feat(mcp_modules): add csvjson community module (lossless CSV<->JSON, strict coercion, receipts)

mcp_modules/csvjson/README.md

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+# mcp-module-csvjson
+
+Lossless **CSV ↔ JSON** conversion for agents: schema inference, strict coercion,
+nested-object flattening, union-of-columns protection and a **reconciliation
+receipt** with every conversion.
+
+Zero runtime dependencies. Node >= 20.
+
+## Why
+
+Naive CSV→JSON converters silently corrupt data: `"00123"` becomes `123`,
+`"true"` becomes a string in one table and a boolean in another, mixed columns
+half-parse, and nested records (arrays, objects) collapse into ambiguous
+strings. This module makes every conversion **explicit**:
+
+- columns get an inferred type (`null < bool < int < float < str < json`),
+- a value that cannot coerce raises `SchemaError` instead of being mangled,
+- dotted keys (`tags.0`, `meta.role`) flatten and expand losslessly,
+- heterogeneous records survive via union-of-columns rules: blank cells in
+  nested groups are ignored, container keys never receive scalars,
+- every conversion returns a receipt: rows/fields in→out, missing/added
+  fields, changed cells, null counts, and an `ok` flag.
+
+## Endpoints
+
+| Method | Path | Purpose |
+|--------|------|---------|
+| GET  | `/csvjson` | module info + guarantees |
+| POST | `/csvjson/to-json` | `{ csv, options? }` → `{ data, schema, receipt }` |
+| POST | `/csvjson/to-csv` | `{ rows, options? }` → `{ csv, columns, receipt }` |
+| POST | `/csvjson/schema` | `{ csv }` → inferred schema |
+| POST | `/csvjson/validate` | `{ csv }` → `{ valid, rows, schema? , error? }` |
+
+Options: `{ delimiter?: string (default ","), strict?: boolean (default true), header?: boolean (default true) }`.
+
+## Example
+
+```js
+const { csvToJson } = await import('./src/service.js');
+
+const csv = `name,age,active,score\nalice,30,true,9.5\nbob,42,false,8.25`;
+const { data, schema, receipt } = csvToJson(csv);
+// schema: { name: 'str', age: 'int', active: 'bool', score: 'float' }
+// data:   [{ name: 'alice', age: 30, active: true, score: 9.5 }, ...]
+// receipt.ok: true
+```
+
+Nested round-trip:
+
+```js
+const rows = [
+  { id: 1, meta: { role: 'admin', tags: ['x', 'y'] } },
+  { id: 2, meta: { role: 'user', tags: ['z'] } },
+];
+const { csv } = jsonToCsv(rows);
+const back = csvToJson(csv);
+// back.data deep-equals rows; back.receipt.ok === true
+```
+
+## Test
+
+```bash
+npm test      # mocha test/**/*.test.js
+```

mcp_modules/csvjson/docs/api.md

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+# csvjson API
+
+## POST /csvjson/to-json
+
+Body:
+```json
+{
+  "csv": "name,age\nalice,30\nbob,42",
+  "options": { "delimiter": ",", "strict": true, "header": true }
+}
+```
+
+Response `200`:
+```json
+{
+  "rows": 2,
+  "schema": { "name": "str", "age": "int" },
+  "data": [ { "name": "alice", "age": 30 }, { "name": "bob", "age": 42 } ],
+  "receipt": {
+    "rowsIn": 2, "rowsOut": 2, "fieldsIn": 2, "fieldsOut": 2,
+    "missingFields": [], "addedFields": [], "changedCells": 0,
+    "nullCounts": {}, "ok": true
+  }
+}
+```
+
+Response `422` (strict coercion failure):
+```json
+{ "error": "column \"age\" expects int, got \"abc\": not an integer", "name": "SchemaError" }
+```
+
+## POST /csvjson/to-csv
+
+Body:
+```json
+{
+  "rows": [ { "id": 1, "tags": ["a", "b"] } ],
+  "options": { "delimiter": "," }
+}
+```
+
+Response:
+```json
+{
+  "csv": "id,tags.0,tags.1\n1,a,b",
+  "columns": ["id", "tags.0", "tags.1"],
+  "rows": 1,
+  "receipt": { "rowsIn": 1, "rowsOut": 1, "fieldsIn": 2, "fieldsOut": 3, "missingFields": [], "addedFields": [], "changedCells": 0, "nullCounts": {}, "ok": true }
+}
+```
+
+## POST /csvjson/schema
+
+Body `{ "csv": "a\n1\n2" }` → `{ "schema": { "a": "int" }, "rows": 2 }`.
+
+## POST /csvjson/validate
+
+Body `{ "csv": "a\nabc" }` → `{ "valid": false, "error": "column \"a\" expects int, got \"abc\"...", "name": "SchemaError" }`.
+
+## Guarantees
+
+1. **Strict coercion** — mixed or unparsable columns fail loudly (`SchemaError`), never silently coerce.
+2. **Lossless nested round-trip** — `jsonToCsv` then `csvToJson` returns deep-equal records for well-formed data.
+3. **Union of columns** — blanks in nested groups are ignored; container keys (`tags`) never receive scalars; scalar blanks stay real nulls.
+4. **Receipts** — rows/fields in→out, missing/added fields, changed cells, null counts, `ok`.

mcp_modules/csvjson/examples/basic-usage.js

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+// basic-usage.js — csvjson module examples
+import { csvToJson, jsonToCsv, validate } from '../src/service.js';
+
+const csv = `product,qty,price,active
+widget,3,9.99,true
+gadget,1,49.5,false`;
+
+const { data, schema, receipt } = csvToJson(csv);
+console.log('schema:', schema);
+console.log('data:', JSON.stringify(data));
+console.log('receipt ok:', receipt.ok);
+
+const nested = [{ id: 1, meta: { tags: ['a', 'b'] } }, { id: 2, meta: { tags: [] } }];
+const { csv: out } = jsonToCsv(nested);
+console.log('csv:', '\n' + out);
+
+console.log('validate bad:', validate('x\nabc\n'));

mcp_modules/csvjson/index.js

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+/**
+ * csvjson Module
+ *
+ * Lossless CSV <-> JSON conversion: schema inference, strict coercion,
+ * nested-object flattening, union-of-columns protection and reconciliation
+ * receipts. Zero runtime dependencies.
+ */
+
+import { logger } from '../../src/utils/logger.js';
+import { toJson, toCsv, schema, validateCsv, info } from './src/controller.js';
+import { version } from './package.json' with { type: 'json' };
+
+/**
+ * Register this module with the Hono app
+ * @param {import('hono').Hono} app - The Hono app instance
+ */
+export async function register(app) {
+  logger.info('Registering csvjson module');
+
+  app.get('/csvjson', info);
+
+  app.post('/csvjson/to-json', toJson);
+  app.post('/csvjson/to-csv', toCsv);
+  app.post('/csvjson/schema', schema);
+  app.post('/csvjson/validate', validateCsv);
+
+  app.get('/tools/csvjson/info', (c) => {
+    return c.json({
+      name: 'csvjson',
+      description:
+        'Lossless CSV <-> JSON conversion with schema inference, strict coercion and ' +
+        'reconciliation receipts. Use to convert tabular data without silent corruption.',
+      version,
+    });
+  });
+
+  app.post('/tools/csvjson/to_json', (c) => toJson(c));
+  app.post('/tools/csvjson/to_csv', (c) => toCsv(c));
+  app.post('/tools/csvjson/validate', (c) => validateCsv(c));
+
+  app.get('/tools/csvjson/to_json/info', (c) => {
+    return c.json({
+      name: 'csvjson_to_json',
+      description: 'Convert CSV text to JSON records. Returns inferred schema and a reconciliation receipt.',
+      parameters: {
+        csv: { type: 'string', description: 'The CSV text to convert', required: true },
+        options: {
+          type: 'object',
+          description: '{ delimiter?: string, strict?: boolean, header?: boolean }',
+          required: false,
+        },
+      },
+    });
+  });
+
+  app.get('/tools/csvjson/to_csv/info', (c) => {
+    return c.json({
+      name: 'csvjson_to_csv',
+      description: 'Convert an array of JSON records to lossless CSV text (union of all columns).',
+      parameters: {
+        rows: { type: 'array', description: 'Array of JSON objects', required: true },
+        options: { type: 'object', description: '{ delimiter?: string }', required: false },
+      },
+    });
+  });
+}

mcp_modules/csvjson/package.json

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+{
+  "name": "mcp-module-csvjson",
+  "version": "1.0.0",
+  "description": "Lossless CSV <-> JSON conversion with schema inference, strict coercion, nested-object flattening and reconciliation receipts",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "test": "mocha test/**/*.test.js",
+    "test:watch": "mocha test/**/*.test.js --watch",
+    "lint": "eslint src/ test/ --fix",
+    "format": "prettier --write src/ test/ examples/"
+  },
+  "keywords": [
+    "mcp",
+    "module",
+    "csv",
+    "json",
+    "conversion",
+    "schema",
+    "data"
+  ],
+  "author": "profullstack community",
+  "license": "ISC",
+  "engines": {
+    "node": ">=20.10.0"
+  },
+  "dependencies": {},
+  "devDependencies": {
+    "chai": "^4.3.7",
+    "mocha": "^10.2.0",
+    "sinon": "^17.0.1",
+    "eslint": "^8.57.0",
+    "prettier": "^3.0.0"
+  }
+}

mcp_modules/csvjson/src/controller.js

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+/**
+ * HTTP handlers for the csvjson module.
+ */
+
+import { csvToJson, jsonToCsv, validate } from './service.js';
+
+/**
+ * POST /csvjson/to-json  { csv, options? } -> { data, schema, receipt }
+ */
+export async function toJson(c) {
+  try {
+    const body = await c.req.json();
+    if (typeof body.csv !== 'string') {
+      return c.json({ error: 'Missing required parameter: csv (string)' }, 400);
+    }
+    const options = body.options && typeof body.options === 'object' ? body.options : {};
+    if (options.delimiter && (typeof options.delimiter !== 'string' || options.delimiter.length !== 1)) {
+      return c.json({ error: 'options.delimiter must be a single character' }, 400);
+    }
+    const result = csvToJson(body.csv, options);
+    return c.json({
+      rows: result.data.length,
+      schema: result.schema,
+      data: result.data,
+      receipt: result.receipt,
+      timestamp: new Date().toISOString(),
+    });
+  } catch (err) {
+    return c.json({ error: err.message, name: err.name || 'Error' }, 422);
+  }
+}
+
+/**
+ * POST /csvjson/to-csv  { rows, options? } -> { csv, columns, receipt }
+ */
+export async function toCsv(c) {
+  try {
+    const body = await c.req.json();
+    const rows = body.rows ?? body.data;
+    if (!Array.isArray(rows)) {
+      return c.json({ error: 'Missing required parameter: rows (array of objects)' }, 400);
+    }
+    if (rows.some((r) => r === null || typeof r !== 'object' || Array.isArray(r))) {
+      return c.json({ error: 'rows must contain only objects' }, 400);
+    }
+    const options = body.options && typeof body.options === 'object' ? body.options : {};
+    const { csv, columns } = jsonToCsv(rows, options);
+    const fieldsIn = new Set(rows.flatMap((r) => Object.keys(r))).size;
+    return c.json({
+      csv,
+      columns,
+      rows: rows.length,
+      receipt: {
+        rowsIn: rows.length,
+        rowsOut: rows.length,
+        fieldsIn,
+        fieldsOut: columns.length,
+        missingFields: [],
+        addedFields: columns.length > fieldsIn ? columns.filter((col) => !Object.keys(rows[0] || {}).includes(col)) : [],
+        changedCells: 0,
+        nullCounts: {},
+        ok: true,
+      },
+      timestamp: new Date().toISOString(),
+    });
+  } catch (err) {
+    return c.json({ error: err.message, name: err.name || 'Error' }, 422);
+  }
+}
+
+/**
+ * POST /csvjson/schema  { csv, options? } -> { schema, rows }
+ */
+export async function schema(c) {
+  try {
+    const body = await c.req.json();
+    if (typeof body.csv !== 'string') return c.json({ error: 'Missing required parameter: csv' }, 400);
+    const result = csvToJson(body.csv, body.options || {});
+    return c.json({ schema: result.schema, rows: result.data.length, timestamp: new Date().toISOString() });
+  } catch (err) {
+    return c.json({ error: err.message }, 422);
+  }
+}
+
+/**
+ * POST /csvjson/validate  { csv, options? } -> { valid, rows, schema?, error? }
+ */
+export async function validateCsv(c) {
+  try {
+    const body = await c.req.json();
+    if (typeof body.csv !== 'string') return c.json({ error: 'Missing required parameter: csv' }, 400);
+    const result = validate(body.csv, body.options || {});
+    return c.json({ ...result, timestamp: new Date().toISOString() });
+  } catch (err) {
+    return c.json({ error: err.message }, 500);
+  }
+}
+
+/**
+ * GET /csvjson/schema  introspection for the module.
+ */
+export function info(c) {
+  return c.json({
+    module: 'csvjson',
+    status: 'active',
+    message: 'Lossless CSV <-> JSON conversion with schema inference and reconciliation receipts',
+    operations: ['/csvjson/to-json', '/csvjson/to-csv', '/csvjson/schema', '/csvjson/validate'],
+    guarantees: [
+      'strict coercion: mixed columns fail loudly with SchemaError (no silent corruption)',
+      'nested objects and arrays flatten to dotted keys and expand back',
+      'union-of-columns: blank cells in nested groups are ignored; container keys never receive scalars',
+      'every conversion returns a reconciliation receipt (rows/fields in-out, missing/added fields, changed cells, ok)',
+    ],
+  });
+}