieveBlob(content);
     const accountId = this.getSieveAccountId();
 
+    const setArgs: Record<string, unknown> = {
+      accountId,
+      update: {
+        [scriptId]: { blobId }
+      },
+    };
+    if (activate) {
+      setArgs.onSuccessActivateScript = scriptId;
+    }
+
     const response = await this.request([
-      ["SieveScript/set", {
-        accountId,
-        update: {
-          [scriptId]: { blobId }
-        }
-      }, "0"]
+      ["SieveScript/set", setArgs, "0"]
     ], this.sieveUsing());
 
     if (response.methodResponses?.[0]?.[0] === "SieveScript/set") {
@@ -1582,44 +1592,36 @@ export class JMAPClient {
     const response = await this.request([
       ["SieveScript/set", {
         accountId,
-        update: {
-          [scriptId]: { isActive: true }
-        }
+        onSuccessActivateScript: scriptId,
       }, "0"]
     ], this.sieveUsing());
 
-    if (response.methodResponses?.[0]?.[0] === "SieveScript/set") {
-      const result = response.methodResponses[0][1];
-      if (result.notUpdated?.[scriptId]) {
-        const error = result.notUpdated[scriptId];
-        throw new Error(error.description || "Failed to activate sieve script");
-      }
-      return;
+    const [methodName, result] = response.methodResponses?.[0] || [];
+    if (methodName === "error") {
+      throw new Error(result?.description || "Failed to activate sieve script");
+    }
+    if (methodName !== "SieveScript/set") {
+      throw new Error("Failed to activate sieve script");
     }
-    throw new Error("Failed to activate sieve script");
   }
 
-  async deactivateSieveScript(scriptId: string): Promise<void> {
+  async deactivateSieveScript(): Promise<void> {
     const accountId = this.getSieveAccountId();
 
     const response = await this.request([
       ["SieveScript/set", {
         accountId,
-        update: {
-          [scriptId]: { isActive: false }
-        }
+        onSuccessActivateScript: null,
       }, "0"]
     ], this.sieveUsing());
 
-    if (response.methodResponses?.[0]?.[0] === "SieveScript/set") {
-      const result = response.methodResponses[0][1];
-      if (result.notUpdated?.[scriptId]) {
-        const error = result.notUpdated[scriptId];
-        throw new Error(error.description || "Failed to deactivate sieve script");
-      }
-      return;
+    const [methodName, result] = response.methodResponses?.[0] || [];
+    if (methodName === "error") {
+      throw new Error(result?.description || "Failed to deactivate sieve script");
+    }
+    if (methodName !== "SieveScript/set") {
+      throw new Error("Failed to deactivate sieve script");
     }
-    throw new Error("Failed to deactivate sieve script");
   }
 
   async validateSieveScript(content: string): Promise<{ isValid: boolean; errors?: string[] }> {
diff --git a/lib/sieve/__tests__/generator.test.ts b/lib/sieve/__tests__/generator.test.ts
index 140c7d93..9b59c831 100644
--- a/lib/sieve/__tests__/generator.test.ts
+++ b/lib/sieve/__tests__/generator.test.ts
@@ -399,4 +399,72 @@ describe('generateScript', () => {
     const secondIdx = script.indexOf('# Rule: Second');
     expect(firstIdx).toBeLessThan(secondIdx);
   });
+
+  describe('edge cases', () => {
+    it('skips rules with empty conditions', () => {
+      const script = generateScript([makeRule({ name: 'Empty', conditions: [], actions: [{ type: 'keep' }] })]);
+      expect(script).not.toContain('# Rule: Empty');
+      expect(script).not.toContain('if ');
+    });
+
+    it('skips rules with empty actions', () => {
+      const script = generateScript([makeRule({ name: 'NoAction', actions: [] })]);
+      expect(script).not.toContain('# Rule: NoAction');
+      expect(script).not.toContain('if ');
+    });
+
+    it('uses X-Unknown for header field without headerName', () => {
+      const script = generateScript([makeRule({
+        conditions: [{ field: 'header', comparator: 'contains', value: 'test' }],
+      })]);
+      expect(script).toContain('header :contains "X-Unknown" "test"');
+    });
+
+    it('handles all enabled rules with different extensions combined', () => {
+      const rules = [
+        makeRule({ id: '1', actions: [{ type: 'move', value: 'A' }] }),
+        makeRule({ id: '2', actions: [{ type: 'reject', value: 'No' }] }),
+        makeRule({ id: '3', conditions: [{ field: 'body', comparator: 'contains', value: 'x' }], actions: [{ type: 'star' }] }),
+      ];
+      const script = generateScript(rules);
+      const requireLine = script.split('\n').find(l => l.startsWith('require'))!;
+      expect(requireLine).toContain('"fileinto"');
+      expect(requireLine).toContain('"reject"');
+      expect(requireLine).toContain('"body"');
+      expect(requireLine).toContain('"imap4flags"');
+    });
+
+    it('generates no require line when only keep/discard/stop/forward actions', () => {
+      const script = generateScript([makeRule({
+        actions: [{ type: 'keep' }, { type: 'forward', value: 'a@b.com' }],
+      })]);
+      expect(script).not.toContain('require');
+    });
+
+    it('handles multiple actions on same rule', () => {
+      const script = generateScript([makeRule({
+        actions: [
+          { type: 'move', value: 'Folder' },
+          { type: 'mark_read' },
+          { type: 'star' },
+          { type: 'stop' },
+        ],
+      })]);
+      expect(script).toContain('fileinto "Folder";');
+      expect(script).toContain('addflag "\\\\Seen";');
+      expect(script).toContain('addflag "\\\\Flagged";');
+      expect(script).toContain('stop;');
+    });
+
+    it('generates valid script for all-disabled rules', () => {
+      const rules = [
+        makeRule({ id: '1', enabled: false }),
+        makeRule({ id: '2', enabled: false }),
+      ];
+      const script = generateScript(rules);
+      expect(script).toContain('@metadata:begin');
+      expect(script).not.toContain('if ');
+      expect(script).not.toContain('require');
+    });
+  });
 });
diff --git a/lib/sieve/__tests__/parser.test.ts b/lib/sieve/__tests__/parser.test.ts
index 2511146a..b8412be1 100644
--- a/lib/sieve/__tests__/parser.test.ts
+++ b/lib/sieve/__tests__/parser.test.ts
@@ -144,4 +144,70 @@ describe('parseScript', () => {
       expect(result.rules).toEqual(rules);
     });
   });
+
+  describe('validation edge cases', () => {
+    it('returns isOpaque when rule has non-string id', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [{ id: 123, name: 'x', enabled: true, matchType: 'all', conditions: [{ field: 'from', comparator: 'contains', value: 'a' }], actions: [{ type: 'keep' }], stopProcessing: false }] })}\n@metadata:end */`;
+      expect(parseScript(script).isOpaque).toBe(true);
+    });
+
+    it('returns isOpaque when rule has non-boolean enabled', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [{ id: '1', name: 'x', enabled: 'yes', matchType: 'all', conditions: [{ field: 'from', comparator: 'contains', value: 'a' }], actions: [{ type: 'keep' }], stopProcessing: false }] })}\n@metadata:end */`;
+      expect(parseScript(script).isOpaque).toBe(true);
+    });
+
+    it('returns isOpaque when rule has invalid matchType', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [{ id: '1', name: 'x', enabled: true, matchType: 'none', conditions: [{ field: 'from', comparator: 'contains', value: 'a' }], actions: [{ type: 'keep' }], stopProcessing: false }] })}\n@metadata:end */`;
+      expect(parseScript(script).isOpaque).toBe(true);
+    });
+
+    it('returns isOpaque when condition missing value', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [{ id: '1', name: 'x', enabled: true, matchType: 'all', conditions: [{ field: 'from', comparator: 'contains' }], actions: [{ type: 'keep' }], stopProcessing: false }] })}\n@metadata:end */`;
+      expect(parseScript(script).isOpaque).toBe(true);
+    });
+
+    it('returns isOpaque when action missing type', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [{ id: '1', name: 'x', enabled: true, matchType: 'all', conditions: [{ field: 'from', comparator: 'contains', value: 'a' }], actions: [{ value: 'Inbox' }], stopProcessing: false }] })}\n@metadata:end */`;
+      expect(parseScript(script).isOpaque).toBe(true);
+    });
+
+    it('accepts valid empty rules array', () => {
+      const script = `/* @metadata:begin\n${JSON.stringify({ version: 1, rules: [] })}\n@metadata:end */`;
+      const result = parseScript(script);
+      expect(result.isOpaque).toBe(false);
+      expect(result.rules).toEqual([]);
+    });
+
+    it('preserves all comparator types through round-trip', () => {
+      const comparators = ['contains', 'not_contains', 'is', 'not_is', 'starts_with', 'ends_with', 'matches'] as const;
+      const rules = comparators.map((comparator, i) => makeRule({
+        id: `r${i}`,
+        name: `Rule ${comparator}`,
+        conditions: [{ field: 'from', comparator, value: 'test' }],
+      }));
+      const script = generateScript(rules);
+      const result = parseScript(script);
+      expect(result.isOpaque).toBe(false);
+      expect(result.rules).toEqual(rules);
+    });
+
+    it('preserves size comparators through round-trip', () => {
+      const rules = [
+        makeRule({ id: 'r1', conditions: [{ field: 'size', comparator: 'greater_than', value: '1000' }], actions: [{ type: 'discard' }] }),
+        makeRule({ id: 'r2', conditions: [{ field: 'size', comparator: 'less_than', value: '500' }], actions: [{ type: 'keep' }] }),
+      ];
+      const script = generateScript(rules);
+      const result = parseScript(script);
+      expect(result.rules).toEqual(rules);
+    });
+
+    it('preserves header field with custom headerName', () => {
+      const rules = [makeRule({
+        conditions: [{ field: 'header', comparator: 'contains', value: 'test', headerName: 'X-My-Header' }],
+      })];
+      const script = generateScript(rules);
+      const result = parseScript(script);
+      expect(result.rules).toEqual(rules);
+    });
+  });
 });
diff --git a/stores/__tests__/filter-store.test.ts b/stores/__tests__/filter-store.test.ts
new file mode 100644
index 00000000..30d68532
--- /dev/null
+++ b/stores/__tests__/filter-store.test.ts
@@ -0,0 +1,342 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { useFilterStore } from '../filter-store';
+import type { FilterRule } from '@/lib/jmap/sieve-types';
+
+const makeRule = (overrides: Partial<FilterRule> = {}): FilterRule => ({
+  id: 'rule-1',
+  name: 'Test Rule',
+  enabled: true,
+  matchType: 'all',
+  conditions: [{ field: 'from', comparator: 'contains', value: 'test@example.com' }],
+  actions: [{ type: 'move', value: 'Archive' }],
+  stopProcessing: false,
+  ...overrides,
+});
+
+describe('filter-store', () => {
+  beforeEach(() => {
+    useFilterStore.getState().clearState();
+  });
+
+  describe('addRule', () => {
+    it('should append a rule', () => {
+      useFilterStore.getState().addRule(makeRule());
+      expect(useFilterStore.getState().rules).toHaveLength(1);
+      expect(useFilterStore.getState().rules[0].id).toBe('rule-1');
+    });
+
+    it('should not replace existing rules', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1' }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r2' }));
+      expect(useFilterStore.getState().rules).toHaveLength(2);
+    });
+  });
+
+  describe('updateRule', () => {
+    it('should update matching rule', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', name: 'Old' }));
+      useFilterStore.getState().updateRule('r1', { name: 'New' });
+      expect(useFilterStore.getState().rules[0].name).toBe('New');
+    });
+
+    it('should not modify other rules', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', name: 'A' }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r2', name: 'B' }));
+      useFilterStore.getState().updateRule('r1', { name: 'Updated' });
+      expect(useFilterStore.getState().rules[1].name).toBe('B');
+    });
+
+    it('should no-op for non-existent rule', () => {
+      useFilterStore.getState().addRule(makeRule());
+      useFilterStore.getState().updateRule('nonexistent', { name: 'X' });
+      expect(useFilterStore.getState().rules[0].name).toBe('Test Rule');
+    });
+  });
+
+  describe('deleteRule', () => {
+    it('should remove rule by id', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1' }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r2' }));
+      useFilterStore.getState().deleteRule('r1');
+      expect(useFilterStore.getState().rules).toHaveLength(1);
+      expect(useFilterStore.getState().rules[0].id).toBe('r2');
+    });
+
+    it('should no-op for unknown id', () => {
+      useFilterStore.getState().addRule(makeRule());
+      useFilterStore.getState().deleteRule('unknown');
+      expect(useFilterStore.getState().rules).toHaveLength(1);
+    });
+  });
+
+  describe('toggleRule', () => {
+    it('should toggle enabled to disabled', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', enabled: true }));
+      useFilterStore.getState().toggleRule('r1');
+      expect(useFilterStore.getState().rules[0].enabled).toBe(false);
+    });
+
+    it('should toggle disabled to enabled', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', enabled: false }));
+      useFilterStore.getState().toggleRule('r1');
+      expect(useFilterStore.getState().rules[0].enabled).toBe(true);
+    });
+
+    it('should not affect other rules', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', enabled: true }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r2', enabled: true }));
+      useFilterStore.getState().toggleRule('r1');
+      expect(useFilterStore.getState().rules[1].enabled).toBe(true);
+    });
+  });
+
+  describe('reorderRules', () => {
+    it('should reorder rules by id array', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1', name: 'First' }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r2', name: 'Second' }));
+      useFilterStore.getState().addRule(makeRule({ id: 'r3', name: 'Third' }));
+      useFilterStore.getState().reorderRules(['r3', 'r1', 'r2']);
+      const names = useFilterStore.getState().rules.map(r => r.name);
+      expect(names).toEqual(['Third', 'First', 'Second']);
+    });
+
+    it('should filter out unknown ids', () => {
+      useFilterStore.getState().addRule(makeRule({ id: 'r1' }));
+      useFilterStore.getState().reorderRules(['r1', 'unknown']);
+      expect(useFilterStore.getState().rules).toHaveLength(1);
+    });
+  });
+
+  describe('setRawScript', () => {
+    it('should update rawScript', () => {
+      useFilterStore.getState().setRawScript('require ["fileinto"];');
+      expect(useFilterStore.getState().rawScript).toBe('require ["fileinto"];');
+    });
+  });
+
+  describe('resetToVisualBuilder', () => {
+    it('should clear opaque state, rawScript, and rules', () => {
+      useFilterStore.setState({ isOpaque: true, rawScript: 'some script', rules: [makeRule()] });
+      useFilterStore.getState().resetToVisualBuilder();
+      expect(useFilterStore.getState().isOpaque).toBe(false);
+      expect(useFilterStore.getState().rawScript).toBe('');
+      expect(useFilterStore.getState().rules).toEqual([]);
+    });
+  });
+
+  describe('clearState', () => {
+    it('should reset all state to defaults', () => {
+      useFilterStore.setState({
+        rules: [makeRule()],
+        isLoading: true,
+        isSaving: true,
+        error: 'some error',
+        isSupported: true,
+        activeScriptId: 'script-1',
+        isOpaque: true,
+        rawScript: 'content',
+      });
+      useFilterStore.getState().clearState();
+      const state = useFilterStore.getState();
+      expect(state.rules).toEqual([]);
+      expect(state.isLoading).toBe(false);
+      expect(state.isSaving).toBe(false);
+      expect(state.error).toBeNull();
+      expect(state.isSupported).toBe(false);
+      expect(state.activeScriptId).toBeNull();
+      expect(state.isOpaque).toBe(false);
+      expect(state.rawScript).toBe('');
+    });
+  });
+
+  describe('fetchFilters', () => {
+    it('should set isOpaque for scripts without metadata', async () => {
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => [{ id: 's1', name: 'main', blobId: 'b1', isActive: true }],
+        getSieveScriptContent: async () => 'require ["fileinto"];\nif header :contains "From" "x" { fileinto "Y"; }',
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().isOpaque).toBe(true);
+      expect(useFilterStore.getState().rules).toEqual([]);
+    });
+
+    it('should parse rules from metadata-bearing script', async () => {
+      const rules = [makeRule()];
+      const { generateScript } = await import('@/lib/sieve/generator');
+      const script = generateScript(rules);
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => [{ id: 's1', name: 'main', blobId: 'b1', isActive: true }],
+        getSieveScriptContent: async () => script,
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().isOpaque).toBe(false);
+      expect(useFilterStore.getState().rules).toEqual(rules);
+    });
+
+    it('should handle empty script list', async () => {
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => [],
+        getSieveScriptContent: async () => '',
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().rules).toEqual([]);
+      expect(useFilterStore.getState().activeScriptId).toBeNull();
+    });
+
+    it('should set error on failure', async () => {
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => { throw new Error('Network error'); },
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().error).toBe('Network error');
+      expect(useFilterStore.getState().isLoading).toBe(false);
+    });
+  });
+
+  describe('saveFilters', () => {
+    it('should call updateSieveScript with activate when activeScriptId exists', async () => {
+      const calls: Array<{ method: string; args: unknown[] }> = [];
+      const mockClient = {
+        updateSieveScript: async (...args: unknown[]) => { calls.push({ method: 'updateSieveScript', args }); },
+        createSieveScript: async (...args: unknown[]) => { calls.push({ method: 'createSieveScript', args }); return { id: 'new-id' }; },
+      };
+      useFilterStore.setState({
+        activeScriptId: 'existing-id',
+        rules: [makeRule()],
+        isOpaque: false,
+      });
+      await useFilterStore.getState().saveFilters(mockClient as any);
+      expect(calls).toHaveLength(1);
+      expect(calls[0].method).toBe('updateSieveScript');
+      expect(calls[0].args[0]).toBe('existing-id');
+      expect(calls[0].args[2]).toBe(true); // activate flag
+    });
+
+    it('should call createSieveScript with activate when no activeScriptId', async () => {
+      const calls: Array<{ method: string; args: unknown[] }> = [];
+      const mockClient = {
+        updateSieveScript: async (...args: unknown[]) => { calls.push({ method: 'updateSieveScript', args }); },
+        createSieveScript: async (...args: unknown[]) => {
+          calls.push({ method: 'createSieveScript', args });
+          return { id: 'new-id', name: 'filters', blobId: 'b1', isActive: true };
+        },
+      };
+      useFilterStore.setState({
+        activeScriptId: null,
+        rules: [makeRule()],
+        isOpaque: false,
+      });
+      await useFilterStore.getState().saveFilters(mockClient as any);
+      expect(calls).toHaveLength(1);
+      expect(calls[0].method).toBe('createSieveScript');
+      expect(calls[0].args[2]).toBe(true); // activate flag
+      expect(useFilterStore.getState().activeScriptId).toBe('new-id');
+    });
+
+    it('should use rawScript when isOpaque', async () => {
+      let savedContent = '';
+      const mockClient = {
+        updateSieveScript: async (_id: string, content: string) => { savedContent = content; },
+      };
+      useFilterStore.setState({
+        activeScriptId: 'existing-id',
+        rules: [],
+        isOpaque: true,
+        rawScript: 'require ["fileinto"];\nif header :contains "From" "x" { fileinto "Y"; }',
+      });
+      await useFilterStore.getState().saveFilters(mockClient as any);
+      expect(savedContent).toContain('require ["fileinto"]');
+    });
+
+    it('should set error on failure', async () => {
+      const mockClient = {
+        updateSieveScript: async () => { throw new Error('Server error'); },
+      };
+      useFilterStore.setState({ activeScriptId: 'existing-id', rules: [makeRule()] });
+      await expect(useFilterStore.getState().saveFilters(mockClient as any)).rejects.toThrow('Server error');
+      expect(useFilterStore.getState().error).toBe('Server error');
+      expect(useFilterStore.getState().isSaving).toBe(false);
+    });
+
+    it('should generate script content from rules when not opaque', async () => {
+      let savedContent = '';
+      const mockClient = {
+        updateSieveScript: async (_id: string, content: string) => { savedContent = content; },
+      };
+      const rules = [makeRule({ name: 'My Filter' })];
+      useFilterStore.setState({ activeScriptId: 'existing-id', rules, isOpaque: false });
+      await useFilterStore.getState().saveFilters(mockClient as any);
+      expect(savedContent).toContain('@metadata:begin');
+      expect(savedContent).toContain('My Filter');
+      expect(savedContent).toContain('fileinto "Archive"');
+    });
+
+    it('should update rawScript after successful save', async () => {
+      const mockClient = {
+        updateSieveScript: async () => {},
+      };
+      useFilterStore.setState({ activeScriptId: 'existing-id', rules: [makeRule()], isOpaque: false, rawScript: '' });
+      await useFilterStore.getState().saveFilters(mockClient as any);
+      expect(useFilterStore.getState().rawScript).toContain('@metadata:begin');
+    });
+  });
+
+  describe('setSupported', () => {
+    it('should set isSupported flag', () => {
+      useFilterStore.getState().setSupported(true);
+      expect(useFilterStore.getState().isSupported).toBe(true);
+      useFilterStore.getState().setSupported(false);
+      expect(useFilterStore.getState().isSupported).toBe(false);
+    });
+  });
+
+  describe('fetchFilters', () => {
+    it('should prefer the active script over the first script', async () => {
+      const { generateScript } = await import('@/lib/sieve/generator');
+      const activeRules = [makeRule({ name: 'Active' })];
+      const inactiveRules = [makeRule({ name: 'Inactive' })];
+
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => [
+          { id: 's1', name: 'old', blobId: 'b1', isActive: false },
+          { id: 's2', name: 'main', blobId: 'b2', isActive: true },
+        ],
+        getSieveScriptContent: async (blobId: string) => {
+          if (blobId === 'b2') return generateScript(activeRules);
+          return generateScript(inactiveRules);
+        },
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().activeScriptId).toBe('s2');
+      expect(useFilterStore.getState().rules[0].name).toBe('Active');
+    });
+
+    it('should set sieveCapabilities from client', async () => {
+      const caps = { implementation: 'test', maxSizeScript: 10000, sieveExtensions: ['fileinto'], notificationMethods: [], externalLists: [] };
+      const mockClient = {
+        getSieveCapabilities: () => caps,
+        getSieveScripts: async () => [],
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().sieveCapabilities).toEqual(caps);
+    });
+
+    it('should set rawScript from script content', async () => {
+      const { generateScript } = await import('@/lib/sieve/generator');
+      const rules = [makeRule()];
+      const script = generateScript(rules);
+      const mockClient = {
+        getSieveCapabilities: () => null,
+        getSieveScripts: async () => [{ id: 's1', name: 'main', blobId: 'b1', isActive: true }],
+        getSieveScriptContent: async () => script,
+      };
+      await useFilterStore.getState().fetchFilters(mockClient as any);
+      expect(useFilterStore.getState().rawScript).toBe(script);
+    });
+  });
+});
diff --git a/stores/filter-store.ts b/stores/filter-store.ts
index a5bc40d2..25f2aaad 100644
--- a/stores/filter-store.ts
+++ b/stores/filter-store.ts
@@ -94,11 +94,9 @@ export const useFilterStore = create<FilterStore>()((set, get) => ({
       }
 
       if (activeScriptId) {
-        await client.updateSieveScript(activeScriptId, content);
-        await client.activateSieveScript(activeScriptId);
+        await client.updateSieveScript(activeScriptId, content, true);
       } else {
-        const script = await client.createSieveScript('filters', content);
-        await client.activateSieveScript(script.id);
+        const script = await client.createSieveScript('filters', content, true);
         set({ activeScriptId: script.id });
       }