feat: add environment configuration loader

PROJECT_STATE.md

@@ -7,7 +7,7 @@ ChatGPT MCP Server
 ## Status
 
 Planning complete.
-Phase 0 implementation in progress.
+Phase 0 complete. Phase 1 in progress.
 
 ## Current Phase
 
@@ -16,11 +16,9 @@ Phase 0 - Repository Setup
 ## Completed Tasks
 
 - Task 0.1 — Create repository skeleton ✅
-
+- Task 0.2 — package.json with dependencies ✅
-## In Progress
+- Task 1.1 — Configuration loader ✅
-
-- Task 0.2 — package.json created, dependencies not yet installed
 
 ## Next Task
 
-Task 0.2 (continued) — Add package.json and dependencies
+Task 1.2 — Secret redaction utility (`src/utils/redact.js`)

TASKS.md

@@ -23,4 +23,62 @@ Status: ✅ Complete
 
 Add `package.json` with MCP SDK, OpenAI SDK, Zod, Vitest.
 
+Status: ✅ Complete
+
+---
+
+## Phase 1 - Core Utilities
+
+### Task 1.1 - Configuration loader
+
+Create `src/config/env.js`.
+
+Requirements:
+- Read environment variables and validate OPENAI_API_KEY exists.
+- Apply defaults from ARCHITECTURE.md section 13.
+- Return a structured config object.
+- Throw clear configuration errors for missing or invalid values.
+- Use plain JavaScript validation (no Zod yet).
+- Single exported `loadConfig()` function.
+
+Create `test/config/env.test.js`.
+
+Requirements:
+- Test all default values.
+- Test all custom overrides (strings, numbers, booleans).
+- Test error cases: missing API key, invalid numbers, invalid booleans.
+- No external dependencies in the loader.
+
+Status: ✅ Complete
+
+### Task 1.2 - Secret redaction utility
+
+Create `src/utils/redact.js`.
+
+Requirements:
+- Detect likely secrets (API keys, tokens, passwords, Bearer tokens, private keys, SSH keys, PEM blocks, DB URLs with credentials).
+- Replace detected secrets with `[REDACTED]`.
+- Return the redacted string.
+
+Status: ⏳ Pending
+
+### Task 1.3 - Context budget utility
+
+Create `src/utils/context-budget.js`.
+
+Requirements:
+- Character limit checks (max total, per file, max files).
+- Priority-based trimming when limits exceeded.
+- Reject oversized input with safe message.
+
+Status: ⏳ Pending
+
+### Task 1.4 - Error formatting utility
+
+Create `src/utils/errors.js` and `src/utils/logging.js`.
+
+Requirements:
+- Safe error message formatting (no stack traces).
+- Minimal logging to stderr only.
+
 Status: ⏳ Pending

package.json

@@ -6,7 +6,7 @@
   "type": "module",
   "scripts": {
     "start": "node src/server.js",
-    "test": "echo \"No tests yet\""
+    "test": "vitest"
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.7.0",

src/config/env.js

@@ -1 +1,44 @@
 // Environment variable loading and validation.
+
+export function loadConfig() {
+  const key = process.env.OPENAI_API_KEY;
+
+  if (!key) {
+    throw new Error('Configuration error: OPENAI_API_KEY is missing.');
+  }
+
+  const parseNum = (name, raw, fallback) => {
+    if (raw === undefined || raw === '') return fallback;
+    const n = Number(raw);
+    if (isNaN(n) || !Number.isFinite(n) || n < 0) {
+      throw new Error(
+        `Configuration error: ${name} must be a positive number, got "${raw}".`
+      );
+    }
+    return n;
+  };
+
+  const parseBool = (name, raw, fallback) => {
+    if (raw === undefined || raw === '') return fallback;
+    if (raw === 'true') return true;
+    if (raw === 'false') return false;
+    throw new Error(
+      `Configuration error: ${name} must be true or false, got "${raw}".`
+    );
+  };
+
+  return {
+    openaiApiKey: key,
+    openaiModel: process.env.OPENAI_MODEL || 'gpt-5.1',
+    temperature: parseNum('OPENAI_TEMPERATURE', process.env.OPENAI_TEMPERATURE, 0.2),
+    maxOutputTokens: parseNum('OPENAI_MAX_OUTPUT_TOKENS', process.env.OPENAI_MAX_OUTPUT_TOKENS, 2000),
+    logLevel: process.env.CHATGPT_MCP_LOG_LEVEL || 'info',
+    enableFileContext: parseBool('CHATGPT_MCP_ENABLE_FILE_CONTEXT', process.env.CHATGPT_MCP_ENABLE_FILE_CONTEXT, false),
+    contextDir: process.env.CHATGPT_MCP_CONTEXT_DIR || './context',
+    maxInputChars: parseNum('CHATGPT_MCP_MAX_INPUT_CHARS', process.env.CHATGPT_MCP_MAX_INPUT_CHARS, 30000),
+    maxFileChars: parseNum('CHATGPT_MCP_MAX_FILE_CHARS', process.env.CHATGPT_MCP_MAX_FILE_CHARS, 12000),
+    maxFiles: parseNum('CHATGPT_MCP_MAX_FILES', process.env.CHATGPT_MCP_MAX_FILES, 5),
+    maxLogChars: parseNum('CHATGPT_MCP_MAX_LOG_CHARS', process.env.CHATGPT_MCP_MAX_LOG_CHARS, 10000),
+    redactSecrets: parseBool('CHATGPT_MCP_REDACT_SECRETS', process.env.CHATGPT_MCP_REDACT_SECRETS, true),
+  };
+}

test/config/env.test.js

@@ -0,0 +1,144 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { loadConfig } from '../../src/config/env.js';
+
+const originalEnv = { ...process.env };
+
+function setEnv(partial) {
+  for (const key of Object.keys(process.env)) {
+    if (key.startsWith('OPENAI_') || key.startsWith('CHATGPT_MCP_')) {
+      delete process.env[key];
+    }
+  }
+  Object.assign(process.env, partial);
+}
+
+beforeEach(() => {
+  setEnv({ OPENAI_API_KEY: 'test-key' });
+});
+
+afterEach(() => {
+  for (const key of Object.keys(process.env)) {
+    if (key.startsWith('OPENAI_') || key.startsWith('CHATGPT_MCP_')) {
+      delete process.env[key];
+    }
+  }
+  Object.assign(process.env, originalEnv);
+});
+
+describe('loadConfig', () => {
+  it('throws when OPENAI_API_KEY is missing', () => {
+    delete process.env.OPENAI_API_KEY;
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: OPENAI_API_KEY is missing.'
+    );
+  });
+
+  it('returns defaults when no optional vars are set', () => {
+    const cfg = loadConfig();
+    expect(cfg.openaiApiKey).toBe('test-key');
+    expect(cfg.openaiModel).toBe('gpt-5.1');
+    expect(cfg.temperature).toBe(0.2);
+    expect(cfg.maxOutputTokens).toBe(2000);
+    expect(cfg.logLevel).toBe('info');
+    expect(cfg.enableFileContext).toBe(false);
+    expect(cfg.contextDir).toBe('./context');
+    expect(cfg.maxInputChars).toBe(30000);
+    expect(cfg.maxFileChars).toBe(12000);
+    expect(cfg.maxFiles).toBe(5);
+    expect(cfg.maxLogChars).toBe(10000);
+    expect(cfg.redactSecrets).toBe(true);
+  });
+
+  it('applies custom string values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      OPENAI_MODEL: 'gpt-4',
+      CHATGPT_MCP_LOG_LEVEL: 'debug',
+      CHATGPT_MCP_CONTEXT_DIR: './custom',
+    });
+    const cfg = loadConfig();
+    expect(cfg.openaiModel).toBe('gpt-4');
+    expect(cfg.logLevel).toBe('debug');
+    expect(cfg.contextDir).toBe('./custom');
+  });
+
+  it('applies custom numeric values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      OPENAI_TEMPERATURE: '0.5',
+      OPENAI_MAX_OUTPUT_TOKENS: '4096',
+      CHATGPT_MCP_MAX_INPUT_CHARS: '15000',
+      CHATGPT_MCP_MAX_FILE_CHARS: '8000',
+      CHATGPT_MCP_MAX_FILES: '3',
+      CHATGPT_MCP_MAX_LOG_CHARS: '5000',
+    });
+    const cfg = loadConfig();
+    expect(cfg.temperature).toBe(0.5);
+    expect(cfg.maxOutputTokens).toBe(4096);
+    expect(cfg.maxInputChars).toBe(15000);
+    expect(cfg.maxFileChars).toBe(8000);
+    expect(cfg.maxFiles).toBe(3);
+    expect(cfg.maxLogChars).toBe(5000);
+  });
+
+  it('applies custom boolean values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_ENABLE_FILE_CONTEXT: 'true',
+      CHATGPT_MCP_REDACT_SECRETS: 'false',
+    });
+    const cfg = loadConfig();
+    expect(cfg.enableFileContext).toBe(true);
+    expect(cfg.redactSecrets).toBe(false);
+  });
+
+  it('throws on invalid numeric values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_MAX_INPUT_CHARS: 'abc',
+    });
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: CHATGPT_MCP_MAX_INPUT_CHARS must be a positive number, got "abc".'
+    );
+  });
+
+  it('throws on invalid boolean values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_ENABLE_FILE_CONTEXT: 'yes',
+    });
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: CHATGPT_MCP_ENABLE_FILE_CONTEXT must be true or false, got "yes".'
+    );
+  });
+
+  it('throws on negative numeric values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_MAX_FILES: '-1',
+    });
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: CHATGPT_MCP_MAX_FILES must be a positive number, got "-1".'
+    );
+  });
+
+  it('throws on NaN numeric values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_MAX_FILES: 'NaN',
+    });
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: CHATGPT_MCP_MAX_FILES must be a positive number, got "NaN".'
+    );
+  });
+
+  it('throws on Infinity numeric values', () => {
+    setEnv({
+      OPENAI_API_KEY: 'test-key',
+      CHATGPT_MCP_MAX_FILES: 'Infinity',
+    });
+    expect(() => loadConfig()).toThrow(
+      'Configuration error: CHATGPT_MCP_MAX_FILES must be a positive number, got "Infinity".'
+    );
+  });
+});