fix: coerce corpus route filters (#1776)

* fix: coerce corpus route filters

* test: cover unsupported corpus type filters

src/services/worker/http/routes/CorpusRoutes.ts

@@ -12,6 +12,8 @@ import { CorpusBuilder } from '../../knowledge/CorpusBuilder.js';
 import { KnowledgeAgent } from '../../knowledge/KnowledgeAgent.js';
 import type { CorpusFilter } from '../../knowledge/types.js';
 
+const ALLOWED_CORPUS_TYPES = new Set(['decision', 'bugfix', 'feature', 'refactor', 'discovery', 'change']);
+
 export class CorpusRoutes extends BaseRouteHandler {
   constructor(
     private corpusStore: CorpusStore,
@@ -49,15 +51,31 @@ export class CorpusRoutes extends BaseRouteHandler {
 
     const { name, description, project, types, concepts, files, query, date_start, date_end, limit } = req.body;
 
+    const coercedTypes = this.coerceStringArray(types, 'types', res);
+    if (coercedTypes === null) return;
+    if (coercedTypes && !coercedTypes.every(type => ALLOWED_CORPUS_TYPES.has(type))) {
+      this.badRequest(res, 'types must contain valid observation types');
+      return;
+    }
+
+    const coercedConcepts = this.coerceStringArray(concepts, 'concepts', res);
+    if (coercedConcepts === null) return;
+
+    const coercedFiles = this.coerceStringArray(files, 'files', res);
+    if (coercedFiles === null) return;
+
+    const coercedLimit = this.coercePositiveInteger(limit, 'limit', res);
+    if (coercedLimit === null) return;
+
     const filter: CorpusFilter = {};
     if (project) filter.project = project;
-    if (types) filter.types = types;
-    if (concepts) filter.concepts = concepts;
-    if (files) filter.files = files;
+    if (coercedTypes && coercedTypes.length > 0) filter.types = coercedTypes as CorpusFilter['types'];
+    if (coercedConcepts && coercedConcepts.length > 0) filter.concepts = coercedConcepts;
+    if (coercedFiles && coercedFiles.length > 0) filter.files = coercedFiles;
     if (query) filter.query = query;
     if (date_start) filter.date_start = date_start;
     if (date_end) filter.date_end = date_end;
-    if (limit) filter.limit = limit;
+    if (coercedLimit !== undefined) filter.limit = coercedLimit;
 
     const corpus = await this.corpusBuilder.build(name, description || '', filter);
 
@@ -66,6 +84,42 @@ export class CorpusRoutes extends BaseRouteHandler {
     res.json(metadata);
   });
 
+  private coerceStringArray(value: unknown, fieldName: string, res: Response): string[] | null | undefined {
+    if (value === undefined || value === null || value === '') {
+      return undefined;
+    }
+
+    let parsed = value;
+    if (typeof value === 'string') {
+      try {
+        parsed = JSON.parse(value);
+      } catch {
+        parsed = value.split(',').map(part => part.trim()).filter(Boolean);
+      }
+    }
+
+    if (!Array.isArray(parsed) || !parsed.every(item => typeof item === 'string')) {
+      this.badRequest(res, `${fieldName} must be an array of strings`);
+      return null;
+    }
+
+    return parsed.map(item => item.trim()).filter(Boolean);
+  }
+
+  private coercePositiveInteger(value: unknown, fieldName: string, res: Response): number | null | undefined {
+    if (value === undefined || value === null || value === '') {
+      return undefined;
+    }
+
+    const parsed = typeof value === 'string' ? Number(value) : value;
+    if (typeof parsed !== 'number' || !Number.isInteger(parsed) || parsed <= 0) {
+      this.badRequest(res, `${fieldName} must be a positive integer`);
+      return null;
+    }
+
+    return parsed;
+  }
+
   /**
    * List all corpora with stats
    * GET /api/corpus

tests/worker/http/routes/corpus-routes-coercion.test.ts

@@ -0,0 +1,174 @@
+/**
+ * CorpusRoutes Type Coercion Tests
+ *
+ * Tests that MCP/HTTP clients sending string-encoded corpus filters are coerced
+ * before CorpusBuilder assumes array and number fields.
+ */
+
+import { describe, it, expect, mock, beforeEach } from 'bun:test';
+import type { Request, Response } from 'express';
+import { CorpusRoutes } from '../../../../src/services/worker/http/routes/CorpusRoutes.js';
+
+function createMockReqRes(body: any): {
+  req: Partial<Request>;
+  res: Partial<Response>;
+  jsonSpy: ReturnType<typeof mock>;
+  statusSpy: ReturnType<typeof mock>;
+} {
+  const jsonSpy = mock(() => {});
+  const statusSpy = mock(() => ({ json: jsonSpy }));
+  return {
+    req: { body, path: '/api/corpus', params: {}, query: {} } as Partial<Request>,
+    res: { json: jsonSpy, status: statusSpy, headersSent: false } as unknown as Partial<Response>,
+    jsonSpy,
+    statusSpy,
+  };
+}
+
+function createCorpus(name: string, filter: any) {
+  return {
+    version: 1 as const,
+    name,
+    description: '',
+    created_at: '2026-04-14T00:00:00.000Z',
+    updated_at: '2026-04-14T00:00:00.000Z',
+    filter,
+    stats: {
+      observation_count: 0,
+      token_estimate: 0,
+      date_range: { earliest: '', latest: '' },
+      type_breakdown: {},
+    },
+    system_prompt: '',
+    session_id: null,
+    observations: [],
+  };
+}
+
+async function flushPromises(): Promise<void> {
+  await Promise.resolve();
+  await Promise.resolve();
+}
+
+describe('CorpusRoutes Type Coercion', () => {
+  let handler: (req: Request, res: Response) => void;
+  let mockBuild: ReturnType<typeof mock>;
+
+  beforeEach(() => {
+    mockBuild = mock((name: string, description: string, filter: any) => Promise.resolve(createCorpus(name, filter)));
+
+    const routes = new CorpusRoutes(
+      { list: mock(() => []), read: mock(() => null), delete: mock(() => false) } as any,
+      { build: mockBuild } as any,
+      {} as any
+    );
+
+    const mockApp = {
+      post: mock((path: string, fn: any) => {
+        if (path === '/api/corpus') handler = fn;
+      }),
+      get: mock(() => {}),
+      delete: mock(() => {}),
+    };
+
+    routes.setupRoutes(mockApp as any);
+  });
+
+  it('accepts native array filters and numeric limit', async () => {
+    const { req, res, jsonSpy } = createMockReqRes({
+      name: 'native',
+      types: ['decision', 'bugfix'],
+      concepts: ['hooks'],
+      files: ['src/a.ts'],
+      limit: 10,
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(mockBuild).toHaveBeenCalledWith('native', '', {
+      types: ['decision', 'bugfix'],
+      concepts: ['hooks'],
+      files: ['src/a.ts'],
+      limit: 10,
+    });
+    expect(jsonSpy).toHaveBeenCalled();
+  });
+
+  it('coerces JSON-encoded string filters and string limit', async () => {
+    const { req, res } = createMockReqRes({
+      name: 'json-strings',
+      types: '["decision","bugfix"]',
+      concepts: '["hooks","agent"]',
+      files: '["src/a.ts","src/b.ts"]',
+      limit: '25',
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(mockBuild).toHaveBeenCalledWith('json-strings', '', {
+      types: ['decision', 'bugfix'],
+      concepts: ['hooks', 'agent'],
+      files: ['src/a.ts', 'src/b.ts'],
+      limit: 25,
+    });
+  });
+
+  it('coerces comma-separated filters and trims whitespace', async () => {
+    const { req, res } = createMockReqRes({
+      name: 'comma-strings',
+      types: 'decision, bugfix',
+      concepts: 'hooks, agent',
+      files: 'src/a.ts, src/b.ts',
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(mockBuild).toHaveBeenCalledWith('comma-strings', '', {
+      types: ['decision', 'bugfix'],
+      concepts: ['hooks', 'agent'],
+      files: ['src/a.ts', 'src/b.ts'],
+    });
+  });
+
+  it('rejects invalid array items before calling CorpusBuilder', async () => {
+    const { req, res, statusSpy } = createMockReqRes({
+      name: 'bad-array',
+      concepts: ['hooks', 42],
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(statusSpy).toHaveBeenCalledWith(400);
+    expect(mockBuild).not.toHaveBeenCalled();
+  });
+
+  it('rejects unsupported corpus types before calling CorpusBuilder', async () => {
+    const { req, res, statusSpy } = createMockReqRes({
+      name: 'bad-type',
+      types: ['typo'],
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(statusSpy).toHaveBeenCalledWith(400);
+    expect(mockBuild).not.toHaveBeenCalled();
+  });
+
+  it('rejects invalid limit before calling CorpusBuilder', async () => {
+    const { req, res, statusSpy } = createMockReqRes({
+      name: 'bad-limit',
+      limit: 'many',
+    });
+
+    handler(req as Request, res as Response);
+    await flushPromises();
+
+    expect(statusSpy).toHaveBeenCalledWith(400);
+    expect(mockBuild).not.toHaveBeenCalled();
+  });
+});