fix(api): address bugbot findings on apply dispatcher PR

- HIGH: parseFtSearchKeys was iterating with i+=2, missing every other
  key when FT.SEARCH was called with RETURN 0 (which behaves like
  NOCONTENT and returns just [count, key1, key2, ...]). Step by 1.
- LOW: extract optionalString, optionalFiniteNumber, formatApprovalResult
  to controller-helpers.ts, share between cache-proposal.controller and
  mcp.controller
- Add regression test exercising RETURN 0 response shape

Author: jamby77

apps/api/src/cache-proposals/__tests__/cache-apply.dispatcher.spec.ts

@@ -24,8 +24,10 @@ class FakeClient {
     return [cursor === '0' ? '0' : '0', []];
   }
 
+  public ftSearchResponse: unknown = [0];
+
   async call(): Promise<unknown> {
-    return [0];
+    return this.ftSearchResponse;
   }
 }
 
@@ -133,6 +135,24 @@ describe('CacheApplyDispatcher', () => {
     ]);
   });
 
+  it('semantic invalidate parses FT.SEARCH RETURN 0 response without skipping keys', async () => {
+    const client = new FakeClient();
+    client.ftSearchResponse = [3, 'sc:prod:k1', 'sc:prod:k2', 'sc:prod:k3'];
+    const dispatcher = buildDispatcher(SEMANTIC_CACHE, client);
+    const out = await dispatcher.dispatch(
+      proposal({
+        proposal_type: 'invalidate',
+        proposal_payload: {
+          filter_kind: 'valkey_search',
+          filter_expression: '@model:{gpt}',
+          estimated_affected: 10,
+        },
+      }),
+    );
+    expect(client.deletes).toEqual(['sc:prod:k1', 'sc:prod:k2', 'sc:prod:k3']);
+    expect(out.actualAffected).toBe(3);
+  });
+
   it('fails when cache type changed since proposal creation', async () => {
     const client = new FakeClient();
     const dispatcher = buildDispatcher(AGENT_CACHE, client);

apps/api/src/cache-proposals/cache-apply.dispatcher.ts

@@ -235,7 +235,7 @@ function parseFtSearchKeys(raw: unknown): string[] {
     return [];
   }
   const keys: string[] = [];
-  for (let i = 1; i < raw.length; i += 2) {
+  for (let i = 1; i < raw.length; i += 1) {
     const key = raw[i];
     if (typeof key === 'string') {
       keys.push(key);

apps/api/src/cache-proposals/cache-proposal.controller.ts

@@ -17,6 +17,7 @@ import { ConnectionId } from '../common/decorators';
 import { parseOptionalInt } from '../common/utils/parse-query-param';
 import { CacheProposalService } from './cache-proposal.service';
 import { mapCacheProposalErrorToHttp } from './errors-http';
+import { formatApprovalResult, optionalFiniteNumber, optionalString } from './controller-helpers';
 
 const ACTOR_SOURCE_UI = 'ui' as const;
 
@@ -129,8 +130,8 @@ export class CacheProposalController {
     },
   ): Promise<unknown> {
     try {
-      const newThreshold = optionalNumber(body?.new_threshold, 'new_threshold');
-      const newTtlSeconds = optionalNumber(body?.new_ttl_seconds, 'new_ttl_seconds');
+      const newThreshold = optionalFiniteNumber(body?.new_threshold, 'new_threshold');
+      const newTtlSeconds = optionalFiniteNumber(body?.new_ttl_seconds, 'new_ttl_seconds');
       const actor = optionalString(body?.actor, 'actor') ?? null;
       if (newThreshold === undefined && newTtlSeconds === undefined) {
         throw new BadRequestException('Either new_threshold or new_ttl_seconds is required');
@@ -148,34 +149,3 @@ export class CacheProposalController {
   }
 }
 
-function optionalString(value: unknown, field: string): string | undefined {
-  if (value === undefined || value === null) {
-    return undefined;
-  }
-  if (typeof value !== 'string') {
-    throw new BadRequestException(`${field} must be a string when provided`);
-  }
-  return value;
-}
-
-function optionalNumber(value: unknown, field: string): number | undefined {
-  if (value === undefined || value === null) {
-    return undefined;
-  }
-  if (typeof value !== 'number' || !Number.isFinite(value)) {
-    throw new BadRequestException(`${field} must be a finite number when provided`);
-  }
-  return value;
-}
-
-function formatApprovalResult(result: {
-  proposal: StoredCacheProposal;
-  appliedResult: { success: boolean; error?: string; details?: Record<string, unknown> } | null;
-}): unknown {
-  return {
-    proposal_id: result.proposal.id,
-    status: result.proposal.status,
-    applied_result: result.appliedResult,
-  };
-}
-

apps/api/src/cache-proposals/controller-helpers.ts

@@ -0,0 +1,39 @@
+import { BadRequestException } from '@nestjs/common';
+import type { AppliedResult, StoredCacheProposal } from '@betterdb/shared';
+
+export function optionalString(value: unknown, field: string): string | undefined {
+  if (value === undefined || value === null) {
+    return undefined;
+  }
+  if (typeof value !== 'string') {
+    throw new BadRequestException(`${field} must be a string when provided`);
+  }
+  return value;
+}
+
+export function optionalFiniteNumber(value: unknown, field: string): number | undefined {
+  if (value === undefined || value === null) {
+    return undefined;
+  }
+  if (typeof value !== 'number' || !Number.isFinite(value)) {
+    throw new BadRequestException(`${field} must be a finite number when provided`);
+  }
+  return value;
+}
+
+export interface ApprovalResultPayload {
+  proposal_id: string;
+  status: string;
+  applied_result: AppliedResult | null;
+}
+
+export function formatApprovalResult(result: {
+  proposal: StoredCacheProposal;
+  appliedResult: AppliedResult | null;
+}): ApprovalResultPayload {
+  return {
+    proposal_id: result.proposal.id,
+    status: result.proposal.status,
+    applied_result: result.appliedResult,
+  };
+}

apps/api/src/mcp/mcp.controller.ts

@@ -12,6 +12,11 @@ import { StoragePort } from '../common/interfaces/storage-port.interface';
 import { CacheProposalService } from '../cache-proposals/cache-proposal.service';
 import { CacheReadonlyService } from '../cache-proposals/cache-readonly.service';
 import { mapCacheProposalErrorToHttp } from '../cache-proposals/errors-http';
+import {
+  formatApprovalResult,
+  optionalFiniteNumber,
+  optionalString,
+} from '../cache-proposals/controller-helpers';
 import type { StoredCacheProposal } from '@betterdb/shared';
 
 const INSTANCE_ID_RE = /^[a-zA-Z0-9_-]+$/;
@@ -789,16 +794,6 @@ function requireString(value: unknown, field: string): string {
   return value;
 }
 
-function optionalString(value: unknown, field: string): string | undefined {
-  if (value === undefined || value === null) {
-    return undefined;
-  }
-  if (typeof value !== 'string') {
-    throw new BadRequestException(`${field} must be a string when provided`);
-  }
-  return value;
-}
-
 function optionalNullableString(value: unknown, field: string): string | null | undefined {
   if (value === undefined) {
     return undefined;
@@ -829,24 +824,4 @@ function formatProposalResult(result: { proposal: StoredCacheProposal; warnings:
   };
 }
 
-function formatApprovalResult(result: {
-  proposal: StoredCacheProposal;
-  appliedResult: { success: boolean; error?: string; details?: Record<string, unknown> } | null;
-}) {
-  return {
-    proposal_id: result.proposal.id,
-    status: result.proposal.status,
-    applied_result: result.appliedResult,
-  };
-}
-
-function optionalFiniteNumber(value: unknown, field: string): number | undefined {
-  if (value === undefined || value === null) {
-    return undefined;
-  }
-  if (typeof value !== 'number' || !Number.isFinite(value)) {
-    throw new BadRequestException(`${field} must be a finite number when provided`);
-  }
-  return value;
-}