feat: add environment configuration loader

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